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  • richardmitnick 5:35 pm on January 27, 2016 Permalink | Reply
    Tags: , , Keck Observatory, Laser frequency combs   

    From Keck: “New Calibration Tool Will Help Astronomers Look for Habitable Exoplanets” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    January 27, 2016
    Adam Hadhazy

    Promising new calibration tools, called laser frequency combs, could allow astronomers to take a major step in discovering and characterizing earthlike planets around other stars. These devices generate evenly spaced lines of light, much like the teeth on a comb for styling hair or the tick marks on a ruler — hence their nickname of “optical rulers.” The tick marks serve as stable reference points when making precision measurements such as those of the small shifts in starlight caused by planets pulling gravitationally on their parent stars.

    Yet today’s commercially available combs have a significant drawback. Because their tick marks are so finely spaced, the light output of these combs must be filtered to produce useful reference lines. This extra step adds complexity to the system and requires costly additional equipment.

    To resolve these kinds of issues, Caltech researchers looked to a kind of comb not previously deployed for astronomy. The novel comb produces easily resolvable lines, without any need for filtering. Furthermore, the Caltech comb is built from off-the-shelf components developed by the telecommunications industry.

    “We have demonstrated an alternative approach that is simple, reliable, and relatively inexpensive,” says paper coauthor Kerry Vahala, the Ted and Ginger Jenkins Professor of Information Science and Technology and Applied Physics as well as the executive officer for Applied Physics and Materials Science in Caltech’s Division of Engineering and Applied Science. The kind of frequency comb used by the researchers previously has been studied in the Vahala group in a different application, the generation of high-stability microwaves.

    “We believe members of the astronomical community could greatly benefit in their exoplanet hunting and characterization studies with this new laser frequency comb instrument,” says Xu Yi, a graduate student in Vahala’s lab and the lead author of a paper describing the work published in the January 27, 2016, issue of the journal Nature Communications.

    Scientists first began widely using laser frequency combs as precision rulers in the late 1990s in fields like metrology and spectroscopy; for their work, the technology’s developers (John L. Hall of JILA and the National Institute of Standards and Technology (NIST) and Theodor Hänsch of the Max Planck Institute of Quantum Optics and Ludwig Maximilians University Munich) were awarded half of the Nobel Prize in Physics in 2005. In astronomy, the combs are starting to be utilized in the radial velocity, or “wobble” method, the earliest and among the most successful methods for identifying exoplanets.

    The “wobble” refers to the periodic changes in a star’s motion, accompanied by starlight shifts owing to the Doppler effect, that are induced by the gravitational pull of an exoplanet orbiting around the star. The magnitude of the shift in the starlight’s wavelength — on the order of quadrillionths of a meter — together with the period of the wobble can be used to determine an exoplanet’s mass and orbital distance from its star. These details are critical for assessing habitability parameters such as surface temperature and the eccentricity of the exoplanet’s orbit. With exoplanets that pass directly in front of (or “transit”) their host star, allowing their radius to be determined directly, it is even possible to determine the bulk composition — for example, if the planet is built up primarily of gas, ice, or rock.

    In recent years, so-called mode-locked laser combs have proven useful in this task. These lasers generate a periodic stream of ultrashort light pulses to create the comb. With such combs, however, approximately 49 out of every 50 tick marks must be blocked out. This requires temperature- and vibration-insensitive filtering equipment.

    The new electro-optical comb that the Caltech team studied relies on microwave modulation of a continuous laser source, rather than a pulsed laser. It produces comb lines spaced by tens of gigahertz. These lines have from 10 to 100 times wider spacing than the tick marks of pulsed laser combs.

    To see how well a prototype would work in the field, the researchers took their comb to Mauna Kea in Hawaii. In September 2014, the instrument was tested at the NASA Infrared Telescope Facility (IRTF);

    NASA Infrared Telescope facility
    IRTF

    in March 2015, it was tested with the Near Infrared Spectrometer on the W. M. Keck Observatory’s Keck II telescope with the assistance of UCLA astronomer Mike Fitzgerald (BS ’00) and UCLA graduate student Emily Martin, coauthors on the paper.

    The researchers found that their simplified comb (the entire electro-optical comb apparatus requires only half of the space available on a standard 19-inch instrumentation rack) provided steady calibration at room temperature for more than five days at IRTF. The comb also operated flawlessly during the second test—despite having been disassembled, stored for six months, and reassembled.

    “From a technological maturity point of view, the frequency comb we have developed is already basically ready to go and could be installed at many telescopes,” says paper coauthor Scott Diddams of NIST.

    The Caltech comb produces spectral lines in the infrared, making it ideal for studying red dwarf stars, the most common stars in the Milky Way. Red dwarf stars are brightest in infrared wavelengths. Because red dwarfs are small, cool, and dim, planets orbiting these types of stars are easier to detect and analyze than those orbiting hotter sun-like stars. NASA’s Kepler space observatory has shown that almost all red dwarf stars host planets in the range of one to four times the size of Earth, with up to 25 percent of these planets located in the temperate, or “habitable,” zone around their host stars.

    NASA Kepler Telescope
    NASA/Kepler

    Thus, many astronomers predict that red dwarfs provide the best chance for the first discovery of a world capable of supporting life.

    “Our goal is to make these laser frequency combs simple and sturdy enough that you can slap them onto every telescope, and you don’t have to think about them anymore,” says paper coauthor Charles Beichman, senior faculty associate in astronomy and the executive director of the NASA ExoPlanet Science Institute at Caltech. “Having these combs routinely available as a modest add-on to current and future instrumentation really will expand our ability to find potentially habitable planets, particularly around very cool red dwarf stars,” he says.

    The research team is planning to double the frequency of the prototype comb’s light output — now centered around 1,550 nanometers, in the infrared—to reach into the visible light range. Doing so would allow the comb also to calibrate spectra from sun-like stars, whose light output is at shorter, visible wavelengths, and thus seek out planets that are Earth’s “twins.”

    Other authors of the paper are Jiang Li, a visitor in applied physics and materials science, graduate students Peter Gao and Michael Bottom, and scientific research assistant Elise Furlan, all from Caltech; Stephanie Leifer, Jagmit Sandhu, Gautam Vasisht, and Pin Chen of JPL; Peter Plavchan (BS ’01), formerly at Caltech and now a professor at Missouri State University; G. Ycas of NIST; Jonathan Gagne of the University of Montréal; and Greg Doppmann of the Keck Observatory.

    The paper is titled Demonstration of a near-IR line-referenced electro-optical laser frequency comb for precision radial velocity measurements in astronomy. The research performed at Caltech and JPL was funded through the President’s and Director’s Fund Program, and the work at NIST was funded by the National Science Foundation.

    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

    Keck NASA

    Keck Caltech

     
  • richardmitnick 10:02 pm on January 11, 2016 Permalink | Reply
    Tags: , , Damped Lyman-alpha systems, Keck Observatory   

    From Keck: “Solved! 40 Year-old Mystery on the Size of Shadowy Galaxies” 

    Keck Observatory

    Keck Observatory.
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    January 5, 2016
    Steve Jefferson
    Communication Officer
    W. M. Keck Observatory
    sjefferson@keck.hawaii.edu

    SCIENCE
    Jeff Cooke
    Swinburne University
    jcooke@astro.swin.edu.au

    John O’Meara
    St. Michael’s College
    jomeara@smcvt.edu

    Temp 1
    Artists impression of the power of background galaxies to measure the size of gas clouds as compared to the conventional method of using quasars. The plane to the far right shows the background galaxy and overlaid in the center of the galaxy is a bright white light representing a quasar. The DLA gas cloud is shown at the center of the plane in between the galaxy and Earth. The blue/white narrow beam indicates the small area of the DLA gas cloud probed by quasars, the wider red cone of light indicates the large area of the DLA probed by galaxies, which is a 100 million-fold increase in area. Credit: Adrian Malec (Swinburne University) and Marie Martig (Max Planck Institute for Astronomy, Heidelberg)

    Using the world’s largest telescopes, researchers discovered ancient cold gas clouds larger than galaxies in the early Universe. The discovery was announced today at a press conference at the 227th meeting of the American Astronomical Society in Orlando, Florida.

    The discovery, led by Associate Professor Jeff Cooke, Swinburne University of Technology, and Associate Professor John O’Meara, St. Michael’s College, has helped solve a decades-old puzzle on the nature of gas clouds, known as Damped Lyman-alpha systems, or DLAs.

    Cooke and O’Meara realized that finding DLA gas clouds in the line of sight to background galaxies would enable measurements of their size by determining how much of the galaxy they cover.

    “Our new method first identifies galaxies that are more likely to have intervening DLA gas clouds and then searches for them using long, deep exposures on the powerful Keck Observatory 10m telescopes on Maunakea and deep data from the VLT 8m telescopes in Chile,” Cooke said.

    ESO VLT Interferometer
    ESO/VLT

    “The technique is timely as the next generation of giant 30m telescopes will be online in several years and are ideal to take advantage of this method to routinely gather large numbers of DLAs for study.”

    DLA clouds contain most of the cool gas in the Universe and are predicted to contain enough gas to form most of the stars we see in galaxies around us today, like the Milky Way. However, this prediction has yet to be confirmed.

    DLAs currently have little ongoing star formation, making them too dim to observe directly from their emitted light alone. Instead, they are detected when they happen to fall in the line of sight to a more distant bright object and leave an unmistakeable absorption signature in the background object’s light.

    Previously, researchers used quasars as the background objects to search for DLAs. Although quasars can be very bright, they are rare and are comparatively small, only a fraction of a light year across, whereas galaxies are quite common and provide a 100 million-fold increase in area to probe DLAs.

    “Using the galaxy technique, DLAs can be studied in large numbers to provide a 3-D tomographic picture of distribution of gas clouds in the early Universe and help complete our understanding of how galaxies formed and evolved over cosmic time,” O’Meara said.

    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

    Keck NASA

    Keck Caltech

     
  • richardmitnick 3:01 pm on December 8, 2015 Permalink | Reply
    Tags: , , , Keck Observatory   

    From Keck: “$4 Million Laser Marks Ground Zero for Adaptive Optics Science” 

    Keck Observatory

    Keck Observatory
    Keck, with Subaru and IRTF (NASA Infrared Telescope Facility). Vadim Kurland

    Keck Observatory

    December 8, 2015
    MEDIA
    Steve Jefferson
    Communication Officer
    W. M. Keck Observatory
    sjefferson@keck.hawaii.edu

    1
    Image from the launching point of the telescope looking up into the night sky. The central hole in the beam is due to the secondary mirror obscuration on the laser beam launch telescope and is used to align the laser beam. Credit: W. M. Keck Observatory

    2
    The top spot is the artificially created laser guide star in the mesosphere with sodium atoms excited by the laser. The star pattern and surrounding lopes, seen by the acquisition camera, show the structures of the telescope and the equipment in the light path. The bottom spot is a reflection of the laser star on the camera optics. Credit: W. M. Keck Observatory

    3
    A point spread image shows the symmetry of the artificially created guide star in the mesosphere.

    Hawaii’s W. M. Keck Observatory has successfully deployed a $4 million laser system that provides a marked increase in the resolution and clarity of what are already the most scientifically productive telescopes on Earth. The new laser was projected on the sky for the first time on the evening of December 1, 2015 and will allow scientists from around the world to observe the heavens above Maunakea in unprecedented detail.

    “The Next Generation Laser System is the third generation of lasers at Keck Observatory, which has been pioneering Laser Guide Star Adaptive Optics on big telescopes since 2001,” said Jason Chin, the project manager for the new laser at Keck Observatory.

    The first Laser Guide Star Adaptive Optics system on a large telescope was commissioned on the Keck II telescope in 2004 and, among many other firsts, helped reveal the black hole at the center of the Milky Way – one the most significant astronomical discoveries. The second laser system was installed in 2011 on the Keck I telescope, propelling Keck Observatory’s lead as the premiere Adaptive Optics research facility in the world. To date more than 240 science results from these laser systems have been published in astronomical journals.

    Keck Observatory’s Laser Guide Star systems create an artificial star in the earth’s mesosphere, at an altitude of roughly 60 miles, by energizing a naturally occurring layer of sodium atoms, causing them to fluoresce. The adaptive optics system uses this artificial laser guide star to measure the aberrations introduced by turbulence in the earth’s atmosphere. A six-inch diameter deformable mirror with 349 actuators is then used to correct for these aberrations at a rate of 1,000 times per second, effectively taking the twinkle out of the stars and providing near-perfect detail for planets, stars and galaxies. Combined with the 10-meter diameter primary mirror, Keck Observatory can offer images with five times the resolution of even the Hubble Space Telescope.

    The new laser is the result of a collaboration between Keck Observatory and the European Southern Observatory to develop a more efficient and powerful facility class, commercial laser for astronomy. The new laser, fabricated by TOPTICA in Germany and MPBC in Canada meets both goals handily: the power consumption on the new system is down to 1.2 kW from the previous 80 kW used by the former dye laser system while performance has increased by a factor of ten. Further, the new laser can transition from off to an operational state in five minutes – a dramatic improvement over the five to six hours for the dye laser, which was decommissioned in October to make room for the new laser.

    Perhaps most significantly, this is first of the new generation of lasers that all future telescopes are planning on and are looking to Hawaii’s findings to build their systems.

    Funding for the project came from the Gordon and Betty Moore Foundation, the W. M. Keck Foundation and Friends of Keck Observatory. Initial seed funding was provided by the National Science Foundation.

    More than one-third of the budget was spent in Hawaii designing and installing the systems and related infrastructure to support and operate the new laser. The remaining budget was spent on the laser itself – more than $2.5 million. The project also provided infrastructure for adding two additional lasers to support laser tomography in order to determine the distribution of atmospheric turbulence versus altitude. Once funded, the additional lasers can be easily added to the system and would allow a much larger area of the sky to be sampled with even better correction of the atmospheric turbulence.

    The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes near the summit of Maunakea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrographs and world-leading laser guide star adaptive optics systems.

    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

    Keck NASA

    Keck Caltech

     
  • richardmitnick 8:25 pm on November 24, 2015 Permalink | Reply
    Tags: , , Keck Observatory   

    From Keck: “Keck Observatory Celebrates 25 Years of Discovery” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    11.24.15
    Nick Yee

    Twenty five years ago- the Keck Observatory opened the dome above its telescope to look into the night sky. Since then- its twin domes on top of Mauna Kea have hosted generations of scientists and students.

    The telescope’s design was radical for its time –using small hexagon shaped segmented mirrors and controlling them so that they would act as a single, giant mirror. Today, many telescopes on both ground and space, are being designed using the architecture developed and perfected by the Keck. Once completed the observatory could immediately make discoveries considered impossible at other locations, and would completely change the understanding of the universe.

    Keck was the first telescope to directly image planets orbiting another star, prove the existence of super-massive black holes, and observe the most distant galaxies formed after the big bang. Anne Kinney is the Chief Scientist at the Keck Observatory.

    To mark the anniversary- the observatory is hosting Hawai‘i Island school groups throughout the day at its base facility in Waimea.

    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

    Keck NASA

    Keck Caltech

     
  • richardmitnick 11:12 pm on November 12, 2015 Permalink | Reply
    Tags: , , Keck Observatory   

    From Keck: “Prodigious ‘Brightest Cluster Galaxy’ Discovered Churning Trillions of Stars” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    11.12.15
    Originally September 10, 2015, but not presented.

    1
    A massive cluster of galaxies, called SpARCS1049+56, can be seen in this multi-wavelength view from NASA’s Hubble and Spitzer space telescopes. At the middle of the picture is the largest, central member of the family of galaxies (upper right red dot of central pair). Unlike other central galaxies in clusters, this one is bursting with the birth of new stars. Scientists say this star birth was triggered by a collision between a smaller galaxy and the giant, central galaxy. The smaller galaxy’s wispy, shredded parts, called a tidal tail, can be seen coming out below the larger galaxy. Throughout this region are features called “beads on a string,” which are areas where gas has clumped to form new stars. This type of “feeding” mechanism for galaxy clusters — where gas from the merging of galaxies is converted to new stars — is rare. The Hubble data in this image show infrared light with a wavelength of 1 micron in blue, and 1.6 microns in green. The Spitzer data show infrared light of 3.6 microns in red. Credit: NASA/STScI/ESA/JPL-Caltech/McGill

    An international team of astronomers has discovered a distant massive galaxy cluster with a core bursting with new stars. The discovery, made with the help of the Maunakea-based W. M. Keck Observatory and Canada-France Hawaii Telescope [CFHT], is the first to show that gigantic galaxies at the centers of massive clusters can grow significantly by feeding off gas stolen from other galaxies. The study has been accepted for publication in The Astrophysical Journal.

    CFHT
    CFHT

    “Clusters of galaxies are rare regions of the Universe consisting of hundreds of galaxies containing trillions of stars, as well as hot gas and mysterious dark matter,” said the lead author, Tracy Webb of McGill University, Canada. “The galaxies at the centers of clusters, called Brightest Cluster Galaxies, are the most massive galaxies in the Universe. How they become so huge is not well understood.”

    What is so unusual about SpARCS1049+56 is that it is forming stars at a prodigious rate, more than 800 solar masses per year – 800 times faster than in our own Milky Way.

    This surprising new discovery was the result of collaborative synergy from ground-based observations from Keck Observatory and CFHT as well as space-based observations from NASA’s Hubble, Spitzer and [ESA]Herschel Space Telescopes.

    NASA Hubble Telescope
    NASA/ESA Hubble

    NASA Spitzer Telescope
    NASA/Spitzer

    ESA Herschel
    ESA/Herschel

    The Keck Observatory data was gathered by the powerful MOSFIRE infrared spectrograph and was crucial to determining SpARCS1049+56’s distance from Earth as 9.8 billion light-years, that it contains at least 27 galaxies and that it has a total mass equal to about 400 trillion Suns.

    Keck MOSFIRE
    MOSFIRE infrared spectrograph

    The cluster was first identified from the University of California, Riverside-led, Spitzer Adaptation of the Red-sequence Cluster Survey, or SpARCS, which has discovered about 200 new distant galaxy clusters using deep ground-based optical observations combined with Spitzer Space Telescope infrared observations.

    Because Spitzer and Herschel Space Telescopes detect infrared light – enabling observers to see hidden, dusty regions of star formation – they were able to reveal the full extent of the massive amount of star formation going on in SpARCS1049+56. However, the resolution of the infrared observations was insufficient to pinpoint where all this star formation was coming from. Therefore, high-resolution follow-up optical observations were performed by the Hubble Space Telescope to reveal “beads on a string” at the center of SpARCS1049+56 which occur when, similar to a necklace, clumps of new star formation appear strung out like beads on filaments of hydrogen gas.

    “Beads on a string” is a telltale sign of something known as a wet merger, which occurs when at least one galaxy in a collision between galaxies is gas rich, and this gas is converted quickly into new stars. The large amount of star formation and the “beads on a string” feature in the core of SpARCS1049+56 are likely the result of the Brightest Cluster Galaxy in the process of gobbling up a gas-rich spiral galaxy.

    What is particularly interesting is that Brightest Cluster Galaxies closer to the Milky Way are thought to grow by so-called dry mergers, collisions between gas-poor galaxies that do not result in the formation of new stars. The new discovery is one of the only known cases of a wet merger at the core of a galaxy cluster, and the most distant example ever found.

    The team now aims to explore how common this type of growth mechanism is in galaxy clusters. Are there other messy eaters out there similar to SpARCS1049+56, which are also munching on gas-rich galaxies? SpARCS1049+56 may be a rarity or it may be the first of many cases at early times in our Universe when messy eating was the norm.

    The Keck Observatory findings were obtained as the result of a collaboration amongst UC faculty members Gillian Wilson (UCR), Michael Cooper(UCI) and Saul Perlmutter (UCB), postdoctoral researcher Brian Hayden (UCB), and graduate students Andrew DeGroot (UCR) and Ryan Foltz (UCR).

    “It is very exciting to have discovered such an interesting object,” Wilson said. “Understanding its nature proved to be a real scientific challenge which required the combined efforts of an international team of astronomers and many of the world’s best telescopes to solve.”

    The W. M. Keck Observatory operates the largest, most scientifically productive telescopes on Earth. The two, 10-meter optical/infrared telescopes near the summit of Maunakea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrographs and world-leading laser guide star adaptive optics systems.

    MOSFIRE (Multi-Object Spectrograph for Infrared Exploration) is a highly-efficient instrument that can take images or up to 46 simultaneous spectra. Using a sensitive state-of-the-art detector and electronics system, MOSFIRE obtains observations fainter than any other near infrared spectrograph. MOSFIRE is an excellent tool for studying complex star or galaxy fields, including distant galaxies in the early Universe, as well as star clusters in our own Galaxy. MOSFIRE was made possible by funding provided by the National Science Foundation and astronomy benefactors Gordon and Betty Moore.

    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

    Keck NASA

    Keck Caltech

     
  • richardmitnick 3:49 pm on September 3, 2015 Permalink | Reply
    Tags: , , , Keck Observatory   

    From Caltech: “Farthest Galaxy Detected” 

    Caltech Logo
    Caltech

    09/03/2015
    Rod Pyle

    Caltech astronomers detect the farthest galaxy yet with Keck telescope.

    1
    Galaxy EGS8p7, as seen from the Hubble Space Telescope (wide and top right) and Spitzer Space Telescope (inset, bottom right), taken in infrared. Credit: I. Labbé (Leiden University), NASA/ESA/JPL-Caltech

    NASA Hubble Telescope
    NASA/ESA Hubble

    NASA Spitzer Telescope
    NASA/Spitzer

    4
    A graphic representation of the extreme distance of galaxy EGS8p7. To the far right is the W. M. Keck telescope used for the observation, to the far left is the Big Bang, and at the center is the galaxy. The scale above indicates the progression of ever more distant discoveries and the corresponding year, and at the bottom is a time scale equivalent to distance. Finally, the inset to top left charts the observations made across two nights with the MOSFIRE spectrometer that resulted in the detect. Credit: Adi Zitrin/ Caltech.

    A team of Caltech researchers that has spent years searching for the earliest objects in the universe now reports the detection of what may be the most distant galaxy ever found. In an article published August 28, 2015 in Astrophysical Journal Letters, Adi Zitrin, a NASA Hubble Postdoctoral Scholar in Astronomy, and Richard Ellis—who recently retired after 15 years on the Caltech faculty and is now a professor of astrophysics at University College, London—describe evidence for a galaxy called EGS8p7 that is more than 13.2 billion years old. The universe itself is about 13.8 billion years old.

    Earlier this year, EGS8p7 had been identified as a candidate for further investigation based on data gathered by NASA’s Hubble Space Telescope and the Spitzer Space Telescope. Using the multi-object spectrometer for infrared exploration (MOSFIRE) at the W.M. Keck Observatory in Hawaii, the researchers performed a spectrographic analysis of the galaxy to determine its redshift.

    Keck MOSFIRE
    MOSFIRE

    Keck Observatory
    Keck Observatory Interior
    Keck Observatory

    Redshift results from the Doppler effect, the same phenomenon that causes the siren on a fire truck to drop in pitch as the truck passes. With celestial objects, however, it is light that is being “stretched” rather than sound; instead of an audible drop in tone, there is a shift from the actual color to redder wavelengths.

    Redshift is traditionally used to measure distance to galaxies, but is difficult to determine when looking at the universe’s most distant—and thus earliest—objects. Immediately after the Big Bang, the universe was a soup of charged particles—electrons and protons—and light (photons). Because these photons were scattered by free electrons, the early universe could not transmit light. By 380,000 years after the Big Bang, the universe had cooled enough for free electrons and protons to combine into neutral hydrogen atoms that filled the universe, allowing light to travel through the cosmos. Then, when the universe was just a half-billion to a billion years old, the first galaxies turned on and reionized the neutral gas. The universe remains ionized today.

    Prior to reionization, however, clouds of neutral hydrogen atoms would have absorbed certain radiation emitted by young, newly forming galaxies—including the so-called Lyman-alpha line, the spectral signature of hot hydrogen gas that has been heated by ultraviolet emission from new stars, and a commonly used indicator of star formation.

    Because of this absorption, it should not, in theory, have been possible to observe a Lyman-alpha line from EGS8p7.

    “If you look at the galaxies in the early universe, there is a lot of neutral hydrogen that is not transparent to this emission,” says Zitrin. “We expect that most of the radiation from this galaxy would be absorbed by the hydrogen in the intervening space. Yet still we see Lyman-alpha from this galaxy.”

    They detected it using the MOSFIRE spectrometer, which captures the chemical signatures of everything from stars to the distant galaxies at near-infrared wavelengths (0.97-2.45 microns, or millionths of a meter).

    “The surprising aspect about the present discovery is that we have detected this Lyman-alpha line in an apparently faint galaxy at a redshift of 8.68, corresponding to a time when the universe should be full of absorbing hydrogen clouds,” Ellis says. Prior to their discovery, the farthest detected galaxy had a redshift of 7.73.

    One possible reason the object may be visible despite the hydrogen-absorbing clouds, the researchers say, is that hydrogen reionization did not occur in a uniform manner. “Evidence from several observations indicate that the reionization process probably is patchy,” Zitrin says. “Some objects are so bright that they form a bubble of ionized hydrogen. But the process is not coherent in all directions.”

    “The galaxy we have observed, EGS8p7, which is unusually luminous, may be powered by a population of unusually hot stars, and it may have special properties that enabled it to create a large bubble of ionized hydrogen much earlier than is possible for more typical galaxies at these times,” says Sirio Belli, a Caltech graduate student who worked on the project.

    “We are currently calculating more thoroughly the exact chances of finding this galaxy and seeing this emission from it, and to understand whether we need to revise the timeline of the reionization, which is one of the major key questions to answer in our understanding of the evolution of the universe,” Zitrin says.

    The paper was co-authored by Ivo Labbe, Rychard Bouwens, Guido Roberts-Borsani, Daniel P. Stark, Pascal A. Oesch, and Renske Smit. The research was sponsored by NASA through a Hubble Fellowship, the Institute of Astronomy at the University of Edinburgh, and the National Science Foundation. MOSFIRE was made possible by funding provided by the National Science Foundation and astronomy benefactors Gordon and Betty Moore. Cooperating institutions include Yale University, the University of Arizona, University College London, Leiden University (Netherlands), and the University of Durham (UK).

    See the full article here.

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
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  • richardmitnick 3:06 pm on August 13, 2015 Permalink | Reply
    Tags: , , Keck Observatory   

    From Keck: “Hot Jupiter-esque Discovery Hints at Planet Formation” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    August 13, 2015
    SCIENCE CONTACTS
    Bruce Macintosh
    Department of Physics, Stanford University
    (650) 725-4116
    bmacintosh@stanford.edu

    Franck Marchis
    SETI Institute
    650-960-4236
    fmarchis@seti.org

    Eric Nielson
    SETI Institute
    408-394-4582
    enielsen@seti.org

    MEDIA CONTACT
    Steve Jefferson
    W. M. Keck Observatory
    808-881-3827
    sjefferson@keck.hawaii.edu

    1

    A team of astronomers discovered a Jupiter-like planet within a young system that could serve as a decoder ring for understanding how planets formed around our sun. The W. M. Keck Observatory on Maunakea, Hawaii confirmed the discovery. The findings were headed by Bruce Macintosh, a professor of physics at Stanford University, and show the new planet, 51 Eridani b, is one million times fainter than its parent star and shows the strongest methane signature ever detected on an alien planet, which should yield additional clues as to how the planet formed. The results are published in the current issue of Science.

    “This is the first exoplanet discovered with the Gemini Planet Imager [GPI], one of the new generation instruments designed specifically for discovering and analyzing faint, young planets orbiting bright stars,” said Franck Marchis, Senior Planetary Astronomer at the SETI Institute and member of the team that built the instrument and now conducts the survey.

    Gemini Planet Imager
    GPI

    While NASA’s Kepler space observatory has discovered thousands of planets, it does so indirectly by detecting a loss of starlight as a planet passes in front of its star, the Gemini Planet Imager was designed specifically for discovering and analyzing faint, young planets orbiting bright stars.

    NASA Kepler Telescope
    Kepler

    “To detect planets, Kepler sees their shadow,” said Macintosh, who is also a member of the Kavli Institute for Particle Astrophysics and Cosmology. “The Gemini Planet Imager instead sees their glow, which we refer to as direct imaging.”

    Akin to trying to detect a firefly in front of a lighthouse, the team analyzed the light from the star, then blocked it out. The remaining incoming light was analyzed, with the brightest spots indicating a possible planet.

    The team then turned to the largest optical/infrared telescopes on Earth at Keck Observaotry to verify their findings.

    “Observations using the NIRC2 camera and adaptive optics system at the Keck Observatory allowed the GPI team to independently verify the existence of the planet,” Macintosh said.

    Keck NIRC2 Camera
    NIRC2

    “NIRC2 can observe at longer infrared wavelengths than GPI, where a cool planet like 51 Eri b is brighter. These longer-wavelength observations helped to measure the properties of clouds in the planet’s atmosphere that absorb and re-radiate infrared emission.”

    “The Keck Observatory data was crucial to confirm the existence of the planet, and to properly characterize its atmosphere,” said Christian Marois, an astronomer at the University of Victoria, Canada. “With a versatile set of instruments and a larger primary mirror, the Keck Observatory telescopes provide the perfect platform to verify these findings.”

    Last year, the GPI was installed on the 8-meter Gemini South Telescope in Chile, and the team set out to look for planets orbiting nearly 100 young stars so far.

    Gemini South telescope
    Gemini South Interior
    Gemini South

    The host star, 51 Eri, is very young, a mere 20 million years old, and is slightly hotter than the Sun. The exoplanet 51 Eri b, whose mass is estimated to be roughly twice that of Jupiter, appears to orbit its host star at a distance 13 times greater than the Earth-Sun distance. If placed in our own solar system, 51 Eri b’s orbit would lie between those of Saturn and Neptune.

    “51 Eri has everything we’re looking for in a target star,” notes Eric Nielsen, a postdoctoral fellow at the SETI Institute. “It’s relatively close and young. Indeed, the last dinosaur died 40 million years before this star was even born.”

    As far as the cosmic clock is concerned, 20 million years is young, and that is exactly what made the direct detection of the planet possible. When planets coalesce, material falling into the planet releases energy and heats it up. Over the next hundred million years the planet radiates that energy away, mostly as infrared light.

    In addition to being the lowest-mass planet ever imaged, it’s also one of the coldest – 800 degrees Fahrenheit, whereas others are around 1,200 F – and features the strongest atmospheric methane signal on record. Previous Jupiter-like exoplanets have shown only faint traces of methane, far different from the heavy methane atmospheres of the gas giants in our solar system.

    “In the atmospheres of the cold giant planets of our solar system, carbon is found as methane, unlike most exoplanets, where carbon has mostly been found in the form of carbon monoxide,” said Mark Marley, an astrophysicist at NASA Ames Research Center. “Since the atmosphere of 51 Eri b is also methane rich, it signifies that this planet is well on its way to becoming a cousin of our own familiar Jupiter.”

    All of these characteristics, the researchers say, point to a planet that is very much what models suggest Jupiter was like in its infancy. Of course, it’s not exactly like Jupiter – its 800 F temperature is still hot enough to melt lead – but there are signs it will evolve into a familiar shape.

    In addition to expanding the universe of known planets, GPI will provide key clues as to how solar systems form. Astronomers believe that the gas giants in our solar system formed by building up a large core over a few million years and then pulling in a huge amount of hydrogen and other gases to form an atmosphere.

    But the Jupiter-like exoplanets that have so far been discovered are much hotter than models have predicted, hinting that they could have formed much faster as material collapses quickly to make a very hot planet. This is an important difference. The core-buildup process can also form rocky planets like Earth; a fast and hot collapse might only make giant gassy planets. 51 Eridani b is young enough that it “remembers” its formation.

    “51 Eri b is the first one that’s cold enough and close enough to the star that it could have indeed formed right where it is the ‘old-fashioned way,” Macintosh said. “This planet really could have formed the same way Jupiter did – the whole solar system could be a lot like ours.”

    There are hundreds of planets a little bigger than Earth out there, Macintosh said, but there is so far no way to know if most of them are really “super-Earths” or just micro-sized gas and ice planets like Neptune, or something different altogether. Studying younger solar systems such as 51 Eridani will help astronomers understand the formation of our neighbor planets, and how common that planet-forming mechanism is throughout the universe.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

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    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.
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  • richardmitnick 1:37 pm on August 5, 2015 Permalink | Reply
    Tags: , , Keck Observatory, Reionization   

    From Keck: “New Record: Keck Observatory Measures Most Distant Galaxy” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    August 5, 2015
    SCIENCE CONTACTS
    Adi Zitrin
    California Institute of Technology
    adizitrin@gmail.com
    626-278-5854

    Richard Ellis
    California Institute of Technology
    rse@astro.caltech.edu
    626-676-5530

    MEDIA CONTACT
    Steve Jefferson
    W. M. Keck Observatory
    sjefferson@keck.hawaii.edu
    808-881-3827

    1
    Credit: Adi Zitrin, California Institute of Technology, 2015

    EGSY8p7 is the most distant confirmed galaxy whose spectrum obtained with the W. M. Keck Observatory places it at a redshift of 8.68 at a time when the Universe was less than 600 million years old. The illustration shows the remarkable progress made in recent years in probing early cosmic history. Such studies are important in understanding how the Universe evolved from an early dark period to one when galaxies began to shine. Hydrogen emission from EGSY8p7 may indicate it is the first known example of an early generation of young galaxies emitting unusually strong radiation.

    A team of astrophysicists using the W. M. Keck Observatory in Hawaii has successfully measured the farthest galaxy ever recorded and more interestingly, captured its hydrogen emission as seen when the Universe was less than 600 million years old. Additionally, the method in which the galaxy called EGSY8p7 was detected gives important insight into how the very first stars in the Universe lit-up after the Big Bang. The paper will be published shortly in the Astrophysical Journal Letters.

    Using Keck Observatory’s powerful infrared spectrograph called MOSFIRE, the team dated the galaxy by detecting its Lyman-alpha emission line – a signature of hot hydrogen gas heated by strong ultraviolet emission from newly born stars.

    Keck MOSFIRE
    MOSFIRE

    Although this is a frequently detected signature in galaxies close to Earth, the detection of Lyman-alpha emission at such a great distance is unexpected as it is easily absorbed by the numerous hydrogen atoms thought to pervade the space between galaxies at the dawn of the Universe. The result gives new insight into `cosmic reionization’, the process by which dark clouds of hydrogen were split into their constituent protons and electrons by the first generation of galaxies.

    “We frequently see the Lyman-alpha emission line of hydrogen in nearby objects as it is one of most reliable tracers of star-formation,” said California Institute of Technology (Caltech) astronomer, Adi Zitrin, lead author of the discovery paper. “However, as we penetrate deeper into the Universe, and hence back to earlier times, the space between galaxies contains an increasing number of dark clouds of hydrogen which absorb this signal.”

    Recent work has found the fraction of galaxies showing this prominent line declines markedly after when the Universe was about a billion years old, which is equivalent to a redshift of about 6. Redshift is a measure of how much the Universe has expanded since the light left a distant source and can only be determined for faint objects with a spectrograph on a powerful large telescope such as the Keck Observatory’s twin 10-meter telescopes, the largest on Earth.

    “The surprising aspect about the present discovery is that we have detected this Lyman-alpha line in an apparently faint galaxy at a redshift of 8.68, corresponding to a time when the Universe should be full of absorbing hydrogen clouds,” said co-author and Caltech astronomer Richard Ellis. “Quite apart from breaking the earlier record redshift of 7.73, also obtained at the Keck Observatory, this detection is telling us something new about how the Universe evolved in its first few hundred million years.”

    Computer simulations of cosmic reionization suggest the Universe was fully opaque to Lyman-alpha radiation in the first 400 million years of cosmic history and then gradually, as the first galaxies were born, the intense ultraviolet radiation from their young stars, burned off this obscuring hydrogen in bubbles of increasing radius which, eventually, overlapped so the entire space between galaxies became `ionized’, that is composed of free electrons and protons. At this point the Lyman-alpha radiation was free to travel through space unimpeded.

    It may be that the galaxy we have observed, EGSY8p7, which is unusually (intrinsically) luminous, has special properties that enabled it to create a large bubble of ionized hydrogen much earlier than is possible for more typical galaxies at these times,” said Sirio Belli, a Caltech graduate student who helped undertake the key observations. “EGSY8p7 was found to be both luminous and at high redshift, and its colors measured by the Hubble and Spitzer Space Telescopes indicate it may be powered by a population of unusually hot stars.”

    Because the discovery of such an early source with powerful Lyman-alpha is somewhat unexpected, it provides new insight into the manner by which galaxies contributed to the process of reionization. Conceivably the process is patchy with some regions of space evolving faster than others, for example due to variations in the density of matter from place to place. Alternatively, EGSY8p7 may be the first example of an early generation which unusually strong ionizing radiation.

    “In some respects, the period of cosmic reionization is the final missing piece in our overall understanding of the evolution of the Universe,” says Zitrin. “In addition to pushing back the frontier to a time when the Universe was only 600 million years old, what is exciting about the present discovery is that the study of sources such as EGSY8p7 will offer new insight into how this process occurred.”

    The Caltech team reporting on this discovery consists of Zitrin, Ellis, and Belli who lead an international collaboration involving astronomers at Yale and the University of Arizona, and fellow European researchers from Leiden University in the Netherlands and the University of Durham and the Univeristy College London in England.

    The research was funded in part by NASA.

    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.
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  • richardmitnick 4:54 pm on July 31, 2015 Permalink | Reply
    Tags: , , , Keck Observatory   

    From Keck: “Keck Observatory Astronomer Wins Major Prize” Andrea Ghez 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    July 31, 2015
    Christopher Dibble

    1
    Andrea Ghez, Keck Observatory astronomer and UCLA’s Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics.

    UCLA professor and longtime W. M. Keck Observatory astronomer, Andrea Ghez will be awarded the 2015 Bakerian Medal, the Royal Society’s premiere prize lecture in the physical sciences, the organization announced this week.

    “I’m thrilled to receive the Bakerian Medal from the Royal Society,” said Ghez, who is UCLA’s Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics. “The research that is being recognized is the product of a wonderful collaboration among the scientists in the UCLA Galactic Center Group and the University of California’s tremendous investment in the W. M. Keck Observatory. Having cutting-edge tools and a great team makes discovery easy.”

    The medal is accompanied by a cash prize of 10,000 pounds (approximately $15,500), and Ghez will deliver the Bakerian Lecture in London in November. The organization, the oldest scientific academy in continuous existence, cited Ghez’s “acclaimed discoveries using the techniques of optical astronomy, especially her sustained work on the motions and nature of the stars orbiting the black hole in the centre of our Galaxy.”

    “All the data for this project came from Keck Observatory,” Ghez said. “We were able to launch this project 20 years ago because of the unique way that Keck Observatory works. We were able to modify instrumentation and try new approaches to data collection in a way that simply isn’t possible at other observatories. Working at Keck Observatory and with the staff there has been an amazing experience.”

    Since 1995, Ghez has used the Keck Observatory, which sits near the summit of Hawaii’s dormant volcano Maunakea, to study the rotational center of the Milky Way and the movement of thousands of stars close to this galactic center. Keck Observatory operates the two largest and most scientifically productive telescopes on Earth.

    Ghez, a 2008 MacArthur Fellow, uses novel, ground-based telescopic techniques to remove the blurring effects of the Earth’s atmosphere, making the sharpest possible images of the center of our galaxy.

    By measuring the orbits of stars at the center of our galaxy, she showed that a monstrous black hole resides at the center of our Milky Way galaxy, some 26,000 light-years away from Earth, with a mass 4 million times that of the sun. The finding provided the best evidence yet that supermassive black holes exist in our universe. Ghez and her research team have revealed many unexpected mysteries about the role that black holes play in the formation and evolution of galaxies.

    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.
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  • richardmitnick 3:42 pm on July 30, 2015 Permalink | Reply
    Tags: , , Keck Observatory,   

    From Keck: “Telescopes Team Up to Find Distant Uranus-Sized Planet Through Microlensing” 

    Keck Observatory

    Keck Observatory

    Keck Observatory

    July 30, 2015
    SCIENCE CONTACT
    Dave Bennett
    University of Notre Dame
    bennett@nd.edu
    574-315-6621

    Jean-Phillipe Beaulieu
    Institut d’Astrophysique de Paris
    Beaulieu@iap.fr
    +33 6 03 98 73 11

    MEDIA CONTACT
    Steve Jefferson
    W. M. Keck Observatory
    sjefferson@keck.hawaii.edu
    808-881-3827

    1
    Credit: NASA, ESA, and A. Feild (STScI)

    The W. M. Keck Observatory in Hawaii and NASA’s Hubble Space Telescope have made independent confirmations of an exoplanet orbiting far from its central star.

    NASA Hubble Telescope
    NASA/ESA Hubble

    The planet was discovered through a technique called gravitational microlensing. This finding opens a new piece of discovery space in the extrasolar planet hunt: to uncover planets as far from their central stars as Jupiter and Saturn are from our sun. The Hubble and Keck Observatory results will appear in two papers in the July 30 edition of The Astrophysical Journal.

    The large majority of exoplanets cataloged so far are very close to their host stars because several current planet-hunting techniques favor finding planets in short-period orbits. But this is not the case with the microlensing technique, which can find more distant and colder planets in long-period orbits that other methods cannot detect.

    Microlensing occurs when a foreground star amplifies the light of a background star that momentarily aligns with it. If the foreground star has planets, then the planets may also amplify the light of the background star, but for a much shorter period of time than their host star. The exact timing and amount of light amplification can reveal clues to the nature of the foreground star and its accompanying planets.

    “Microlensing is currently the only method to detect the planets close to their birth place,” said team member, Jean-Philippe Beaulieu, Institut d’Astrophysique de Paris. “Indeed, planets are being mostly formed at a certain distance from the central star where it is cold enough for volatile compounds to condense into solid ice grains. These grains will then aggregate and will ultimately evolve into planets.”

    The system, cataloged as OGLE-2005-BLG-169, was discovered in 2005 by the Optical Gravitational Lensing Experiment (OGLE), the Microlensing Follow-Up Network (MicroFUN), and members of the Microlensing Observations in Astrophysics (MOA) collaborations—groups that search for extrasolar planets through gravitational microlensing.

    Without conclusively identifying and characterizing the foreground star, however, astronomers have had a difficult time determining the properties of the accompanying planet. Using Hubble and the Keck Observatory, two teams of astronomers have now found that the system consists of a Uranus-sized planet orbiting about 370 million miles from its parent star, slightly less than the distance between Jupiter and the sun. The host star, however, is about 70 percent as massive as our sun.

    “These chance alignments are rare, occurring only about once every 1 million years for a given planet, so it was thought that a very long wait would be required before the planetary microlensing signal could be confirmed,” said David Bennett, the lead of the team that analyzed the Hubble data. “Fortunately, the planetary signal predicts how fast the apparent positions of the background star and planetary host star will separate, and our observations have confirmed this prediction. The Hubble and Keck Observatory data, therefore, provide the first confirmation of a planetary microlensing signal.”

    In fact, microlensing is such a powerful tool that it can uncover planets whose host stars cannot be seen by most telescopes. “It is remarkable that we can detect planets orbiting unseen stars, but we’d really like to know something about the stars that these planets orbit,” explained Virginie Batista, leader of the Keck Observatory analysis. “The Keck and Hubble telescopes allow us to detect these faint planetary host stars and determine their properties.”

    Planets are small and faint compared to their host stars; only a few have been observed directly outside our solar system. Astronomers often rely on two indirect techniques to hunt for extrasolar planets. The first method detects planets by the subtle gravitational tug they give to their host stars. In another method, astronomers watch for small dips in the amount of light from a star as a planet passes in front of it.

    Both of these techniques work best when the planets are either extremely massive or when they orbit very close to their parent stars. In these cases, astronomers can reliably determine their short orbital periods, ranging from hours to days to a couple years.

    But to fully understand the architecture of distant planetary systems, astronomers must map the entire distribution of planets around a star. Astronomers, therefore, need to look farther away from the star—from about the distance of Jupiter is from our sun, and beyond.

    “It’s important to understand how these systems compare with our solar system,” said team member Jay Anderson of the Space Telescope Science Institute in Baltimore, MD. “So we need a complete census of planets in these systems. Gravitational microlensing is critical in helping astronomers gain insights into planetary formation theories.”

    The planet in the OGLE system is probably an example of a “failed-Jupiter” planet, an object that begins to form a Jupiter-like core of rock and ice weighing around 10 Earth masses, but it doesn’t grow fast enough to accrete a significant mass of hydrogen and helium. So it ends up with a mass more than 20 times smaller than that of Jupiter. “Failed-Jupiter planets, like OGLE-2005-BLG-169Lb, are predicted to be more common than Jupiters, especially around stars less massive than the sun, according to the preferred theory of planet formation. So this type of planet is thought to be quite common,” Bennett said.

    Microlensing takes advantage of the random motion of stars, which are generally too small to be noticed without precise measurements. If one star, however, passes nearly precisely in front of a farther background star, the gravity of the foreground star acts like a giant lens, magnifying the light from the background star.

    A planetary companion around the foreground star can produce a variation in the brightening of the background star. This brightening fluctuation can reveal the planet, which can be too faint, in some cases, to be seen by telescopes. The duration of an entire microlensing event is several months, while the variation in brightening due to a planet lasts a few hours to a couple of days.

    The initial microlensing data of OGLE-2005-BLG-169 had indicated a combined system of foreground and background stars plus a planet. But due to the blurring effects of our atmosphere, a number of unrelated stars are also blended with the foreground and background stars in the very crowded star field in the direction of our galaxy’s center.

    “The Hubble Space telescope and KECK2 are unique facilities providing complementary high angular resolution observations to characterise these cold planets orbiting very distant stars,” Beaulieu said.

    The sharp Hubble and Keck Observatory images allowed the research teams to separate out the background source star from its neighbors in the very crowded star field in the direction of our galaxy’s center. Although the Hubble images were taken 6.5 years after the lensing event, the source and lens star were still so close together on the sky that their images merged into what looked like an elongated stellar image.

    Astronomers can measure the brightness of both the source and planetary host stars from the elongated image. When combined with the information from the microlensing light curve, the lens brightness reveals the masses and orbital separation of the planet and its host star, as well as the distance of the planetary system from Earth. The foreground and background stars were observed in several different colors with Hubble’s Wide Field Camera 3 (WFC3), allowing independent confirmations of the mass and distance determinations.

    NASA Hubble WFC3
    WFC3

    The observations, taken with the Near Infrared Camera 2 (NIRC2) on the Keck 2 telescope more than eight years after the microlensing event, provided a precise measurement of the foreground and background stars’ relative motion.

    Keck NIRC2
    NIRC2

    “It is the first time we were able to completely resolve the source star and the lensing star after a microlensing event. This enabled us to discriminate between two models that fit the data of the microlensing light curve,” Batista said.

    The Hubble and Keck Observatory data are providing proof of concept for the primary method of exoplanet detection that will be used by NASA’s planned, space-based Wide-Field Infrared Survey Telescope (WFIRST), which will allow astronomers to determine the masses of planets found with microlensing.

    NASA WFIRST telescope
    WFIRST

    WFIRST will have Hubble’s sharpness to search for exoplanets using the microlensing technique. The telescope will be able to observe foreground, planetary host stars approaching the background source stars prior to the microlensing events, and receding from the background source stars after the microlensing events.

    “WFIRST will make measurements like we have made for OGLE-2005-BLG-169 for virtually all the planetary microlensing events it observes. We’ll know the masses and distances for the thousands of planets discovered by WFIRST,” Bennett explained.

    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.
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