Tagged: Astronomy Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 2:55 pm on February 23, 2018 Permalink | Reply
    Tags: Astronomy, , , , , ,   

    From UCSC: ” Novel search strategy advances the hunt for primordial black holes” 

    UC Santa Cruz

    UC Santa Cruz

    February 21, 2018
    Tim Stephens
    stephens@ucsc.edu

    Some theories of the early universe predict density fluctuations that would have created small “primordial black holes,” some of which could be drifting through our galactic neighborhood today and might even be bright sources of gamma rays.

    Researchers analyzing data from the Fermi Gamma-ray Space Telescope for evidence of nearby primordial black holes have come up empty, but their negative findings still allow them to put an upper limit on the number of these tiny black holes that might be lurking in the vicinity of Earth.

    NASA/Fermi Gamma Ray Space Telescope


    NASA’s Fermi Gamma-ray Space Telescope is a powerful space observatory that opens a wide window on the universe. Primordial black holes are a potential source of gamma rays, the highest-energy form of light. (Illustration credit: NASA)

    “Understanding how many primordial black holes are around today can help us understand the early universe better,” said Christian Johnson, a graduate student in physics at UC Santa Cruz who developed an algorithm to search data from Fermi’s Large Area Telescope (LAT) for the signatures of primordial black holes. Johnson is a corresponding author of a paper on the findings that has been accepted for publication in The Astrophysical Journal.

    Low-mass black holes are expected to emit gamma rays due to Hawking radiation, a theoretical prediction from the work of physicist Stephen Hawking and others. Hawking showed that quantum effects can give rise to particle-antiparticle pairs near the event horizon of a black hole, allowing one of the particles to fall into the black hole and the other to escape. The result is that the black hole emits radiation and loses mass.

    A small black hole that isn’t absorbing enough from its environment to offset the losses from Hawking radiation will steadily lose mass and eventually evaporate entirely. The smaller it gets, the brighter it “burns,” emitting more and more Hawking radiation before exploding in a final cataclysm. Previous searches for primordial black holes using ground-based gamma-ray observatories have looked for these brief explosions, but Fermi should be able to detect the “burn phase” occurring over a period of several years.

    A limitation of the Fermi search was that it could only extend a relatively short distance from Earth (a small fraction of the distance to the nearest star). The advantage of looking nearby, however, is that primordial black holes could be distinguished from other sources of gamma rays by their movement on the sky.

    “It’s like looking at the sky at night and trying to decide if something is an airplane or a star,” Johnson explained. “If it’s an airplane, it will move, and if it’s a star it will stay put.”

    Any primordial black holes still around today would have started out much larger and have been gradually losing mass for billions of years. To detect one with Fermi, it would have to have reached the final burn phase during the roughly four-year observation period of the study. Over a period of a few years, it would go from undetectably dim to extremely bright, and would burn brightly for several years before exploding, Johnson said.

    “Even though we didn’t detect any, the non-detection sets a limit on the rate of explosions and gives us better constraints than previous research,” he said.

    In addition to Johnson, the other corresponding authors of the paper include Steven Ritz, professor of physics and director of the Santa Cruz Institute of Particle Physics at UCSC; and Stefan Funk and Dmitry Malyshev at the Erlangen Centre for Astroparticle Physics in Germany. Other members of the Fermi-LAT Collaboration also contributed to this work and are coauthors of the paper.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    UCO Lick Shane Telescope
    UCO Lick Shane Telescope interior
    Shane Telescope at UCO Lick Observatory, UCSC

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    UC Santa Cruz campus
    The University of California, Santa Cruz, opened in 1965 and grew, one college at a time, to its current (2008-09) enrollment of more than 16,000 students. Undergraduates pursue more than 60 majors supervised by divisional deans of humanities, physical & biological sciences, social sciences, and arts. Graduate students work toward graduate certificates, master’s degrees, or doctoral degrees in more than 30 academic fields under the supervision of the divisional and graduate deans. The dean of the Jack Baskin School of Engineering oversees the campus’s undergraduate and graduate engineering programs.

    UCSC is the home base for the Lick Observatory.

    Lick Observatory's Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building
    Lick Observatory’s Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building

    Search for extraterrestrial intelligence expands at Lick Observatory
    New instrument scans the sky for pulses of infrared light
    March 23, 2015
    By Hilary Lebow
    1
    The NIROSETI instrument saw first light on the Nickel 1-meter Telescope at Lick Observatory on March 15, 2015. (Photo by Laurie Hatch) UCSC Lick Nickel telescope

    Astronomers are expanding the search for extraterrestrial intelligence into a new realm with detectors tuned to infrared light at UC’s Lick Observatory. A new instrument, called NIROSETI, will soon scour the sky for messages from other worlds.

    “Infrared light would be an excellent means of interstellar communication,” said Shelley Wright, an assistant professor of physics at UC San Diego who led the development of the new instrument while at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics.

    Wright worked on an earlier SETI project at Lick Observatory as a UC Santa Cruz undergraduate, when she built an optical instrument designed by UC Berkeley researchers. The infrared project takes advantage of new technology not available for that first optical search.

    Infrared light would be a good way for extraterrestrials to get our attention here on Earth, since pulses from a powerful infrared laser could outshine a star, if only for a billionth of a second. Interstellar gas and dust is almost transparent to near infrared, so these signals can be seen from great distances. It also takes less energy to send information using infrared signals than with visible light.

    5
    UCSC alumna Shelley Wright, now an assistant professor of physics at UC San Diego, discusses the dichroic filter of the NIROSETI instrument. (Photo by Laurie Hatch)

    Frank Drake, professor emeritus of astronomy and astrophysics at UC Santa Cruz and director emeritus of the SETI Institute, said there are several additional advantages to a search in the infrared realm.

    “The signals are so strong that we only need a small telescope to receive them. Smaller telescopes can offer more observational time, and that is good because we need to search many stars for a chance of success,” said Drake.

    The only downside is that extraterrestrials would need to be transmitting their signals in our direction, Drake said, though he sees this as a positive side to that limitation. “If we get a signal from someone who’s aiming for us, it could mean there’s altruism in the universe. I like that idea. If they want to be friendly, that’s who we will find.”

    Scientists have searched the skies for radio signals for more than 50 years and expanded their search into the optical realm more than a decade ago. The idea of searching in the infrared is not a new one, but instruments capable of capturing pulses of infrared light only recently became available.

    “We had to wait,” Wright said. “I spent eight years waiting and watching as new technology emerged.”

    Now that technology has caught up, the search will extend to stars thousands of light years away, rather than just hundreds. NIROSETI, or Near-Infrared Optical Search for Extraterrestrial Intelligence, could also uncover new information about the physical universe.

    “This is the first time Earthlings have looked at the universe at infrared wavelengths with nanosecond time scales,” said Dan Werthimer, UC Berkeley SETI Project Director. “The instrument could discover new astrophysical phenomena, or perhaps answer the question of whether we are alone.”

    NIROSETI will also gather more information than previous optical detectors by recording levels of light over time so that patterns can be analyzed for potential signs of other civilizations.

    “Searching for intelligent life in the universe is both thrilling and somewhat unorthodox,” said Claire Max, director of UC Observatories and professor of astronomy and astrophysics at UC Santa Cruz. “Lick Observatory has already been the site of several previous SETI searches, so this is a very exciting addition to the current research taking place.”

    NIROSETI will be fully operational by early summer and will scan the skies several times a week on the Nickel 1-meter telescope at Lick Observatory, located on Mt. Hamilton east of San Jose.

    The NIROSETI team also includes Geoffrey Marcy and Andrew Siemion from UC Berkeley; Patrick Dorval, a Dunlap undergraduate, and Elliot Meyer, a Dunlap graduate student; and Richard Treffers of Starman Systems. Funding for the project comes from the generous support of Bill and Susan Bloomfield.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    UCSC is the home base for the Lick Observatory.

    Advertisements
     
  • richardmitnick 1:58 pm on February 23, 2018 Permalink | Reply
    Tags: Astronomy, , , , ESO’s Training Programmes: Investing in the Future of Astronomy,   

    From ESOblog: “ESO’s Training Programmes: Investing in the Future of Astronomy” 

    ESO 50 Large

    ESOblog

    23 February 2018

    1

    With most of 2018 ahead of us, many people choose to condense their hopes, aims and regrets into firm statements of resolution. In this year’s first instalment of Letters from the DG, Xavier Barcons uses this period of reflection to talk about ESO’s training programmes set up to achieve the values and aims that underpin our work here, and to help foster collaboration in astronomy — one of ESO’s missions.

    Greetings and welcome back to the ESOBlog!

    Besides building and operating world-class astronomical facilities, ESO’s mission also includes fostering cooperation in astronomy, across our Member States and beyond. Attracting early-career scientists and engineers interested in astronomy and training them in the unique international environment that ESO represents is an incredibly successful recipe to promote cooperation, particularly when these talented people continue their professional careers elsewhere. Many internationally-renowned astronomical institutions around the world are now home to ESO’s former students, fellows and trainees, and in some cases, our alumni have leading responsibilities.

    Lifelong training

    Astronomy is constantly evolving, and ESO strives to ensure that not only astronomers, but also engineers, support staff and interested members of the public are kept at the forefront of this exciting and dynamic field of research.

    For this reason, we maintain an arsenal of fellowships, studentships, internships and training programmes for a diverse range of people. ESO’s multinational environment means we are in a unique position to provide varied and complex development and support, sustained by a diverse set of people, and this cannot start too young.


    Find out about the ESO Studentship Programme and hear students share stories of their time at ESO.
    Credit: ESO. Music: STAN DART (www.stan-dart.com)

    3
    A group of PhD students at the IMPRS Workshop 2017
    Credit: IMPRS on Astrophysics at the Ludwig-Maximilians Universität München

    Many of our in-house programmes focus on nurturing young astronomers as they progress from their studies into research and academia. The ever-popular Studentship Programme has been running since 1990, giving PhD students the opportunity to spend up to two years of their PhD programme at ESO to get hands-on research experience. So far, more than 200 students have participated in the programme either in Germany or Chile, remaining under the formal supervision of their home university, but with the benefit of co-supervision by an ESO staff astronomer and the mentorship of an ESO Fellow. Leading scientists, instrument experts and other professionals are all within easy reach, providing students with opportunities and skills invaluable to their future careers.

    Located at the renowned Garching Forschungszentrum campus near Munich in Germany, ESO is in a prime position to offer unique opportunities through partnerships with some of our incredible neighbouring institutions. Together, ESO, the MPE, MPA and USM have joined forces to coordinate a PhD programme: the IMPRS (International Max-Planck Research School on Astrophysics). Every year ESO hosts two to four PhD students within the IMPRS programme at Garching.

    But astronomers are not the only ones who benefit from lifelong training — astronomical research is ultimately funded by society and it appeals innately to people of all ages and cultures. ESO currently offers a range of unique learning experiences for school students. This includes visits to ESO during our annual Open House Days and participation in Germany’s “Girls’ Day”, when ESO opens its doors to female school students with tours of the main laboratories, as well as hands-on workshops in astronomy and engineering.

    ESO is also thrilled to be opening the new ESO Supernova Planetarium & Visitor Centre in April 2018, which will be a beacon of science education and outreach here at ESO Headquarters in Garching. School students and the general public will visit to learn about the Universe, and teachers will be offered training to keep up with advances in astronomy.

    4
    The participants of Girls’ Day 2014 at ESO Headquarters in Garching, Germany
    Credit: ESO

    High school students can also have life-changing experiences at the summer and winter astronomy camps, of which ESO is a proud partner. These camps include night-time observations with professional astronomers, lectures and social activities, and can be a formative part of young people’s academic and personal lives.

    5
    Students participating in the Summer AstroCamp 2016.
    Credit: ESO/C. Martins

    In 2016, the first ESO/NEON Observing School was held at the La Silla Observatory for postdoctoral researchers, PhD students, and advanced master’s students. This school provided hands-on real-life experience in the full astronomical research cycle, from proposal preparation to data reduction, as well as career advice for future astronomers. Thanks to the success of the first edition, a second edition will take place in February–March 2018.

    Supporting the Leaders of Tomorrow

    ESO Fellowships are another incredibly rewarding part of ESO’s training arsenal. Several postdoctoral fellowships are awarded to scientists with a PhD each year in Germany and in Chile. ESO Fellows can conduct independent research in a supportive and highly-motivating world-class scientific environment. The years spent at ESO enrich Fellows with invaluable practical experience in supporting instrumentation, science data archive developments, public outreach activities, or science operations at ESO’s observatories in Chile. Previous Fellows have found these duties to be much more rewarding and helpful in their career than anticipated.

    In Germany, Fellows spend up to 25% of their time on such functional activities during their three-year fellowship; in Chile they spend 50%. For this reason, Fellows in Chile have a fourth year to work purely on their own research, which can be spent in any institute in Chile or in an ESO Member State.

    The fellowship programme has recently been expanded to other areas of expertise at ESO; in 2018 we are excited to kickstart the ESO Engineering and Technology Research Fellowship. This programme offers early-career researchers with a PhD in an engineering-related discipline the opportunity to take part in ESO projects.

    Some of the most encouraging feedback from young ESO Fellows has been the sense of community, friendship and collaboration they felt while working at ESO. The wide variety of people encountered at ESO makes it a great place to forge connections and develop key skills for the future. Many former ESO Fellows are now in leading positions at top astronomical research institutions around the world. In my first six months at ESO, I have seen a fabulous diaspora of our former early-career professionals coming back to ESO for short visits, maintaining valuable links with colleagues at their alma mater. To learn more about our impressive range of Fellows, past and present, I recommend this brochure.

    Encouraging Collaboration and Exchange

    A focus on community and international collaboration is at the heart of ESO’s ethical framework. Our goal is to foster strong and enjoyable relationships between everybody who passes through our doors, and we understand that no astronomer is an island. A scientific or technical career in astronomy involves teamwork, supervising other people, writing job and grant applications, collaborations between different countries and cultures, as well as some sleepless nights, stressful deadlines and great emotional investment. Diversity is a highly treasured asset at ESO, where people from more than 40 countries share a workplace and a great enthusiasm for their field. The fact that no one at ESO is a clone of any other makes our work especially enjoyable and productive.

    6
    Three Telescope and Instrument Operators joining forces to set up the complex system of the VLTI for an interferometric observation.
    Credit: ESO/H.H.Heyer

    Astronomy, like many other fields, requires a great deal of written and verbal communication. ESO has links with organisations such as the renowned Astronomy and Astrophysics journal, which is a partner in training schools for writing scientific papers. Specific to science communication, over the years ESO has also offered 3–6 month internships in graphic design and science communication to more than a hundred young people from ESO Member States and beyond.

    Astronomy is a fluid and dynamic field, where people move between organisations and learn new skills along the way. ESO trains people knowing they will at some point move to new pastures, and we benefit from people joining us with fresh perspectives and ideas. Ultimately, ESO aims to nurture people who will become ambassadors when they leave, promoting not just the work that we do but the values we hold dear.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition
    Visit ESO in Social Media-

    Facebook

    Twitter

    YouTube

    ESO Bloc Icon

    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT
    VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ALMA Array
    ALMA on the Chajnantor plateau at 5,000 metres.

    ESO E-ELT
    ESO/E-ELT to be built at Cerro Armazones at 3,060 m.

    ESO APEX
    APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.

    Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)

    ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level

    SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level

    ESO TAROT telescope at Paranal, 2,635 metres (8,645 ft) above sea level

    ESO ExTrA telescopes at Cerro LaSilla at an altitude of 2400 metres

     
  • richardmitnick 1:32 pm on February 23, 2018 Permalink | Reply
    Tags: , Astronomy, , , , , ,   

    From ALMA: “Large Magellanic Cloud Contains Surprisingly Complex Organic Molecules” 

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    ALMA

    30 January, 2018

    Nicolás Lira
    Education and Public Outreach Coordinator
    Joint ALMA Observatory, Santiago – Chile
    Phone: +56 2 2467 6519
    Cell phone: +56 9 9445 7726
    Email: nicolas.lira@alma.cl

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory Charlottesville, Virginia – USA
    Phone: +1 434 296 0314
    Cell phone: +1 202 236 6324
    Email: cblue@nrao.edu

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory
, Tokyo – Japan
    Phone: +81 422 34 3630
    Email: hiramatsu.masaaki@nao.ac.jp

    Richard Hook
    Public Information Officer, ESO
    Garching bei München, Germany
    Phone: +49 89 3200 6655
    Cell phone: +49 151 1537 3591
    Email: rhook@eso.org

    1
    Astronomers using ALMA have uncovered chemical “fingerprints” of methanol, dimethyl ether, and methyl formate in the Large Magellanic Cloud. The latter two molecules are the largest organic molecules ever conclusively detected outside the Milky Way. The far-infrared image on the left shows the full galaxy. The zoom-in image shows the star-forming region observed by ALMA. It is a combination of mid-infrared data from Spitzer and visible (H-alpha) data from the Blanco 4-meter telescope. Credit: NRAO/AUI/NSF; ALMA (ESO/NAOJ/NRAO); Herschel/ESA; NASA/JPL-Caltech; NOAO

    NASA/Spitzer Infrared Telescope

    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    ESA/Herschel spacecraft

    The nearby dwarf galaxy known as the Large Magellanic Cloud (LMC) is a chemically primitive place.

    Large Magellanic Cloud. Adrian Pingstone December 2003

    Unlike the Milky Way, this semi-spiral collection of a few tens-of-billions of stars lacks our galaxy’s rich abundance of heavy elements, like carbon, oxygen, and nitrogen. With such a dearth of heavy elements, astronomers predict that the LMC should contain comparatively paltry amounts of complex carbon-based molecules. Previous observations of the LMC seem to support that view.

    New observations with the Atacama Large Millimeter/submillimeter Array (ALMA), however, have uncovered the surprisingly clear chemical “fingerprints” of the complex organic molecules methanol, dimethyl ether, and methyl formate. Though previous observations found hints of methanol in the LMC, the latter two are unprecedented findings and stand as the most complex molecules ever conclusively detected outside of our galaxy.

    Astronomers discovered the molecules’ faint millimeter-wavelength “glow” emanating from two dense star-forming embryos in the LMC, regions known as “hot cores.” These observations may provide insights into the formation of similarly complex organic molecules early in the history of the universe.

    “Even though the Large Magellanic Cloud is one of our nearest galactic companions, we expect it should share some uncanny chemical similarity with distant, young galaxies from the early universe,” said Marta Sewiło, an astronomer with NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author on a paper appearing in the Astrophysical Journal Letters.

    Astronomers refer to this lack of heavy elements as “low metallicity.” It takes several generations of star birth and star death to liberally seed a galaxy with heavy elements, which then get taken up in the next generation of stars and become the building blocks of new planets.

    “Young, primordial galaxies simply didn’t have enough time to become so chemically enriched,” said Sewiło. “Dwarf galaxies like the LMC probably retained this same youthful makeup because of their relatively low masses, which severely throttles back the pace of star formation.”

    “Due to its low metallicity, the LMC offers a window into these early, adolescent galaxies,” noted Remy Indebetouw, an astronomer at the National Radio Astronomy Observatory in Charlottesville, Virginia, and coauthor on the study. “Star-formation studies of this galaxy provide a stepping stone to understand star formation in the early universe.”

    The astronomers focused their study on the N113 Star Formation Region in the LMC, which is one of the galaxy’s most massive and gas-rich regions. Earlier observations of this area with NASA’s Spitzer Space Telescope and ESA’s Herschel Space Observatory revealed a startling concentration of young stellar objects – protostars that have just begun to heat their stellar nurseries, causing them to glow brightly in infrared light. At least a portion of this star formation is due to a domino-like effect, where the formation of massive stars triggers the formation of other stars in the same general vicinity.

    Sewiło and her colleagues used ALMA to study several young stellar objects in this region to better understand their chemistry and dynamics. The ALMA data surprisingly revealed the telltale spectral signatures of dimethyl ether and methyl formate, molecules that have never been detected so far from Earth.

    Complex organic molecules, those with six or more atoms including carbon, are some of the basic building blocks of molecules that are essential to life on Earth and – presumably – elsewhere in the universe. Though methanol is a relatively simple compound compared to other organic molecules, it nonetheless is essential to the formation of more complex organic molecules, like those that ALMA recently observed, among others.

    If these complex molecules can readily form around protostars, it’s likely that they would endure and become part of the protoplanetary disks of young star systems. Such molecules were likely delivered to the primitive Earth by comets and meteorites, helping to jumpstart the development of life on our planet.

    The astronomers speculate that since complex organic molecules can form in chemically primitive environments like the LMC, it’s possible that the chemical framework for life could have emerged relatively early in the history of the universe.
    Additional Information

    This research is presented in a paper titled “’The detection of hot cores and complex organic molecules in the Large Magellanic Cloud,” by M. Sewiło, et al., which appears in The Astrophysical Journal Letters.

    The research team was composed by Marta Sewilo [1], Remy Indebetouw [2, 3], Steven B. Charnley [1], Sarolta Zahorecz [4, 5], Joana M. Oliveira [6], Jacco Th. van Loon [6], Jacob L. Ward [7], C.-H. Rosie Chen [8], Jennifer Wiseman [1], Yasuo Fukui [9], Akiko Kawamura [10], Margaret Meixner [11], Toshikazu Onishi [4], and Peter Schilke [12].

    [1] NASA Postdoctoral Program Fellow, NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771, USA
    [2] Department of Astronomy, University of Virginia, PO Box 400325, Charlottesville, VA 22904, USA
    [3] National Radio Astronomy Observatory, 520 Edgemont Rd, Charlottesville, VA 22903, USA
    [4] Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531, Japan
    [5] Chile Observatory, National Astronomical Observatory of Japan, National Institutes of Natural Science, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan
    [6] Lennard-Jones Laboratories, Keele University, ST5 5BG, UK
    [7] Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstr. 12-14, 69120 Heidelberg Germany
    [8] Max-Planck-Institut für Radioastronomie, Auf dem Hügel, 69 D-53121 Bonn, Germany
    [9] School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan
    [10] National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
    [11] Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
    [12] I. Physikalisches Institut der Universität zu Köln, Zülpicher Str. 77, 50937, Köln, Germany

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon
    Stem Education Coalition

    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

    ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

    NRAO Small
    ESO 50 Large
    NAOJ

     
  • richardmitnick 12:59 pm on February 23, 2018 Permalink | Reply
    Tags: Astronomy, , , , , ,   

    From University of Arizona: “UA Leads Project on Big Data and Black Holes” 

    U Arizona bloc

    University of Arizona

    Feb. 21, 2018
    Daniel Stolte

    Chi-Kwan Chan waves his hand a few inches above a matchbox-size device. On a dark computer monitor, a million light dots appear as a solid sheet, each dot representing a light particle.

    1
    The Event Horizon Telescope is a virtual Earth-size telescope, achieving its globe-spanning baseline by combining precisely synchronized observations made at various sites around the world. (Image: Dan Marrone)

    The photon sheet hovers above a black disc simulating a black hole. With a slow turn of the hand, the sheet approaches the black hole. As it passes, the gravitational monster swallows any light particles in its direct path, creating a circular cutout in the sheet of particles. The rest of the particles are on track to move past the black hole, or so it seems. But they don’t get very far: Instead of continuing along their straight lines of travel, their paths bend inward and they loop around the black hole and converge in one point, forming a sphere of photons around it.

    “What you see here is light trapped in the fabric of space and time, curving around the black hole by its massive gravity,” explains Chan, an assistant astronomer at the University of Arizona’s Steward Observatory, who developed the computer simulation as part of his research into how black holes interact with things that happen to be nearby.

    U Arizona Steward Observatory at Kitt Peak, AZ, USA, altitude 2,096 m (6,877 ft)

    The demonstration was part of an event at UA’s Flandrau Science Center & Planetarium on Feb. 16 to kick off a UA-led, international project to develop new technologies that enable scientists to transfer, use and interpret massive datasets.

    Known as Partnerships for International Research and Education program, or PIRE, the effort is funded with $6 million over five years by the National Science Foundation, with an additional $3 million provided by partnering institutions around the world. While the award’s primary goal is to spawn technology that will help scientists take the first-ever picture of the supermassive black hole at the center of our Milky Way, the project’s scope is much bigger.

    What looks like a fun little animation on Chan’s computer screen is in fact a remarkable feat of computing and programming: As the computational astrophysicist drags virtual photons around a virtual black hole, a powerful graphics processor solves complex equations that dictate how each individual light particle would behave under the influence of the nearby black hole — simultaneously and in real time.

    Study Relies on Simulations

    Unlike the crew in the movie “Interstellar,” astrophysicists can’t travel to a black hole and study it from close range. Instead, they have to rely on simulations that mimic black holes based on their physical properties that are known to — or thought to — govern these most extreme objects in the universe.

    Chan belongs to a group of researchers in an international collaboration called the Event Horizon Telescope, or EHT, that is gearing up to capture the first picture of a black hole — not just any black hole, but the supermassive black hole in the center of our galaxy. Called Sagittarius A* (referred to as “Sgr A Star,” pronounced Sag A Star), this object has the mass of more than 4 million suns.

    SGR A* , the supermassive black hole at the center of the Milky Way. NASA’s Chandra X-Ray Observatory

    Since nothing, not even light, can escape a black hole, it casts a silhouette in the background of in-falling plasma that is too small to be resolved by any single telescope. So far, the existence of Sgr A* has been inferred from indirect observations only, such as the intriguing choreography of stars in its vicinity, whose orbits clearly outline an unseen, incomprehensibly large mass.

    “Imaging the black hole at the center of our galaxy from Earth is like trying to read the date on a dime on the East Coast from the UA campus,” says Feryal Özel, a professor of astronomy and physics at Steward and a co-investigator on the project. “There is not one telescope in existence that could do that.”

    The EHT is an array of radio telescopes on five continents that together act as a virtual telescope the size of the Earth — the aperture needed to image “the date on the dime,” or in this case the supermassive black hole Sag A*.

    Event Horizon Telescope Array

    Arizona Radio Observatory
    Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

    ESO/APEX
    Atacama Pathfinder EXperiment

    CARMA Array no longer in service
    Combined Array for Research in Millimeter-wave Astronomy (CARMA)

    Atacama Submillimeter Telescope Experiment (ASTE)
    Atacama Submillimeter Telescope Experiment (ASTE)

    Caltech Submillimeter Observatory
    Caltech Submillimeter Observatory (CSO)

    IRAM NOEMA interferometer
    Institut de Radioastronomie Millimetrique (IRAM) 30m

    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA
    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano

    CfA Submillimeter Array Hawaii SAO
    Submillimeter Array Hawaii SAO

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array, Chile

    South Pole Telescope SPTPOL
    South Pole Telescope SPTPOL

    Future Array/Telescopes

    Plateau de Bure interferometer
    Plateau de Bure interferometer

    NSF CfA Greenland telescope

    Greenland Telescope

    To accomplish this, the individual telescopes must be precisely synced in time. Because existing internet cables and even satellite communication are too coarse to ensure this, the researchers rely on atomic clocks and … FedEx (more on that later).

    “Our PIRE project is a prime example of the kind of innovation you can only get by leveraging the innovative, intellectual capital in academia,” says Dimitrios Psaltis, the principal investigator on the project. “By its very nature, this project is multidisciplinary and requires expertise in areas ranging from detector development to high-performance computing and theoretical physics.”

    At peak activity, the EHT will collect more data than any project before, according to Psaltis, a professor of astronomy and physics at the UA.

    “We’re talking petabytes every single night,” he says, and this is comparable to the three petabytes of video uploaded each day on YouTube. “Post-processing is a huge effort, and we will need additional data to improve the science that we hope will come from these observations.”

    The team uses graphic processing units, or GPUs — processors developed for gaming that are capable of performing many calculations in parallel. This makes them more efficient and energy-saving than “regular” computer processing units, or CPUs.

    “We hope that this technology will transfer to other areas of science and life,” said Joaquin Ruiz, dean of the UA College of Science, at the launch event.

    Applications Could Be Extensive

    The PIRE project is expected to spin off technologies that go beyond the project’s primary goal. The fast processing of large data in real time and the efficient use of resources distributed across the globe will have applications ranging from self-driving cars to renewable energy production and national defense. Examples also include augmented reality applications that are good at fast computing with real-time input and minimum computing resources, Özel explains.

    “This could be used, for example, in visual aids for security efforts around the globe where data connection bandwidth and energy supplies are limited,” she says, “so you want devices that make maximum use of precious resources available in those scenarios.”

    The PIRE project team integrates researchers in the U.S., Germany, Mexico and Taiwan. Education of students and early career scientists is a key component, providing internally collaborative, hands-on experience in instrument technology, high-performance computing, and big and distributed data science. There also are monthly webinars and hackathons, as well as summer schools, that will be sponsored every year.

    Fast and reliable real-time communication channels are crucial in syncing up telescopes scattered around the globe for observations, and improving such technology is one of PIRE’s goals. For now, EHT scientists rely on video chat, phones and whiteboards to keep track of each telescope location’s status. During a rare stretch of a few days in April 2017, skies were mostly clear in all nine observing sites that are part of the EHT array — including Arizona, Hawaii, Chile, Mexico and Antarctica.

    The South Pole Telescope, or SPT, site was incorporated under another NSF grant to the UA, with Dan Marrone as principal investigator. Last year was the first year that the full EHT observed as an array, and the first year in which the SPT participated.

    During that first observation run, the observing stations that together make up the EHT pointed at the Milky Way’s center and collected radio waves originating from the supermassive black hole over the course of several nights. By obtaining the first-ever images of black holes, researchers will be able to directly test Einstein’s theory of general relativity in extreme conditions.

    “Each telescope records its observation data onto a bunch of physical hard drives,” explains Marrone, an associate professor at Steward and a co-investigator on the PIRE award. “Precisely time-stamped, the drives are loaded into crates and delivered to processing centers in Cambridge, Massachusetts, and Bonn, Germany, via FedEx.”

    The EHT data are shipped on physical carriers because current internet data pipelines aren’t up to the scope this endeavor requires. Then data experts combine the literal truckloads of data, synchronize it according to their time stamps and process it to extract the signal from the black hole, which in the raw data is buried under a blanket of noise and error — the inevitable side effects of turning the Earth into one giant telescope.

    “PIRE is an international project that not only will revolutionize worldwide efforts to study black holes, but usher astronomical projects into the era of big and distributed data science,” Psaltis says. “By awarding the PIRE project, the NSF has tasked the UA and its collaborators to contribute solutions that may inform many areas of technology, including the internet of tomorrow.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium? An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.

     
  • richardmitnick 11:00 am on February 23, 2018 Permalink | Reply
    Tags: , Astronomy, , , , , S0-2 Star is Single and Ready for Big Einstein Test, ,   

    From Keck: “Astronomers Discover S0-2 Star is Single and Ready for Big Einstein Test” 

    Keck Observatory, Maunakea, Hawaii, USA.4,207 m (13,802 ft) above sea level, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland


    Keck Observatory

    February 21, 2018
    Mari-Ela Chock, Communications Officer
    (808) 554-0567
    mchock@keck.hawaii.edu

    1
    Credit: S. SAKAI/The Great Astronomer Andrea Ghez who spotted SgrA* by waching S0-2 Star /W. M. KECK OBSERVATORY/ UCLA GALACTIC CENTER GROUP
    The orbit of S0-2 (light blue) located near the Milky Way’s supermassive black hole will be used to test Einstein’s Theory of General Relativity and generate potentially new gravitational models.

    Andrea Ghez, UCLA

    No companion found for famous young bright star orbiting Milky Way’s supermassive black hole SgrA*.

    2
    Lead author Devin Chu of Hilo, Hawaii is an astronomy graduate student at UCLA. The Hilo High School and 2014 Dartmouth College alumnus conducts his research with the UCLA Galactic Center Group, which uses the W. M. Keck Observatory on Hawaii Island to obtain scientific data. “Growing up on Hawaii Island, it feels surreal doing important research with telescopes on my home island. I find it so rewarding to be able to return home to conduct observations,” Chu said. Credit: D. CHU

    3
    The UCLA Galactic Center Group takes a photo together during a visit to Keck Observatory, located atop Maunakea, Hawaii. Members of the group will return to the Observatory this spring to begin observations of S0-2 as the star travels towards its closest distance to the Galactic Center’s supermassive black hole. Credit: UCLA GALACTIC CENTER GROUP

    Astronomers have the “all-clear” for an exciting test of Einstein’s Theory of General Relativity, thanks to a new discovery about S0-2’s star status.

    Up until now, it was thought that S0-2 may be a binary, a system where two stars circle around each other. Having such a partner would have complicated the upcoming gravity test.

    But in a study published recently in The Astrophysical Journal, a team of astronomers led by a UCLA scientist from Hawaii has found that S0-2 does not have a significant other after all, or at least one that is massive enough to get in the way of critical measurements that astronomers need to test Einstein’s theory.

    The researchers made their discovery by obtaining spectroscopic measurements of S0-2 using W. M. Keck Observatory’s OH-Suppressing Infrared Imaging Spectrograph (OSIRIS) and Laser Guide Star Adaptive Optics.

    Keck OSIRIS

    “This is the first study to investigate S0-2 as a spectroscopic binary,” said lead author Devin Chu of Hilo, an astronomy graduate student with UCLA’s Galactic Center Group. “It’s incredibly rewarding. This study gives us confidence that a S0-2 binary system will not significantly affect our ability to measure gravitational redshift.”

    Einstein’s Theory of General Relativity predicts that light coming from a strong gravitational field gets stretched out, or “redshifted.” Researchers expect to directly measure this phenomenon beginning in the spring as S0-2 makes its closest approach to the supermassive black hole at the center of our Milky Way galaxy.

    This will allow the Galactic Center Group to witness the star being pulled at maximum gravitational strength – a point where any deviation to Einstein’s theory is expected to be the greatest.

    “It will be the first measurement of its kind,” said co-author Tuan Do, deputy director of the Galactic Center Group. “Gravity is the least well-tested of the forces of nature. Einstein’s theory has passed all other tests with flying colors so far, so if there are deviations measured, it would certainly raise lots of questions about the nature of gravity!”

    “We have been waiting 16 years for this,” said Chu. “We are anxious to see how the star will behave under the black hole’s violent pull. Will S0-2 follow Einstein’s theory or will the star defy our current laws of physics? We will soon find out!”

    The study also sheds more light on the strange birth of S0-2 and its stellar neighbors in the S-Star Cluster. The fact that these stars exist so close to the supermassive black hole is unusual because they are so young; how they could’ve formed in such a hostile environment is a mystery.

    “Star formation at the Galactic Center is difficult because the brute strength of tidal forces from the black hole can tear gas clouds apart before they can collapse and form stars,” said Do.

    “S0-2 is a very special and puzzling star,” said Chu. “We don’t typically see young, hot stars like S0-2 form so close to a supermassive black hole. This means that S0-2 must have formed a different way.”

    There are several theories that provide a possible explanation, with S0-2 being a binary as one of them. “We were able to put an upper limit on the mass of a companion star for S0-2,” said Chu. This new constraint brings astronomers closer to understanding this unusual object.

    “Stars as massive as S0-2 almost always have a binary companion. We are lucky that having no companion makes the measurements of general relativistic effects easier, but it also deepens the mystery of this star,” said Do.

    The Galactic Center Group now plans to study other S-Stars orbiting the supermassive black hole, in hopes of differentiating between the varying theories that attempt to explain why S0-2 is single.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Mission
    To advance the frontiers of astronomy and share our discoveries with the world.

    The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometer and world-leading laser guide star adaptive optics systems. Keck Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

    Today Keck Observatory is supported by both public funding sources and private philanthropy. As a 501(c)3, the organization is managed by the California Association for Research in Astronomy (CARA), whose Board of Directors includes representatives from the California Institute of Technology and the University of California, with liaisons to the board from NASA and the Keck Foundation.


    Keck UCal

     
  • richardmitnick 9:59 am on February 23, 2018 Permalink | Reply
    Tags: Astronomy, , , , Supernova DES16C2nm, The most distant supernova ever discovered,   

    From University of Southampton: “Astronomers reveal secrets of most distant supernova ever detected” 

    U Southampton bloc

    University of Southampton

    21 February 2018

    An international team of astronomers led by the University of Southampton has confirmed the discovery of the most distant supernova ever detected – a huge cosmic explosion that took place 10.5 billion years ago, or three-quarters the age of the Universe itself.

    The exploding star, named DES16C2nm, was detected by the Dark Energy Survey (DES), an international collaboration to map several hundred million galaxies in order to find out more about dark energy – the mysterious force believed to be causing the accelerated expansion of the Universe.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    As detailed in a new study published in The Astrophysical Journal, light from the event has taken 10.5 billion years to reach Earth, making it the oldest supernova ever discovered and studied. The Universe itself is thought to be 13.8 billion years old.

    A supernova is the explosion of a massive star at the end of its life cycle. DES16C2nm is classified as a superluminous supernova (SLSN), the brightest and rarest class of supernovae, first discovered ten years ago, thought to be caused by material falling onto the densest object in the Universe – a rapidly rotating neutron star newly formed in the explosion of a massive star.

    Lead author of the study Dr Mathew Smith, of the University of Southampton, said: “It’s thrilling to be part of the survey that has discovered the oldest known supernova. DES16C2nm is extremely distant, extremely bright, and extremely rare – not the sort of thing you stumble across every day as an astronomer.

    “As well as being a very exciting discovery in its own right, the extreme distance of DES16C2nm gives us a unique insight into the nature of SLSN.

    “The ultraviolet light from SLSN informs us of the amount of metal produced in the explosion and the temperature of the explosion itself, both of which are key to understanding what causes and drives these cosmic explosions.”

    Study co-author Professor Mark Sullivan, also of the University of Southampton, said: “Finding more distant events, to determine the variety and sheer number of these events, is the next step.

    “Now we know how to find these objects at even greater distances, we are actively looking for more of them as part of the Dark Energy Survey.”

    DES16C2nm was first detected in August 2016, and its distance and extreme brightness confirmed in October that year using three of the world’s most powerful telescopes – the Very Large Telescope and the Magellan, in Chile, and the Keck Observatory, in Hawaii.

    Study co-author Bob Nichol, Professor of Astrophysics at the University of Portsmouth, commented: “Such supernovae were not thought of when we started DES over a decade ago. Such discoveries show the importance of empirical science; sometimes you just have to go out and look up to find something amazing.”

    More than 400 scientists from over 25 institutions worldwide are involved in the DES, a five-year project which began in 2013.

    The collaboration built and is using an extremely sensitive 570-megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over five years (2013-2018), the DES collaboration is using 525 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth.

    The survey is imaging 5,000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    U Southampton campus

    The University of Southampton is a world-class university built on the quality and diversity of our community. Our staff place a high value on excellence and creativity, supporting independence of thought, and the freedom to challenge existing knowledge and beliefs through critical research and scholarship. Through our education and research we transform people’s lives and change the world for the better.

    Vision 2020 is the basis of our strategy.

    Since publication of the previous University Strategy in 2010 we have achieved much of what we set out to do against a backdrop of a major economic downturn and radical change in higher education in the UK.

    Vision 2020 builds on these foundations, describing our future ambition and priorities. It presents a vision of the University as a confident, growing, outwardly-focused institution that has global impact. It describes a connected institution equally committed to education and research, providing a distinctive educational experience for its students, and confident in its place as a leading international research university, achieving world-wide impact.

     
  • richardmitnick 9:22 am on February 23, 2018 Permalink | Reply
    Tags: Aecibo, Astronomy, , , , ,   

    From Science: “Iconic Arecibo radio telescope saved by university consortium” 

    AAAS
    Science Magazine

    1
    The Arecibo radio telescope will soon be managed by a university consortium. GDA/AP Images

    Feb. 22, 2018
    Daniel Clery
    Adrian Cho

    A consortium led by the University of Central Florida (UCF) in Orlando will take over management of the Arecibo Observatory in Puerto Rico, home to one of the world’s largest radio telescope, the National Science Foundation (NSF) in Alexandria, Virginia, announced today. NSF has been looking for another body to take over the running of the iconic facility ever since a 2006 review suggested the agency ramp down its funding to free up money for newer projects.

    “We’re delighted that there are signatures on paper,” says Richard Green, director of NSF’s astronomical sciences division. “That’s a fabulous moment at the end of a long process.” NSF now spends $8 million a year to run Arecibo, with NASA pitching in another $3.6 million. Under the agreement signed today, by 1 October 2022, NSF’s contribution will shrink to $2 million per year, with the UCF consortium making up the difference. UCF will complete the takeover as operator on 1 April, although an agreement detailing the transfer of funds must still be finalized, says James Ulvestad, NSF’s chief officer for scientific facilities.

    UCF has teamed up with the Metropolitan University in San Juan and Yang Enterprises in Oviedo, Florida, a company that has NASA and U.S. Air Force contracts to operate and maintain facilities. Ray Lugo, head of UCF’s Florida Space Institute, says the consortium hopes to bring in new users to contribute toward costs. He says the U.S. Department of Defense may want to use Arecibo to test sensors, while space mining companies may want to scope out target asteroids. “We want to bring other customers to the table,” he says. The consortium also wants to expand the telescope’s scientific capabilities, in part by upgrading equipment as repairs are carried out in the wake of damage suffered during following Hurricane Maria.

    Users of the 305-meter radio dish include astronomers, planetary scientists, and atmospheric physicists, and Arecibo is still a powerful scientific tool for them, even at 54 years old. The agreement with UCF also recognizes Arecibo’s significance beyond the scientific community, Ulvestad says. “It’s a hugely important technological icon in an underserved community,” he says.

    Some scientists are relieved that the facility avoided closure, even though they lament the handover from NSF. “I am pleased by the commitment of new management to continue and to expand the scientific and educational excellence of Arecibo Observatory,” says Robert Kerr, former Arecibo director. “I am disappointed by the tragic and ill-conceived divestment by NSF. That is a net loss for the foundation, and for basic U.S. scientific research and development.”

    NSF views the agreement with UCF as a possible blueprint for efforts to finding alternative funding for other aging telescopes, Green says. In particular, in 2012 a review committee recommended that the agency ramp down its funding for the 100-meter Green Bank Telescope in West Virginia.

    GBO radio telescope, Green Bank, West Virginia, USA

    “We’re hoping that [the Arecibo agreement] will give us and the community confidence that as other divestment efforts proceed, we can reach similar outcomes,” Green says.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
  • richardmitnick 8:10 am on February 23, 2018 Permalink | Reply
    Tags: Astronomy, , , Canada’s Cassiope satellite a.k.a. Echo, , ,   

    From ESA: “Swarm trio becomes a quartet” 

    ESA Space For Europe Banner

    European Space Agency

    22 February 2018

    With the aim of making the best possible use of existing satellites, ESA and Canada have made a deal that turns Swarm into a four-satellite mission to shed even more light on space weather and features such as the aurora borealis.

    ESA/Swarm

    In orbit since 2013, ESA’s three identical Swarm satellites have been returning a wealth of information about how our magnetic field is generated and how it protects us from dangerous electrically charged atomic particles in the solar wind.

    Magnetosphere of Earth, original bitmap from NASA. SVG rendering by Aaron Kaase

    Canada’s Cassiope satellite carries three instrument packages, one of which is e-POP.

    1
    Canada’s Cassiope satellite carries three instrument packages, one of which is e-POP
    Cassiope carries e-POP
    Released 22/02/2018
    Copyright © Canadian Space Agency, 2018
    Canada’s Cassiope satellite carries e-POP, which consists of eight instruments to provide information on Earth’s ionosphere, thermosphere and magnetosphere for a better understanding of space weather. Under a new agreement signed in February 2018, e-POP joins ESA’s magnetic field Swarm mission as a fourth element.

    It delivers information on space weather which complements that provided by Swarm. Therefore, the mission teams began looking into how they could work together to make the most of the two missions.

    To make life easier, it also just so happens that Cassiope’s orbit is ideal to improve Swarm’s readings.

    And now, thanks to this international cooperation and formalised through ESA’s Third Party Mission programme, e-POP has effectively become a fourth element of the Swarm mission. It joins Swarm’s Alpha, Bravo and Charlie satellites as Echo.

    Josef Aschbacher, ESA’s Director of Earth Observation Programmes, noted, “This is a textbook example of how virtual constellations and collaborative initiatives can be realised, even deep into the missions’ exploitation phases.

    “We embrace the opportunity to include e-POP in the Swarm mission, especially because it is clear that the more data we get, the better the picture we have of complex space weather dynamics.

    “ESA is looking forward to seeing the fruits of this collaboration and the improved return on investment for both Europe and Canada.”

    Andrew Yau from the University of Calgary added, “Swarm and e-POP have several unique measurement capabilities that are highly complementary.

    “By integrating e-POP into the Swarm constellation, the international scientific community will be able to pursue a host of new scientific investigations into magnetosphere–ionosphere coupling, including Earth’s magnetic field and related current systems, upper-atmospheric dynamics and aurora dynamics.”

    John Manuel from the Canadian Space Agency noted, “We are pleased to see e-POP join ESA’s three Swarm satellites in their quest to unravel the mysteries of Earth’s magnetic field.

    “Together, they will further improve our understanding of Earth’s magnetic field and role it plays in shielding Canada and the world from the effects of space weather.”

    Giuseppe Ottavianelli, Third-Party Mission Manager at ESA concluded, “I am pleased that the e-POP ensemble is now formally integrated into our Swarm constellation.

    “This milestone achievement confirms the essential role of ESA’s Earthnet programme, enabling synergies across missions, fostering international cooperation, and supporting data access.”

    While e-POP changes its name to Echo as part of the Swarm mission, it will also continue to provide information for its original science investigations.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

    ESA50 Logo large

     
  • richardmitnick 7:52 am on February 23, 2018 Permalink | Reply
    Tags: , Astronomy, , , , , ESA HERA spacecraft, SCITECH Europa   

    From ESA via SCITECH Europa: “Crash investigation” 

    ESA Space For Europe Banner

    European Space Agency

    1

    SCITECH Europa

    21st February 2018
    Ian Carnelli
    Programme Manager
    General Studies Programme (GSP)
    European Space Agency (ESA)

    1
    ESA HERA

    2
    Hera will provide humanity’s first view of a binary asteroid system, proceeding to map the entire surface of ‘Didymoon’ down to a size resolution of a few meters and the tenth of the surface surrounding the DART impact to better than 10cm, through a series of daring flybys © ESA – ScienceOffice.org

    ESA’s Hera mission is designed to test deep space technology while exploring a distant asteroid and investigating a unique, man-made crater, testing a deflection method that may one day prove literally Earth-saving.

    If all goes to plan, October 2022 will mark a significant achievement in the life of our species: the first time that Homo sapiens shifts the orbit of a body in the Solar System in a measureable way. The target is an approximately 170-m diameter asteroid – about the same size as the Great Pyramid of Giza – which is in orbit around another, larger asteroid: the 780m diameter Didymos (Greek for ‘twin’) near-Earth asteroid.The method is a NASA spacecraft called the Double Asteroid Redirection Test (DART), which will autonomously fly itself into the smaller body at 6km/s, nine times faster than a bullet.

    NASA DART Double Imact Redirection Test vehicle

    The result of the collision with this refrigerator-sized DART spacecraft is expected to be an alteration in the tight 11.9-hour orbit of ‘Didymoon’ around its parent asteroid. This shift should be observable from Earth-based telescopes, because the Didymos binary pair will be on an unusually close approach to our planet at that point, coming just 11 million kilometres away at its nearest.

    Didymoon’s degree of orbital shift will give researchers essential insights into the internal structure of asteroids and the potential of deflecting them as a means of planetary defence. But monitoring this historic event from a distance will not be sufficient by itself if we are to learn all its lessons.

    By its very nature the Double Asteroid Redirection Test is a suicide mission, which has some unavoidable drawbacks. The last thing Earth will see in advance of the collision will be a close-up of Didymoon’s surface features – and then nothing. Potentially, DART might also carry a small ‘selfie-sat’ that it deploys beforehand in order to capture imagery of the moment of impact – but even so, past experience suggests nothing will be viewable directly at that point and only very limited data will be available on the surface properties of Didymoon.

    Deep impact

    On 4 July 2005, NASA’s spacecraft shot a 370kg copper impactor into comet Tempel 1.

    NASA Deep Impact spacecraft

    Shifting the orbit of this massive 7.6km × 4.9km body was never on the agenda; instead the aim was to expose the comet’s interior. However, in the impact’s aftermath millions of kilograms of dust and ice continued to outgas from the impact zone for days on end.

    Deep Impact’s follow-on flyby showed nothing; it took a new visit by a separate spacecraft, NASA’s Stardust, in 2011 to finally measure the fresh 150m diameter crater scarring the comet’s surface.

    NASA Stardust spacecraft

    Plus, the distance involved means that terrestrial observatories’ measurement of Didymoon’s altered orbit will be stuck with a 10% residual uncertainty. The only way to improve on this, and really hone our understanding of this grand-scale space experiment, and see how the Double Asteroid Redirection Test impact has affected the surface of Didymoon, is to venture much, much nearer.

    ESA’s Hera mission

    That is the task of ESA’s Hera mission, the optimised design of which benefits from multiple ESA studies of asteroid missions across the last two decades – most recently the proposed Asteroid Impact Mission (AIM), which was planned in conjunction with the Double Asteroid Redirection Test. Hera is a small-scale mission in planetary terms, a large desk-sized spacecraft weighing in at less than 800kg fully fuelled (compared, for instance, to the van-sized, three tonne Rosetta comet-chaser). But it is also a highly agile, ambitious one.

    Europe’s first deep-space CubeSat

    In addition to its primary planetary defence objectives, Hera will demonstrate the ability to operate at close proximity around a low-gravity asteroid with some on-board autonomy similar in scope to a self-driving car, going on to deploy Europe’s first deep-space CubeSat, and potentially also a micro-lander, to test out a new multi-point intersatellite link technology.

    Hera will also provide humanity’s first view of a binary asteroid system, proceeding to map the entire surface of Didymoon down to a size resolution of a few meters and the tenth of the surface surrounding the Double Asteroid Redirection Test impact to better than 10cm, through a series of daring flybys. How large a crater will Double Asteroid Redirection Test end up leaving? Will there be larger morphological effects, such as ground cracking, or stones and dust scattered widely compared to DART’s pre-impact images, implying post-collision quaking?

    Planetary defence

    Precise mapping of Didymoon’s volume will be combined with radio science experiments to assess how Didymoon’s gravity influences the spacecraft’s trajectory, to derive the asteroid’s density and constrain our models of its internal structure. Hera will also be a pioneer in the novel field of planetary defence: by pinpointing the shift in Didymoon’s orbit to a much greater precision than is achievable from Earth, the mission will give the fullest possible insight into the end result of the Double Asteroid Redirection Test collision – serving up hard data that might one day be used to safeguard Earth, demonstrating how to divert an incoming body before it becomes a threat.

    What is Hera’s Asteroid Framing Camera (AFC)?

    Hera’s baseline payload begins with an instrument called the Asteroid Framing Camera (AFC), to be used for guidance and navigation as well as scientific observation, which is an already-existing flight spare of a German contribution to NASA’s Dawn mission to the asteroid belt.

    NASA Dawn Spacescraft

    This camera has been distinguished by returning remarkable images of the largest single asteroid, Ceres, and its mysterious bright spots.

    Now, its sister camera is set to survey the smallest asteroid humankind has visited as well. The AFC is joined by a compact lidar (or ‘laser radar’) instrument to be used for measuring surface altimetry, plus one or more deployable six-unit CubeSat nanosatellites to carry a hyperspectral imager and a second instrument still to be finalised.

    At the time of writing, Hera still has another 40kg of payload capacity available, which could take the shape of a high-frequency radar for measurement of subsurface properties, a mini-impactor proposed by Japan (a twin of the version currently in flight on Japan’s Hayabusa-2 asteroid mission, see below) or a mini-lander, currently under study by Airbus and DLR, the German Aerospace Center (based on a version also in flight aboard Hayabusa-2).

    Space servicing vehicles

    ESA has a long tradition of technology-testing missions being used for ambitious science goals, exemplified since the turn of the century by the Proba series of minisatellites, variously tasked with gathering data for environmental and solar science. Hera follows the same philosophy, even though it will go one better than the Proba family by departing Earth orbit entirely.

    The single most significant technology Hera will demonstrate during its mission to the Didymos binary is intangible in nature, a software algorithm rather than physical hardware, but one seen as essential to a coming class of autonomous ‘space servicing vehicles’.

    Hera’s streamlined nature means it will perform its guidance, navigation and control (GNC) activities through an innovative data fusion strategy, combining inputs from multiple sensors to build up a detailed picture of its surroundings in space. That would mean the bringing together second-by-second of visual tracking of distinctive features on the asteroid surface with altimeter distances plus onboard inertial and star tracker measurements. Future servicing vehicles would need to perform comparable data fusion when it comes to rendezvous and docking with satellites intended to be refurbished, refuelled or potentially deorbited. Any mistake in this scenario would lead to catastrophic collision, and plentiful space debris.

    Failure is not an option

    In the case of Hera, failure will not be an option when it comes to key manoeuvres such as CubeSat (and possibly lander) deployment or close Didymoon flybys, down to a matter of metres above the surface. But what if one or more of the sensor inputs is in error or an actuator delivers the wrong correction to the spacecraft trajectory or attitude? That is where Hera’s ‘Fault Detection, Isolation and Recovery’ (FDIR) technique comes in.

    FDIR is an approach widely applied in space engineering, ranging from protecting individual electronic components to safeguarding the entire spacecraft: for example, modern space computer chips seeking to make up for memory ‘bit flips’ due to space radiation can perform calculations on a multiple, parallel basis, sometimes voting to decide the most likely truthful result. In a similar fashion, Hera’s data-fusion-based GNC FDIR is designed to identify errors in real time through ongoing sensor cross-checks, isolating them and then making up for them by triggering sensor or actuator reconfigurations or even, in case of extreme emergency, triggering an autonomous collision avoidance manoeuvre.

    The combination of GNC and FDIR using vision-based sensing was achieved by ESA for the first time in the relatively straightforward but safety-critical case of semi-autonomous docking by the Automated Transfer Vehicle cargo spacecraft to the International Space Station (ISS). Expanding the technique to more challenging rendezvouses in space and increasing its degree of autonomy has been worked on for years in the context of this mission, most recently by GMV in Spain. Success will mark a giant leap forward for mission-critical autonomy.

    What new discoveries will asteroid missions make?

    Plenty of new discoveries can be expected from Hera. Each fresh close encounter with an asteroid has led to a fresh transformation in our understanding. A decade ago Europe took its first asteroid close-up, as ESA’s Rosetta probe performed a flyby of 2867 Šteins, a Gibraltar-sized diamond-shaped asteroid in the main Asteroid Belt. Dozens of craters were seen, including a gaping hole at the south pole of Steins – a large impact crater about 2km wide and nearly 300 m deep.

    ESA Rosetta spacecraft

    A chain of several craters ran towards the north pole from this crater. The low density of Šteins suggests it is a ‘rubble pile’ asteroid, broken apart by previous impacts and held together weakly by its gravity – and probably fated to one day break apart. A second Main Belt asteroid flyby took place in 2010, as Rosetta passed the mammoth 100km 21 Lutetia. This higher-density asteroid was similarly studded with craters, confirming that collision is the main shaper of these primitive bodies.

    Europe plays a key role in a new asteroid encounter scheduled for this July, when Japan’s Hayabusa 2 reaches near-Earth asteroid 162173 Ryugu.

    JAXA/Hayabusa 2

    It will put down a micro-lander called the Mobile Asteroid Surface Scout (Mascot), developed by the German Aerospace Center [DLR] (who previously contributed the Philae lander to Rosetta) and French space agency CNES, carrying an infrared spectrometer, a magnetometer, a radiometer and camera. A follow-on version of the Mascot lander, known as Mascot+, is currently under study to be carried by Hera.

    5
    DLR Mobile Asteroid Surface Scout (Mascot)

    Additionally Hayabusa 2 will perform its own miniature version of an impactor experiment, called the Small Carry-on Impactor (SCI), consisting of a small 2.5kg copper projectile given added force by a high-explosive charge. SCI will strike with a velocity of 2km/s, offering a valuable bridge between the kind of simulated impact tests performed in terrestrial labs and the full-scale Double Asteroid Redirection Test collision, allowing the testing of impact scaling laws. A follow-up SCI payload is also being considered for Hera, not to attempt to change Didymoon’s trajectory any further but to produce a second crater at a different energy level than DART. This experiment will provide invaluable data to fully validate numerical impact algorithms that will be key to designing any future planetary defence missions.

    Exploration of these asteroids, and the many others surveyed so far, have highlighted their striking variety in terms of size, shape, surface characteristics and constituent materials. Similarly, asteroids rotate in various ways, from simple rotation to slow precession or rapid tumbling. It is possible that asteroid rotation is constrained by fundamental ‘spin limits’, beyond which centrifugal acceleration would lead material to escape from the surface of rubble-pile bodies. Indeed, such escapes might explain the origin of many binary asteroid systems, which make up 15% of the known total.

    New light on collisional dynamics

    The internal structure of asteroids remains a blank spot in scientific understanding. Are there large voids within their deep interior, or are they composed of loose regolith or conglomerates of monolithic rock? In particular, there is no way of knowing how an actual asteroid would respond to the specific external stimulus of an impact – short of trying it for real.

    By shedding new light on collisional dynamics, the combination of the Double Asteroid Redirection Test plus Hera will add to our understanding not just of asteroid formation and evolution but the creation and ongoing history of our entire Solar System – a story etched in impacts.

    Down at smaller scales, Hera’s surface observations will reveal the range of physical phenomena other than gravity that govern asteroid surfaces, influence their material properties and keep them bound together. What are the relative roles of electrostatic and Van der Waals forces, for instance? One proposal is that the most finely-grained asteroids might resemble ‘fairy castles’, crumbling to the touch. Such findings would hold relevance for asteroid mining as well as planetary defence, while also offering insight into the very earliest microscopic-scale processes of accretion, right back at the dawn of this and other planetary systems.

    Historic moment

    Hera is currently preparing for its Phase B1 study, along with a set of technology developments. The decision on whether the mission will progress to flight will be taken by Europe’s leaders at the end of next year. But certainly planetary defence is a global responsibility, and ESA is currently readying a new programme to be presented at the next Ministerial Council called Space Safety, that places planetary defence together with related topics such as space debris and space weather.

    DART and Hera were originally conceived as one – the origin of the two missions can be traced back to an ESA 2002 study of a double spacecraft asteroid deflection mission called Don Quijote. If approved, Hera is on track for a 2023 launch, arriving at Didymos for its ‘crime scene investigation’ a couple of years later. The experience of the Stardust crater – as well as the recently discovered crater of ESA’s Smart-1 spacecraft on the Moon – suggests DART’s impact point will be largely unchanged from the moment of collision. Or, in the event of a delay in the Double Asteroid Redirection Test mission, then the pair might reach Didymos at the same time. Either way, a historic moment is coming in the shape of the DART impact. Humankind will draw maximum benefit from it through a close-up view.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

    ESA50 Logo large

     
  • richardmitnick 6:41 am on February 23, 2018 Permalink | Reply
    Tags: Astronomy, , , , Improved Hubble Yardstick Gives Fresh Evidence for New Physics in the Universe,   

    From Hubble: “Improved Hubble Yardstick Gives Fresh Evidence for New Physics in the Universe” 

    NASA Hubble Banner

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble Telescope

    Feb 22, 2018

    Donna Weaver
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4493
    dweaver@stsci.edu

    Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4514
    villard@stsci.edu

    Adam Riess
    Space Telescope Science Institute/Johns Hopkins University, Baltimore, Maryland
    410-338-6707
    ariess@stsci.edu

    1

    Astronomers have used NASA’s Hubble Space Telescope to make the most precise measurements of the expansion rate of the universe since it was first calculated nearly a century ago. Intriguingly, the results are forcing astronomers to consider that they may be seeing evidence of something unexpected at work in the universe.

    That’s because the latest Hubble finding confirms a nagging discrepancy showing the universe to be expanding faster now than was expected from its trajectory seen shortly after the big bang. Researchers suggest that there may be new physics to explain the inconsistency.

    “The community is really grappling with understanding the meaning of this discrepancy,” said lead researcher and Nobel Laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University, both in Baltimore, Maryland.

    Riess’s team, which includes Stefano Casertano, also of STScI and Johns Hopkins, has been using Hubble over the past six years to refine the measurements of the distances to galaxies, using their stars as milepost markers. Those measurements are used to calculate how fast the universe expands with time, a value known as the Hubble constant. The team’s new study extends the number of stars analyzed to distances up to 10 times farther into space than previous Hubble results.

    But Riess’s value reinforces the disparity with the expected value derived from observations of the early universe’s expansion, 378,000 years after the big bang — the violent event that created the universe roughly 13.8 billion years ago. Those measurements were made by the European Space Agency’s Planck satellite, which maps the cosmic microwave background [CMB], a relic of the big bang.

    CMB per ESA/Planck

    ESA/Planck

    The difference between the two values is about 9 percent. The new Hubble measurements help reduce the chance that the discrepancy in the values is a coincidence to 1 in 5,000.

    Planck’s result predicted that the Hubble constant value should now be 67 kilometers per second per megaparsec (3.3 million light-years), and could be no higher than 69 kilometers per second per megaparsec. This means that for every 3.3 million light-years farther away a galaxy is from us, it is moving 67 kilometers per second faster. But Riess’s team measured a value of 73 kilometers per second per megaparsec, indicating galaxies are moving at a faster rate than implied by observations of the early universe.

    The Hubble data are so precise that astronomers cannot dismiss the gap between the two results as errors in any single measurement or method. “Both results have been tested multiple ways, so barring a series of unrelated mistakes,” Riess explained, “it is increasingly likely that this is not a bug but a feature of the universe.”

    Explaining a Vexing Discrepancy

    Riess outlined a few possible explanations for the mismatch, all related to the 95 percent of the universe that is shrouded in darkness. One possibility is that dark energy, already known to be accelerating the cosmos, may be shoving galaxies away from each other with even greater — or growing — strength. This means that the acceleration itself might not have a constant value in the universe but changes over time in the universe. Riess shared a Nobel Prize for the 1998 discovery of the accelerating universe.

    Another idea is that the universe contains a new subatomic particle that travels close to the speed of light. Such speedy particles are collectively called “dark radiation” and include previously known particles like neutrinos, which are created in nuclear reactions and radioactive decays. Unlike a normal neutrino, which interacts by a subatomic force, this new particle would be affected only by gravity and is dubbed a “sterile neutrino.”

    Yet another attractive possibility is that dark matter (an invisible form of matter not made up of protons, neutrons, and electrons) interacts more strongly with normal matter or radiation than previously assumed.

    Any of these scenarios would change the contents of the early universe, leading to inconsistencies in theoretical models. These inconsistencies would result in an incorrect value for the Hubble constant, inferred from observations of the young cosmos. This value would then be at odds with the number derived from the Hubble observations.

    Riess and his colleagues don’t have any answers yet to this vexing problem, but his team will continue to work on fine-tuning the universe’s expansion rate. So far, Riess’s team, called the Supernova H0 for the Equation of State (SH0ES), has decreased the uncertainty to 2.3 percent. Before Hubble was launched in 1990, estimates of the Hubble constant varied by a factor of two. One of Hubble’s key goals was to help astronomers reduce the value of this uncertainty to within an error of only 10 percent. Since 2005, the group has been on a quest to refine the accuracy of the Hubble constant to a precision that allows for a better understanding of the universe’s behavior.

    Building a Strong Distance Ladder

    The team has been successful in refining the Hubble constant value by streamlining and strengthening the construction of the cosmic distance ladder, which the astronomers use to measure accurate distances to galaxies near to and far from Earth.

    The researchers have compared those distances with the expansion of space as measured by the stretching of light from receding galaxies. They then have used the apparent outward velocity of galaxies at each distance to calculate the Hubble constant.

    But the Hubble constant’s value is only as precise as the accuracy of the measurements. Astronomers cannot use a tape measure to gauge the distances between galaxies. Instead, they have selected special classes of stars and supernovae as cosmic yardsticks or milepost markers to precisely measure galactic distances.

    Among the most reliable for shorter distances are Cepheid variables, pulsating stars that brighten and dim at rates that correspond to their intrinsic brightness. Their distances, therefore, can be inferred by comparing their intrinsic brightness with their apparent brightness as seen from Earth.

    Astronomer Henrietta Leavitt was the first to recognize the utility of Cepheid variables to gauge distances in 1913. But the first step is to measure the distances to Cepheids independent of their brightness, using a basic tool of geometry called parallax. Parallax is the apparent shift of an object’s position due to a change in an observer’s point of view. This technique was invented by the ancient Greeks who used it to measure the distance from Earth to the Moon.

    The latest Hubble result is based on measurements of the parallax of eight newly analyzed Cepheids in our Milky Way galaxy. These stars are about 10 times farther away than any studied previously, residing between 6,000 light-years and 12,000 light-years from Earth, making them more challenging to measure. They pulsate at longer intervals, just like the Cepheids observed by Hubble in distant galaxies containing another reliable yardstick, exploding stars called Type Ia supernovae. This type of supernova flares with uniform brightness and is brilliant enough to be seen from relatively farther away. Previous Hubble observations studied 10 faster-blinking Cepheids located 300 light-years to 1,600 light-years from Earth.

    Scanning the Stars

    To measure parallax with Hubble, the team had to gauge the apparent tiny wobble of the Cepheids due to Earth’s motion around the Sun. These wobbles are the size of just 1/100 of a single pixel on the telescope’s camera, which is roughly the apparent size of a grain of sand seen 100 miles away.

    Therefore, to ensure the accuracy of the measurements, the astronomers developed a clever method that was not envisioned when Hubble was launched. The researchers invented a scanning technique in which the telescope measured a star’s position a thousand times a minute every six months for four years.

    The team calibrated the true brightness of the eight slowly pulsating stars and cross-correlated them with their more distant blinking cousins to tighten the inaccuracies in their distance ladder. The researchers then compared the brightness of the Cepheids and supernovae in those galaxies with better confidence, so they could more accurately measure the stars’ true brightness, and therefore calculate distances to hundreds of supernovae in far-flung galaxies with more precision.

    Another advantage to this study is that the team used the same instrument, Hubble’s Wide Field Camera 3, to calibrate the luminosities of both the nearby Cepheids and those in other galaxies, eliminating the systematic errors that are almost unavoidably introduced by comparing those measurements from different telescopes.

    “Ordinarily, if every six months you try to measure the change in position of one star relative to another at these distances, you are limited by your ability to figure out exactly where the star is,” Casertano explained. Using the new technique, Hubble slowly slews across a stellar target, and captures the image as a streak of light. “This method allows for repeated opportunities to measure the extremely tiny displacements due to parallax,” Riess added. “You’re measuring the separation between two stars, not just in one place on the camera, but over and over thousands of times, reducing the errors in measurement.”

    The team’s goal is to further reduce the uncertainty by using data from Hubble and the European Space Agency’s Gaia space observatory, which will measure the positions and distances of stars with unprecedented precision. “This precision is what it will take to diagnose the cause of this discrepancy,” Casertano said.

    The team’s results have been accepted for publication by The Astrophysical Journal.

    The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

    ESA50 Logo large

    AURA Icon

    NASA image

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: