Friday, December 15, 2017

Cosmic fireflies

Credit: ESA/Hubble & NASA


Galaxies glow like fireflies in this spectacular NASA/ESA Hubble Space Telescope image! This flickering swarm of cosmic fireflies is a rich cluster of galaxies called Abell 2163. Abell 2163 is a member of the Abell catalogue, an all-sky catalogue of over 4000 galaxy clusters. It is particularly well-studied because the material sitting at its core (its intracluster medium) exhibits exceptional properties, including a large and bright radio halo and extraordinarily high temperatures and X-ray luminosities. It is the hottest cluster in the catalogue! Observing massive clusters like Abell 2163 can contribute to the study of dark matter, and provide a new perspective on the distant Universe via phenomena such as gravitational lensing

This image was taken by Hubble’s Advanced Camera for Surveys and Wide-Field Camera 3, partially for an extensive observing programme called RELICS. The programme is imaging 41 massive galaxy clusters to find the brightest distant galaxies, which will be studied in more detail using both current telescopes and the future NASA/ESA/CSA James Webb Space Telescope (JWST).



Thursday, December 14, 2017

Mars Mission Sheds Light on Habitability of Distant Planets

This illustration depicts charged particles from a solar storm stripping away charged particles of Mars' atmosphere, one of the processes of Martian atmosphere loss studied by NASA's MAVEN mission, beginning in 2014. Unlike Earth, Mars lacks a global magnetic field that could deflect charged particles emanating from the Sun. Image credit: NASA/GSFC.  › Full image and caption


To receive the same amount of starlight as Mars receives from our Sun, a planet orbiting an M-type red dwarf would have to be positioned much closer to its star than Mercury is to the Sun. Image credit: NASA/GSFC.  › Full image and caption


How long might a rocky, Mars-like planet be habitable if it were orbiting a red dwarf star? It's a complex question but one that NASA's Mars Atmosphere and Volatile Evolution mission can help answer.

"The MAVEN mission tells us that Mars lost substantial amounts of its atmosphere over time, changing the planet's habitability," said David Brain, a MAVEN co-investigator and a professor at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder. "We can use Mars, a planet that we know a lot about, as a laboratory for studying rocky planets outside our solar system, which we don't know much about yet."

At the fall meeting of the American Geophysical Union on Dec. 13, 2017, in New Orleans, Louisiana, Brain described how insights from the MAVEN mission could be applied to the habitability of rocky planets orbiting other stars. 

MAVEN carries a suite of instruments that have been measuring Mars' atmospheric loss since November 2014. The studies indicate that Mars has lost the majority of its atmosphere to space over time through a combination of chemical and physical processes. The spacecraft's instruments were chosen to determine how much each process contributes to the total escape.

In the past three years, the Sun has gone through periods of higher and lower solar activity, and Mars also has experienced solar storms, solar flares and coronal mass ejections. These varying conditions have given MAVEN the opportunity to observe Mars' atmospheric escape getting cranked up and dialed down.

Brain and his colleagues started to think about applying these insights to a hypothetical Mars-like planet in orbit around some type of M-star, or red dwarf, the most common class of stars in our galaxy.

The researchers did some preliminary calculations based on the MAVEN data. As with Mars, they assumed that this planet might be positioned at the edge of the habitable zone of its star. But because a red dwarf is dimmer overall than our Sun, a planet in the habitable zone would have to orbit much closer to its star than Mercury is to the Sun.

The brightness of a red dwarf at extreme ultraviolet (UV) wavelengths combined with the close orbit would mean that the hypothetical planet would get hit with about 5 to 10 times more UV radiation than the real Mars does. That cranks up the amount of energy available to fuel the processes responsible for atmospheric escape. Based on what MAVEN has learned, Brain and colleagues estimated how the individual escape processes would respond to having the UV cranked up.

Their calculations indicate that the planet's atmosphere could lose 3 to 5 times as many charged particles, a process called ion escape. About 5 to 10 times more neutral particles could be lost through a process called photochemical escape, which happens when UV radiation breaks apart molecules in the upper atmosphere.

Because more charged particles would be created, there also would be more sputtering, another form of atmospheric loss. Sputtering happens when energetic particles are accelerated into the atmosphere and knock molecules around, kicking some of them out into space and sending others crashing into their neighbors, the way a cue ball does in a game of pool.

Finally, the hypothetical planet might experience about the same amount of thermal escape, also called Jeans escape. Thermal escape occurs only for lighter molecules, such as hydrogen. Mars loses its hydrogen by thermal escape at the top of the atmosphere. On the exo-Mars, thermal escape would increase only if the increase in UV radiation were to push more hydrogen to the top of the atmosphere.

Altogether, the estimates suggest that orbiting at the edge of the habitable zone of a quiet M-class star, instead of our Sun, could shorten the habitable period for the planet by a factor of about 5 to 20. For an M-star whose activity is amped up like that of a Tasmanian devil, the habitable period could be cut by a factor of about 1,000 -- reducing it to a mere blink of an eye in geological terms. The solar storms alone could zap the planet with radiation bursts thousands of times more intense than the normal activity from our Sun.

However, Brain and his colleagues have considered a particularly challenging situation for habitability by placing Mars around an M-class star. A different planet might have some mitigating factors -- for example, active geological processes that replenish the atmosphere to a degree, a magnetic field to shield the atmosphere from stripping by the stellar wind, or a larger size that gives more gravity to hold on to the atmosphere. 

"Habitability is one of the biggest topics in astronomy, and these estimates demonstrate one way to leverage what we know about Mars and the Sun to help determine the factors that control whether planets in other systems might be suitable for life," said Bruce Jakosky, MAVEN's principal investigator at the University of Colorado Boulder.

MAVEN's principal investigator is based at the University of Colorado's Laboratory for Atmospheric and Space Physics, Boulder. The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN project and provided two science instruments for the mission. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Exploration Program for NASA's Science Mission Directorate, Washington. 

For more information about MAVEN, visit: https://www.nasa.gov/maven


News Media Contact

Laurie Cantillo / Dwayne Brown
NASA Headquarters, Washington
202-358-1077 / 202-358-1726

laura.l.cantillo@nasa.gov / dwayne.c.brown@nasa.gov

Written by Elizabeth Zubritsky
NASA's Goddard Space Flight Center, Greenbelt, Md.



Wednesday, December 13, 2017

Stellar Nursery Blooms into View

Stellar Nursery Blooms into View

The star formation region NGC 6559 in the constellation of Sagittarius

The rich surroundings of Sharpless 29



Videos

ESOcast 142 Light: Stellar Nursery Blooms into View (4K UHD)
ESOcast 142 Light: Stellar Nursery Blooms into View (4K UHD)

Zooming in on the star-forming region Sharpless 29
Zooming in on the star-forming region Sharpless 29

Panning across the VST’s view of Sharpless 29
Panning across the VST’s view of Sharpless 29



The OmegaCAM camera on ESO’s VLT Survey Telescope has captured this glittering view of the stellar nursery called Sharpless 29. Many astronomical phenomena can be seen in this giant image, including cosmic dust and gas clouds that reflect, absorb, and re-emit the light of hot young stars within the nebula.

The region of sky pictured is listed in the Sharpless catalogue of H II regions: interstellar clouds of ionised gas, rife with star formation. Also known as Sh 2-29, Sharpless 29 is located about 5500 light-years away in the constellation of Sagittarius (The Archer), next door to the larger Lagoon Nebula. It contains many astronomical wonders, including the highly active star formation site of NGC 6559, the nebula at the centre of the image.

This central nebula is Sharpless 29’s most striking feature. Though just a few light-years across, it showcases the havoc that stars can wreak when they form within an interstellar cloud. The hot young stars in this image are no more than two million years old and are blasting out streams of high-energy radiation. This energy heats up the surrounding dust and gas, while their stellar winds dramatically erode and sculpt their birthplace. In fact, the nebula contains a prominent cavity that was carved out by an energetic binary star system. This cavity is expanding, causing the interstellar material to pile up and create the reddish arc-shaped border.

When interstellar dust and gas are bombarded with ultraviolet light from hot young stars, the energy causes them to shine brilliantly. The diffuse red glow permeating this image comes from the emission of hydrogen gas, while the shimmering blue light is caused by reflection and scattering off small dust particles. As well as emission and reflection, absorption takes place in this region. Patches of dust block out the light as it travels towards us, preventing us from seeing the stars behind it, and smaller tendrils of dust create the dark filamentary structures within the clouds.

The rich and diverse environment of Sharpless 29 offers astronomers a smorgasbord of physical properties to study. The triggered formation of stars, the influence of the young stars upon dust and gas, and the disturbance of magnetic fields can all be observed and examined in this single area.
But young, massive stars live fast and die young. They will eventually explosively end their lives in a supernova, leaving behind rich debris of gas and dust. In tens of millions of years, this will be swept away and only an open cluster of stars will remain.

Sharpless 29 was observed with ESO’s OmegaCAM on the VLT Survey Telescope (VST) at Cerro Paranal in Chile. OmegaCAM produces images that cover an area of sky more than 300 times greater than the largest field of view imager of the NASA/ESA Hubble Space Telescope, and can observe over a wide range of wavelengths from the ultraviolet to the infrared. Its hallmark feature is its ability to capture the very red spectral line H-alpha, created when the electron inside a hydrogen atom loses energy, a prominent occurrence in a nebula like Sharpless 29.




More Information


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



Links


Contacts

Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591


Email: rhook@eso.org


Source: ESO

Tuesday, December 12, 2017

Chandra Reveals the Elementary Nature of Cassiopeia A

 Cassiopeia A
 Credit  NASA/CXC/SAO



 
Where do most of the elements essential for life on Earth come from? The answer: inside the furnaces of stars and the explosions that mark the end of some stars' lives.

Astronomers have long studied exploded stars and their remains — known as "supernova remnants" — to better understand exactly how stars produce and then disseminate many of the elements observed on Earth, and in the cosmos at large.

Due to its unique evolutionary status, Cassiopeia A (Cas A) is one of the most intensely studied of these supernova remnants. A new image from NASA's Chandra X-ray Observatory shows the location of different elements in the remains of the explosion: silicon (red), sulfur (yellow), calcium (green) and iron (purple). Each of these elements produces X-rays within narrow energy ranges, allowing maps of their location to be created. The blast wave from the explosion is seen as the blue outer ring.

Location of elements in Cassiopeia A. 
Credit: NASA/CXC/SAO 

X-ray telescopes such as Chandra are important to study supernova remnants and the elements they produce because these events generate extremely high temperatures — millions of degrees — even thousands of years after the explosion. This means that many supernova remnants, including Cas A, glow most strongly at X-ray wavelengths that are undetectable with other types of telescopes.

Chandra's sharp X-ray vision allows astronomers to gather detailed information about the elements that objects like Cas A produce. For example, they are not only able to identify many of the elements that are present, but how much of each are being expelled into interstellar space.

The Chandra data indicate that the supernova that produced Cas A has churned out prodigious amounts of key cosmic ingredients. Cas A has dispersed about 10,000 Earth masses worth of sulfur alone, and about 20,000 Earth masses of silicon. The iron in Cas A has the mass of about 70,000 times that of the Earth, and astronomers detect a whopping one million Earth masses worth of oxygen being ejected into space from Cas A, equivalent to about three times the mass of the Sun. (Even though oxygen is the most abundant element in Cas A, its X-ray emission is spread across a wide range of energies and cannot be isolated in this image, unlike with the other elements that are shown.)

Astronomers have found other elements in Cas A in addition to the ones shown in this new Chandra image. Carbon, nitrogen, phosphorus and hydrogen have also been detected using various telescopes that observe different parts of the electromagnetic spectrum. Combined with the detection of oxygen, this means all of the elements needed to make DNA, the molecule that carries genetic information, are found in Cas A.

Periodic Table of Elements
Credit: NASA/CXC/K. Divona

Oxygen is the most abundant element in the human body (about 65% by mass), calcium helps form and maintain healthy bones and teeth, and iron is a vital part of red blood cells that carry oxygen through the body. All of the oxygen in the Solar System comes from exploding massive stars. About half of the calcium and about 40% of the iron also come from these explosions, with the balance of these elements being supplied by explosions of smaller mass, white dwarf stars.

While the exact date is not confirmed (PDF), many experts think that the stellar explosion that created Cas A occurred around the year 1680 in Earth's timeframe. Astronomers estimate that the doomed star was about five times the mass of the Sun just before it exploded. The star is estimated to have started its life with a mass about 16 times that of the Sun, and lost roughly two-thirds of this mass in a vigorous wind blowing off the star several hundred thousand years before the explosion.

Earlier in its lifetime, the star began fusing hydrogen and helium in its core into heavier elements through the process known as "nucleosynthesis." The energy made by the fusion of heavier and heavier elements balanced the star against the force of gravity. These reactions continued until they formed iron in the core of the star. At this point, further nucleosynthesis would consume rather than produce energy, so gravity then caused the star to implode and form a dense stellar core known as a neutron star.

Pre-Supernova Star: As it nears the end of its evolution, heavy elements produced by nuclear fusion inside the star are concentrated toward the center of the star. Illustration Credit: NASA/CXC/S. Lee 

The exact means by which a massive explosion is produced after the implosion is complicated, and a subject of intense study, but eventually the infalling material outside the neutron star was transformed by further nuclear reactions as it was expelled outward by the supernova explosion.

Chandra has repeatedly observed Cas A since the telescope was launched into space in 1999. The different datasets have revealed new information about the neutron star in Cas A, the details of the explosion, and specifics of how the debris is ejected into space.

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





Fast Facts for Cassiopeia A:

Scale: Image is 8.91 arcmin across (about 29 light years)
Category: Supernovas & Supernova Remnants
Observation Date: 16 pointings between Jan. 2000-Nov. 2010
Observation Time: 353 hours (14 days, 17 hours)
Obs. ID: 114, 1952, 4634-4639, 5196, 5319, 5320, 6690, 10935, 10936, 12020, 13177
Instrument: ACIS
Also Known As: Cas A
References: Hwang and Laming, 2012, ApJ, 746, 130; arXiv:1111.7316; Lee, et al. 2014, ApJ, 789, 7; arXiv:1304.3973
Color Code: X-rays: Red: Silicon, Yellow: Sulphur, Green: Calcium, Purple: Iron, Blue: Blast Wave
Distance Estimate: About 11,000 light years



Saturday, December 09, 2017

Explosive tendencies

Credit: ESA/Hubble & NASA


Don’t be fooled! The subject of this Picture of the Week, ESO 580-49, may seem tranquil and unassuming, but this spiral galaxy actually displays some explosive tendencies.

In October of 2011, a cataclysmic burst of high-energy gamma-ray radiation — known as a gamma-ray burst, or GRB — was detected coming from the region of sky containing ESO 580-49. 
Astronomers believe that the galaxy was the host of the GRB, given that the chance of a coincidental alignment between the two is roughly 1 in 10 million. At a distance of around 185 million light-years from Earth, it was the second-closest gamma-ray burst (GRB) ever detected.

Gamma-ray bursts are among the brightest events in the cosmos, occasionally outshining the combined gamma-ray output of the entire observable Universe for a few seconds. The exact cause of the GRB that probably occurred within this galaxy, catalogued as GRB 111005A, remains a mystery. 

Several events are known to lead to GRBs, but none of these explanations appear to fit the bill in this case. Astronomers have therefore suggested that ESO 580-49 hosted a new type of GRB explosion — one that has not yet been characterised.


Friday, December 08, 2017

Massive Primordial Galaxies Found Swimming in Vast Ocean of Dark Matter

Artist impression of a pair of galaxies from the very early universe.
Credit: NRAO/AUI/NSF; D. Berry

To correct for the effects of gravitational lensing in these galaxies, the ALMA data (left panel) is compared to a lensing-distorted model image (second panel from left). The difference is shown in the third panel from the left. The structure of the galaxy, after removing the lensing effect, is shown at right. This image loops through the different velocity ranges within the galaxy, which appear at different frequencies to ALMA due to the Doppler effect.Credit: ALMA (ESO/NAOJ/NRAO); D. Marrone et al.

A composite image showing ALMA data (red) of the two galaxies of SPT0311-58. These galaxies are shown over a background from the Hubble Space Telescope (blue and green). The ALMA data show the two galaxies' dusty glow. The image of the galaxy on the right is distorted by gravitational lensing. The nearer foreground lensing galaxy is the green object between the two galaxies imaged by ALMA.Credit: ALMA (ESO/NAOJ/NRAO), Marrone, et al.; B. Saxton (NRAO/AUI/NSF); NASA/ESA Hubble 



Astronomers expect that the first galaxies, those that formed just a few hundred million years after the Big Bang, would share many similarities with some of the dwarf galaxies we see in the nearby universe today. These early agglomerations of a few billion stars would then become the building blocks of the larger galaxies that came to dominate the universe after the first few billion years.

Ongoing observations with the Atacama Large Millimeter/submillimeter Array (ALMA), however, have discovered surprising examples of massive, star-filled galaxies seen when the cosmos was less than a billion years old. This suggests that smaller galactic building blocks were able to assemble into large galaxies quite quickly.

The latest ALMA observations push back this epoch of massive-galaxy formation even further by identifying two giant galaxies seen when the universe was only 780 million years old, or about 5 percent its current age. ALMA also revealed that these uncommonly large galaxies are nestled inside an even-more-massive cosmic structure, a halo of dark matter several trillion times more massive than the sun.

The two galaxies are in such close proximity — less than the distance from the Earth to the center of our galaxy — that they will shortly merge to form the largest galaxy ever observed at that period in cosmic history. This discovery provides new details about the emergence of large galaxies and the role that dark matter plays in assembling the most massive structures in the universe.

The researchers report their findings in the journal Nature.

“With these exquisite ALMA observations, astronomers are seeing the most massive galaxy known in the first billion years of the universe in the process of assembling itself,” said Dan Marrone, associate professor of astronomy at the University of Arizona in Tucson and lead author on the paper.

Astronomers are seeing these galaxies during a period of cosmic history known as the Epoch of Reionization, when most of intergalactic space was suffused with an obscuring fog of cold hydrogen gas. As more stars and galaxies formed, their energy eventually ionized the hydrogen between the galaxies, revealing the universe as we see it today.

“We usually view that as the time of little galaxies working hard to chew away at the neutral intergalactic medium,” said Marrone. “Mounting observational evidence with ALMA, however, has helped to reshape that story and continues to push back the time at which truly massive galaxies first emerged in the universe.”

The galaxies that Marrone and his team studied, collectively known as SPT0311-58, were originally identified as a single source by the  South Pole Telescope. These first observations indicated that this object was very distant and glowing brightly in infrared light, meaning that it was extremely dusty and likely going through a burst of star formation. Subsequent observations with ALMA revealed the distance and dual nature of the object, clearly resolving the pair of interacting galaxies.

To make this observation, ALMA had some help from a gravitational lens, which provided an observing boost to the telescope. Gravitational lenses form when an intervening massive object, like a galaxy or galaxy cluster, bends the light from more distant galaxies. They do, however, distort the appearance of the object being studied, requiring sophisticated computer models to reconstruct the image as it would appear in its unaltered state.

This “de-lensing” process provided intriguing details about the galaxies, showing that the larger of the two is forming stars at a rate of 2,900 solar masses per year. It also contains about 270 billion times the mass of our sun in gas and nearly 3 billion times the mass of our sun in dust. “That’s a whopping large quantity of dust, considering the young age of the system,” noted Justin Spilker, a recent graduate of the University of Arizona and now a postdoctoral fellow at the University of Texas at Austin.

The astronomers determined that this galaxy’s rapid star formation was likely triggered by a close encounter with its slightly smaller companion, which already hosts about 35 billion solar masses of stars and is increasing its rate of starburst at the breakneck pace of 540 solar masses per year.

The researchers note that galaxies of this era are “messier” than the ones we see in the nearby universe. Their more jumbled shapes would be due to the vast stores of gas raining down on them and their ongoing interactions and mergers with their neighbors.

The new observations also allowed the researchers to infer the presence of a truly massive dark matter halo surrounding both galaxies. Dark matter provides the pull of gravity that causes the universe to collapse into structures (galaxies, groups and clusters of galaxies, etc.).

“If you want to see if a galaxy makes sense in our current understanding of cosmology, you want to look at the dark matter halo — the collapsed dark matter structure — in which it resides,” said Chris Hayward, associate research scientist at the Center for Computational Astrophysics at the Flatiron Institute in New York City. “Fortunately, we know very well the ratio between dark matter and normal matter in the universe, so we can estimate what the dark matter halo mass must be.”

By comparing their calculations with current cosmological predictions, the researchers found that this halo is one of the most massive that should exist at that time.

“There are more galaxies discovered with the South Pole Telescope that we’re following up on,” said Joaquin Vieira of the University of Illinois at Urbana-Champaign, “and there is a lot more survey data that we are just starting to analyze. Our hope is to find more objects like this, possibly even more distant ones, to better understand this population of extreme dusty galaxies and especially their relation to the bulk population of galaxies at this epoch.”

“In any case, our next round of ALMA observations should help us understand how quickly these galaxies came together and improve our understanding of massive galaxy formation during reionization,” added Marrone.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.



This research is presented in a paper titled “’Galaxy growth in a massive halo in the first billion years of cosmic history,” by D. Marrone, et al., which appears in Advance Online Publication for Nature. [http://www.nature.com/nature].

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) in Taiwan and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

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


Contact:

Charles Blue, Public Information Officer
(434) 296-0314;
cblue@nrao.edu


Thursday, December 07, 2017

Found: Most Distant Black Hole

This artist's concept shows the most distant supermassive black hole ever discovered. It is part of a quasar from just 690 million years after the Big Bang. Credit: Robin Dienel/Carnegie Institution for Science.  › Larger view

Scientists have uncovered a rare relic from the early universe: the farthest known supermassive black hole. This matter-eating beast is 800 million times the mass of our Sun, which is astonishingly large for its young age. Researchers report the find in the journal Nature.

"This black hole grew far larger than we expected in only 690 million years after the Big Bang, which challenges our theories about how black holes form," said study co-author Daniel Stern of NASA's Jet Propulsion Laboratory in Pasadena, California.

Astronomers combined data from NASA's Wide-field Infrared Survey Explorer (WISE) with ground-based surveys to identify potential distant objects to study, then followed up with Carnegie Observatories' Magellan telescopes in Chile. Carnegie astronomer Eduardo Bañados led the effort to identify candidates out of the hundreds of millions of objects WISE found that would be worthy of follow-up with Magellan. 

For black holes to become so large in the early universe, astronomers speculate there must have been special conditions to allow rapid growth -- but the underlying reason remains mysterious. 

The newly found black hole is voraciously devouring material at the center of a galaxy -- a phenomenon called a quasar. This quasar is especially interesting because it comes from a time when the universe was just beginning to emerge from its dark ages. The discovery will provide fundamental information about the universe when it was only 5 percent of its current age.

"Quasars are among the brightest and most distant known celestial objects and are crucial to understanding the early universe," said co-author Bram Venemans of the Max Planck Institute for Astronomy in Germany.

The universe began in a hot soup of particles that rapidly spread apart in a period called inflation. About 400,000 years after the Big Bang, these particles cooled and coalesced into neutral hydrogen gas. But the universe stayed dark, without any luminous sources, until gravity condensed matter into the first stars and galaxies. The energy released by these ancient galaxies caused the neutral hydrogen to get excited and ionize, or lose an electron. The gas has remained in that state since that time. Once the universe became reionzed, photons could travel freely throughout space. This is the point at which the universe became transparent to light.

Much of the hydrogen surrounding the newly discovered quasar is neutral. That means the quasar is not only the most distant -- it is also the only example we have that can be seen before the universe became reionized.

"It was the universe's last major transition and one of the current frontiers of astrophysics," Bañados said. 

The quasar's distance is determined by what's called its redshift, a measurement of how much the wavelength of its light is stretched by the expansion of the universe before reaching Earth. The higher the redshift, the greater the distance, and the farther back astronomers are looking in time when they observe the object. This newly discovered quasar has a redshift of 7.54, based on the detection of ionized carbon emissions from the galaxy that hosts the massive black hole. That means it took more than 13 billion years for the light from the quasar to reach us. 

Scientists predict the sky contains between 20 and 100 quasars as bright and as distant as this quasar. Astronomers look forward to the European Space Agency's Euclid mission, which has significant NASA participation, and NASA's Wide-field Infrared Survey Telescope (WFIRST) mission, to find more such distant objects.

"Withseveral next-generation, even-more-sensitive facilities currentlybeing built, we can expect many exciting discoveries in the very earlyuniverse in the coming years," Stern said.

Caltech in Pasadena, California, manages JPL for NASA.


News Media Contact

Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6425

elizabeth.landau@jpl.nasa.gov

Eduardo Bañados
Carnegie Observatories, Pasadena, Calif.
626-304-0236

ebanados@carnegiescience.edu

Source: NASA/News

Wednesday, December 06, 2017

A New Spin to Solving Mystery of Stellar Companions

Image of the planetary-mass companion VHS 1256-1257 b (bottom right) and its host star (center).
Credit: Gauza, B. et al 2015, MNRAS, 452, 1677-1683

Image of the planetary-mass companion GSC 6214-210 b (bottom) and its host star (top).
Credit: Ireland, M. J. et al 2011, ApJ, 726, 113

Image of the planetary-mass companion ROXs 42B b (right, labeled 'b') and its host star (left, labeled 'A').
Credit: Kraus, A. L. et al. 2014, ApJ, 781, 20



Researchers Measure the Spin Rates of Bodies Thought to be Either Planets or Tiny "Failed" Stars

Maunakea, Hawaii - Taking a picture of an exoplanet—a planet in a solar system beyond our sun—is no easy task. The light of a planet's parent star far outshines the light from the planet itself, making the planet difficult to see. While taking a picture of a small rocky planet like Earth is still not feasible, researchers have made strides by snapping images of about 20 giant planet-like bodies. These objects, known as planetary-mass companions, are more massive than Jupiter, orbit far from the glare of their stars, and are young enough to still glow with heat from their formation—all traits that make them easier to photograph.

But one big question remains: Are these planetary-mass companions actually planets, or are they instead small "failed" stars called brown dwarfs? Brown dwarfs form like stars do—out of collapsing clouds of gas—but they lack the mass to ignite and shine with starlight. They can be found floating on the their own in space, or they can be found orbiting with other brown dwarfs or stars. The smallest brown dwarfs are similar in size to Jupiter and would look just like a planet when orbiting a star.

Using the W. M. Keck Observatory on Maunakea, Hawaii, researchers at Caltech have taken a new approach to the mystery: they have measured the spin rates of three of the photographed planetary-mass companions and compared them to spin rates for small brown dwarfs. The results offer a new set of clues that hint at how the companions may have formed.

"These companions with their high masses and wide separations could have formed either as planets or brown dwarfs," says graduate student Marta Bryan (MS '14), lead author of a new study describing the findings in the journal Nature Astronomy. "In this study, we wanted to shed light on their origins."
"These new spin measurements suggest that if these bodies are massive planets located far away from their stars, they have properties that are very similar to those of the smallest brown dwarfs," 

says Heather Knutson, professor of planetary science at Caltech and a co-author of the paper.

The astronomers measured the spin rate, or the length of a day, of three planetary-mass companions known as ROXs 42B b, GSC 6214-210 b, and VHS 1256-1257 b. They used an instrument at Keck Observatory called the Near Infrared Spectrograph (NIRSpec) to dissect the light coming from the companions. As the objects spin on their axes, light from the side that is turning toward us shifts to shorter, bluer wavelengths, while light from the receding side shifts to longer, redder wavelengths. The degree of this shifting indicates the speed of a rotating body. The results showed that the three companions' spin rates ranged between six to 14 kilometers per second, similar to rotation rates of our solar system's gas giant planets Saturn and Jupiter.

Animation Credit: NASA/JPL-Caltech

For the study, the researchers also included the two planetary-mass companions for which spin rates had already been measured. One, β Pictoris b, has a rotation rate of 25 kilometers per second—the fastest rotation rate of any planetary-mass body measured so far.

The researchers compared the spin rates for the five companions to those measured previously for small free-floating brown dwarfs. The ranges of rotation rates for the two populations were indistinguishable. In other words, the companions are whirling about their own axes at about the same speeds as their free-floating brown-dwarf counterparts.

The results suggest two possibilities. One is that the planetary-mass companions are actually brown dwarfs. The second possibility is that the companions looked at in this study are planets that formed, just as planets do, out of disks of material swirling around their stars, but for reasons not yet understood, the objects ended up with spin rates similar to those of brown dwarfs. Some researchers think that both newly forming planets and brown dwarfs are encircled by miniature gas disks that might be helping to slow their spin rates. In other words, similar physical processes may leave planets and brown dwarfs with similar spin rates.

"It's a question of nature versus nurture," says Knutson. "Were the planetary companions born like brown dwarfs, or did they just end up behaving like them with similar spins?"

The team also says that the companions are spinning more slowly than expected. Growing planets tend to be spun up by the material they pull in from a surrounding gas disk, in the same way that spinning ice skaters increase their speed, or angular momentum, when they pull their arms in. The relatively slow rotation rates observed for these objects indicate that they were able to effectively put the brakes on this spin-up process, perhaps by transferring some of this angular momentum back to encircling gas disks. The researchers are planning future studies of spin rates to further investigate the matter.

"Spin rates of planetary-mass bodies outside our solar system have not been fully explored," says Bryan. "We are just now beginning to use this as a tool for understanding formation histories of planetary-mass objects."

The study, titled, "Constraints on the Spin Evolution of Young Planetary-MassCompanions," was funded by NASA and the Sloan Research Fellowship Program. Other authors include Caltech's Konstantin Batygin (MS '10, PhD '12), assistant professor of planetary science and Van Nuys Page Scholar; Björn Benneke, formerly of Caltech and now of the University of Montreal; and Brendan Bowler of the University of Texas at Austin.





Media Contacts:

Mari-Ela Chock, Keck Observatory
(808) 554-0567
mchock@keck.hawaii.edu

Whitney Clavin, Caltech
(626) 395-1856
wclavin@caltech.edu



About W. M. Keck Observatory

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

The data presented herein were obtained at Keck Observatory, which is a private 501(c) 3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.


Article Summary

Scientists are investigating the nature of planetary-mass bodies that orbit stars, finding new clues to their origins.


Saturday, December 02, 2017

Star formation in the Chamaeleon

Star formation in the Chamaeleon 
Copyright ESA/Herschel; acknowledgement: Á. Ribas 


A dark cloud when observed with optical telescopes, the Chamaeleon I region reveals itself as an active hub of star formation in this far-infrared image from ESA’s Herschel space observatory. Only around 550 light-years away in the southern constellation of Chamaeleon, it is one of the closest areas where stars are bursting into life.

Launched in 2009, Herschel observed the sky at far-infrared and submillimetre wavelengths until 2013. Sensitive to the heat from the small fraction of cold dust mixed in with the clouds of gas where stars form, it provided unprecedented views of the interstellar material that pervades our Milky Way galaxy.

Herschel’s extraordinary scans uncovered a vast and intricate network of filamentary structures everywhere in the Galaxy, confirming that filaments are crucial elements in the process of star formation.

After a filamentary web arises from turbulent motions of gas in the interstellar material, gravity takes over, but only in the densest filaments, which become unstable and fragment into compact objects – the seeds of future stars.

Chamaeleon I is no exception, with several elongated structures weaving their way through the cloud. Most of the star-forming activity is taking place at the convergence of filaments – in the bright area towards the top right and in the vaster region just left of the image centre, sprinkled with newborn stars that are heating up the material in their surroundings.

Analysing images like this, astronomers have identified more than 200 young stars in this two million year-old cloud. Most of these stars are still surrounded by a disc of leftover material from the formation process, which may evolve and later give rise to planets.

Owing to its relative vicinity, Chamaeleon I is an ideal laboratory to explore protoplanetary discs and their properties using Herschel data.

This image was first published in a paper by Á. Ribas et al. (2013), which presents a study of protoplanetary discs in this region. It was also shared as a #HerschelMoment during a public campaign on Twitter to celebrate the legacy of ESA's observatory in September 2017.

This three-colour image combines Herschel observations at 70 microns (blue), 160 microns (green) and 250 microns (red), and spans about 2.5º on the long side; north is to the right and east is up.



Friday, December 01, 2017

ALMA Discovers Infant Stars Surprisingly Near Galaxy’s Supermassive Black Hole

An ALMA image of the center of the Milky Way galaxy showing the location of 11 young protostars within about 3 light-years of our galaxy's supermassive black hole. The lines indicate the direction of the bipolar lobes created by high-velocity jets from the protostars. The illustrated star in the middle of the image indicates the location of Sagittarius A*, the 4 million solar mass supermassive black hole at the center of our galaxy. The next image is a zoom-in to one of the protostars. Credit: ALMA (ESO/NAOJ/NRAO), Yusef-Zadeh et al.; B. Saxton (NRAO/AUI/NSF).  Hi-res images

Double-lobe feature produced by jets from one of the newly forming stars. ALMA discovered 11 of these telltale signs of star formation remarkably close to the supermassive black hole at the center of our galaxy. Credit: ALMA (ESO/NAOJ/NRAO), Yusef-Zadeh et al.; B. Saxton (NRAO/AUI/NSF).  Hi-res images

Infant stars, like those recently identified near the supermassive black hole at the center of our galaxy, are surrounded by a swirling disk of dust and gas. In this artist's conception of an infant solar system, the young star pulls material from its surroundings into a rotating disk (right) and generates outflowing jets of material (left). Credit: Bill Saxton (NRAO/AUI/NSF). Hi-res image



Earliest phase of star formation ever observed in highly hostile environment

At the center of our galaxy, in the immediate vicinity of its supermassive black hole, is a region wracked by powerful tidal forces and bathed in intense ultraviolet light and X-ray radiation. These harsh conditions, astronomers surmise, do not favor star formation, especially low-mass stars like our sun. Surprisingly, new observations from the Atacama Large Millimeter/submillimeter Array (ALMA) suggest otherwise.

ALMA has revealed the telltale signs of eleven low-mass stars forming perilously close — within three light-years — to the Milky Way’s supermassive black hole, known to astronomers as Sagittarius A* (Sgr A*). At this distance, tidal forces driven by the supermassive black hole should be energetic enough to rip apart clouds of dust and gas before they can form stars.

The presence of these newly discovered protostars (the formative stage between a dense cloud of gas and a young, shining star) suggests that the conditions necessary to birth low-mass stars may exist even in one of the most turbulent regions of our galaxy and possibly in similar locales throughout the universe.

The results are published in the Astrophysical Journal, Letters.

“Despite all odds, we see the best evidence yet that low-mass stars are forming startlingly close to the supermassive black hole at the center of the Milky Way,” said Farhad Yusef-Zadeh, an astronomer at Northwestern University in Evanston, Illinois, and lead author on the paper. “This is a genuinely surprising result and one that demonstrates just how robust star formation can be, even in the most unlikely of places.”

The ALMA data also suggest that these protostars are about 6,000 years old. “This is important because it is the earliest phase of star formation we have found in this highly hostile environment,” Yusef-Zadeh said.

The team of researchers identified these protostars by seeing the classic “double lobes” of material that bracket each of them. These cosmic hourglass-like shapes signal the early stages of star formation. Molecules, like carbon monoxide (CO), in these lobes glow brightly in millimeter-wavelength light, which ALMA can observe with remarkable precision and sensitivity.

Protostars form from interstellar clouds of dust and gas. Dense pockets of material in these clouds collapse under their own gravity and grow by accumulating more and more star-forming gas from their parent clouds. A portion of this infalling material, however, never makes it onto the surface of the star. Instead, it is ejected as a pair of high-velocity jets from the protostar’s north and south poles. Extremely turbulent environments can disrupt the normal procession of material onto a protostar, while intense radiation — from massive nearby stars and supermassive black holes — can blast away the parent cloud, thwarting the formation of all but the most massive of stars.

The Milky Way’s galactic center, with its 4 million solar mass black hole, is located approximately 26,000 light-years from Earth in the direction of the constellation Sagittarius. Vast stores of interstellar dust obscure this region, hiding it from optical telescopes. Radio waves, including the millimeter and submillimeter light that ALMA sees, are able to penetrate this dust, giving radio astronomers a clearer picture of the dynamics and content of this hostile environment.

Prior ALMA observations of the region surrounding Sgr A* by Yusef-Zadeh and his team revealed multiple massive infant stars that are estimated to be about 6 million years old. These objects, known as proplyds, are common features in more placid star-forming regions, like the Orion Nebula. Though the galactic center is a challenging environment for star formation, it is possible for particularly dense cores of hydrogen gas to cross the necessary threshold and forge new stars.

The new ALMA observations, however, revealed something even more remarkable, signs that eleven low-mass protostars are forming within 1 parsec – a scant 3 light-years – of the galaxy’s central black hole. Yusef-Zadeh and his team used ALMA to confirm that the masses and momentum transfer rates – the ability of the protostar jets to plow through surrounding interstellar material – are consistent with young protostars found throughout the disk of our galaxy.

“This discovery provides evidence that star formation is taking place within clouds surprisingly close to Sagittarius A*,” said Al Wootten with the National Radio Astronomy Observatory in Charlottesville, Virginia, and co-author on the paper. “Though these conditions are far from ideal, we can envision several pathways for these stars to emerge.”

For this to occur, outside forces would have to compress the gas clouds near the center of our galaxy to overcome the violent nature of the region and allow gravity to take over and form stars. The astronomers speculate that high-velocity gas clouds could aid in star formation as they force their way through the interstellar medium. It is also possible that jets from the black hole itself could be plowing into the surrounding gas clouds, compressing material and triggering this burst of star formation.

“The next step is to take a closer look to confirm that these newly formed stars are orbited by disks of dusty gas,” concluded Mark Wardle, an astronomer at Macquarie University in Sydney, Australia, and co-investigator on the team.  “If so, it’s likely that planets will eventually form from this material, as is the case for young stars in the galactic disk.”

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.



This research is presented in a paper titled “ALMA Detection of Bipolar Outflows: Evidence for Low Mass Star Formation within 1pc of Sgr A*,” by F. Yusef-Zadeh, et al., appearing in the Astrophysical Journal Letters [https://doi.org/10.3847/2041-8213/aa96a2].

This work is partially supported by the grant AST-0807400 from the National Science Foundation.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) in Taiwan and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

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

The team is composed of F. Yusef-Zadeh (Northwestern University), M. Wardle (Macquarie University), D. Kunneriath (National Radio Astronomy Observatory), M. Royster (Northwestern University), A. Wootten (National Radio Astronomy Observatory), and D.A. Roberts (Northwestern University).


Thursday, November 30, 2017

Giant Black Hole Pair Photobombs Andromeda Galaxy

 M31/LGGS J004527.30+413254.3
Credit X-ray: NASA/CXC/Univ. of Washington/T.Dorn-Wallenstein et al.; 
Optical: NASA/ESA/J. Dalcanton, et al. & R. Gendler





An intriguing source has been discovered in the nearby Andromeda galaxy using data from NASA's Chandra X-ray Observatory and ground-based optical telescopes. Previously thought to be part of the Milky Way's neighbor galaxy, the new research shows this source is actually a very distant object 2.6 billion light years away that is acting as a cosmic bomb, as reported in our press release.

This graphic shows the Chandra data (blue in inset) of the source known as LGGS J004527.30+413254.3 (J0045+41 for short) in the context of optical images of Andromeda from the Hubble Space Telescope. In the inset image, north is up and in the large image north is to the lower right. Andromeda, also known as M31, is a spiral galaxy located about 2.5 million light years from Earth.

Even more intriguing than the large distance of J0045+41 is that it likely contains a pair of giant black holes in close orbit around each other. The estimated total mass for these two supermassive black holes is about two hundred million times that of our Sun.

J0045+41 was previously classified as a different type of object — a pair of orbiting stars — when it was thought to occupy Andromeda. A team of researchers combined the Chandra X-ray data with spectra from the Gemini North telescope in Hawaii, providing evidence that J0045+41 contained at least one supermassive black hole. Using data from the Palomar Transient Factory telescopes in California, the team found repeating variations in the light from J0045+41, a pointer to the presence of two orbiting giant black holes.

The researchers estimate that the two putative black holes orbit each other with a separation of only a few hundred times the distance between the Earth and the Sun. This corresponds to less than one hundredth of a light year. By comparison, the nearest star to our Sun is about four light years away.

Such a system could be formed as a consequence of the merger, billions of years earlier, of two galaxies that each contained a supermassive black hole. At their current close separation, the two black holes are inevitably being drawn closer together as they emit gravitational waves.

A paper describing this result was accepted for publication in The Astrophysical Journal and a preprint is available online. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.




Fast Facts for J0045+41:

Scale: Full image is 1 degree across. Inset is 15 arcsec across (172 light years)
Category: Quasars & Active Galaxies, Black Holes
Observation Date: October 19, 2015
Observation Time: 13 hours 43 minutes
Obs. ID: 17010
Instrument: ACIS
References: Dorn-Wallenstein, et al., 2017, ApJ, 850, 86; arXiv:1704.08694
Color Code: X-ray (Blue), Optical (red, green, blue)
Distance Estimate: About 2.6 billion light years (z=0.215)