Friday, October 31, 2014

Hubble Sees 'Ghost Light' From Dead GalaxiesGalaxy Cluster Abell 2744

Galaxy Cluster Abell 2744
Credit: NASA, ESA, M. Montes (IAC), and J. Lotz, M. Mountain, A. Koekemoer, and the HFF Team (STScI).  

NASA's Hubble Space Telescope has picked up the faint, ghostly glow of stars ejected from ancient galaxies that were gravitationally ripped apart several billion years ago. The mayhem happened 4 billion light-years away, inside an immense collection of nearly 500 galaxies nicknamed "Pandora's Cluster," also known as Abell 2744. The scattered stars are no longer bound to any one galaxy, and drift freely between galaxies in the cluster.

By observing the light from the orphaned stars, Hubble astronomers have assembled forensic evidence that suggests as many as six galaxies were torn to pieces inside the cluster over a stretch of 6 billion years. 

Computer modeling of the gravitational dynamics among galaxies in a cluster suggest that galaxies as big as our Milky Way are the likely candidates as the source of the stars. The doomed galaxies would have been pulled apart like taffy if they plunged through the center of the galaxy cluster where gravitational tidal forces are strongest. Astronomers have long hypothesized that the light from scattered stars should be detectable after such galaxies are disassembled. However, the predicted "intracluster" glow of stars is very faint and was therefore a challenge to identify.

"The Hubble data revealing the ghost light are important steps forward in understanding the evolution of galaxy clusters," said Ignacio Trujillo of the Instituto de Astrofísica de Canarias (IAC), La Laguna, Tenerife, Spain, one of the researchers involved in this study of Abell 2744. "It is also amazingly beautiful in that we found the telltale glow by utilizing Hubble's unique capabilities."

"The results are in good agreement with what has been predicted to happen inside massive galaxy clusters," added Mireia Montes of the IAC, lead author of the paper published in the Oct. 1 issue of The Astrophysical Journal.

The team estimates that the combined light of about 200 billion outcast stars contributes approximately 10 percent of the cluster's brightness.

Because these extremely faint stars are brightest at near-infrared wavelengths of light, the team emphasized that this type of observation could only be accomplished with Hubble's infrared sensitivity to extraordinarily dim light.

Hubble measurements determined that the phantom stars are rich in heavier elements like oxygen, carbon, and nitrogen. This means the scattered stars must be second- or third-generation stars that were enriched with the elements forged in the hearts of the universe's first-generation stars. Spiral galaxies — like the ones believed to be torn apart — can sustain ongoing star formation that creates chemically enriched stars.

With the mass of 4 trillion suns, Abell 2744 is a target in the Frontier Fields program. This ambitious three-year effort teams Hubble and NASA's other Great Observatories to look at select massive galaxy clusters to help astronomers probe the remote universe. Galaxy clusters are so massive that their gravity deflects light passing through them, magnifying, brightening, and distorting light in a phenomenon called gravitational lensing. Astronomers exploit this property of space to use the clusters as a zoom lens to magnify the images of far-more-distant galaxies that otherwise would be too faint to be seen.

Montes' team used the Hubble data to probe the environment of the foreground cluster itself. There are five other Frontier Fields clusters in the program, and the team plans to look for the eerie "ghost light" in these clusters, too.


Felicia Chou
NASA Headquarters, Washington, D.C.

Ray Villard
Space Telescope Science Institute, Baltimore, Md.

Mireia Montes
Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain

Source: HubbleSite

A galaxy on the edge

Credit:  ESA/Hubble & NASA
This spectacular image was captured by the NASA/ESA Hubble Space Telescope's Advanced Camera for Surveys (ACS). The bright streak slicing across the frame is an edge-on view of galaxy NGC 4762, and a number of other distant galaxies can be seen scattered in the background.

NGC 4762 lies about 58 million light-years away in the constellation of Virgo (The Virgin). It is part of the Virgo Cluster, hence its alternative designation of VCC 2095 for Virgo Cluster Catalogue entry. This catalogue is a listing of just over 2000 galaxies in the area of the Virgo Cluster. The Virgo Cluster is actually prominently situated, and lies at the centre of the larger Virgo supercluster, of which our galaxy group, the Local Group, is a member.

Previously thought to be a barred spiral galaxy, NGC 4762 has since been found to be a lenticular galaxy, a kind of intermediate step between an elliptical and a spiral. The edge-on view that we have of this particular galaxy makes it difficult to determine its true shape, but astronomers have found the galaxy to consist of four main components — a central bulge, a bar, a thick disc and an outer ring.

The galaxy's disc is asymmetric and warped, which could potentially be explained by NGC 4762 violently cannibalising a smaller galaxy in the past. The remains of this former companion may then have settled within NGC 4762's disc, redistributing the gas and stars and so changing the disc's morphology.

NGC 4762 also contains a Liner-type Active Galactic Nucleus, a highly energetic central region. This nucleus is detectable due to its particular spectral line emission, which acts as a type of "atomic fingerprint", allowing astronomers to measure the composition of the region.

Source:  ESA/Hubble - Space Telescope

Thursday, October 30, 2014

LOFAR discovers largest carbon atoms outside our Milky Way

The starburst galaxy M82, the size of the carbon atoms and the observed spectral line
Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) 

An international team of astronomers under the guidance of graduate student Leah Morabito of Leiden Observatory has for the first time discovered the largest carbon atoms outside our Milky Way with the LOFAR radio telescope. In the future astronomers will be able to measure how cold and dense the gas around these atoms is that influences star formation and the evolution of a galaxy. The results are published in the journal Astrophysical Journal Letters on 28 October.  

"Carbon atoms are about half a million times smaller than the average thickness of a human hair, but they can be a billion times larger in the cold and sparse gas. The outermost electron is then orbiting the nucleus at a much larger distance," explains first author Morabito. The outermost electron can be captured by an atom that is missing an electron. A spectral line will then be visible in the light spectrum. All spectral lines form the chemical fingerprint of an atom such as carbon.
Astronomers predicted in the 70’s that the carbon spectral line would be detectable outside our galaxy. This first observation took 40 years to be made. The line is hard to detect because it is too faint when the gas that is surrounding the atoms is too warm or too dense. The cold, sparse gas is present in starburst galaxies - galaxies in which stars form at a high rate. For this reason the carbon spectral line is easier to detect in galaxies of this type.
Most radio telescopes observe at frequencies at which the carbon line can not be detected. Other telescopes are not sensitive enough to detect the spectral lines of the carbon atoms at low frequencies. The LOFAR radio telescope, that stretches from the northeast of the Netherlands across Europe, is perfect for these kind of observations because of its frequency range and sensitivity. Co-author Raymond Oonk from Leiden Observatory en ASTRON: "LOFAR is an unique telescope. This telescope opens up a new window on the universe."
The carbon atoms are present in the heart of the starburst galaxy M82, where 10 times more stars are being born in the same period as in our Milky Way. The cold and sparse gas in this area impacts star formation, and the evolution of M82. "Since the co-discovery of the hydrogen 21-cm line by Dutch, American and Australian astronomers, we have been looking for a way to determine additional properties of the cold gas such as its temperature and density. It is fantastic that we now have found a way thanks to this carbon line. We can now collect more and better observations, and compare them to predictions from theoretical models," says co-author Huub Röttgering (Leiden Observatory).

Discovery of Carbon Radio Recombination Lines in M82, Leah K. Morabito et al., Astrophysical Journal Letters, 28 oktober 2014. Arxiv:


Existence of a group of “quiet” quasars confirmedQuasar Host Galaxies

Quasar Host Galaxies
PG 0052+251, PHL 909, IRAS04505-2958, PG 1012+008, 0316-346, IRAS13218+0552
Credit: John Bahcall (Institute for Advanced Study, Princeton), Mike Disney (University of Wales), and NASA

An artist´s view of the heart of a quasar 
Credit: NASA

Apart from very distant, ultraluminous quasars -evolving rapidly and associated with galaxy mergers - there is likely another population of quasars that evolves slowly

Aeons ago, the universe was different: mergers of galaxies were common and gigantic black holes with masses equivalent to billions of times that of the Sun formed in their nuclei. As they captured the surrounding gas, these black holes emitted energy.  Known as quasars, these very distant and tremendously high energy objects have  local relatives with much lower energy whose existence raises numerous questions: are there also such “quiet” quasars at much larger distances? Are the latter dying versions of the former or are they completely different? 

Light from distant quasars takes billions of years to reach us, so when we detect  it we are actually looking at the universe as it was a long time ago. "Astronomers have always wanted to compare past and present, but it has been almost impossible because at great distances we can only see the brightest objects and nearby such objects no longer exist", says Jack W. Sulentic, astronomer at the Institute of Astrophysics of Andalusia (IAA-CSIC), who is leading the research. “Until now we have compared very luminous distant quasars with weaker ones closeby, which is tantamount to comparing household light bulbs with the lights in a football stadium”.  Now we are able to detect the household light bulbs very far away in the distant past.

The more distant, the more luminous?

Quasars appear to evolve with distance: the farther away one gets, the brighter they are. This could indicate that quasars extinguish over time or it could be the result of a simple observational bias masking a different reality: that gigantic quasars evolving very quickly, most of them already extinct, coexist with a quiet population that evolves at a much slower rhythm but which our technological limitations do not yet allow us to research.  

To solve this riddle it was necessary to look for low luminosity quasars at enormous  distances and to compare their characteristics with those of nearby quasars of equal luminosity, something thus far almost impossible to do, because it requires observing objects about a hundreds of times weaker than those we are used to studying at those distances.

The tremendous  light-gathering power of the GTC telescope, has recently enabled Sulentic and his team to obtain for the first time spectroscopic data from distant, low luminosity quasars similar to typical nearby ones. Data reliable enough to establish essential parameters such as chemical composition, mass of the central black hole or rate at which it absorbs matter.

"We have been able to confirm that, indeed, apart from the highly energetic and rapidly evolving quasars, there is another population that evolves slowly. This population of quasars  appears to follow the quasar main sequence discovered by Sulentic and colleagues in 2000. There does not even seem to be a strong relation between this type of quasars, which we see in our environment and those “monsters” that started to glow more than ten billion years ago”, says Ascensión del Olmo another IAA-CSIC researcher taking part in the study.  

They have, nonetheless, found differences in this population of quiet quasars. "The local quasars present a higher proportion of heavy elements such as aluminium, iron or magnesium, than the distant relatives, which most likely reflects enrichment by the birth and death of successive generations of stars,” says Jack W. Sulentic (IAA-CSIC). "This result is an excellent example of the new perspectives on the universe which the new 10 meter-class  of telescopes such as GTC are yielding,” the researcher concludes.

J. W. Sulentic1, P. Marziani2, A. del Olmo1, D. Dultzin3, J. Perea1 & C.A. Negrete4. "GTC Spectra of z 2.3 Quasars: Comparison with Local Luminosity Analogues". Astronomy & Astrophysics. DOI: 10.1051/0004-6361/201423975

1Instituto de Astrofísica de Andalucía, IAA-CSIC (Granada, Spain); 2 INAF-Osservatorio Astronomico di Padova (Italy); 3Instituto de Astronomía-UNAM (México); 4Instituto Nacional de Astrofísica, Óptica y Electrónica (Puebla, México).


Instituto de Astrofísica de Andalucía (IAA-CSIC)
Unidad de Divulgación y Comunicación
Silbia López de Lacalle - - 958230532 -

Wednesday, October 29, 2014

Planet-forming Lifeline Discovered in a Binary Star System

Artist’s impression of the double-star system GG Tauri-A
View of the sky around the multiple star system GG Tauri





Artist’s impression of the double-star system GG Tauri-A
Artist’s impression of the double-star system GG Tauri-A

ALMA Examines Ezekiel-like “Wheel in a Wheel” of Dust and Gas

For the first time, researchers using ALMA have detected a streamer of gas flowing from a massive outer disc toward the inner reaches of a binary star system. This never-before-seen feature may be responsible for sustaining a second, smaller disc of planet-forming material that otherwise would have disappeared long ago. Half of Sun-like stars are born in binary systems, meaning that these findings will have major consequences for the hunt for exoplanets. The results are published in the journal Nature on 30 October 2014.

A research group led by Anne Dutrey from the Laboratory of Astrophysics of Bordeaux, France and CNRS used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the distribution of dust and gas in a multiple-star system called GG Tau-A [1]. This object is only a few million years old and lies about 450 light-years from Earth in the constellation of Taurus (The Bull).

Like a wheel in a wheel, GG Tau-A contains a large, outer disc encircling the entire system as well as an inner disc around the main central star. This second inner disc has a mass roughly equivalent to that of Jupiter. Its presence has been an intriguing mystery for astronomers since it is losing material to its central star at a rate that should have depleted it long ago.

While observing these structures with ALMA, the team made the exciting discovery of gas clumps in the region between the two discs. The new observations suggest that material is being transferred from the outer to the inner disc, creating a sustaining lifeline between the two [2].

Material flowing through the cavity was predicted by computer simulations but has not been imaged before. Detecting these clumps indicates that material is moving between the discs, allowing one to feed off the other,” explains Dutrey. “These observations demonstrate that material from the outer disc can sustain the inner disc for a long time. This has major consequences for potential planet formation.”

Planets are born from the material left over from star birth. This is a slow process, meaning that an enduring disc is a prerequisite for planet formation. If the feeding process into the inner disc now seen with ALMA occurs in other multiple-star systems the findings introduce a vast number of new potential locations to find exoplanets in the future.

The first phase of exoplanet searches was directed at single-host stars like the Sun [3]. More recently it has been shown that a large fraction of giant planets orbit binary-star systems. Now, researchers have begun to take an even closer look and investigate the possibility of planets orbiting the individual stars of multiple-star systems. The new discovery supports the possible existence of such planets, giving exoplanet discoverers new happy hunting grounds.

Emmanuel Di Folco, co-author of the paper, concludes: “Almost half the Sun-like stars were born in binary systems. This means that we have found a mechanism to sustain planet formation that applies to a significant number of stars in the Milky Way. Our observations are a big step forward in truly understanding planet formation.



[1] GG Tau-A is part of a more complex multiple-star system called GG Tauri. Recent observations of GG Tau-A using the VLTI have revealed that one of the stars — GG Tau Ab, the one not surrounded by a disc — is itself a close binary, consisting of GG Tau-Ab1 and GG Tau-Ab2. This introduced a fifth component to the GG Tau system.

[2] An earlier result with ALMA showed an example of a single star with material flowing inwards from the outer part of its disc.

[3] Because orbits in binary stars are more complex and less stable, it was believed that forming planets in these systems would be more challenging than around single stars.


More information


This research was presented in a paper entitled “Planet formation in the young, low-mass multiple stellar system GG Tau-A” by A. Dutrey et al., to appear in the journal Nature.

The team is composed of Anne Dutrey (University Bordeaux/CNRS, France), Emmanuel Di Folco (University Bordeaux/CNRS), Stephane Guilloteau (University Bordeaux/CNRS), Yann Boehler (University of Mexico, Michoacan, Mexico), Jeff Bary (Colgate University, Hamilton, USA), Tracy Beck (Space Telescope Science Institute, Baltimore, USA), Hervé Beust (IPAG, Grenoble, France), Edwige Chapillon (University Bordeaux/IRAM, France), Fredéric Gueth (IRAM, Saint Martin d’Hères, France), Jean-Marc Huré (University Bordeaux/CNRS), Arnaud Pierens (University Bordeaux/CNRS), Vincent Piétu (IRAM), Michal Simon (Stony Brook University, USA) and Ya-Wen Tang (Academia Sinica Institute of Astronomy and Astrophysics, Taipei, Taiwan).

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Southern Observatory (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. 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 the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.






Anne Dutrey
Laboratoire d'Astrophysique de Bordeaux / University Bordeaux/CNRS
Tel: +33 5 57 776140

Emmanuel DiFolco
Laboratoire d'Astrophysique de Bordeaux / University Bordeaux/CNRS
Tel: +33 5 57 776136

Richard Hook
ESO education and Public Outreach Department
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591

Source:  ESO 

Confirming a 3-D Structural View of a Quasar Outflow - Conclusions drawn from additional observations

Figure 1: Color image of the region around SDSS J1029+2623, taken with Hubble Space Telescope. Quasar images (marked with A, B, and C) are gravitationally lensed by a foreground cluster of galaxies. Three galaxies of the lensing cluster (marked as G1a, b and G2) are also marked. (Credit: Shinshu University, the National Astronomical Observatory of Japan, and Kavli Institute for the Physics and Mathematics of the Universe)

Figure 2: Comparison of absorption features seen in the spectra of the lensed images A (red line) and B (blue line), taken in 2010 February (left) and 2014 April (right). Absorption profiles of three elements (carbon, nitrogen, and hydrogen) are shown from top to bottom. The horizontal axis represents an outflow velocity from the light source, defined as negative if it heads towards Earth. The shaded area shows a clear difference between the images A and B. Arrows highlight features that are not related to the outflow. (Credit: Shinshu University).

Figure 3: Schematic drawing of the gravitational lensing effect, showing SDSS J1029+2623 (at ~10 billion light years), an intervening cluster of galaxies (at ~5 billion light years), and Earth. The light from quasar reaches Earth through three different routes. Images B and C need an extra time of ~744 days to reach Earth compared to image A. (Credit: Shinshu University, the National Astronomical Observatory of Japan)

Figure 4:Same as Figure 2, but for comparison of absorption features seen in images A (left) and B (right), taken in 2010 February (black) and 2014 April (red/blue). Both did not show any clear time variation in profile, although carbon absorption became slightly shallow. (Credit: Shinshu University).

Figure 5: Possible locations of gas clouds in the outflow shown in an artist's rendition of the central region of the quasar. The outflow is gas streaming outward along the curved mesh, which is distinguished from a jet that is blowing vertically. The lines A and B indicate the light paths observed. A cloud along a sightline A creates absorption only in image A, while those along both sightlines of A and B make absorption features in both images. The current observations do not give information on the size, shape, or density of the clouds. (Credit: Shinshu University).

The following release was received from Shinshu University and is reprinted here in its entirety for the convenience of our readers:


A team of astronomers (Note 1) have observed a distant (Note 2) gravitationally-lensed quasar (i.e., an Active Galactic Nucleus; Note 3) with the Subaru Telescope and concluded that the data indeed present a 3-D view of the structure around a quasar. Although the team had earlier suggested this as a possibility (Note 4), the final conclusion was drawn only through additional observations.

3-D Observation of a distant quasar by "gravitationally-lensed effect" (an observation in 2010)

Quasars are bright central regions present in some distant galaxies, and their luminosities are often hundreds of times greater than those of their host galaxies. It is known that a large amount of gas streams called "outflows" move outward from the central region of quasars. The outflows are eventually distributed to large distances and have a substantial influence on surrounding interstellar/intergalactic regions and on the evolution of galaxies. Although we cannot see outflows directly because of their faintness, we detect them through absorption features that are recorded in the spectra of the bright sources of light behind them (Note 5). However, the weakness of this technique is that it traces outflows only along single sight-lines (i.e., one dimension) toward each quasar. Thus, their internal structures are not easy to investigate.

The team used the Subaru Telescope to observe SDSS J1029+2623, a quasar at ~10 billion light years distance from Earth (from now on referred to as "J 1029"). Due to the gravitational lensing effect (Note 6) by a cluster of galaxies (Note 7) which is located between J 1029 and Earth at a distance of ~5 billion light years, there is significant distortion in the light path from the quasar, which splits the incoming light into three images: A, B, and C (Figure 1). The maximum separation angle, ~22".5 (Note 8), between images A and B is currently a record. The team hypothesized that each lensed image contains information on the outflow from the quasar when viewed from different angles, thus providing a "3-D" view.

As a result of their observation in February 2010, the team discovered a clear difference in absorption profiles between the images A and B (Figure 2, Left). This result supports the idea that the sight lines are going through different areas of the outflow toward different directions. It is surprising that the absorption profiles arising in the outflow show clear difference between them, despite the small separation angle of ~22".5. The outflow could have a complex internal structure with a number of clumpy gas clouds like cirrocumulus clouds in Earth's atmosphere. 

Is difference due to "multiple sightline" or "time variation"?

There is another explanation for the difference between the images A and B. Because the path lengths of lights from the images are different (Figure 3), they have a substantial time delay before reaching Earth. If the internal structure of the outflow varies with time, the two images deliver information about different epochs even if they pass through the same region of the outflow. In this case, the difference between the images is not due to "multiple sightline" but "time-variation".

"Which idea is correct?" To answer this question, additional observations are required. It is already known that the light of the image A reaches Earth about 744 days earlier than the image B does (Figure 3, Note 9). Therefore, a follow-up observation should be performed more than 744 days after the previous observation in February 2010. If the absorption profiles change significantly in both of the images, this would support "time-variation" scenario. On the other hand, if absorption profiles are stable since the previous observation for more than 744 days, we can conclude that the difference between the images A and B are indeed due to the "multiple sightline" scenario.

Further inspection by additional observations (an observation in 2014)

The current team carried out new observations with the Subaru Telescope in April 2014, 1514 days after the previous observation. The absorption profiles in the images A and B did not show any significant changes between the observations (Figure 4) and the difference between the images still remains present (Figure 2, Right). This result is against the "time-variation" scenario. Thus, the team was finally able to conclude that i) we are indeed observing the quasar outflow toward different sightlines, and ii) there exists complex internal structure in the outflow.

The team members also note that the absorption profiles of the images A and B are generally similar to each other, with only exception being that absorption in the image A is deeper than that in the image B at outflow velocities of ~0 – 200 km/s.

These results support a model in which clumpy gas clouds are located in the outflow, some only along the sightline to the image A, while most clouds are visible along both sightlines (Figure 5). These observations are the first time that a detailed internal structure of quasar outflows has been examined.

Another remarkable result is that the absorption depth (especially in Carbon) became slightly shallower in both the images (Figure 4). Such a variation would be a clue that the absorption profiles arise not in foreground galaxies and/or inter-galactic medium but indeed in the quasar outflow itself. If this time-variation is due to "recombination (Note 10)", we can place two constraints: i) the volume density of the outflowing gas must be greater than ten thousands per cubic centimeter (Note 11), and ii) the absorber's distance from the flux source is smaller than 2,000 light years.

Future Work

We cannot estimate a typical size of gas clouds in the outflow from the current results alone. However, the clear difference that the team observed across even a very small separation angle (~22.5") requires that a typical absorber's size should be smaller than its distance from the flux source by more than four orders of magnitude (Note 12). If "recombination" is the source of time variation, an upper limit of the cloud's size would be about 0.2 light years.

Recently, it has been claimed that a typical cloud's size is about 1/1,000 – 1/10,000 of one light year (Note 13). If they really have such small size, it could be possible to detect sightline differences toward other lensed quasars with smaller separation angles.

The team is planning to extend this observation to other quasar images that are gravitationally lensed by a single massive galaxy (not by a cluster of galaxies like J 1029). More than 100 quasars like that have been discovered so far (Note 14). The lensed images of those quasars have smaller separation angles than the images of J 1029 by one order of magnitude. Therefore, they will be able to place more stringent constraints on the cloud sizes if they find sightline differences in these quasar images also.

Taking advantage of this large sample of lensed quasars, it will also be possible to examine correlations between the cloud sizes and other parameters such as quasar's luminosity and ejection velocity of the outflow. The team hopes these result will lead to a comprehensive understanding of the mysterious phenomena of quasar outflow.

The research paper on which this release is based was published on-line in the October 1, 2014 edition of The Astrophysical Journal Letters: T. Misawa et al., "Resolving the Clumpy Structure of the Outflow Winds in the Gravitationally Lensed Quasar SDSS J1029+2623”, vol. 794, article id. 20 (2014). This research was supported by the JGC-S Scholarship Foundation and partially supported by the Japan Society for the Promotion of Science through a Grant-in-Aid for Scientific Research 26800093.


  1. The authors of the paper are T. Misawa (Shinshu University, Japan), N. Inada (Nara National College of Technology, Japan), M. Oguri (The University of Tokyo, Japan), P. Gandhi (Durham University, UK), T. Horiuchi, S. Koyamada, R. Okamoto (Shinshu University, Japan).
  2. The corresponding redshift is z~2.197.
  3. Because their appearance is star-like, they are called "quasi-stellar objects" and abbreviated as  quasars.
  4. See the previous web release at the Subaru Telescope website,
  5. We can examine the physical properties of outflows through absorption features that are recorded in spectra (rainbows) of quasars.
  6. The light from a distant source is bent by the gravitational field around massive objects between the source and the observer. As a result, the light is split into multiple images and/or magnified. This effect is one of the predictions of Einstein's general theory of relativity.
  7. This is a massive structure consisting of several hundreds to thousands of galaxies, intra-cluster gas, and a large amount of dark matter. A cluster of galaxies can cause a strong gravitationally lensing effect.
  8. 1 arcsec (1") is a unit of angle, defined as 1/3600 of 1 degree. Human eyes cannot distinguish such a small angle.
  9. This can be measured by monitoring and comparing variation patterns of image brightness. (Fohlmeister, J. et al., 2013, The Astrophysical Journal, vol. 764, 186).
  10. This is a phenomenon in which electrons are captured by cations in plasma. Recombination rate depends on the electron density, and the relative abundance of specific ions depends on the distance from the flux source.
  11. The volume density of air particles on the ground is of order of 1019 per cubic centimeter.
  12. Size of gas clouds d, its distance from the flux source r, and separation angle between the lensed images θ, should satisfy the relation d < rθ, in order that two lensed images have different absorption profiles.
  13. Gas volume density can be estimated through examination of the ionization conditions of the outflow (for example, Hamann et al. 2013, MNRAS, 435, 133).
  14. A substantial fraction of these have been discovered by an international team led by Naohisa Inada and Masamune Oguri (both are members of the current research team).

Tuesday, October 28, 2014

Here's Looking At You: Spooky Shadow Play Gives Jupiter a Giant Eye

Jupiter's Great Red Spot and Ganymede's Shadow (Full-Disk, Color)
Image Credit: NASA, ESA, and A. Simon (Goddard Space Flight Center)
Acknowledgment: C. Go and the Hubble Heritage Team (STScI/AURA)

Hubble treats astronomers to gorgeous close-up views of the eerie outer planets. But it's a bit of a trick when it seems like the planet's looking back at you! This happened on April 21, 2014, when Hubble was being used to monitor changes in Jupiter's immense Great Red Spot (GRS) storm. During the exposures, the shadow of the Jovian moon Ganymede swept across the center of the GRS. This gave the giant planet the uncanny appearance of having a pupil in the center of a 10,000-mile-diameter "eye." Momentarily, Jupiter took on the appearance of a Cyclops planet! The shadows from Jupiter's four major satellites routinely cross the face of Jupiter. This natural-color picture was taken with Hubble's Wide Field Camera 3.

Source: HubbleSite

Perseus Cluster and Virgo Cluster: NASA's Chandra Observatory Identifies Impact of Cosmic Chaos on Star Birth

 Galaxy Clusters - Perseus e Virgo Cluster
Credit: NASA/CXC/Stanford/I.Zhuravleva et al


These two Chandra images of galaxy clusters - known as Perseus and Virgo - have provided direct evidence that turbulence is helping to prevent stars from forming. These new results could answer a long-standing question about how these galaxy clusters keep their enormous reservoirs of hot gas from cooling down to form stars, as discussed in our latest press release [link to PR].

Galaxy clusters are the largest objects in the Universe held together by gravity. They contain hundreds or thousands of individual galaxies that are immersed in gas with temperatures of millions of degrees. This hot gas, which is the heftiest component of the galaxy clusters aside from dark matter, glows brightly in X-ray light. Over time in the centers of clusters, this gas should cool enough so that stars form at prodigious rates. This, however, is not what astronomers have observed in many galaxy clusters.

A team of researchers have found evidence that the heat is generated by turbulent motions, which they identified from signatures in the Chandra data. Previously, other scientists have shown the key role of supermassive black holes in the centers of large galaxies in the middle of galaxy clusters. These black holes pump vast quantities of energy into the volumes around them through powerful jets of energetic particles. Chandra and other X-ray telescopes have detected giant cavities created in the hot cluster gas by the jets.

The latest research provides insight into just how energy can be transferred from the cavities to the surrounding gas. The interaction of the cavities with the gas may be generating turbulence, or chaotic motion similar to that on a bumpy airplane ride, which then dissipates to keep the gas hot for billions of years.

The scientists targeted Perseus and Virgo because they are both extremely large and relatively bright, thus providing an opportunity to see details that would be very difficult to detect in other clusters. The evidence for turbulence can be seen most clearly in the ripple-like structures in the Chandra image of Perseus. When combined with careful analysis of the data with theoretical models, this new result provides the clearest evidence to date that turbulence is the mechanism that prevents the hot gas in these clusters from cooling.

The paper describing these results is available online.

These results appeared online in the journal Nature on October 26, 2014. The authors were Irina Zhuravleva (Stanford University), Eugene Churazov (Max Planck Institute for Astrophysics), Alexander Schekochinhin (University of Oxford), Steve Allen (Stanford), Patricia Arevalo (Pontificia Universidad Catolica de Chile), Andy Fabian (University of Cambridge), William Forman (Harvard-Smithsonian Center for Astrophysics), Jeremy Sanders (Max Planck Institute for Extraterrestrial Physics), Aurora Simionescu (JAXA), Rasheed Sunayev (Max Planck Institute for Astrophysics), Alexey Vikhlinin (Harvard-Smithsonian Center for Astrophysics), and Norbert Werner (Stanford).

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

Fast Facts for Perseus Cluster: 

Release: Date October 27, 2014
Scale: Image is 20 arcmin across (about 1.5 million light years).
Category: Groups & Clusters of Galaxies
Coordinates (J2000): RA 03h 19m 47.60s | Dec +41° 30' 37.00"
Constellation: Perseus
Observation Dates: 25 pointings between Sep 1999 and Dec 2009
Observation Time: 416 hours 32 min (17 days 8 hours 32 min)
Obs. IDs: 502, 503, 1513, 3209, 3404, 4289, 4946-4953, 6139, 6145, 6146, 11713-11716, 12025, 12033, 12036, 12037
Instrument: ACIS
Also Known As: Abell 426
References: Zhuravleva, I. et al, 2014, Nature (in press); arXiv:1410.6485
Color Code: X-ray: Purple X-ray
Distance Estimate: About 250 million light years

Fast Facts for Virgo Cluster:

Release Date: October 27, 2014  
Scale: Image is 22 arcmin across (about 320,000 light years).  
Category: Groups & Clusters of Galaxies  
Coordinates (J2000): RA 12h 30m 49.40s | Dec +12° 23' 28.00"  
Constellation: Virgo
Observation Dates: 2 pointings in Jul 2002, and 7 between Jan and Nov 2005 
Observation Time: 159 hours (6 days 15 hours) 
Obs. IDs: 2707, 3717, 5826-5828, 6186, 7210-7212 
Instrument: ACIS  
References: Zhuravleva, I. et al, 2014, Nature (in press); arXiv:1410.6485 
Color Code: X-ray: Purple
Distance Estimate: About 55 million light years 

Monday, October 27, 2014

Accreting Supermassive Black Holes in the Early Universe

A multicolor image of galaxies in the field of the Chandra Cosmic Evolution Survey. A large, new study of 209 galaxies in the early universe with X-ray bright supermassive black holes finds that more modest AGN tend to peak later in cosmic history, and that obscured and unobscured AGN evolve in similar ways. Credit: X-ray: NASA/CXC/SAO/F.Civano et al. 

Supermassive black holes containing millions or even billions of solar-masses of material are found at the nuclei of galaxies. Our Milky Way, for example, has a nucleus with a black hole with about four million solar masses of material. Around the black hole, according to theories, is a torus of dust and gas, and when material falls toward the black hole (a process called accretion) the inner edge of the disk can be heated to millions of degrees. Such accretion heating can power dramatic phenomena like bipolar jets of rapidly moving charged particles. Such actively accreting supermassive black holes in galaxies are called active galactic nuclei (AGN).

The evolution of AGN in cosmic time provides a picture of their role in the formation and co-evolution of galaxies. Recently, for example, there has been some evidence that AGN with more modest luminosities and accretion rates (compared to the most dramatic cases) developed later in cosmic history (dubbed "downsizing"), although the reasons for and implications of this effect are debated. CfA astronomers Eleni Kalfontzou, Francesca Civano, Martin Elvis and Paul Green and a colleague have just published the largest study of X-ray selected AGN in the universe from the time when it was only 2.5 billion years old, with the most distant AGN in their sample dating from when the universe was about 1.2 billion years old.

The astronomers studied 209 AGN detected with the Chandra X-ray Observatory. They note that the X-ray observations are less contaminated by host galaxy emission than optical surveys, and consequently that they span a wider, more representative range of physical conditions. The team's analysis confirms the proposed trend towards downsizing, while it also can effectively rule out some alternative proposals. The scientists also find, among other things, that this sample of AGN represents nuclei with a wide range of molecular gas and dust extinction. Combined with the range of AGN dates, this result enables them to conclude that obscured and unobscured phases of AGN evolve in similar ways.

"The largest X-ray-selected sample of z > 3 AGNs: C-COSMOS and ChaMP," E. Kalfountzou, F. Civano, M. Elvis, M. Trichas, and P. Green, MNRAS, 445, 1430, 2014.

NASA Identifies Ice Cloud Above Cruising Altitude on Titan

This cloud in the stratosphere over Titan’s north pole (left) is similar to Earth’s polar stratospheric clouds (right). NASA scientists found that Titan’s cloud contains methane ice, which was not previously thought to form in that part of the atmosphere. Cassini first spotted the cloud in 2006. Image Credit:  L. NASA/JPL/U. of Ariz./LPGNantes; R. NASA/GSFC/M. Schoeberl

NASA scientists have identified an unexpected high-altitude methane ice cloud on Saturn's moon Titan that is similar to exotic clouds found far above Earth's poles.

This lofty cloud, imaged by NASA's Cassini spacecraft, was part of the winter cap of condensation over Titan's north pole. Now, eight years after spotting this mysterious bit of atmospheric fluff, researchers have determined that it contains methane ice, which produces a much denser cloud than the ethane ice previously identified there.

"The idea that methane clouds could form this high on Titan is completely new," said Carrie Anderson, a Cassini participating scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study. "Nobody considered that possible before."
Methane clouds were already known to exist in Titan's troposphere, the lowest layer of the atmosphere. Like rain and snow clouds on Earth, those clouds form through a cycle of evaporation and condensation, with vapor rising from the surface, encountering cooler and cooler temperatures and falling back down as precipitation. On Titan, however, the vapor at work is methane instead of water.

The newly identified cloud instead developed in the stratosphere, the layer above the troposphere. Earth has its own polar stratospheric clouds, which typically form above the North Pole and South Pole between 49,000 and 82,000 feet (15 to 25 kilometers) -- well above cruising altitude for airplanes. These rare clouds don't form until the temperature drops to minus 108 degrees Fahrenheit (minus 78 degrees Celsius).

Other stratospheric clouds had been identified on Titan already, including a very thin, diffuse cloud of ethane, a chemical formed after methane breaks down. Delicate clouds made from cyanoacetylene and hydrogen cyanide, which form from reactions of methane byproducts with nitrogen molecules, also have been found there.

But methane clouds were thought unlikely in Titan's stratosphere. Because the troposphere traps most of the moisture, stratospheric clouds require extreme cold. Even the stratosphere temperature of minus 333 degrees Fahrenheit (minus 203 degrees Celsius), observed by Cassini just south of the equator, was not frigid enough to allow the scant methane in this region of the atmosphere to condense into ice.

What Anderson and her Goddard co-author, Robert Samuelson, noted is that temperatures in Titan's lower stratosphere are not the same at all latitudes. Data from Cassini's Composite Infrared Spectrometer and the spacecraft's radio science instrument showed that the high-altitude temperature near the north pole was much colder than that just south of the equator.

It turns out that this temperature difference -- as much as 11 degrees Fahrenheit (minus 12 degrees Celsius) -- is more than enough to yield methane ice.

Other factors support the methane identification. Initial observations of the cloud system were consistent with small particles composed of ethane ice. Later observations revealed some regions to be clumpier and denser, suggesting that more than one ice could be present. The team confirmed that the larger particles are the right size for methane ice and that the expected amount of methane -- one-and-a-half percent, which is enough to form ice particles -- is present in the lower polar stratosphere.

The mechanism for forming these high-altitude clouds appears to be different from what happens in the troposphere. Titan has a global circulation pattern in which warm air in the summer hemisphere wells up from the surface and enters the stratosphere, slowly making its way to the winter pole. There, the air mass sinks back down, cooling as it descends, which allows the stratospheric methane clouds to form.

"Cassini has been steadily gathering evidence of this global circulation pattern, and the identification of this new methane cloud is another strong indicator that the process works the way we think it does," said Michael Flasar, Goddard scientist and principal investigator for Cassini's Composite Infrared Spectrometer (CIRS).

Like Earth's stratospheric clouds, this methane cloud was located near the winter pole, above 65 degrees north latitude. Anderson and Samuelson estimate that this type of cloud system -- which they call subsidence-induced methane clouds, or SIMCs for short -- could develop between 98,000 to 164,000 feet (30 to 50 kilometers) in altitude above Titan's surface.

"Titan continues to amaze with natural processes similar to those on the Earth, yet involving materials different from our familiar water," said Scott Edgington, Cassini deputy project scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. "As we approach southern winter solstice on Titan, we will further explore how these cloud formation processes might vary with season."
The results of this study are available online in the journal Icarus.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The CIRS team is based at Goddard. The radio science team is based at JPL.

More information about Cassini is available at the following sites:  -

Elizabeth Zubritsky
NASA's Goddard Space Flight Center, Greenbelt, Maryland

Preston Dyches
NASA's Jet Propulsion Laboratory, Pasadena, California

Source:  NASA's  - Cassini-Huygens Mission

Saturday, October 25, 2014

Galactic Wheel of Life Shines in Infrared

A new image from NASA's Spitzer Space Telescope, taken in infrared light, shows where the action is taking place in galaxy NGC 1291. 
Image credit: NASA/JPL-Caltech.  › Full image and caption

It might look like a spoked wheel or even a "Chakram" weapon wielded by warriors like "Xena," from the fictional TV show, but this ringed galaxy is actually a vast place of stellar life. A newly released image from NASA's Spitzer Space Telescope shows the galaxy NGC 1291. Though the galaxy is quite old, roughly 12 billion years, it is marked by an unusual ring where newborn stars are igniting. 

"The rest of the galaxy is done maturing," said Kartik Sheth of the National Radio Astronomy Observatory of Charlottesville, Virginia. "But the outer ring is just now starting to light up with stars."

NGC 1291 is located about 33 million light-years away in the constellation Eridanus. It is what's known as a barred galaxy, because its central region is dominated by a long bar of stars (in the new image, the bar is within the blue circle and looks like the letter "S"). 

The bar formed early in the history of the galaxy. It churns material around, forcing stars and gas from their original circular orbits into large, non-circular, radial orbits. This creates resonances -- areas where gas is compressed and triggered to form new stars. Our own Milky Way galaxy has a bar, though not as prominent as the one in NGC 1291.

Sheth and his colleagues are busy trying to better understand how bars of stars like these shape the destinies of galaxies. In a program called Spitzer Survey of Stellar Structure in Galaxies, or S4G, Sheth and his team of scientists are analyzing the structures of more than 3,000 galaxies in our local neighborhood. The farthest galaxy of the bunch lies about 120 million light-years away -- practically a stone's throw in comparison to the vastness of space. 

The astronomers are documenting structural features, including bars. They want to know how many of the local galaxies have bars, as well as the environmental conditions in a galaxy that might influence the formation and structure of bars.

"Now, with Spitzer we can measure the precise shape and distribution of matter within the bar structures," said Sheth. "The bars are a natural product of cosmic evolution, and they are part of the galaxies' endoskeleton. Examining this endoskeleton for the fossilized clues to their past gives us a unique view of their evolution."

In the Spitzer image, shorter-wavelength infrared light has been assigned the color blue, and longer-wavelength light, red. The stars that appear blue in the central, bulge region of the galaxy are older; most of the gas, or star-making fuel, there was previously used up by earlier generations of stars. When galaxies are young and gas-rich, stellar bars drive gas toward the center, feeding star formation. 

Over time, as the fuel runs out, the central regions become quiescent and star-formation activity shifts to the outskirts of a galaxy. There, spiral density waves and resonances induced by the central bar help convert gas to stars. The outer ring, seen here in red, is one such resonance area, where gas has been trapped and ignited into star-forming frenzy.

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. 

For more information about Spitzer, visit: and

Media Contact
Whitney Clavin
Jet Propulsion Laboratory, Pasadena, California

Source:  JPL - Caltech

Friday, October 24, 2014

The whirling disc of NGC 4526

Credit: ESA/Hubble & NASA
Acknowledgement: Judy Schmidt

This neat little galaxy is known as NGC 4526. Its dark lanes of dust and bright diffuse glow make the galaxy appear to hang like a halo in the emptiness of space in this new image from the NASA/ESA Hubble Space Telescope.

Although this image paints a picture of serenity, the galaxy is anything but. It is one of the brightest lenticular galaxies known, a category that lies somewhere between spirals and ellipticals. It has hosted two known supernova explosions, one in 1969 and another in 1994, and is known to have a colossal supermassive black hole at its centre that has the mass of 450 million Suns.

NGC 4526 is part of the Virgo cluster of galaxies. Ground-based observations of galaxies in this cluster have revealed that a quarter of these galaxies seem to have rapidly rotating discs of gas at their centres. The most spectacular of these is this galaxy, NGC 4526, whose spinning disc of gas, dust, and stars reaches out uniquely far from its heart, spanning some 7% of the galaxy's entire radius.

This disc is moving incredibly fast, spinning at more than 250 kilometres per second. The dynamics of this quickly whirling region were actually used to infer the mass of NGC 4526’s central black hole — a technique that had not been used before to constrain a galaxy’s central black hole.

This image was taken using Hubble’s Wide Field Planetary Camera 2. 

A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Judy Schmidt. Hidden Treasures was an initiative to invite astronomy enthusiasts to search the Hubble archive for stunning images that have never been seen by the general public.

Source:  ESA/Hubble  - Space Telescope

Thursday, October 23, 2014

NASA-led Study Sees Titan Glowing at Dusk and Dawn

High in the atmosphere of Titan, large patches of two trace gases glow near the north pole, on the dusk side of the moon, and near the south pole, on the dawn side. Brighter colors indicate stronger signals from the two gases, HNC (left) and HC3N (right); red hues indicate less pronounced signals.Image Credit:  NRAO/AUI/NSF

New maps of Saturn’s moon Titan reveal large patches of trace gases shining brightly near the north and south poles. These regions are curiously shifted off the poles, to the east or west, so that dawn is breaking over the southern region while dusk is falling over the northern one.
The pair of patches was spotted by a NASA-led international team of researchers investigating the chemical make-up of Titan’s atmosphere.

“This is an unexpected and potentially groundbreaking discovery,” said Martin Cordiner, an astrochemist working at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the lead author of the study. “These kinds of east-to-west variations have never been seen before in Titan’s atmospheric gases. Explaining their origin presents us with a fascinating new problem.”

The mapping comes from observations made by the Atacama Large Millimeter/submillimeter Array (ALMA), a network of high-precision antennas in Chile. At the wavelengths used by these antennas, the gas-rich areas in Titan’s atmosphere glowed brightly. And because of ALMA’s sensitivity, the researchers were able to obtain spatial maps of chemicals in Titan’s atmosphere from a “snapshot” observation that lasted less than three minutes.

Titan’s atmosphere has long been of interest because it acts as a chemical factory, using energy from the sun and Saturn’s magnetic field to produce a wide range of organic, or carbon-based, molecules. Studying this complex chemistry may provide insights into the properties of Earth’s very early atmosphere, which may have shared many chemical characteristics with present-day Titan.

In this study, the researchers focused on two organic molecules, hydrogen isocyanide (HNC) and cyanoacetylene (HC3N), that are formed in Titan’s atmosphere. At lower altitudes, the two molecules appear concentrated above Titan’s north and south poles. These findings are consistent with observations made by NASA’s Cassini spacecraft, which has found a cloud cap and high concentrations of some gases over whichever pole is experiencing winter on Titan.

The surprise came when the researchers compared the gas concentrations at different levels in the atmosphere. At the highest altitudes, the gas pockets appeared to be shifted away from the poles. These off-pole locations are unexpected because the fast-moving winds in Titan’s middle atmosphere move in an east–west direction, forming zones similar to Jupiter’s bands, though much less pronounced. Within each zone, the atmospheric gases should, for the most part, be thoroughly mixed.

The researchers do not have an obvious explanation for these findings yet.

“It seems incredible that chemical mechanisms could be operating on rapid enough timescales to cause enhanced ‘pocket’' in the observed molecules,” said Conor Nixon, a planetary scientist at Goddard and a coauthor of the paper, published online today in the Astrophysical Journal Letters. “We would expect the molecules to be quickly mixed around the globe by Titan’s winds.”

At the moment, the scientists are considering a number of potential explanations, including thermal effects, previously unknown patterns of atmospheric circulation, or the influence of Saturn’s powerful magnetic field, which extends far enough to engulf Titan.

Further observations are expected to improve the understanding of the atmosphere and ongoing processes on Titan and other objects throughout the solar system.

NASA’s Astrobiology Program supported this work through a grant to the Goddard Center for Astrobiology, a part of the NASA Astrobiology Institute. Additional funding came from NASA’s Planetary Atmospheres and Planetary Astronomy programs. ALMA, an international astronomy facility, is funded in Europe by the European Southern Observatory, in North America by the U.S. National Science Foundation in cooperation with the National Research Council of Canada and the National Science Council of Taiwan, and in East Asia by the National Institutes of Natural Sciences of Japan in cooperation with the Academia Sinica in Taiwan.

Nancy Neal-Jones/Elizabeth Zubritsky
Goddard Space Flight Center, Greenbelt, Md.