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  • richardmitnick 1:31 pm on July 20, 2017 Permalink | Reply
    Tags: , Astrophysics, , Cluster galaxies, , field galaxies, Scientists Get Best Measure of Star-forming Material in Galaxy Clusters in Early Universe, SpARCS-Spitzer Adaptation of the Red-sequence Cluster Survey,   

    From UC Riverside: “Scientists Get Best Measure of Star-forming Material in Galaxy Clusters in Early Universe” 

    UC Riverside bloc

    UC Riverside

    July 20, 2017
    Iqbal Pittalwala

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    The Tadpole Galaxy is a disrupted spiral galaxy showing streams of gas stripped by gravitational interaction with another galaxy. Molecular gas is the required ingredient to form stars in galaxies in the early universe. Credit: Hubble Legacy Archive, ESA, NASA and Bill Snyder.

    The international Spitzer Adaptation of the Red-sequence Cluster Survey (SpARCS) collaboration based at the University of California, Riverside has combined observations from several of the world’s most powerful telescopes to carry out one of the largest studies yet of molecular gas – the raw material which fuels star formation throughout the universe – in three of the most distant clusters of galaxies ever found, detected as they appeared when the universe was only four billion years old.

    Results were recently published in The Astrophysical Journal Letters. Allison Noble, a postdoctoral researcher at the Massachusetts Institute of Technology, led this newest research from the SpARCS collaboration.

    Clusters are rare regions of the universe consisting of tight groups of hundreds of galaxies containing trillions of stars, as well as hot gas and mysterious dark matter. First, the research team used spectroscopic observations from the W. M. Keck Observatory on Maunakea, Hawai’i, and the Very Large Telescope in Chile that confirmed 11 galaxies were star-forming members of the three massive clusters.


    Keck Observatory, Maunakea, Hawaii, USA

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

    Next, the researchers took images through multiple filters from NASA’s Hubble Space Telescope, which revealed a surprising diversity in the galaxies’ appearance, with some galaxies having already formed large disks with spiral arms.

    NASA/ESA Hubble Telescope

    One of the telescopes the SpARCS scientists used is the extremely sensitive Atacama Large Millimeter Array (ALMA) telescope capable of directly detecting radio waves emitted from the molecular gas found in galaxies in the early universe.

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

    ALMA observations allowed the scientists to determine the amount of molecular gas in each galaxy, and provided the best measurement yet of how much fuel was available to form stars.

    The researchers compared the properties of galaxies in these clusters with the properties of “field galaxies” (galaxies found in more typical environments with fewer close neighbors). To their surprise, they discovered that cluster galaxies had higher amounts of molecular gas relative to the amount of stars in the galaxy, compared to field galaxies. The finding puzzled the team because it has long been known that when a galaxy falls into a cluster, interactions with other cluster galaxies and hot gas accelerate the shut off of its star formation relative to that of a similar field galaxy (the process is known as environmental quenching).

    “This is definitely an intriguing result,” said Gillian Wilson, a professor of physics and astronomy at UC Riverside and the leader of the SpARCS collaboration. “If cluster galaxies have more fuel available to them, you might expect them to be forming more stars than field galaxies, and yet they are not.”

    Noble, a SpARCS collaborator and the study’s leader, suggests several possible explanations: It is possible that something about being in the hot, harsh cluster environment surrounded by many neighboring galaxies perturbs the molecular gas in cluster galaxies such that a smaller fraction of that gas actively forms stars. Alternatively, it is possible that an environmental process, such as increased merging activity in cluster galaxies, results in the observed differences between the cluster and field galaxy populations.

    “While the current study does not answer the question of which physical process is primarily responsible for causing the higher amounts of molecular gas, it provides the most accurate measurement yet of how much molecular gas exists in galaxies in clusters in the early universe,” Wilson said.

    The SpARCS team has developed new techniques using infrared observations from NASA’s Spitzer Space Telescope to identify hundreds of previously undiscovered clusters of galaxies in the early universe.

    NASA/Spitzer Telescope

    In the future, they plan to study a larger sample of clusters. The team has recently been awarded additional time on ALMA, the W. M. Keck Observatory, and the Hubble Space Telescope to continue investigating how the neighborhood in which a galaxy lives determines for how long it can form stars.

    See the full article here .

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    UC Riverside Campus

    The University of California, Riverside is one of 10 universities within the prestigious University of California system, and the only UC located in Inland Southern California.

    Widely recognized as one of the most ethnically diverse research universities in the nation, UCR’s current enrollment is more than 21,000 students, with a goal of 25,000 students by 2020. The campus is in the midst of a tremendous growth spurt with new and remodeled facilities coming on-line on a regular basis.

    We are located approximately 50 miles east of downtown Los Angeles. UCR is also within easy driving distance of dozens of major cultural and recreational sites, as well as desert, mountain and coastal destinations.

     
  • richardmitnick 11:33 am on July 20, 2017 Permalink | Reply
    Tags: , Astrophysics, , , Cygnus X-1: NASA's Chandra Adds to Black Hole Birth Announcement 2011,   

    From Chandra: “Cygnus X-1: NASA’s Chandra Adds to Black Hole Birth Announcement” 2011 

    NASA Chandra Banner

    NASA Chandra Telescope

    NASA Chandra

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    Credit Optical: DSS; Illustration: NASA/CXC/M.Weiss

    Cygnus X-1 is a black hole about 15 times the mass of the Sun in orbit with a massive blue companion star.

    Astronomers used several telescopes including Chandra to study Cygnus X-1.

    The combined data have revealed the spin, mass, and distance of this black hole more precisely than ever before.

    Stephen Hawking lost a bet — originally placed in 1974 — that Cygnus X-1 did not contain a black hole.

    On the left, an optical image from the Digitized Sky Survey shows Cygnus X-1, outlined in a red box. Cygnus X-1 is located near large active regions of star formation in the Milky Way, as seen in this image that spans some 700 light years across. An artist’s illustration on the right depicts what astronomers think is happening within the Cygnus X-1 system. Cygnus X-1 is a so-called stellar-mass black hole, a class of black holes that comes from the collapse of a massive star. The black hole pulls material from a massive, blue companion star toward it. This material forms a disk (shown in red and orange) that rotates around the black hole before falling into it or being redirected away from the black hole in the form of powerful jets.

    A trio of papers with data from radio, optical and X-ray telescopes, including NASA’s Chandra X-ray Observatory, has revealed new details about the birth of this famous black hole that took place millions of years ago.

    The Extreme Spin of the Black Hole in Cygnus X-1 ApJ in press

    The Mass of the Black Hole in Cygnus X-1 ApJ in press

    The Trigonometric Parallax of Cygnus X-1 ApJ in press

    Using X-ray data from Chandra, the Rossi X-ray Timing Explorer, and the Advanced Satellite for Cosmology and Astrophysics, scientists were able to determine the spin of Cygnus X-1 with unprecedented accuracy, showing that the black hole is spinning at very close to its maximum rate. Its event horizon — the point of no return for material falling towards a black hole — is spinning around more than 800 times a second.

    NASA RXTE

    JAXA ASCA ASTRO-D satellite

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    Chandra X-ray of Cygnus X-1.

    Using optical observations of the companion star and its motion around its unseen companion, the team also made the most precise determination ever for the mass of Cygnus X-1, of 14.8 times the mass of the Sun. It was likely to have been almost this massive at birth, because of lack of time for it to grow appreciably.

    The researchers also announced that they have made the most accurate distance estimate yet of Cygnus X-1 using the National Radio Observatory’s Very Long Baseline Array (VLBA).

    NRAO VLBA

    The new distance is about 6,070 light years from Earth. This accurate distance was a crucial ingredient for making the precise mass and spin determinations.

    See the full article here .

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    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

     
  • richardmitnick 11:05 am on July 20, 2017 Permalink | Reply
    Tags: , Astrophysics, , , CTIO 36 Inch (.91 meter) Telescope, DLR/NASA ROSAT satellite, , RX J0822-4300 in Puppis A: Chandra Discovers Cosmic Cannonball   

    From Chandra: “RX J0822-4300 in Puppis A: Chandra Discovers Cosmic Cannonball” 2007 

    NASA Chandra Banner

    NASA Chandra Telescope

    NASA Chandra

    November 28, 2007

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    Credit Chandra: NASA/CXC/Middlebury College/F.Winkler et al; ROSAT: NASA/GSFC/S.Snowden et al.; Optical: NOAO/AURA/NSF/Middlebury College/F.Winkler et al.

    This graphic shows a wide-field view of the Puppis A supernova remnant along with a close-up image of the neutron star, known as RX J0822-4300, that is moving at a blistering pace. The larger field-of-view is a composite of X-ray data from the ROSAT satellite (pink) and optical data (purple), from the Cerro Tololo Inter-American Observatory 0.9-meter telescope, which highlights oxygen emission.

    DLR/NASA ROSAT satellite


    CTIO 36 Inch (.91 meter) Telescope

    Astronomers think Puppis A was created when a massive star ended its life in a supernova explosion about 3,700 years ago, forming an incredibly dense object called a neutron star and releasing debris into space.

    The neutron star was ejected by the explosion. The inset box shows two observations of this neutron star obtained with the Chandra X-ray Observatory over the span of five years, between December 1999 and April 2005. By combining how far it has moved across the sky with its distance from Earth, astronomers determined the cosmic cannonball is moving at over 3 million miles per hour, one of the fastest moving stars ever observed. At this rate, RX J0822-4300 is destined to escape from the Milky Way after millions of years, even though it has only traveled about 20 light years so far.

    The results from this study suggest the supernova explosion was lop-sided, kicking the neutron star in one direction and much of the debris from the explosion in the other. The estimated location of the explosion is shown in a labeled version of the composite image. The direction of motion of the cannonball, shown by an arrow, is in the opposite direction to the overall motion of the oxygen debris, seen in the upper left. In each case, the arrows show the estimated motion over the next 1,000 years. The oxygen clumps are believed to be massive enough so that momentum is conserved in the aftermath of the explosion, as required by fundamental physics.

    Science paper:
    EXPANDING EJECTA IN THE OXYGEN-RICH SUPERNOVA REMNANT G292.0+1.8: DIRECT MEASUREMENT THROUGH PROPER MOTIONS The Astrophysical Journal.

    See the full article here .

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    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

     
  • richardmitnick 9:39 am on July 20, 2017 Permalink | Reply
    Tags: , , Astrophysics, , ,   

    From NASA- “Asteroids: In Depth” 

    NASA image
    NASA

    Undated
    No writer credit

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    Artist’s rendering of the the Near Earth Asteroid Rendezvous (NEAR) spacecraft’s rendezvous with the asteroid Eros. NASA.

    Asteroids, sometimes called minor planets, are rocky remnants left over from the early formation of our solar system about 4.6 billion years ago.

    Most of this ancient space rubble can be found orbiting the sun between Mars and Jupiter within the main asteroid belt. Asteroids range in size from Vesta – the largest at about 329 miles (530 kilometers) in diameter – to bodies that are less than 33 feet (10 meters) across. . The total mass of all the asteroids combined is less than that of Earth’s Moon.

    Editor’s note: Even with more than one-half million asteroids known (and there are probably many more), they are still much more widely separated than sometimes seen in Hollywood movies: on average, their separation is in excess of 1-3 million km (depending on how one calculates it).

    Most asteroids are irregularly shaped, though a few are nearly spherical, and they are often pitted or cratered. As they revolve around the sun in elliptical orbits, the asteroids also rotate, sometimes quite erratically, tumbling as they go. More than 150 asteroids are known to have a small companion moon (some have two moons). There are also binary (double) asteroids, in which two rocky bodies of roughly equal size orbit each other, as well as triple asteroid systems.

    The three broad composition classes of asteroids are C-, S-, and M-types. The C-type (chondrite) asteroids are most common, probably consist of clay and silicate rocks, and are dark in appearance. They are among the most ancient objects in the solar system. The S-types (“stony”) are made up of silicate materials and nickel-iron. The M-types are metallic (nickel-iron). The asteroids’ compositional differences are related to how far from the sun they formed. Some experienced high temperatures after they formed and partly melted, with iron sinking to the center and forcing basaltic (volcanic) lava to the surface. Only one such asteroid, Vesta, survives to this day.

    Jupiter’s massive gravity and occasional close encounters with Mars or another object change the asteroids’ orbits, knocking them out of the main belt and hurling them into space in all directions across the orbits of the other planets. Stray asteroids and asteroid fragments slammed into Earth and the other planets in the past, playing a major role in altering the geological history of the planets and in the evolution of life on Earth.

    Scientists continuously monitor Earth-crossing asteroids, whose paths intersect Earth’s orbit, and near-Earth asteroids that approach Earth’s orbital distance to within about 45 million kilometers (28 million miles) and may pose an impact danger. Radar is a valuable tool in detecting and monitoring potential impact hazards. By reflecting transmitted signals off objects, images and other information can be derived from the echoes. Scientists can learn a great deal about an asteroid’s orbit, rotation, size, shape, and metal concentration.

    Several missions have flown by and observed asteroids. The Galileo spacecraft flew by asteroids Gaspra in 1991 and Ida in 1993; the Near-Earth Asteroid Rendezvous (NEAR-Shoemaker) mission studied asteroids Mathilde and Eros;

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    https://www.britannica.com/topic/Near-Earth-Asteroid-Rendezvous-Shoemaker

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    The Near Earth Asteroid Rendezvous (NEAR) Shoemaker spacecraft being assembled. NASA.

    and the Rosetta mission encountered Steins in 2008 and Lutetia in 2010.

    ESA/Rosetta spacecraft

    Deep Space 1 and Stardust both had close encounters with asteroids.

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    Deep Space 1. NASA.

    NASA Stardust spacecraft

    In 2005, the Japanese spacecraft Hayabusa landed on the near-Earth asteroid Itokawa and attempted to collect samples. On June 3, 2010, Hayabusa successfully returned to Earth a small amount of asteroid dust now being studied by scientists.

    JAXA/Hayabusa 2

    NASA’s Dawn spacecraft, launched in 2007, orbited and explored asteroid Vesta for over a year.

    NASA/Dawn Spacecraft

    Once it left in September 2012, it headed towards dwarf planet Ceres, with a planned arrival of 2015. Vesta and Ceres are two of the largest surviving protoplanet bodies that almost became planets. By studying them with the same complement of instruments on board the same spacecraft, scientists will be able to compare and contrast the different evolutionary path each object took to help understand the early solar system overall.

    Asteroid Classifications

    Main asteroid belt: The majority of known asteroids orbit within the asteroid belt between Mars and Jupiter, generally with not very elongated orbits. The belt is estimated to contain between 1.1 and 1.9 million asteroids larger than 1 kilometer (0.6 mile) in diameter, and millions of smaller ones. Early in the history of the solar system, the gravity of newly formed Jupiter brought an end to the formation of planetary bodies in this region and caused the small bodies to collide with one another, fragmenting them into the asteroids we observe today.

    Trojans: These asteroids share an orbit with a larger planet, but do not collide with it because they gather around two special places in the orbit (called the L4 and L5 Lagrangian points). There, the gravitational pull from the sun and the planet are balanced by a trojan’s tendency to otherwise fly out of the orbit. The Jupiter trojans form the most significant population of trojan asteroids. It is thought that they are as numerous as the asteroids in the asteroid belt. There are Mars and Neptune trojans, and NASA announced the discovery of an Earth trojan in 2011.

    Near-Earth asteroids: These objects have orbits that pass close by that of Earth. Asteroids that actually cross Earth’s orbital path are known as Earth-crossers. As of June 19, 2013, 10,003 near-Earth asteroids are known and the number over 1 kilometer in diameter is thought to be 861, with 1,409 classified as potentially hazardous asteroids – those that could pose a threat to Earth.

    How Asteroids Get Their Names

    The International Astronomical Union’s Committee on Small Body Nomenclature.is a little less strict when it comes to naming asteroids than other IAU naming committees. So out there orbiting the sun we have giant space rocks named for Mr. Spock (a cat named for the character of “Star Trek” fame), rock musician Frank Zappa, regular guys like Phil Davis, and more somber tributes such as the seven asteroids named for the crew of the Space Shuttle Columbia killed in 2003. Asteroids are also named for places and a variety of other things. (The IAU discourages naming asteroids for pets, so Mr. Spock stands alone).

    Asteroids are also given a number, for example (99942) Apophis. The Harvard Smithsonian Center for Astrophysics keeps a fairly current list of asteroid names.

    Significant Dates

    1801: Giuseppe Piazzi discovers the first and largest asteroid, Ceres, orbiting between Mars and Jupiter.
    1898: Gustav Witt discovers Eros, one of the largest near-Earth asteroids.
    1991-1994: The Galileo spacecraft takes the first close-up images of an asteroid (Gaspra) and discovers the first moon (later named Dactyl) orbiting an asteroid (Ida).
    1997-2000 : The NEAR Shoemaker spacecraft flies by Mathilde and orbits and lands on Eros.
    1998: NASA establishes the Near Earth Object Program Office to detect, track and characterize potentially hazardous asteroids and comets that could approach Earth.
    2006: Japan’s Hayabusa becomes the first spacecraft to land on, collect samples and take off from an asteroid.
    2006: Ceres attains a new classification — dwarf planet — but retains its distinction as the largest known asteroid.
    2007: The Dawn spacecraft is launched on its journey to the asteroid belt to study Vesta and Ceres.
    2008: The European spacecraft Rosetta, on its way to study a comet in 2014, flies by and photographs asteroid Steins, a type of asteroid composed of silicates and basalts.
    2010: Japan’s Hayabusa returns its asteroid sample to Earth.
    2010: Rosetta flies by asteroid Lutetia, revealing a primitive survivor from the violent birth of our solar system.
    2011-2012: Dawn studies Vesta. Dawn is the first spacecraft to orbit a main-belt asteroid and continues on to dwarf planet Ceres in 2015.

    See the full article here .

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    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 9:07 am on July 20, 2017 Permalink | Reply
    Tags: , Astrophysics, , , , Impressive Emissions Nebula IC 1396,   

    From Manu Garcia at IAC: “IC 1396: Emission Nebula in Cepheus 


    Manu Garcia, a friend from IAC.

    The universe around us.
    Astronomy, everything you wanted to know about our local universe and never dared to ask.

    IAC

    Instituto de Astrofísica de Canarias – IAC

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    Credit and copyright: Cesar Blanco González

    The Impressive Emissions Nebula IC 1396 mixes the brilliant cosmic gas and dark dust clouds in the high and distant constellation of Cepheus. Energized by the brilliant central star you see here, this star-forming region extends over hundreds of light years, spanning more than three degrees in the sky, about 3.000 Light-years from planet earth. Among the intriguing dark forms within IC 1396, the elephant’s winding trunk nebula is located just below the center. The stars could still be forming within the dark shapes by gravitational collapse. But as the denser clouds are eroded by strong stellar winds and radiation, any star in formation will ultimately be cut off from the star reservoir. The magnificent color view is an image composition of narrow band filters, atomic oxygen emission mapping of the nebula, hydrogen and sulfur in blue, green and red tones.

    See the full article here.

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    The Instituto de Astrofísica de Canarias(IAC) is an international research centre in Spain which comprises:

    The Instituto de Astrofísica, the headquarters, which is in La Laguna (Tenerife).
    The Centro de Astrofísica en La Palma (CALP)
    The Observatorio del Teide (OT), in Izaña (Tenerife).
    The Observatorio del Roque de los Muchachos (ORM), in Garafía (La Palma).

    These centres, with all the facilities they bring together, make up the European Northern Observatory(ENO).

    The IAC is constituted administratively as a Public Consortium, created by statute in 1982, with involvement from the Spanish Government, the Government of the Canary Islands, the University of La Laguna and Spain’s Science Research Council (CSIC).

    The International Scientific Committee (CCI) manages participation in the observatories by institutions from other countries. A Time Allocation Committee (CAT) allocates the observing time reserved for Spain at the telescopes in the IAC’s observatories.

    The exceptional quality of the sky over the Canaries for astronomical observations is protected by law. The IAC’s Sky Quality Protection Office (OTPC) regulates the application of the law and its Sky Quality Group continuously monitors the parameters that define observing quality at the IAC Observatories.

    The IAC’s research programme includes astrophysical research and technological development projects.

    The IAC is also involved in researcher training, university teaching and outreachactivities.

    The IAC has devoted much energy to developing technology for the design and construction of a large 10.4 metre diameter telescope, the ( Gran Telescopio CANARIAS, GTC), which is sited at the Observatorio del Roque de los Muchachos.


    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, SpainGran Telescopio CANARIAS, GTC

     
  • richardmitnick 8:32 am on July 20, 2017 Permalink | Reply
    Tags: , , Astrophysics, , , ,   

    From New Horizons: “NASA’s New Horizons Team Strikes Gold in Argentina” 

    NASA image

    NASA

    NASA/New Horizons spacecraft

    New Horizons

    July 19, 2017
    Editor: Tricia Talbert

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    No image caption or credit.

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    An artist’s rendition of Kuiper Belt Object MU69, which New Horizons will visit in January 2019.
    NASA, ESA, SWRI, JHU/APL, AND THE NEW HORIZONS KBO SEARCH TEAM

    A primitive solar system object that’s more than four billion miles (6.5 billion kilometers) away passed in front of a distant star as seen from Earth. Just before midnight Eastern Time Sunday (12:50 a.m. local time July 17), several telescopes deployed by the New Horizons team in a remote part of Argentina were in precisely the right place at the right time to catch its fleeting shadow — an event that’s known as an occultation.

    In a matter of seconds, NASA’s New Horizons team captured new data on its elusive target, an ancient Kuiper Belt object known as 2014 MU69.

    Kuiper Belt. Minor Planet Center

    Weary but excited team members succeeded in detecting the spacecraft’s next destination, in what’s being called the most ambitious and challenging ground occultation observation campaign in history.

    “So far we have five confirmed occultations,” said Marc Buie of the Southwest Research Institute (SwRI) in Boulder, Colorado, holding up five fingers as New Horizons scientists pored over the exhilarating initial data. Buie led a team of more than 60 observers who battled high winds and cold to set up a “picket fence” of 24 mobile telescopes in a remote region of Chubut and Santa Cruz, Argentina. Their goal: to spot the shadow of the mysterious Kuiper Belt object (KBO) where New Horizons will fly by on New Year’s Day 2019 – to better understand its size, shape, orbit and the environment around it. Before these observations, only the Hubble Space Telescope successfully detected MU69, and even it had not been able to determine MU69’s size or shape.

    NASA/ESA Hubble Telescope

    “It was the most historic occultation on the face of the Earth,” said Jim Green, NASA’s director of planetary science in a congratulatory call to the team. “You pulled it off and you made it happen.”

    The first MU69 occultation campaign scientist to see the telltale signature of MU69 was Amanda Zangari, a New Horizons co-investigator from SwRI, who said, “We nailed it spectacularly.”

    The New Horizons team enjoyed strong support from Argentinian scientists, government officials, and locals, who went above and beyond to ensure mission success. “I’ve been calling the people who helped us, our ‘twelfth player,’” Buie said. “The Comodoro Rivadavia community came together and did some amazing things for us.” A major national highway was closed for two hours to keep car headlights away. Street lights were turned off to ensure absolute darkness. People like the Intendente or Mayor of the Comodoro parked trucks as wind breaks. Said Buie, “The local people were a major team player.”

    “Planning for this complex astronomical deployment started just a few months ago and although the odds seem daunting — like finding a needle in a haystack — the team succeeded, thanks to the help of institutions like CONAE (Argentina’s National Commission on Space Activities), and all the goodwill of the Argentinian people. This is another example of how space exploration brings out the best in us,” said New Horizons Program Executive Adriana Ocampo.

    This was the third of three ambitious occultation observations for New Horizons, and all contributed to the success of the campaign. On June 3, teams in both Argentina and South Africa attempted to observe MU69. On July 10, researchers using NASA’s Stratospheric Observatory for Infrared Astronomy, or SOFIA, studied the environment around MU69 while flying over the Pacific Ocean from Christchurch, New Zealand.

    NASA/DLR SOFIA

    When New Horizons flies by it, MU69 will be the most distant object ever explored by a spacecraft, over a billion miles farther from our sun than Pluto. This ancient Kuiper Belt object is not well understood, because it is faint (likely 14-25 miles or 22-40 kilometers across) and so far away. To study this distant object from Earth, the New Horizons team used Hubble Space Telescope and Gaia satellite data to calculate where MU69 would cast a shadow on Earth’s surface. Both satellites were crucial to the occultation campaign.

    ESA/GAIA satellite

    It will take weeks for scientists to analyze the many datasets from the multi-faceted campaign. This advance observation is a critical step in flyby planning before the New Horizons spacecraft arrives at MU69 on Jan. 1, 2019.

    “This effort, spanning six months, three spacecraft, 24 portable ground-based telescopes, and NASA’s SOFIA airborne observatory was the most challenging stellar occultation in the history of astronomy, but we did it!” said Alan Stern, New Horizons principal investigator from SwRI. “We spied the shape and size of 2014 MU69 for the first time, a Kuiper Belt scientific treasure we will explore just over 17 months from now. Thanks to this success we can now plan the upcoming flyby with much more confidence.”

    To see a video of preparations for the July 17 observations in Argentina: tinyurl.com/KBprep

    Follow the mission at the NASA New Horizons website, the mission’s KBO Chasers page, and #mu69occ.

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    Marc Buie, New Horizons occultation campaign lead, holds up five fingers to represent the number of mobile telescopes in Argentina initially thought to have detected the fleeting shadow of 2014 MU69. The New Horizons spacecraft will fly by the ancient Kuiper Belt object on Jan. 1, 2019. Credits: NASA/JHUAPL/SwRI/Adriana Ocampo.

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    New Horizons Co-Investigator Amanda Zangari was the first occultation campaign scientist to see the telltale signature of MU69 while analyzing data from July 17, saying, “We nailed it spectacularly.” Credits: NASA/JHUAPL/SwRI/Adriana Ocampo.

    See the full article here .

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    The New Horizons mission is helping us understand worlds at the edge of our solar system by making the first reconnaissance of the dwarf planet Pluto and by venturing deeper into the distant, mysterious Kuiper Belt – a relic of solar system formation.

    The Journey

    New Horizons launched on Jan. 19, 2006; it swung past Jupiter for a gravity boost and scientific studies in February 2007, and conducted a six-month-long reconnaissance flyby study of Pluto and its moons in summer 2015, culminating with Pluto closest approach on July 14, 2015. As part of an extended mission, pending NASA approval, the spacecraft is expected to head farther into the Kuiper Belt to examine another of the ancient, icy mini-worlds in that vast region, at least a billion miles beyond Neptune’s orbit.

    Sending a spacecraft on this long journey is helping us to answer basic questions about the surface properties, geology, interior makeup and atmospheres on these bodies.

    New Science

    The National Academy of Sciences has ranked the exploration of the Kuiper Belt – including Pluto – of the highest priority for solar system exploration. Generally, New Horizons seeks to understand where Pluto and its moons “fit in” with the other objects in the solar system, such as the inner rocky planets (Earth, Mars, Venus and Mercury) and the outer gas giants (Jupiter, Saturn, Uranus and Neptune).

    Pluto and its largest moon, Charon, belong to a third category known as “ice dwarfs.” They have solid surfaces but, unlike the terrestrial planets, a significant portion of their mass is icy material.

    Using Hubble Space Telescope images, New Horizons team members have discovered four previously unknown moons of Pluto: Nix, Hydra, Styx and Kerberos.

    A close-up look at these worlds from a spacecraft promises to tell an incredible story about the origins and outskirts of our solar system. New Horizons is exploring – for the first time – how ice dwarf planets like Pluto and Kuiper Belt bodies have evolved over time.

    The Need to Explore

    The United States has been the first nation to reach every planet from Mercury to Neptune with a space probe. New Horizons is allowing the U.S. to complete the initial reconnaissance of the solar system.

    A Team Approach

    The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, designed, built, and operates the New Horizons spacecraft and manages the mission for NASA’s Science Mission Directorate.
    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

     
  • richardmitnick 7:58 am on July 20, 2017 Permalink | Reply
    Tags: , Astrophysics, , , , Nickel 1-meter telescope at Lick Observatory, NIROSETI-Near-Infrared Optical SETI instrument, Optical SETI, Radio SETI, , Shelley Wright, UCSC Lick Observatory   

    From Centauri Dreams: “Making Optical SETI Happen” 

    Centauri Dreams

    July 18, 2017
    Paul Gilster

    Yesterday I made mention of the Schwartz and Townes paper “Interstellar and Interplanetary Communication by Optical Masers,” which ran in Nature in 1961 (Vol. 190, Issue 4772, pp. 205-208). Whereas the famous Cocconi and Morrison paper that kicked off radio SETI quickly spawned an active search in the form of Project Ozma, optical SETI was much slower to develop. The first search I can find is a Russian project called MANIA, in the hands of V. F. Shvartsman and G. M. Beskin, who searched about 100 objects in the early 1970s, finding no significant brightness variations within the parameters of their search.

    If you want to track this one down, you’ll need a good academic library, as it appears in the conference proceedings for the Third Decennial US-USSR Conference on SETI, published in 1993. Another Shvartsman investigation under the MANIA rubric occurred in 1978. Optical SETI did not seem to seize the public’s imagination, perhaps partially because of the novelty of communications through the recently discovered laser. We do see several optical SETI studies at UC-Berkeley’s Leuschner Observatory and Kitt Peak from 1979 to 1981, the work of Francisco Valdes and Robert Freitas, though these were searches for Bracewell probes within the Solar System rather than attempts to pick up laser transmissions from other star systems.

    1
    Harvard’s Paul Horowitz, a key player in the development of optical SETI. Credit: Harvard University.

    This was an era when radio searches for extraterrestrial technology had begun to proliferate, but despite the advocacy of Townes and others (and three conferences Townes helped create), it wasn’t until the 1990s that optical SETI began to come into its own. Charles Townes himself was involved in a search for laser signals from about 300 nearby stars in the ‘90s, using the 1.7-meter telescope on Mt. Wilson and reported on at the 1993 conference. Stuart Kingsley began an optical SETI search using the 25-centimeter telescope at the Columbus Optical SETI Observatory (COSETI) in 1990, while Gregory Beskin searched for optical signals at the Special Astrophysical Observatory run by the Russian Academy of Sciences in the Caucasus in 1995.

    Optical SETI’s advantages were beginning to be realized, as Andrew Howard (Caltech) commented in a 2004 paper:

    “The rapid development of laser technology since that time—a Moore’s law doubling of capability roughly every year—along with the discovery of many microwave lines of astronomical interest, have lessened somewhat the allure of hydrogen-line SETI. Indeed, on Earth the exploitation of photonics has revolutionized communications technology, with high-capacity fibers replacing both the historical copper cables and the long-haul microwave repeater chains. In addition, the elucidation (Cordes & Lazio 1991) of the consequences to SETI of interstellar dispersion (first seen in pulsar observations) has broadened thinking about optimum wavelengths. Even operating under the prevailing criterion of minimum energy per bit transmitted, one is driven upward to millimetric wavelengths.”

    In the late 90’s, the SETI Institute, as part of a reevaluation of SETI methods, recommended and then co-funded several optical searches including one by Dan Werthimer and colleagues at UC Berkeley and another by a Harvard-Smithsonian team including Paul Horowitz and Andrew Howard. The Harvard-Smithsonian group also worked in conjunction with Princeton University on a detector system similar to the one mounted on Harvard’s 155-centimeter optical telescope. A newer All-Sky Optical SETI (OSETI) telescope, set up at the Oak Ridge Observatory at Harvard and funded by The Planetary Society, dates from 2006.

    4
    http://seti.harvard.edu/oseti/allsky/allsky.htm

    5
    http://www.setileague.org/photos/oseti3.htm

    6
    http://seti.harvard.edu/oseti/

    At Berkeley, the optical SETI effort is led by Werthimer, who had built the laser detector for the Harvard-Smithsonian team. Optical SETI efforts from Leuschner Observatory and Lick Observatory were underway by 1999. Collaborating with Shelley Wright (UC Santa Cruz), Remington Stone (UC Santa Cruz/Lick Observatory), and Frank Drake (SETI Institute), the Berkeley group has gone on to develop new detector systems to improve sensitivity. As I mentioned yesterday, UC-Berkeley’s Nate Tellis, working with Geoff Marcy, has analyzed Keck archival data for 5,600 stars between 2004 and 2016 in search of optical signals.

    Working in the infrared, the Near-Infrared Optical SETI instrument (NIROSETI) is designed to conduct searches at infrared wavelengths. Shelley Wright is the principal investigator for NIROSETI, which is mounted on the Nickel 1-meter telescope at Lick Observatory, seeing first light in March of 2015. The project is designed to search for nanosecond pulses in the near-infrared, with a goal “to search not only for transient phenomena from technological activity, but also from natural objects that might produce very short time scale pulses from transient sources.” The advantage of near-infrared is the decrease in interstellar extinction, the absorption by dust and gas that can sharply impact the strength of a signal.

    7
    Shelley Wright, then a student at UC-Santa Cruz, helped build a detector that divides the light beam from a telescope into three parts, rather than just two, and sends it to three photomultiplier tubes. This arrangement greatly reduces the number of false alarms; very rarely will instrumental noise trigger all three detectors at once. The three-tube detector is in the white box attached here to the back of the 1-meter Nickel Telescope at Lick Observatory. Credit: Seth Shostak.

    8
    UCSC Lick Observatory Nickel Telescope

    I might also mention METI International’s Optical SETI Observatory at Boquete, Panama. The idea is to put the optical SETI effort in context. With the SETI Institute now raising money for its Laser SETI initiative — all-sky all-the-time — the role of private funding in making optical SETI happen is abundantly clear. And now, of course, we also have Breakthrough Listen, which in addition to listening at radio wavelengths at the Parkes instrument in Australia and the Green Bank radio telescope in West Virginia, is using the Automated Planet Finder at Lick Observatory to search for optical laser transmissions.

    CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia



    GBO radio telescope, Green Bank, West Virginia, USA

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

    Funded by the Breakthrough Prize Foundation, the project continues the tradition of private funding from individuals, institutions (the SETI Institute) and organizations like The Planetary Society to get optical SETI done.

    Centauri Dreams


    See the full article here .

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    Tracking Research into Deep Space Exploration

    Alpha Centauri and other nearby stars seem impossible destinations not just for manned missions but even for robotic probes like Cassini or Galileo. Nonetheless, serious work on propulsion, communications, long-life electronics and spacecraft autonomy continues at NASA, ESA and many other venues, some in academia, some in private industry. The goal of reaching the stars is a distant one and the work remains low-key, but fascinating ideas continue to emerge. This site will track current research. I’ll also throw in the occasional musing about the literary and cultural implications of interstellar flight. Ultimately, the challenge may be as much philosophical as technological: to reassert the value of the long haul in a time of jittery short-term thinking.

     
  • richardmitnick 7:23 am on July 20, 2017 Permalink | Reply
    Tags: , Astrophysics, , , Measuring black holes, Spiral arms allow school children to weigh black holes,   

    From Swinburne University: “Spiral arms allow school children to weigh black holes” 

    Swinburne U bloc

    Swinburne University

    20 July 2017
    Contact
    Lea Kivivali
    +61 3 9214 5428
    lkivivali@swin.edu.au

    Expert for comment
    Professor Alister Graham
    9214 8784
    agraham@swin.edu.au

    1
    Artistic rendering of a black hole accumulating matter at the centre of a galaxy. Credit: James Josephides.

    Astronomers from Swinburne University of Technology, Australia, and the University of Minnesota Duluth, USA, have provided a way for armchair astronomers, and even primary school children, to merely look at a spiral galaxy and estimate the mass of its hidden, central black hole.

    Given that black holes emit no discernible light, they have traditionally been studied via highly technical observations of the stars and gas orbiting around them, which in turn provide a measurement of how massive they must be.

    Now, new research based on these pre-existing measurements has shown that a black hole’s mass can be accurately estimated by simply looking at the spiral arms of its host galaxy.

    Nearly a century ago, Sir James Jeans and Edwin Hubble noted how spiral galaxies with large central bulges possess tightly wound spiral arms, while spiral galaxies with small bulges display wide open spiral arms. Since then, hundreds of thousands, if not millions, of spiral galaxies have been classified as type Sa, Sb, Sc, Sd, depending on their spiral arms.

    Professsor Marc Seigar, Associate Dean of the Swenson College of Science and Engineering at the University of Minnesota Duluth, and co-author of the study, discovered a relationship between central black hole mass and the tightness of a galaxy’s spiral arms nearly a decade ago.

    Dr Benjamin Davis and Professor Alister Graham, from Swinburne’s Centre for Astrophysics and Supercomputing, led the new research revising this connection between black hole mass and spiral arm geometry.

    After carefully analysing a larger sample of galaxies, imaged by an array of space telescopes, the researchers observed an unexpectedly strong relationship, and one which predicts lower mass black holes in galaxies with open spiral arms (types Sc and Sd).

    2
    Spiral galaxy arms with varying degrees of tightness, and the corresponding galaxy type and central black hole mass in units of our Sun’s mass. This template can be used to estimate the black hole masses in spiral galaxies. Credit: Benjamin Davis.

    “The strength of the correlation is competitive with, if not better than, all our other methods used to predict black hole masses,” says Dr Davis. “Anyone can now look at an image of a spiral galaxy and immediately gauge how massive its black hole should be.”

    Given that it is the discs of galaxies that host the spiral pattern, the study highlights the poorly-known connection between galaxy discs and black holes. Moreover, the procedure allows for the prediction of black hole masses in pure disc galaxies with no stellar bulge. “This implies that black holes and the discs of their host galaxies must co-evolve,” says Dr Davis.

    “It’s now as easy as ‘a,b,c’ to unlock this mystery of our Universe and reveal the black hole masses in spiral galaxies.” says Professor Graham.

    “Importantly, the relation will also help searches for the suspected, but currently missing, population of intermediate-mass black holes with masses between 100 and 100,000 times the mass of our Sun. Difficult to pin down, they have masses greater than that of any single star, but are smaller than the supermassive black holes which grow to billions of times the mass of our Sun in giant galaxies,” Professor Graham says.

    3
    The ‘Sab’ type galaxy Messier 81, located in the northern constellation of Ursa Major, has a black hole mass of 68 million Suns. Credit: Spitzer Space Telescope and Benjamin Davis.

    Working within the Australian Research Council’s OzGrav Centre for Excellence, the astronomers intend to hunt down these elusive black holes, and investigate implications for the production of gravitational waves: those ripples in the fabric of Einstein’s space-time that were first announced by the LIGO and Virgo collaborations in 2016.

    This research was supported by the Australian Research Council and has been published by the Monthly Notices of the Royal Astronomical Society. The research can be downloaded here.

    See the full article here .

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    Swinburne U Campus

    Swinburne is a large and culturally diverse organisation. A desire to innovate and bring about positive change motivates our students and staff. The result is in an institution that grows and evolves each year.

     
  • richardmitnick 1:47 pm on July 19, 2017 Permalink | Reply
    Tags: , Astrophysics, , , , , Scientists Are Using the Universe as a "Cosmological Collider", Standard Model of Particle Physics   

    From CfA: “Scientists Are Using the Universe as a “Cosmological Collider” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

    July 19, 2017
    Megan Watzke
    Harvard-Smithsonian Center for Astrophysics
    +1 617-496-7998
    mwatzke@cfa.harvard.edu

    Peter Edmonds
    Harvard-Smithsonian Center for Astrophysics
    +1 617-571-7279
    pedmonds@cfa.harvard.edu

    1

    Physicists are capitalizing on a direct connection between the largest cosmic structures and the smallest known objects to use the universe as a “cosmological collider” and investigate new physics.

    The three-dimensional map of galaxies throughout the cosmos and the leftover radiation from the Big Bang – called the cosmic microwave background (CMB) – are the largest structures in the universe that astrophysicists observe using telescopes.

    CMB per ESA/Planck

    ESA/Planck

    Subatomic elementary particles, on the other hand, are the smallest known objects in the universe that particle physicists study using particle colliders.

    LHC

    CERN/LHC Map

    CERN LHC Tunnel

    CERN LHC particles

    A team including Xingang Chen of the Harvard-Smithsonian Center for Astrophysics (CfA), Yi Wang from the Hong Kong University of Science and Technology (HKUST) and Zhong-Zhi Xianyu from the Center for Mathematical Sciences and Applications at Harvard University has used these extremes of size to probe fundamental physics in an innovative way. They have shown how the properties of the elementary particles in the Standard Model of particle physics may be inferred by studying the largest cosmic structures. This connection is made through a process called cosmic inflation.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Inflationary Universe. NASA/WMAP

    Cosmic inflation is the most widely accepted theoretical scenario to explain what preceded the Big Bang. This theory predicts that the size of the universe expanded at an extraordinary and accelerating rate in the first fleeting fraction of a second after the universe was created.

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

    It was a highly energetic event, during which all particles in the universe were created and interacted with each other. This is similar to the environment physicists try to create in ground-based colliders, with the exception that its energy can be 10 billion times larger than any colliders that humans can build.

    Inflation was followed by the Big Bang, where the cosmos continued to expand for more than 13 billion years, but the expansion rate slowed down with time. Microscopic structures created in these energetic events got stretched across the universe, resulting in regions that were slightly denser or less dense than surrounding areas in the otherwise very homogeneous early universe. As the universe evolved, the denser regions attracted more and more matter due to gravity. Eventually, the initial microscopic structures seeded the large-scale structure of our universe, and determined the locations of galaxies throughout the cosmos.

    In ground-based colliders, physicists and engineers build instruments to read the results of the colliding events. The question is then how we should read the results of the cosmological collider.

    “Several years ago, Yi Wang and I, Nima Arkani-Hamed and Juan Maldacena from the Institute of Advanced Study, and several other groups, discovered that the results of this cosmological collider are encoded in the statistics of the initial microscopic structures. As time passes, they become imprinted in the statistics of the spatial distribution of the universe’s contents, such as galaxies and the cosmic microwave background, that we observe today,” said Xingang Chen. “By studying the properties of these statistics we can learn more about the properties of elementary particles.”

    As in ground-based colliders, before scientists explore new physics, it is crucial to understand the behavior of known fundamental particles in this cosmological collider, as described by the Standard Model of particle physics.

    “The relative number of fundamental particles that have different masses – what we call the mass spectrum – in the Standard Model has a special pattern, which can be viewed as the fingerprint of the Standard Model,” explained Zhong-Zhi Xiangyu. “However, this fingerprint changes as the environment changes, and would have looked very different at the time of inflation from how it looks now.”

    The team showed what the mass spectrum of the Standard Model would look like for different inflation models. They also showed how this mass spectrum is imprinted in the appearance of the large-scale structure of our universe. This study paves the way for the future discovery of new physics.

    “The ongoing observations of the CMB and large-scale structure have achieved impressive precision from which valuable information about the initial microscopic structures can be extracted,” said Yi Wang. “In this cosmological collider, any observational signal that deviates from that expected for particles in the Standard Model would then be a sign of new physics.”

    The current research is only a small step towards an exciting era when precision cosmology will show its full power.

    “If we are lucky enough to observe these imprints, we would not only be able to study particle physics and fundamental principles in the early universe, but also better understand cosmic inflation itself. In this regard, there are still a whole universe of mysteries to be explored,” said Xianyu.

    This research is detailed in a paper published in the journal Physical Review Letters on June 29, 2017, and the preprint is available online.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 1:20 pm on July 19, 2017 Permalink | Reply
    Tags: , , Astrophysics, , , Distant radio quasars, , Nearby Hot Stars May Change Our View of Distant Sources, Variable twinkling   

    From AAS NOVA: “Nearby Hot Stars May Change Our View of Distant Sources” 

    AASNOVA

    American Astronomical Society

    19 July 2017
    Susanna Kohler

    1
    Clumps of hydrogen gas in the Helix Nebula have been drawn out into long, ionized streamers, as visible in this Hubble image. Could gas like this be responsible for the twinkling of distant quasars? [C. R. O’Dell/K. Handron/NASA/Manly Astrophysics]

    As if it weren’t enough that quasars — distant and bright nuclei of galaxies — twinkle of their own accord due to internal processes, nature also provides another complication: these distant radio sources can also appear to twinkle because of intervening material between them and us. A new study has identified a possible source for the material getting in the way.

    2
    A Spitzer infrared view of the Helix nebula, which contains ionized streamers of gas extending radially outward from the central star. [NASA/JPL-Caltech/Univ. of Ariz.]

    NASA/Spitzer Telescope

    Unexplained Variability

    Distant quasars occasionally display extreme scintillation, twinkling with variability timescales shorter than a day. This intra-day variability is much greater than we can account for with standard models of the interstellar medium lying between the quasar and us. So what could cause this extreme scattering instead?

    The first clue to this mystery came from the discovery of strong variability in the radio source PKS 1322–110. In setting up follow-up observations of this object, Mark Walker (Manly Astrophysics, Australia) and collaborators noticed that, in the plane of the sky, PKS 1322–110 lies very near the bright star Spica. Could this be coincidence, or might this bright foreground star have something to do with the extreme scattering observed?

    3
    Diagram explaining the source of the intra-day radio source variability as intervening filaments surrounding a hot star. [M. Walker/CSIRO/Manly Astrophysics]

    Swarms of Clumps

    Walker and collaborators put forward a hypothesis: perhaps the ultraviolet photons of nearby hot stars ionize plasma around them, which in turn causes the extreme scattering of the distant background sources.

    As a model, the authors consider the Helix Nebula, in which a hot, evolved star is surrounded by cool globules of molecular hydrogen gas. The radiation from the star hits these molecular clumps, dragging them into long radial streamers and ionizing their outer skins.

    Though the molecular clumps in the Helix Nebula were thought to have formed only as the star evolved late into its lifetime, Walker and collaborators are now suggesting that all stars — regardless of spectral type or evolutionary stage — may be surrounded by swarms of tiny molecular clumps. Around stars that are hot enough, these clumps become the ionized plasma streamers that can cause interference with the light traveling to us from distant sources.

    Significant Mass

    To test this theory, Walker and collaborators explore observations of two distant radio quasars that have both exhibited intra-day variability over many years of observations. The team identified a hot A-type star near each of these two sources: J1819+3845 has Vega nearby, and PKS 1257–326 has Alhakim.

    4
    Locations of stars along the line of site to two distant quasars, J1819+3845 (top panel) and PKS 1257–326 (bottom panel). Both have a nearby, hot star (blue markers) radially within 2 pc: Vega (z = 7.7 pc) and Alhakim (z = 18 pc), respectively. [Walker et al. 2017]

    By modeling the systems of the sources and stars, the authors show that the size, location, orientation, and numbers of plasma concentrations necessary to explain observations are all consistent with an environment similar to that of the Helix Nebula. Walker and collaborators find that the total mass in the molecular clumps surrounding the two stars would need to be comparable to the mass of the stars themselves.

    If this picture is correct, and if all stars are indeed surrounded by molecular clumps like these, then a substantial fraction of the mass of our galaxy could be contained in these clumps. Besides explaining distant quasar scintillation, this idea would therefore have a significant impact on our overall understanding of how mass in galaxies is distributed. More observations of twinkling quasars are the next step toward confirming this picture.

    Citation

    Mark A. Walker et al 2017 ApJ 843 15. doi:10.3847/1538-4357/aa705c

    Related Journal Articles
    Further references complete with links on the full article.

    See the full article here .

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    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
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