NASA Missions Harvest a Passel of ‘Pumpkin’ Stars

NASA - Kepler Mission patch / NASA - SWIFT Mission patch.

Oct. 27, 2016

Astronomers using observations from NASA's Kepler and Swift missions have discovered a batch of rapidly spinning stars that produce X-rays at more than 100 times the peak levels ever seen from the sun. The stars, which spin so fast they've been squashed into pumpkin-like shapes, are thought to be the result of close binary systems where two sun-like stars merge.

NASA's Kepler, Swift Missions Harvest ‘Pumpkin’ Stars

Video above: Dive into the Kepler field and learn more about the origins of these rapidly spinning stars. Video Credits: Credits: NASA's Goddard Space Flight Center/Scott Wiessinger, producer.

"These 18 stars rotate in just a few days on average, while the sun takes nearly a month," said Steve Howell, a senior research scientist at NASA's Ames Research Center in Moffett Field, California, and leader of the team. "The rapid rotation amplifies the same kind of activity we see on the sun, such as sunspots and solar flares, and essentially sends it into overdrive."

The most extreme member of the group, a K-type orange giant dubbed KSw 71, is more than 10 times larger than the sun, rotates in just 5.5 days, and produces X-ray emission 4,000 times greater than the sun does at solar maximum.

Image above: This artist's concept illustrates how the most extreme "pumpkin star" found by Kepler and Swift compares with the sun. Both stars are shown to scale. KSw 71 is larger, cooler and redder than the sun and rotates four times faster. Rapid spin causes the star to flatten into a pumpkin shape, which results in brighter poles and a darker equator. Rapid rotation also drives increased levels of stellar activity such as starspots, flares and prominences, producing X-ray emission over 4,000 times more intense than the peak emission from the sun. KSw 71 is thought to have recently formed following the merger of two sun-like stars in a close binary system. Image Credits: NASA's Goddard Space Flight Center/Francis Reddy.

These rare stars were found as part of an X-ray survey of the original Kepler field of view, a patch of the sky comprising parts of the constellations Cygnus and Lyra. From May 2009 to May 2013, Kepler measured the brightness of more than 150,000 stars in this region to detect the regular dimming from planets passing in front of their host stars. The mission was immensely successful, netting more than 2,300 confirmed exoplanets and nearly 5,000 candidates to date. An ongoing extended mission, called K2, continues this work in areas of the sky located along the ecliptic, the plane of Earth's orbit around the sun.

"A side benefit of the Kepler mission is that its initial field of view is now one of the best-studied parts of the sky," said team member Padi Boyd, a researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who designed the Swift survey. For example, the entire area was observed in infrared light by NASA's Wide-field Infrared Survey Explorer, and NASA's Galaxy Evolution Explorer observed many parts of it in the ultraviolet. "Our group was looking for variable X-ray sources with optical counterparts seen by Kepler, especially active galaxies, where a central black hole drives the emissions," she explained.

Using the X-ray and ultraviolet/optical telescopes aboard Swift, the researchers conducted the Kepler–Swift Active Galaxies and Stars Survey (KSwAGS), imaging about six square degrees, or 12 times the apparent size of a full moon, in the Kepler field.

"With KSwAGS we found 93 new X-ray sources, about evenly split between active galaxies and various types of X-ray stars," said team member Krista Lynne Smith, a graduate student at the University of Maryland, College Park who led the analysis of Swift data. "Many of these sources have never been observed before in X-rays or ultraviolet light."

Kepler Space Telescope (K2). Image Credit: NASA

For the brightest sources, the team obtained spectra using the 200-inch telescope at Palomar Observatory in California. These spectra provide detailed chemical portraits of the stars and show clear evidence of enhanced stellar activity, particularly strong diagnostic lines of calcium and hydrogen.

The researchers used Kepler measurements to determine the rotation periods and sizes for 10 of the stars, which range from 2.9 to 10.5 times larger than the sun. Their surface temperatures range from somewhat hotter to slightly cooler than the sun, mostly spanning spectral types F through K. Astronomers classify the stars as subgiants and giants, which are more advanced evolutionary phases than the sun's caused by greater depletion of their primary fuel source, hydrogen. All of them eventually will become much larger red giant stars.

A paper detailing the findings will be published in the Nov. 1 edition of the Astrophysical Journal and is now available online: http://iopscience.iop.org/article/10.3847/0004-637X/831/1/27

Forty years ago, Ronald Webbink at the University of Illinois, Urbana-Champaign noted that close binary systems cannot survive once the fuel supply of one star dwindles and it starts to enlarge. The stars coalesce to form a single rapidly spinning star initially residing in a so-called "excretion" disk formed by gas thrown out during the merger. The disk dissipates over the next 100 million years, leaving behind a very active, rapidly spinning star.

Howell and his colleagues suggest that their 18 KSwAGS stars formed by this scenario and have only recently dissipated their disks. To identify so many stars passing through such a cosmically brief phase of development is a real boon to stellar astronomers.

Swift observatory. Image Credit: NASA

"Webbink's model suggests we should find about 160 of these stars in the entire Kepler field," said co-author Elena Mason, a researcher at the Italian National Institute for Astrophysics Astronomical Observatory of Trieste. "What we have found is in line with theoretical expectations when we account for the small portion of the field we observed with Swift."

The team has already extended their Swift observations to additional fields mapped by the K2 mission.

Ames manages the Kepler and K2 missions for NASA’s Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corp. operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

Goddard manages the Swift mission in collaboration with Pennsylvania State University in University Park, the Los Alamos National Laboratory in New Mexico and Orbital Sciences Corp. in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional collaborators in Germany and Japan.

Related Links:

NASA's Kepler and K2 mission website: http://www.nasa.gov/kepler

NASA's Swift mission website: http://www.nasa.gov/swift

Images (mentioned), Text, Credits: NASA's Goddard Space Flight Center, by Francis Reddy.

Greetings, Orbiter.ch

A Dead Star's Ghostly Glow

NASA - Hubble Space Telescope patch.

Oct. 27, 2016

The eerie glow of a dead star, which exploded long ago as a supernova, reveals itself in this NASA Hubble Space Telescope image of the Crab Nebula. But don't be fooled. The ghoulish-looking object still has a pulse. Buried at its center is the star's tell-tale heart, which beats with rhythmic precision.

Image above: Astronomers discovered a real "tell-tale heart" in space, 6,500 light-years from Earth. The "heart" is the crushed core of a long-dead star, called a neutron star, which exploded as a supernova and is now still beating with rhythmic precision. Evidence of its heartbeat are rapid-fire, lighthouse-like pulses of energy from the fast-spinning neutron star. The stellar relic is embedded in the center of the Crab Nebula, the expanding, tattered remains of the doomed star. Image Credits: NASA and ESA, Acknowledgment: M. Weisskopf/Marshall Space Flight Center.

The "heart" is the crushed core of the exploded star. Called a neutron star, it has about the same mass as the sun but is squeezed into an ultra-dense sphere that is only a few miles across and 100 billion times stronger than steel. The tiny powerhouse is the bright star-like object near the center of the image.

This surviving remnant is a tremendous dynamo, spinning 30 times a second. The wildly whirling object produces a deadly magnetic field that generates an electrifying 1 trillion volts. This energetic activity unleashes wisp-like waves that form an expanding ring, most easily seen to the upper right of the pulsar.

The nebula's hot gas glows in radiation across the electromagnetic spectrum, from radio to X-rays. The Hubble exposures were taken in visible light as black-and-white exposures. The Advanced Camera for Surveys made the observations between January and September 2012. The green hue that gives the nebula a Halloween theme, represents the color range of filter used in the observation.

Animation above: This time-lapse movie of the Crab Nebula, made from NASA Hubble Space Telescope observations, reveals wave-like structures expanding outward from the "heart" of an exploded star. The waves look like ripples in a pond. The heart is the crushed core of the exploded star, or supernova. Called a neutron star, it has about the same mass as the sun but is squeezed into an ultra-dense sphere that is only a few miles across and 100 billion times stronger than steel. This surviving relic is a tremendous dynamo, spinning 30 times a second. The rapidly spinning neutron star is visible in the image as the bright object just below center. The bright object to the left of the neutron star is a foreground or background star. The movie is assembled from 10 Hubble exposures taken between September and November 2005 by the Advanced Camera for Surveys.
Animation Credits: NASA and ESA, Acknowledgment: J. Hester (Arizona State University).

Hubble and the sunrise over Earth

The Crab Nebula is one of the most historic and intensively studied supernova remnants. Observations of the nebula date back to 1054 A.D., when Chinese astronomers first recorded seeing a "guest star" during the daytime for 23 days. The star appeared six times brighter than Venus. Japanese, Arabic, and Native American stargazers also recorded seeing the mystery star. In 1758, while searching for a comet, French astronomer Charles Messier discovered a hazy nebula near the location of the long-vanished supernova. He later added the nebula to his celestial catalog as "Messier 1," marking it as a "fake comet." Nearly a century later British astronomer William Parsons sketched the nebula. Its resemblance to a crustacean led to M1's other name, the Crab Nebula. In 1928 astronomer Edwin Hubble first proposed associating the Crab Nebula to the Chinese "guest star" of 1054.

The nebula, bright enough to be visible in amateur telescopes, is located 6,500 light-years away in the constellation Taurus.

For images and more information about Hubble Space Telescope, visit:

http://hubblesite.org/
http://www.nasa.gov/hubble
http://www.spacetelescope.org/

Image (mentioned), Animation (mentioned), Text, Credits: NASA/Karl Hille/STSI/Ray Villard/Video Credit: European Space Agency (ESA).

Greetings, Orbiter.ch

15 000 space rocks and counting

Asteroid Watch logo.

27 October 2016

The international effort to find, confirm and catalogue the multitude of asteroids that pose a threat to our planet has reached a milestone: 15 000 discovered – with many more to go.

The number of catalogued asteroids approaching Earth has grown rapidly since the count reached 10 000 only three years ago.

Near-Earth objects, or NEOs, are asteroids or comets with sizes ranging from metres to tens of kilometres whose orbits come close to ours, meaning they could hit our planet.

The discovered NEOs are part of a much larger population of more than 700 000 known asteroids in our Solar System.

Asteroid Lutetia

“The rate of discovery has been high in the past few years, and teams worldwide have been discovering on average 30 new ones per week,” says Ettore Perozzi, manager of the NEO Coordination Centre at ESA’s centre near Rome, Italy.

“A few decades back, 30 were found in a typical year, so international efforts are starting to pay off. We believe that 90% of objects larger than 1000 m have been discovered, but – even with the recent milestone – we’ve only found just 10% of the 100 m NEOs and less than 1% of the 40 m ones.”

Today, the two main discovery efforts are in the US: the Catalina Sky Survey in Arizona, and the Pan-STARRS project in Hawaii, jointly accounting for about 90% of the new bodies found.

Chelyabinsk asteroid trail

ESA is contributing through its Space Situational Awareness programme, setting up the centre in Italy to combine new and existing European telescope data and support a new network to distribute information.

Maintaining the European risk list

“The centre maintains the European Risk List, containing all objects for which an Earth-impact probability cannot yet be ruled out, however low,” says Detlef Koschny, heading the NEO element of the Space Situational Awareness office.

“There is only a tiny impact probability for any known object in the next 40 years, but all NEOs bear close watching to refine and understand their orbits.”

The coordination centre is also the focal point for scientific studies needed to improve warning services and provide near-realtime data to scientific bodies, international organisations and government decision-makers.

In recent years, astronomers working with or sponsored by ESA have concentrated on follow-up observations, confirming new objects and obtaining more reliable orbits. Some of this work was done with ESA’s own observatory on Tenerife in the Canary Islands.

Others have been instrumental in imaging or confirming the orbits of particularly interesting objects, such as asteroid 2016 RB1, which grazed our planet on 7 September 2016 by 34 000 km, within the orbit of many telecom satellites.

Future fly-eye telescope

In the coming years, the pace of discovery is likely to increase.

ESA is developing new ‘fly eye’ telescopes to conduct automated nightly wide-sky surveys with their very large fields of view. These are expected to begin operating around 2018. The Large Synoptic Survey Telescope, being built in Chile, is set to begin hunting space rocks in the near future.

These future telescopes offer the almost complete sky coverage and depth needed for humanity to be sure that as many NEOs as possible are discovered and identified before posing any threat.

More information and related links:

Large Synoptic Survey Telescope: https://www.lsst.org/

Catalina Sky Survey: http://www.lpl.arizona.edu/css/

Pan-STARRS project: http://pan-starrs.ifa.hawaii.edu/public/

SSA NEO Coordination Centre (NEOCC): http://neo.ssa.esa.int/

Minor Planet Center: http://www.minorplanetcenter.org/iau/mpc.html

Spaceguard Central Node: http://spaceguard.rm.iasf.cnr.it/

European Asteroid Research Node: http://earn.dlr.de/

Near-Earth Objects - Dynamic Site: http://newton.dm.unipi.it/neodys/

UK Spaceguard Centre: http://www.spaceguarduk.com/

NASA NEO Office: http://neo.jpl.nasa.gov/

UNOOSA/UN-SPIDER: http://www.un-spider.org/

Images, Text, Credits: ESA/A. Baker/MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA/Alex Alishevskikh CC BY-SA 2.0.


Greetings, Orbiter.ch

Detailed images of Schiaparelli and its descent hardware on Mars

NASA - Mars Reconnaissance Orbiter (MRO) patch / ESA & ROSCOSMOS - ExoMars Mission patch.

27 October 2016

A high-resolution image taken by a NASA Mars orbiter this week reveals further details of the area where the ExoMars Schiaparelli module ended up following its descent on 19 October.

The latest image was taken on 25 October by the high-resolution camera on NASA’s Mars Reconnaissance Orbiter and provides close-ups of new markings on the planet’s surface first found by the spacecraft’s ‘context camera’ last week.

Zooming in on Schiaparelli components on Mars

Both cameras had already been scheduled to observe the centre of the landing ellipse after the coordinates had been updated following the separation of Schiaparelli from ESA’s Trace Gas Orbiter on 16 October. The separation manoeuvre, hypersonic atmospheric entry and parachute phases of Schiaparelli’s descent went according to plan, the module ended up within the main camera’s footprint, despite problems in the final phase.

The new images provide a more detailed look at the major components of the Schiaparelli hardware used in the descent sequence.

The main feature of the context images was a dark fuzzy patch of roughly 15 x 40 m, associated with the impact of Schiaparelli itself. The high-resolution images show a central dark spot, 2.4 m across, consistent with the crater made by a 300 kg object impacting at a few hundred km/h.

The crater is predicted to be about 50 cm deep and more detail may be visible in future images.

The asymmetric surrounding dark markings are more difficult to interpret. In the case of a meteoroid hitting the surface at 40 000­–80 000 km/h, asymmetric debris surrounding a crater would typically point to a low incoming angle, with debris thrown out in the direction of travel.

Schiaparelli landing site

But Schiaparelli was travelling considerably slower and, according to the normal timeline, should have been descending almost vertically after slowing down during its entry into the atmosphere from the west.

It is possible the hydrazine propellant tanks in the module exploded preferentially in one direction upon impact, throwing debris from the planet’s surface in the direction of the blast, but more analysis is needed to explore this idea further

An additional long dark arc is seen to the upper right of the dark patch but is currently unexplained. It may also be linked to the impact and possible explosion.

Finally, there are a few white dots in the image close to the impact site, too small to be properly resolved in this image. These may or may not be related to the impact – they could just be ‘noise’. Further imaging may help identify their origin.

Mars Reconnaissance Orbiter view of Schiaparelli landing site

Some 1.4 km south of Schiaparelli, a white feature seen in last week’s context image is now revealed in more detail. It is confirmed to be the 12 m-diameter parachute used during the second stage of Schiaparelli’s descent, after the initial heatshield entry into the atmosphere. Still attached to it, as expected, is the rear heatshield, now clearly seen.

The parachute and rear heatshield were ejected from Schiaparelli earlier than anticipated. Schiaparelli is thought to have fired its thrusters for only a few seconds before falling to the ground from an altitude of 2–4 km and reaching the surface at more than 300 km/h.

In addition to the Schiaparelli impact site and the parachute, a third feature has been confirmed as the front heatshield, which was ejected about four minutes into the six-minute descent, as planned.

The ExoMars and MRO teams identified a dark spot last week’s image about 1.4 km east of the impact site and this seemed to be a plausible location for the front heatshield considering the timing and direction of travel following the module’s entry.

The mottled bright and dark appearance of this feature is interpreted as reflections from the multilayered thermal insulation that covers the inside of the front heatshield. Further imaging from different angles should be able to confirm this interpretation.

The dark features around the front heatshield are likely from surface dust disturbed during impact.

Zooming in on Schiaparelli landing site

Additional imaging by MRO is planned in the coming weeks. Based on the current data and observations made after 19 October, this will include images taken under different viewing and lighting conditions, which in turn will use shadows to help determine the local heights of the features and therefore a more conclusive analysis of what the features are.

A full investigation is now underway involving ESA and industry to identify the cause of the problems encountered by Schiaparelli in its final phase. The investigation started as soon as detailed telemetry transmitted by Schiaparelli during its descent had been relayed back to Earth by the Trace Gas Orbiter.

The full set of telemetry has to be processed, correlated and analysed in detail to provide a conclusive picture of Schiaparelli’s descent and the causes of the anomaly.

Until this full analysis has been completed, there is a danger of reaching overly simple or even wrong conclusions. For example, the team were initially surprised to see a longer-than-expected ‘gap’ of two minutes in the telemetry during the peak heating of the module as it entered the atmosphere: this was expected to last up to only one minute. However, further processing has since allowed the team to retrieve half of the ‘missing’ data, ruling out any problems with this part of the sequence.

The latter stages of the descent sequence, from the jettisoning of the rear shield and parachute, to the activation and early shut-off of the thrusters, are still being explored in detail. A report of the findings of the investigative team is expected no later than mid-November 2016.

The same telemetry is also an extremely valuable output of the Schiaparelli entry, descent and landing demonstration, as was the main purpose of this element of the ExoMars 2016 mission. Measurements were made on both the front and rear shields during entry, the first time that such data have been acquired from the back heatshield of a vehicle entering the martian atmosphere.

The team can also point to successes in the targeting of the module at its separation from the orbiter, the hypersonic atmospheric entry phase, and the parachute deployment at supersonic speeds, and the subsequent slowing of the module.

These and other data will be invaluable input into future lander missions, including the joint European–Russian ExoMars 2020 rover and surface platform.

Finally, the orbiter is working well and being prepared to make its first set of measurements on 20 November to calibrate its science instruments.

Related article:

Mars Reconnaissance Orbiter Views Schiaparelli Landing Site
http://orbiterchspacenews.blogspot.ch/2016/10/mars-reconnaissance-orbiter-views.html

Related links:

NASA's Mars Reconnaissance Orbiter (MRO): http://www.nasa.gov/mission_pages/MRO/main/index.html

ESA Robotic exploration of Mars: http://exploration.esa.int/

Roscosmos: http://en.federalspace.ru/

ExoMars at IKI: http://exomars.cosmos.ru/

Thales Alenia Space: https://www.thalesgroup.com/en/worldwide/space/space

NASA In 2016 ExoMars orbiter (Electra radio): http://mars.nasa.gov/programmissions/missions/future/exomarsorbiter2016/

Where on Mars?: http://whereonmars.co/

More about...

ExoMars Factsheet: http://www.esa.int/Our_Activities/Space_Science/ExoMars/ExoMars_Factsheet

ExoMars frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/ExoMars/ExoMars_frequently_asked_questions

ExoMars brochure: http://www.esa.int/About_Us/ESA_Publications/ESA_Publications_Brochures/ESA_BR-327_EXOMARS_2016

Images, Text, Credits: European Space Agency (ESA)/Markus Bauer/NASA/JPL-Caltech/MSSS/University of Arizona.

Best regards, Orbiter.ch

Accompanying satellite launched from Tiangong-2

CASC - Shenzhou-11 Mission patch.

26 October 2016

An accompanying satellite was launched from space lab Tiangong-2 at 7:31 a.m. on Oct. 23，2016, said Chinese scientists.

The satellite, which weighs 47 kilograms and is the size of a printer, was launched into space aboard Tiangong-2 on Sept. 15, said the Technology and Engineering Center for Space Utilization under the Chinese Academy of Sciences.

The micro satellite is able to conduct efficient orbit control, process tasks autonomously and transmit data at high speeds, with stronger capabilities compared with the accompanying satellite of the Shenzhou-7 spacecraft, it said.

At the end of October, the satellite will orbit close to Tiangong-2 and Shenzhou-11 and take photos with the high-resolution camera installed on it.

The accompanying satellite will also carry out space experiments with Tiangong-2 to expand the use of space.

The Shenzhou-11 spacecraft carried two astronauts into space on Oct. 17 from northwest China's Gobi Desert. It docked with Tiangong-2 six days later.

For more information, visit:

http://www.cnsa.gov.cn/n6443408/index.html
http://english.spacechina.com/n16421/index.html

Image, Text, Credits: CASC/Xinhua/News.cn.

Best regards, Orbiter.ch

NASA's Juno Mission Exits Safe Mode, Performs Trim Maneuver

NASA - JUNO Mission logo.

Oct. 26, 2016

NASA’s Juno spacecraft at Jupiter has left safe mode and has successfully completed a minor burn of its thruster engines in preparation for its next close flyby of Jupiter.

Mission controllers commanded Juno to exit safe mode Monday, Oct. 24, with confirmation of safe mode exit received on the ground at 10:05 a.m. PDT (1:05 p.m. EDT). The spacecraft entered safe mode on Oct. 18 when a software performance monitor induced a reboot of the spacecraft's onboard computer. The team is still investigating the cause of the reboot and assessing two main engine check valves.

"Juno exited safe mode as expected, is healthy and is responding to all our commands,” said Rick Nybakken, Juno project manager from NASA's Jet Propulsion Laboratory in Pasadena, California. "We anticipate we will be turning on the instruments in early November to get ready for our December flyby."

Image above: This artist's rendering shows NASA's Juno spacecraft making one of its close passes over Jupiter. Image Credit: NASA.

In preparation for that close flyby of Jupiter, Juno executed an orbital trim maneuver Tuesday at 11:51 a.m. PDT (2:51 p.m. EDT) using its smaller thrusters. The burn, which lasted just over 31 minutes, changed Juno’s orbital velocity by about 5.8 mph (2.6 meters per second) and consumed about 8 pounds (3.6 kilograms) of propellant. Juno will perform its next science flyby of Jupiter on Dec. 11, with time of closest approach to the gas giant occurring at 9:03 a.m. PDT (12:03 p.m. EDT). The complete suite of Juno’s science instruments, as well as the JunoCam imager, will be collecting data during the upcoming flyby.

“We are all excited and eagerly anticipating this next pass close to Jupiter,” said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio. “The science collected so far has been truly amazing."

The Juno spacecraft launched on Aug. 5, 2011, from Cape Canaveral, Florida, and arrived at Jupiter on July 4, 2016. During its mission of exploration, Juno soars low over the planet's cloud tops -- as close as about 2,600 miles (4,100 kilometers). During these flybys, Juno probes beneath the obscuring cloud cover of Jupiter and studies its auroras to learn more about the planet's origins, structure, atmosphere and magnetosphere.

More information on the Juno mission is available at: http://www.nasa.gov/juno

The public can follow the mission on Facebook and Twitter at:

http://www.facebook.com/NASAJuno

http://www.twitter.com/NASAJuno

Images and information on how members of the public can participate in JunoCam’s mission, can be found at:  http://www.missionjuno.swri.edu/junocam

Image (mentioned), Text, Credits: NASA/Dwayne Brown/Laurie Cantillo/Tony Greicius/JPL/DC Agle.

Greetings, Orbiter.ch

ESO’s VLT Detects Unexpected Giant Glowing Halos around Distant Quasars

ESO - European Southern Observatory logo.

26 October 2016

Bright halos around distant quasars

An international team of astronomers has discovered glowing gas clouds surrounding distant quasars. This new survey by the MUSE instrument on ESO’s Very Large Telescope indicates that halos around quasars are far more common than expected. The properties of the halos in this surprising find are also in striking disagreement with currently accepted theories of galaxy formation in the early Universe.

An international collaboration of astronomers, led by a group at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland, has used the unrivalled observing power of MUSE on the Very Large Telescope (VLT) at ESO’s Paranal Observatory to study gas around distant active galaxies, less than two billion years after the Big Bang. These active galaxies, called quasars, contain supermassive black holes in their centres, which consume stars, gas, and other material at an extremely high rate. This, in turn, causes the galaxy centre to emit huge amounts of radiation, making quasars the most luminous and active objects in the Universe.

Bright halos around distant quasars

The study involved 19 quasars, selected from among the brightest that are observable with MUSE. Previous studies have shown that around 10% of all quasars examined were surrounded by halos, made from gas known as the intergalactic medium. These halos extend up to 300 000 light-years away from the centres of the quasars. This new study, however, has thrown up a surprise, with the detection of large halos around all 19 quasars observed  — far more than the two halos that were expected statistically. The team suspects this is due to the vast increase in the observing power of MUSE over previous similar instruments, but further observations are needed to determine whether this is the case.

“It is still too early to say if this is due to our new observational technique or if there is something peculiar about the quasars in our sample. So there is still a lot to learn; we are just at the beginning of a new era of discoveries”, says lead author Elena Borisova, from the ETH Zurich.

The original goal of the study was to analyse the gaseous components of the Universe on the largest scales; a structure sometimes referred to as the cosmic web, in which quasars form bright nodes [1]. The gaseous components of this web are normally extremely difficult to detect, so the illuminated halos of gas surrounding the quasars deliver an almost unique opportunity to study the gas within this large-scale cosmic structure.

3D animation of quasar halo

The 19 newly-detected halos also revealed another surprise: they consist of relatively cold intergalactic gas — approximately 10 000 degrees Celsius. This revelation is in strong disagreement with currently accepted models of the structure and formation of galaxies, which suggest that gas in such close proximity to galaxies should have temperatures upwards of a million degrees.

The discovery shows the potential of MUSE for observing this type of object [2]. Co-author Sebastiano Cantalupo is very excited about the new instrument and the opportunities it provides: “We have exploited the unique capabilities of MUSE in this study, which will pave the way for future surveys. Combined with a new generation of theoretical and numerical models, this approach will continue to provide a new window on cosmic structure formation and galaxy evolution.”

Notes:

[1] The cosmic web is the structure of the Universe at the largest scale. It is comprised of spindly filaments of primordial material (mostly hydrogen and helium gas) and dark matter which connect galaxies and span the chasms between them. The material in this web can feed along the filaments into galaxies and drive their growth and evolution.

[2] MUSE is an integral field spectrograph and combines spectrographic and imaging capabilities. It can observe large astronomical objects in their entirety in one go, and for each pixel measure the intensity of the light as a function of its colour, or wavelength.

More information:

This research was presented in the paper "Ubiquitous giant Lyα nebulae around the brightest quasars at z ~ 3.5 revealed with MUSE", to appear in the Astrophysical Journal.

The team is composed of Elena Borisova, Sebastiano Cantalupo, Simon J. Lilly, Raffaella A. Marino and Sofia G. Gallego (Institute for Astronomy, ETH Zurich, Switzerland), Roland Bacon and Jeremy Blaizot (University of Lyon, Centre de Recherche Astrophysique de Lyon, Saint-Genis-Laval, France), Nicolas Bouché (Institut de Recherche en Astrophysique et Planétologie, Toulouse, France), Jarle Brinchmann (Leiden Observatory, Leiden, The Netherlands; Instituto de Astrofísica e Ciências do Espaço, Porto, Portugal), C Marcella Carollo (Institute for Astronomy, ETH Zurich, Switzerland), Joseph Caruana (Department of Physics, University of Malta, Msida, Malta; Institute of Space Sciences & Astronomy, University of Malta, Malta), Hayley Finley (Institut de Recherche en Astrophysique et Planétologie, Toulouse, France), Edmund C. Herenz (Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany), Johan Richard (Univ Lyon, Centre de Recherche Astrophysique de Lyon, Saint-Genis-Laval, France), Joop Schaye and Lorrie A. Straka (Leiden Observatory, Leiden, The Netherlands), Monica L. Turner (MIT-Kavli Center for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA), Tanya Urrutia (Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany), Anne Verhamme (University of Lyon, Centre de Recherche Astrophysique de Lyon, Saint-Genis-Laval, France), Lutz Wisotzki (Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany).

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Links:

Research paper: http://www.eso.org/public/archives/releases/sciencepapers/eso1638/eso1638a.pdf

Photos of the VLT: http://www.eso.org/public/images/archive/category/paranal/

Swiss Federal Institute of Technology (ETH): https://www.ethz.ch/en.html

MUSE: https://www.eso.org/public/teles-instr/vlt/vlt-instr/muse/

Very Large Telescope (VLT): http://eso.org/vlt

Image, Videos, Text, Credits: ESO/S. Cantalupo/Borisova et al.

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