Monday, December 31, 2018

ALMA Discover Early Protostar With a Warped Disk

Artist’s impression of a warped disk around a protostar. ALMA observed the protostar IRAS04368+2557 in the dark cloud L1527 and discovered that the protostar has a disk with two misaligned parts. Credit: RIKEN


Using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, researchers have observed, for the first time, a warped disk around an infant protostar that formed just several tens of thousands of years ago. This implies that the misalignment of planetary orbits in many planetary systems, including our own, may be caused by distortions in the planet-forming disk early in their existence.

The planets in the Solar System orbit the Sun in planes that are at most about seven degrees offset from the equator of the Sun itself. It has been known for some time that many extrasolar systems have planets that are not lined up in a single plane or with the equator of the star. One explanation for this is that some of the planets might have been affected by collisions with other objects in the system or by stars passing by the system, ejecting them from the initial plane.

However, the possibility remained that the formation of planets out of the normal plane was actually caused by a warping of the star-forming cloud out of which the planets were born. Recently, images of protoplanetary disks, rotating disks where planets form around a star, have in fact showed such warping. But it was still unclear how early this happened.

In the latest findings, published in Nature, the group from the RIKEN Cluster for Pioneering Research (CPR) and Chiba University in Japan have discovered that L1527; an infant protostar still embedded within a cloud, has a disk that has two parts, an inner one rotating in one plane, and an outer one in a different plane. The disk is very young and still growing. L1527, which is about 450 light years away in the Taurus Molecular Cloud, is a good object for study as it has a disk that is nearly edge-on to our view.

According to Nami Sakai, who led the research group, “this observation shows that it is conceivable that the misalignment of planetary orbits can be caused by a warp structure formed in the earliest stages of planetary formation. We will have to investigate more systems to find out if this is a common phenomenon or not.”

The remaining question is what caused the warping of the disk. Sakai suggests two reasonable explanations. “One possibility,” she says, “is that irregularities in the flow of gas and dust in the protostellar cloud are still preserved and manifest themselves as the warped disk. A second possibility is that the magnetic field of the protostar is in a different plane from the rotational plane of the disk, and that the inner disk is being pulled into a different plane from the rest of the disk by the magnetic field.” She says they plan further work to determine which is responsible for the warping of the disk.

Additional Information

This research has been published in Nature (Advanced Online Publication) under the title “Warped disk around an infant protostar” by N. Sakai et al.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Southern Observatory (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.

RIKEN is Japan’s largest research institute for basic and applied research. Over 2500 papers by RIKEN researchers are published every year in leading scientific and technology journals covering a broad spectrum of disciplines including physics, chemistry, biology, engineering, and medical science. RIKEN’s research environment and strong emphasis on interdisciplinary collaboration and globalization has earned a worldwide reputation for scientific excellence.




Contacts

Jens Wilkinson
RIKEN Global Communications
Japan
Phone: +81-(0)48-462-1225
Email: pr@riken.jp

Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago - Chile
Phone: +56 2 2467 6519
Cell phone: +56 9 9445 7726
Email: nicolas.lira@alma.cl

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
, Tokyo - Japan
Phone: +81 422 34 3630
Email: hiramatsu.masaaki@nao.ac.jp

Calum Turner
ESO Assistant Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
Email: calum.turner@eso.org

Charles E. Blue
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia - USA
Phone: +1 434 296 0314
Cell phone: +1 202 236 6324
Email: cblue@nrao.edu



Saturday, December 29, 2018

Seeds of Giant Galaxies formed in the Early Universe

Figure 1: A wide field-of-view false-color image of a massive quiescent galaxy taken by Surpime-Cam on the Subaru Telescope (main image) and a high resolution close-up (inset) by IRCS (Infrared Camera and Spectrograph) on the Subaru Telescope. The yellow circle shows the point spread function of this observation corrected with the AO188 adaptive optics system. (Credit: NAOJ)

An international research team has shown that the largest galaxies in the Universe may have started out as ultra-dense objects in the very early Universe that then expanded over time.

Modern galaxies show a wide diversity, including dwarf galaxies, irregular galaxies, spiral galaxies, and massive elliptical galaxies. This final type, massive elliptical galaxies, provides astronomers with a puzzle. Although they are the most massive galaxies with the most stars, almost all of their stars are old. At some time during the past the progenitors of massive elliptical galaxies must have rapidly formed many stars and then stopped for some reason.

Fortunately, the finite speed of light gives scientists a way to turn back the clock and view the early Universe. If a galaxy is located 12 billion light-years away, then light from that galaxy must have traveled for 12 billion years before it reached Earth. This means that the light we observe today must have left the galaxy 12 billion years ago. In other words the light is the image of what the galaxy looked like 12 billion years ago. By observing galaxies at various distances from Earth, astronomers can reconstruct the history of the Universe.

An international team including researchers from the National Astronomical Observatory of Japan (NAOJ), the University of Tokyo, and Copenhagen University used data from NAOJ's Subaru Telescope and other telescopes to search for galaxies located 12 billion light-years away. Among this sample they identified massive quiescent galaxies, meaning massive galaxies without active star formation, as the probable progenitors of modern giant elliptical galaxies. It is surprising that mature giant galaxies already existed very early, when the Universe was only about ~13% of its current age.v The team then used the Subaru Telescope to perform high resolution follow-up observations in near infrared for the 5 brightest massive quiescent galaxies located 12 billion light-years away.

The results show that although the massive quiescent galaxies are compact (only about 2% the size of the Milky Way) they are almost as heavy as modern galaxies. This means that to become modern giant elliptical galaxies they must puff up about 100 times in size, but only increase in mass by about 5 times. Comparing the observations to toy models, the team showed that this would be possible if the growth was driven, not by major mergers where two similar galaxies merge to form a larger one, but by minor mergers where a large galaxy cannibalizes smaller ones.


Figure 2: The stellar mass (x-axis) and size (y-axis) relation derived assuming that the most massive galaxies at each epoch are the progenitors of the modern most massive giant elliptical galaxies (red). Gray solid and dashed curves show the size evolution driven by many minor mergers and major mergers, respectively. (Credit: NAOJ)

"We are very excited about the implications of our findings," explains corresponding author Mariko Kubo, a post-doctoral researcher at NAOJ. "But we are now at the resolution limit of existing telescopes. The superior spatial resolution of the Thirty Meter Telescope currently under development will allow us to study the morphologies of distant galaxies more precisely. For more distant galaxies beyond 12 billion light-years, we need the next generation James Webb Space Telescope."

These results appeared as Kubo et al. 2018,  "The Rest-frame Optical Sizes of Massive Galaxies with Suppressed Star Formation at z∼4" in the Astrophysical Journal on November 20, 2018. This research paper is also available as a preprint (Kubo et al., arXiv:1810.00543) on arxiv.org. This research is supported by KAKENHI Grant Numbers JP15K17617, JP16K17659, and JP18K13578.



Friday, December 28, 2018

The Most-Distant Solar System Object ever observerd

Artist concept of 2018 VG18, nicknamed "Farout,” with a scale of other Solar System objects.
Illustration by Roberto Molar Candanosa is courtesy of the Carnegie Institution for Science.

Solar System distances to scale showing the newly discovered 2018 VG18, nicknamed "Farout," compared to other known Solar System objects. Illustration by Roberto Molar Candanosa and Scott S. Sheppard is courtesy of the Carnegie Institution for Science.

Washington, DC— A team of astronomers has discovered the most-distant body ever observed in our Solar System. It is the first known Solar System object that has been detected at a distance that is more than 100 times farther than Earth is from the Sun.

The new object was announced on Monday, December 17, 2018, by the International Astronomical Union’s Minor Planet Center and has been given the provisional designation 2018 VG18. The discovery was made by Carnegie’s Scott S. Sheppard, the University of Hawaii’s David Tholen, and Northern Arizona University’s Chad Trujillo.

2018 VG18, nicknamed “Farout” by the discovery team for its extremely distant location, is at about 120 astronomical units (AU), where 1 AU is defined as the distance between the Earth and the Sun. The second-most-distant observed Solar System object is Eris, at about 96 AU. Pluto is currently at about 34 AU, making 2018 VG18 more than three-and-a-half times more distant than the Solar System’s most-famous dwarf planet.

Solar System distances to scale showing the newly discovered 2018 VG18, nicknamed "Farout," compared to other known Solar System objects. Illustration by Roberto Molar Candanosa and Scott S. Sheppard is courtesy of the Carnegie Institution for Science.

2018 VG18 was discovered as part of the team’s continuing search for extremely distant Solar System objects, including the suspected Planet X, which is sometimes also called Planet 9. In October, the same group of researchers announced the discovery of another distant Solar System object, called 2015 TG387 and nicknamed “The Goblin,” because it was first seen near Halloween. The Goblin was discovered at about 80 AU and has an orbit that is consistent with it being influenced by an unseen Super-Earth-sized Planet X on the Solar System’s very distant fringes.

The existence of a ninth major planet at the fringes of the Solar System was first proposed by this same research team in 2014 when they discovered 2012 VP113, nicknamed Biden, which is currently near 84 AU.

2015 TG387 and 2012 VP113 never get close enough to the Solar System’s giant planets, like Neptune and Jupiter, to have significant gravitational interactions with them. This means that these extremely distant objects can be probes of what is happening in the Solar System’s outer reaches. The team doesn’t know 2018 VG18’s orbit very well yet, so they have not been able to determine if it shows signs of being shaped by Planet X.

“2018 VG18 is much more distant and slower moving than any other observed Solar System object, so it will take a few years to fully determine its orbit,” said Sheppard. “But it was found in a similar location on the sky to the other known extreme Solar System objects, suggesting it might have the same type of orbit that most of them do. The orbital similarities shown by many of the known small, distant Solar System bodies was the catalyst for our original assertion that there is a distant, massive planet at several hundred AU shepherding these smaller objects.”

“All that we currently know about 2018 VG18 is its extreme distance from the Sun, its approximate diameter, and its color,” added Tholen “Because 2018 VG18 is so distant, it orbits very slowly, likely taking more than 1,000 years to take one trip around the Sun.”

The discovery images of 2018 VG18 were taken at the Japanese Subaru 8-meter telescope located atop Mauna Kea in Hawaii on November 10, 2018.

Discovery images of 2018 VG18, nicknamed "Farout," from the Subaru Telescope on November 10, 2018. Farout moves between the two discovery images while the background stars and galaxies do not move over the one hour between images. Image is courtesy of Scott S. Sheppard and David Tholen.

Once 2018 VG18 was found, it needed to be re-observed to confirm its very distant nature. (It takes multiple nights of observing to accurately determine an object’s distance.) 2018 VG18 was seen for the second time in early December at the Magellan telescope at Carnegie’s Las Campanas Observatory in Chile. These recovery observations were performed by the team with the addition of graduate student Will Oldroyd of Northern Arizona University. Over the next week, they monitored 2018 VG18 with the Magellan telescope to secure its path across the sky and obtain its basic physical properties such as brightness and color.

The Magellan observations confirmed that 2018 VG18 is around 120 AU, making it the first Solar System object observed beyond 100 AU. Its brightness suggests that it is about 500 km in diameter, likely making it spherical in shape and a dwarf planet. It has a pinkish hue, a color generally associated with ice-rich objects.

“This discovery is truly an international achievement in research using telescopes located in Hawaii and Chile, operated by Japan, as well as by a consortium of research institutions and universities in the United States,” concluded Trujillo. “With new wide-field digital cameras on some of the world’s largest telescopes, we are finally exploring our Solar System’s fringes, far beyond Pluto.”

The Subaru telescope is owned and operated by Japan and the valuable telescope access that the team obtained was thanks to a combination of time allocated to the University of Hawaii, as well as to the U.S. National Science Foundation (NSF) through telescope time exchanges between the US National Optical Astronomy Observatory (NOAO) and National Astronomical Observatory of Japan (NAOJ).

High Resolution images are available here.

This research was funded by NASA Planetary Astronomy grants NNX17AK35G and 80NSSC18K1006.


Based, in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. This work includes data gathered with the 6.5-meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory in Chile.


Scientific Area:  Earth & Planetary Science

Reference to Person:  Scott Sheppard

Reference to Department:  Terrestrial Magnetism

News Topic:  Earth/Planetary Science



Thursday, December 27, 2018

Outer Solar System Object has Astronomers Seeing Double

Gemini South DSSI image of star pair occulted by Orcus’ satellite Vanth. Image reveals bright primary star in the center of the image and a companion at upper right (approximately 2:00 position). The other “star” at lower left (8:00 position) is an artifact of processing. This image consists of 1000 seconds of data subtracted to remove atmospheric distortions to reveal the close binary pair responsible for the Vanth double occultation.

Extremely high-resolution speckle observations by Gemini South deliver critical details on a star (or stars) lying in the apparent path of remnants from the early formation of our Solar System.

In early March of 2017 the outer Solar System object Orcus, and its one known satellite Vanth, were on an apparent collision course with a star – at least that’s the way it appeared from our perspective on Earth. Original calculations showed that Orcus would pass in front of a relatively bright star and temporarily block the star’s light. However, later refinements to the calculations revealed that the shadow of Vanth would trace a path across the Earth’s surface.

These events, known as occultations, are only visible from a thin swath on Earth’s surface and calculations have small uncertainties due to observations of the orbits and estimates of the objects’ size. But even with these uncertainties, what happened surprised astronomers.

Because of these uncertainties observations were conducted by five telescopes distributed geographically to be sure to catch the event. While neither of the Gemini telescopes were scheduled to observe the occultation, Gemini was called into action when the coordinated observations detected two separate, non-simultaneous occultations by widely separated telescopes. The detections were made by the NASA Infrared Telescope Facility on Maunakea, and the Las Cumbres 1-meter telescope at the McDonald Observatory in Texas.

Based on the observations, and earlier Hubble Space Telescope observations, the team ruled out the possibility of another yet-undiscovered satellite. The separation of the events also precluded Vanth or Orcus from being responsible for both occultations.

Following the recommendation of an external reviewer of the submitted paper on the work, team member Amanda Bosh of the Massachusetts Institute of Technology asked for Fast Turnaround time on the Gemini South telescope in Chile. These observations would scrutinize the star in extremely high resolution and look for a yet unseen companion which could explain the double occultation. A visiting instrument, called the Differential Speckle Survey Instrument (DSSI), would be used due to its powerful ability to resolve stars in exquisite detail.

DSSI uses a technique called “speckle imaging,” which takes thousands of very quick exposures that can capture fine details, including artifacts due to atmospheric blurring. By averaging out the effects of the ever-changing atmospheric turbulence, what remains is an ultra-sharp image of the stars in the field. When this technique was applied to the target star for this occultation, the result was clear: the star was a double and separated by only 250 milliarcseconds from each other (comparable to separating two automobile headlamps from approximately 600 miles, or 1,000 kilometers, away). Furthermore, the alignment of the star pair fit the paths of the occultations, proving that Vanth was observed to occult the two different stars from the two different sites. Mystery solved!

“Without the high-resolution data provided by Gemini, we would not have been able to accurately determine which body occulted which star(s). Speckle imaging is a powerful technique, and it ensured correct interpretation of these stellar occultation data,” said Amanda Sickafoose, lead author on the published results.

Stellar occultations provide an extremely reliable way to determine the sizes of distant Solar System objects so these observations were critical in refining the size of Vanth. Amanda Sickafoose adds, “Occultations are extremely sensitive to atmospheres and our results place a limit of a few microbars for any possible global atmosphere on Vanth.” From other observations astronomers also estimate that Orcus has a diameter of about 900 kilometers and the new occultation measurements from this work show that Vanth’s diameter is about 450 kilometers which is almost double the previously estimated size. The pair are known as trans-Neptunian objects (TNOs) which are thought to be remnants from the formation of our Solar System. Orcus and Vanth orbit in the outer Solar System in resonance with Neptune and in an orbit similar to Pluto in distance from the Sun, but in a position about 180 degrees from Pluto relative to the Sun. “This is why the Orcus system is sometimes described as an ‘anti-Pluto’,” said Sickafoose.

DSSI has visited both Gemini telescopes several times, thanks to the instrument’s Principal Investigator (PI) Elliott Horch of Southern Connecticut State University. Based on the instrument’s success, two updated versions of DSSI are slated for Gemini, one on Gemini North (called ‘Alopeke, Hawaiian for fox, which is already in use), and at Gemini South (called Zorro, Spanish for fox, which is slated for installation in early 2019). Steve Howell of NASA’s Ames Research Center serves as PI for both of these new instruments.

The paper describing these observations was led by Amanda A. Sickafoose of the South African Astronomical Observatory and the Massachusetts Institute of Technology. The paper has been published in Icarus and the preprint is available at: https://arxiv.org/abs/1810.08977.



Monday, December 24, 2018

ALMA Gives Passing Comet Its Close-up

Side-by-side comparison shows an ALMA image of comet 46P/Wirtanen (left) and an optical image (right). The ALMA image has approximately 1000 times the resolution of the optical image and zooms in on the inner portion of the comet's diffuse coma. Credit: ALMA (ESO/NAOJ/NRAO), M. Cordiner, NASA/CUA; Derek Demeter, Emil Buehler Planetarium. Hi-Res File

ALMA image of comet 46P/Wirtanen taken on December 2 as the comet approached Earth. The ALMA image shows the concentration and distribution of hydrogen cyanide (HCN) molecules near the center of the comet's coma. Credit: ALMA (ESO/NAOJ/NRAO); M. Cordiner, NASA/CUA. Hi-Res File

An optical image of comet 46P/Wirtanen taken from Chiefland, Florida, on December 4, 2018. Camera details: Canon 6D camera, MN190mm astrograph telescope. Credit: Derek Demeter, Emil Buehler Planetarium. Hi-Res File


Animation of comet 46P/Wirtanen taken from Chiefland, Florida, on December 4, 2018. Camera details: Canon 6D camera, MN190mm astrograph telescope. Credit: Derek Demeter, Emil Buehler Planetarium.



As comet 46P/Wirtanen neared Earth on December 2, astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) took a remarkably close look the innermost regions of the comet’s coma, the gaseous envelope around its nucleus.

ALMA imaged the comet when it was approximately 16.5 million kilometers from Earth. At its closet on December 16, the comet – one of the brightest in years — was approximately 11.6 million kilometers from Earth, or about 30 times the distance from the Earth to the moon.

“This comet is causing a stir in the professional and amateur astronomy communities due to its combined brightness and proximity, which allows us to study it in unprecedented detail” said NASA’s Martin Cordiner, who led the team that made the ALMA observations. “As the comet drew nearer to the Sun, its icy body heated up, releasing water vapor and various other particles stored inside, forming the characteristic puffed-up coma and elongated tail.”

The ALMA image of comet 46P/Wirtanen zooms-in to very near its nucleus – the solid “dirty snowball” of the comet itself — to image the natural millimeter-wavelength “glow” emitted by molecules of hydrogen cyanide (HCN), a simple organic molecule that forms an ethereal atmosphere around the comet. ALMA, using its remarkable ability to see fine details, was able to detect and image the fine-scale distribution of this particular molecule.

The HCN image shows a compact region of gas and an extended, diffuse, and somewhat asymmetrical, pattern in the inner portion of the coma. Due to the extreme proximity of this comet, most of the extended coma is resolved out, so these observations are only sensitive to the innermost regions, in the immediate vicinity of the nucleus.

The astronomers also performed observations of more complex molecules on Dec 9, when the comet was 13.6 million kilometers from Earth.

Comet 46P/Wirtanen orbits the Sun once every five-and-a-half years, which is remarkably brisk compared to its more famous cousin Halley’s Comet, which has an orbital period of about 75 years. Other bright comets can have periods that are on the order of hundreds and even thousands of years. The comet may yet be visible to the naked eye.

For comparison, an optical view of the comet taken by an amateur astrophotographer is shown. Though they appear to be similar, the ALMA image spans an area of the sky only about 5 arcseconds – about 1000 times smaller than the optical image – meaning ALMA is looking at the very fine-scale features in the coma.

This and previous observations of comets with ALMA confirm that they are rich in organic molecules, and may therefore have seeded the early Earth with the chemical building blocks of life.

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



Contact:

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




The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Southern Observatory (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.


Sunday, December 23, 2018

Sapphires and Rubies in the Sky

Illustration of one of the exotic super-Earth candidates, 55 Cnc e, that are rich in sapphires and rubies and might shimmer in blue and red colors. Illustration: Thibaut Roger. Hi-res image

Researchers at the Universities of Zurich and Cambridge have discovered a new, exotic class of planets outside our solar system. These so-called super-Earths were formed at high temperatures close to their host star and contain high quantities of calcium, aluminium and their oxides – including sapphire and ruby.

21 light years away from us in the constellation Cassiopeia, a planet orbits its star with a year that is just three days long. Its name is HD219134 b. With a mass almost five times that of Earth it is a so-called “super-Earth”. Unlike the Earth however, it most likely does not have a massive core of iron, but is rich in calcium and aluminium. “Perhaps it shimmers red to blue like rubies and sapphires, because these gemstones are aluminium oxides which are common on the exoplanet,” says Caroline Dorn, astrophysicist at the Institute for Computational Science of the University of Zurich. HD219134 b is one of three candidates likely to belong to a new, exotic class of exoplanets, as Caroline Dorn and her colleagues at the Universities of Zurich and Cambridge now report in the British journal MNRAS. 

The researchers study the formation of planets using theoretical models and compare their results with data from observations. It is known that during their formation, stars such as the Sun were surrounded by a disc of gas and dust in which planets were born. Rocky planets like the Earth were formed out of the solid bodies leftover when the proto-planetary gas disc dispersed. These building blocks condensed out of the nebula gas as the disc cooled. “Normally, these building blocks are formed in regions where rock-forming elements such as iron, magnesium and silicon have condensed,” explains Dorn who is associated to the NCCR PlanetS. The resulting planets have an Earth-like composition with an iron core. Most of the super-Earths known so far have been formed in such regions.

The composition of super-Earths is more diverse than expected

But there are also regions close to the star where it is much hotter. “There, many elements are still in the gas phase and the planetary building blocks have a completely different composition,” says the astrophysicist. With their models, the research team calculated what a planet being formed in such a hot region should look like. Their result: calcium and aluminium are the main constituents alongside magnesium and silicon, and there is hardly any iron. “This is why such planets cannot, for example, have a magnetic field like the Earth,” says Dorn. And because the inner structure is so different, their cooling behavior and atmospheres will also differ from those of normal super-Earths. The team therefore speak of a new, exotic class of super-Earths formed from high-temperature condensates.

“What is exciting is that these objects are completely different from the majority of Earth-like planets,” says Dorn – “if they actually exist.” The probability is high, as the astrophysicists explain in their paper. “In our calculations we found that these planets have 10 to 20 percent lower densities than the Earth,” explains the first author. Other exoplanets with similarly low-densities were also analyzed by the team. “We looked at different scenarios to explain the observed densities,” says Dorn. For example, a thick atmosphere could lead to a lower overall density. But two of the exoplanets studied, 55 Cancri e and WASP-47 e, orbit their star so closely that their surface temperature is almost 3000 degrees and they would have lost this gas envelope long ago. “On HD219134 b it’s less hot and the situation is more complicated,” explains Dorn. At first glance, the lower density could also be explained by deep oceans. But a second planet orbiting the star a little further out makes this scenario unlikely. A comparison of the two objects showed that the inner planet cannot contain more water or gas than the outer one. It is still unclear whether magma oceans can contribute to the lower density.

“So, we have found three candidates that belong to a new class of super-Earths with this exotic composition” the astrophysicist summarizes. The researchers are also correcting an earlier image of super-Earth 55 Cancri e, which had made headlines in 2012 as the “diamond in the sky”. Researchers had previously assumed that the planet consisted largely of carbon, but had to abandon this theory on the basis of subsequent observations. “We are turning the supposed diamond planet into a sapphire planet,” laughs Dorn.


Reference:

Source: NCCR PlanetS


Saturday, December 22, 2018

Fossil from the Big Bang Discovered with W. M. Keck Observatory

Simulation of galaxies and gas in the universe. Within the gas in the (blue) filaments connecting the (orange) galaxies lurk rare pockets of pristine gas – vestiges of the Big Bang that have somehow been orphaned from the explosive, polluting deaths of stars, seen here as circular shock waves around some orange points. Credit: TNG Collaboration


Rare Relic is One of Only Three Fossil Clouds Known in the Universe


Maunakea, Hawaii – A relic cloud of gas, orphaned after the Big Bang, has been discovered in the distant universe by astronomers using the world’s most powerful optical telescope, the W. M. Keck Observatory on Maunakea, Hawaii.

The discovery of such a rare fossil, led by PhD student Fred Robert and Professor Michael Murphy at Swinburne University of Technology, offers new information about how the first galaxies in the universe formed.

“Everywhere we look, the gas in the universe is polluted by waste heavy elements from exploding stars,” says Robert. “But this particular cloud seems pristine, unpolluted by stars even 1.5 billion years after the Big Bang.”

“If it has any heavy elements at all, it must be less than 1/10,000th of the proportion we see in our Sun. This is extremely low; the most compelling explanation is that it’s a true relic of the Big Bang.”

The results will be published in the journal Monthly Notices of the Royal Astronomical Society. A preprint of the paper, “Exploring the origins of a new, apparently metal-free gas cloud at z = 4.4,” is available online at http://arxiv.org/abs/1812.05098.

Robert and his team used two of Keck Observatory’s instruments – the Echellette Spectrograph and Imager (ESI) and the High-Resolution Echelle Spectrometer (HIRES) – to observe the spectrum of a quasar behind the gas cloud.

The quasar, which emits a bright glow of material falling into a supermassive black hole, provides a light source against which the spectral shadows of the hydrogen in the gas cloud can be seen.

“We targeted quasars where previous researchers had only seen shadows from hydrogen and not from heavy elements in lower-quality spectra,” says Robert. “This allowed us to discover such a rare fossil quickly with the precious time on Keck Observatory’s twin telescopes.”

The only two other fossil clouds known were discovered in 2011 by Professor Michele Fumagalli of Durham University, John O’Meara, formerly a professor at St. Michael’s College and now the new Chief Scientist at Keck Observatory, and Professor J. Xavier Prochaska of the University of California, Santa Cruz; both Fumagalli and O’Meara are co-authors of this new research on the third fossil cloud.

“The first two were serendipitous discoveries, and we thought they were the tip of the iceberg. But no one has discovered anything similar – they are clearly very rare and difficult to see. It’s fantastic to finally discover one systematically,” says O’Meara.

“It’s now possible to survey for these fossil relics of the Big Bang,” says Murphy. “That will tell us exactly how rare they are and help us understand how some gas formed stars and galaxies in the early universe, and why some didn’t.”

This research was funded by an Australian Research Council Discovery Project grant and Professor Fumagalli’s contribution was partially funded by a European Research Council grant.





About ESI

The Echellette Spectrograph and Imager (ESI) is a medium-resolution visible-light spectrograph that records spectra from 0.39 to 1.1 microns in each exposure. Built at UCO/Lick Observatory by a team led by Prof. Joe Miller, ESI also has a low-resolution mode and can image in a 2 x 8 arc min field of view. An upgrade provided an integral field unit that can provide spectra everywhere across a small, 5.7 x4.0 arc sec field. Astronomers have found a number of uses for ESI, from observing the cosmological effects of weak gravitational lensing to searching for the most metal-poor stars in our galaxy.

About HIRES

The High-Resolution Echelle Spectrometer (HIRES) produces spectra of single objects at very high spectral resolution, yet covering a wide wavelength range. It does this by separating the light into many “stripes” of spectra stacked across a mosaic of three large CCD detectors. HIRES is famous for finding exoplanets. Astronomers also use HIRES to study important astrophysical phenomena like distant galaxies and quasars, and find cosmological clues about the structure of the early universe, just after the Big Bang.

About W. M. Keck Observatory

The W. M. Keck Observatory telescopes are the most scientifically productive on Earth. The two, 10-meter optical/infrared telescopes atop 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 recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.


Friday, December 21, 2018

Faint Glow Within Galaxy Clusters Illuminates Dark Matter

Galaxy Clusters Abell S1063 and MACS J0416.1-2403
Credits: NASA, ESA, and M. Montes (University of New South Wales)
Acknowledgment: J. Lotz (STScI) and the HFF team

Two massive galaxy clusters — Abell S1063 (left) and MACS J0416.1-2403 (right) — display a soft blue haze, called intracluster light, embedded among innumerable galaxies. The intracluster light is produced by orphan stars that no longer belong to any single galaxy, having been thrown loose during a violent galaxy interaction, and now drift freely throughout the cluster of galaxies. Astronomers have found that intracluster light closely matches with a map of mass distribution in the cluster's overall gravitational field. This makes the blue "ghost light" a good indicator of how invisible dark matter is distributed in the cluster. Dark matter is a key missing link in our understanding of the structure and evolution of the universe. Abell S1063 and MACS J0416.1-2403 were the strongest examples of intracluster light providing a much better match to the cluster's mass map than X-ray light, which has been used in the past to trace dark matter. Release Images

A new look at Hubble images of galaxies could be a step toward illuminating the elusive nature of dark matter, the unobservable material that makes up the majority of the universe, according to a study published online today in the Monthly Notices of the Royal Astronomical Society.

Utilizing Hubble's past observations of six massive galaxy clusters in the Frontier Fields program, astronomers demonstrated that intracluster light — the diffuse glow between galaxies in a cluster — traces the path of dark matter, illuminating its distribution more accurately than existing methods that observe X-ray light.

Intracluster light is the byproduct of interactions between galaxies that disrupt their structures; in the chaos, individual stars are thrown free of their gravitational moorings in their home galaxy to realign themselves with the gravity map of the overall cluster. This is also where the vast majority of dark matter resides. X-ray light indicates where groups of galaxies are colliding, but not the underlying structure of the cluster. This makes it a less precise tracer of dark matter.

"The reason that intracluster light is such an excellent tracer of dark matter in a galaxy cluster is that both the dark matter and these stars forming the intracluster light are free-floating on the gravitational potential of the cluster itself—so they are following exactly the same gravity," said Mireia Montes of the University of New South Wales in Sydney, Australia, who is co-author of the study. "We have found a new way to see the location where the dark matter should be, because you are tracing exactly the same gravitational potential. We can illuminate, with a very faint glow, the position of dark matter."

Montes also highlights that not only is the method accurate, but it is more efficient in that it utilizes only deep imaging, rather than the more complex, time-intensive techniques of spectroscopy. This means more clusters and objects in space can be studied in less time — meaning more potential evidence of what dark matter consists of and how it behaves.

"This method puts us in the position to characterize, in a statistical way, the ultimate nature of dark matter," Montes said.

"The idea for the study was sparked while looking at the pristine Hubble Frontier Field images," said study co-author Ignacio Trujillo of the Canary Islands Institute of Astronomy in Tenerife, Spain, who along with Montes had studied intracluster light for years. "The Hubble Frontier Fields showed intracluster light in unprecedented clarity. The images were inspiring," Trujillo said. "Still, I did not expect the results to be so precise. The implications for future space-based research are very exciting."

"The astronomers used the Modified Hausdorff Distance (MHD), a metric used in shape matching, to measure the similarities between the contours of the intracluster light and the contours of the different mass maps of the clusters, which are provided as part of the data from the Hubble Frontier Fields project, housed in the Mikulski Archive for Space Telescopes (MAST). The MHD is a measure of how far two subsets are from each other. The smaller the value of MHD, the more similar the two point sets are. This analysis showed that the intracluster light distribution seen in the Hubble Frontier Fields images matched the mass distribution of the six galaxy clusters better than did X-ray emission, as derived from archived observations from Chandra X-ray Observatory's Advanced CCD Imaging Spectrometer (ACIS).

Beyond this initial study, Montes and Trujillo see multiple opportunities to expand their research. To start, they would like to increase the radius of observation in the original six clusters, to see if the degree of tracing accuracy holds up. Another important test of their method will be observation and analysis of additional galaxy clusters by more research teams, to add to the data set and confirm their findings.

The astronomers also look forward to the application of the same techniques with future powerful space-based telescopes like the James Webb Space Telescope and WFIRST, which will have even more sensitive instruments for resolving faint intracluster light in the distant universe.

Trujillo would like to test scaling down the method from massive galaxy clusters to single galaxies. "It would be fantastic to do this at galactic scales, for example exploring the stellar halos. In principal the same idea should work; the stars that surround the galaxy as a result of the merging activity should also be following the gravitational potential of the galaxy, illuminating the location and distribution of dark matter."

The Hubble Frontier Fields program was a deep imaging initiative designed to utilize the natural magnifying glass of galaxy clusters' gravity to see the extremely distant galaxies beyond them, and thereby gain insight into the early (distant) universe and the evolution of galaxies since that time. In that study the diffuse intracluster light was an annoyance, partially obscuring the distant galaxies beyond. However, that faint glow could end up shedding significant light on one of astronomy's great mysteries: the nature of dark matter.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.



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Contacts

Leah Ramsay / Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
667-218-6439 / 410-338-4514

lramsay@stsci.edu / villard@stsci.edu

Mireia Montes
University of New South Wales, Sydney, Australia

mireia.montes.quiles@gmail.com




Thursday, December 20, 2018

Young Star Caught in a Fit of Growth

This illustration shows a young star undergoing a growth spurt. Top panel: Material from the dusty and gas-rich disk (orange) plus hot gas (blue) mildly flows onto the star, creating a hot spot. Middle panel: The outburst begins—the inner disk is heated, more material flows to the star, and the disk creeps inward. Lower panel: The outburst is in full throttle, with the inner disk merging into the star and gas flowing outward (green).  Credit: Caltech/T. Pyle (IPAC) -   [Full-size image]

An illustration of a young star undergoing an outburst, in which material from a surrounding disk has drained onto the star itself, bulking up its mass. Gas is seen flowing outward in green. Credit: Caltech/T. Pyle (IPAC) - [Full-size Image]

The location of Gaia 17bpi, which lies in the Sagitta constellation, is indicated in the center of this image taken by NASA’s Spitzer Space Telescope. Credit: NASA/JPL-Caltech/M. Kuhn (Caltech) - [Full-size image]



New visible and infrared observations of young star reveal clues about how it bulks up

Researchers have discovered a young star in the midst of a rare growth spurt—a dramatic phase of stellar evolution when matter swirling around a star falls onto the star, bulking up its mass. The star belongs to a class of fitful stars known as FU Ori's, named after the original member of the group, FU Orionis (the capital letters represent a naming scheme for variable stars, and Orionis refers to its location in the Orion constellation). Typically, these stars, which are less than a few million years old, are hidden behind thick clouds of dust and hard to observe. This new object is only the 25th member of this class found to date and one of only about a dozen caught in the act of an outburst.

"These FU Ori events are extremely important in our current understanding of the process of star formation but have remained almost mythical because they have been so difficult to observe," says Lynne Hillenbrand, professor of astronomy at Caltech and lead author of a new report on the findings appearing in The Astrophysical Journal. "This is actually the first time we've ever seen one of these events as it happens in both optical and infrared light, and these data have let us map the movement of material through the disk and onto the star."

The newfound star, called Gaia 17bpi, was first spotted by the European Space Agency's Gaia satellite, which scans the sky continuously, making precise measurements of stars in visible light. When Gaia spots a change in a star's brightness, an alert goes out to the astronomy community. A graduate student at the University of Exeter and co-author of the new study, Sam Morrell, was the first to notice that the star had brightened. Other members of the team then followed up and discovered that the star's brightening had been serendipitously captured in infrared light by NASA's asteroid-hunting NEOWISE satellite at the same time that Gaia saw it, as well as one-and-a-half-years earlier.

"While NEOWISE's primary mission is detecting nearby solar system objects, it also images all of the background stars and galaxies as it sweeps around the sky every six months," says co-author Roc Cutri, lead scientist for the NEOWISE Data Center at IPAC, an astronomy and data center at Caltech. "NEOWISE has been surveying in this way for five years now, so it is very effective for detecting changes in the brightness of objects."

NASA's infrared-sensing Spitzer Space Telescope also happened to have witnessed the beginning of the star's brightening phase twice back in 2014, giving the researchers a bonanza of infrared data. 

The new findings shine light on some of the longstanding mysteries surrounding the evolution of young stars. One unanswered question is: How does a star acquire all of its mass? Stars form from collapsing balls of gas and dust. With time, a disk of material forms around the star, and the star continues to siphon material from this disk. But, according to previous observations, stars do not pull material onto themselves fast enough to reach their final masses.  

Theorists believe that FU Ori events—in which mass is dumped from the disk onto the star over a total period of about 100 years—may help solve the riddle. The scientists think that all stars undergo around 10 to 20 or so of these FU Ori events in their lifetimes but, because this stellar phase is often hidden behind dust, the data are limited. "Somebody sketched this scenario on the back of an envelope in the 1980s, and, after all this time, we still haven't done much better at determining the event rates," says Hillenbrand.

The new study shows, with the most detail yet, how material moves from the midrange of a disk, in a region located around 1 astronomical unit from the star, to the star itself. (An astronomical unit is the distance between Earth and the sun.) NEOWISE and Spitzer were the first to pick up signs of the buildup of material in the middle of the disk. As the material started to accumulate in the disk, it warmed up, giving off infrared light. Then, as this material fell onto the star, it heated up even more, giving off visible light, which is what Gaia detected. 

"The material in the middle of the disk builds up in density and becomes unstable," says Hillenbrand. "Then it drains onto the star, manifesting as an outburst." 

The researchers used the W. M. Keck Observatory and Caltech's Palomar Observatory to help confirm the FU Ori nature of the newfound star. Says Hillenbrand, "You can think of Gaia as discovering the initial crime scene, while Keck and Palomar pointed us to the smoking gun."

The study is titled, "Gaia 17bpi: An FU Ori Type Outburst." Other authors include: Carlos Contreras Peña and Tim Naylor of the University of Exeter; Michael Kuhn and Luisa Rebull of Caltech; Simon Hodgkin of Cambridge University; Dirk Froebrich of the University of Kent; and Amy Mainzer of JPL. 

Written by Whitney Clavin



Contact:

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

Source: Caltech


Wednesday, December 19, 2018

Fragmenting Disk Gives Birth to Binary Star ‘Odd Couple’

Artists impression of the disk of dust and gas surrounding the massive protostar MM 1a, with its companion MM 1b forming in the outer regions. Credit: J. D. Ilee / University of Leeds.

Observation of the dust emission (green) and the cool gas around MM1a (red is receding gas, blue is approaching gas), indicating that the outflow cavity rotates in the same sense as the central accretion disc. MM1b is seen orbiting in the lower left. Credit: ALMA (ESO/NAOJ/NRAO); J. D. Ilee / University of Leeds.

Observation of the dust emission (green) and hot gas rotating in the disc around MM 1a (red is receding gas, blue is approaching gas). MM 1b is seen the lower left. Credit: ALMA (ESO/NAOJ/NRAO); J. D. Ilee / University of Leeds.


Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered that two young stars forming from the same swirling protoplanetary disk may be twins — in the sense that they came from the same parent cloud of star-forming material. Beyond that, however, they have shockingly little in common.

The main, central star of this system, which is located approximately 11,000 light-years from Earth, is truly colossal — a full 40 times more massive than the Sun. The other star, which ALMA recently discovered just beyond the central star’s disk, is a relatively puny one-eightieth (1/80) that mass.

Their striking difference in size suggests that they formed by following two very different paths. The more massive star took the more traditional route by collapsing under gravity out of a dense “core” of gas. The smaller one likely followed the road less traveled by – at least for stars – by accumulating mass from a portion of the disk that “fragmented” away as it matured, a process that may have more in common with the birth of gas-giant planets.

“Astronomers have known for a long time that most massive stars orbit one or more other stars as partners in a compact system, but how they got there has been a topic of conjecture,” said Crystal Brogan, an astronomer with the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia, and a co-author on the study. “With ALMA, we now have evidence that the disk of gas and dust that encompasses and feeds a growing massive star also produces fragments at early stages that can form a secondary star.”

The main object, known as MM 1a, is a previously identified young massive star surrounded by a rotating disk of gas and dust. A faint protostellar companion to this object, MM 1b, was newly detected by ALMA just outside the MM 1a protoplanetary disk. The team believes this is one of the first examples of a fragmented disk to be detected around a massive young star.

“This ALMA observation opens new questions, such as ‘Does the secondary star also have a disk?’ and ‘How fast can the secondary star grow?’ The amazing thing about ALMA is that we have not yet used its full capabilities in this area, which will someday allow us to answer these new questions,” said co-author Todd Hunter, who is also with the NRAO in Charlottesville.

Stars form within large clouds of gas and dust in interstellar space. When these clouds collapse under gravity, they begin to rotate faster, forming a disk around them.

“In low-mass stars like our Sun, it is in these disks that planets can form,” said John Ilee, an astronomer at Leeds University in England and lead author on the study. “In this case, the star and disk we have observed are so massive that, rather than witnessing a planet forming in the disk, we are seeing another star being born.”

By observing the millimeter wavelength light naturally emitted by the dust, and subtle shifts in the frequency of light emitted by the gas, the researchers were able to calculate the mass of MM 1a and MM 1b.

Their work is published in the Astrophysical Journal Letters.

“Many older massive stars are found with nearby companions,” added Ilee. “But binary stars are often very equal in mass, and so likely formed together as siblings. Finding a young binary system with a mass ratio of 80-to-1 is very unusual and suggests an entirely different formation process for both objects.”

The favored formation process for MM 1b occurs in the outer regions of cold, massive disks. These “gravitationally unstable” disks are unable to hold themselves up against the pull of their own gravity, collapsing into one – or more – fragments.

The researchers note that newly discovered young star MM 1b could also be surrounded by its own circumstellar disk, which may have the potential to form planets of its own – but it will need to be quick.  “Stars as massive as MM 1a only live for around a million years before exploding as powerful supernovae, so while MM 1b may have the potential to form its own planetary system in the future, it won’t be around for long,” Ilee concluded.

Additional Information

This research was published in the Astrophysical Journal Letters in an article titled “G11.92–0.61 MM 1: A Fragmented Keplerian Disk Surrounding a Proto-O Star” by J. D. Ilee.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Southern Observatory (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.



Contacts

Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago - Chile
Phone: +56 2 2467 6519
Cell phone: +56 9 9445 7726
Email: nicolas.lira@alma.cl

Charles E. Blue
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia - USA
Phone: +1 434 296 0314
Cell phone: +1 202 236 6324
Email: cblue@nrao.edu

Calum Turner
ESO Assistant Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
Email: calum.turner@eso.org

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
, Tokyo - Japan
Phone: +81 422 34 3630



Tuesday, December 18, 2018

Chandra Serves up Cosmic Holiday Assortment

Chandra Archive Collection
Credit  NASA/CXC/SAO


Chandra Archive Collection:   



This is the season of celebrating, and the Chandra X-ray Center has prepared a platter of cosmic treats from NASA's Chandra X-ray Observatory to enjoy. This selection represents different types of objects — ranging from relatively nearby exploded stars to extremely distant and massive clusters of galaxies — that emit X-rays detected by Chandra. Each image in this collection blends Chandra data with other telescopes, creating a colorful medley of light from our Universe.



Top row (left to right):

E0102-72.3
This supernova remnant was produced by a massive star that exploded in a nearby galaxy called the Small Magellanic Cloud. X-rays from Chandra (blue and purple) have helped astronomers confirm that most of the oxygen in the universe is synthesized in massive stars. The amount of oxygen in the E0102-72.3 ring shown here is enough for thousands of solar systems. This image also contains optical data from NASA's Hubble Space Telescope and the Very Large Telescope in Chile (red and green).

Abell 370
Located about 4 billion light years from Earth, Abell 370 is a galaxy cluster containing several hundred galaxies. Galaxy clusters are the largest objects in the Universe held together by gravity. In addition to the individual galaxies, they contain vast amounts of multimillion-degree gas that emits X-rays, and dark matter that supplies most of the gravity of the cluster, yet does not produce any light. Chandra reveals the hot gas (diffuse blue regions) in a combined image with optical data from Hubble (red, green, and blue).

Messier 8 (M8)
Also known as NGC 6523 or the Lagoon Nebula, Messier 8 is a giant cloud of gas and dust where stars are currently forming. At a distance of about 4,000 light years from Earth, Messier 8 provides astronomers an excellent opportunity to study the properties of very young stars. Many infant stars give off copious amounts of high-energy light including X-rays, which are seen in the Chandra data (pink). The X-ray data have been combined with an optical image of Messier 8 from the Mt. Lemmon Sky Center in Arizona (blue and white).



Bottom row (left to right):

Orion Nebula
Look just below the middle of the three stars of belt in the constellation of Orion to find the Orion Nebula, which can be seen without a telescope. With a telescope like Chandra, however, the view is much different. In this image, X-rays from Chandra (blue) reveal individual young stars, which are hot and energetic. When combined with radio emission from the NSF's Very Large Array (purple), a vista of this stellar nursery is created that the unaided human eye could never capture.

Messier 33 (M33)
The Triangulum Galaxy, a.k.a., Messier 33, is a spiral galaxy about 3 million light years from Earth. It belongs to the Local Group of galaxies that includes the Milky Way and Andromeda galaxies. Chandra's X-ray data (pink) reveal a diverse range of objects including neutron stars and black holes that are pulling material from a companion star, and supernova remnants. An optical image from amateur astronomer Warren Keller (red, green, and blue) shows the majestic arms of this spiral galaxy that in many ways is a cousin to our own Milky Way.

Abell 2744
This composite image contains the aftermath of a giant collision involving four separate galaxy clusters at a distance of about 3.5 billion light years. Officially known as Abell 2744, this system is also referred to by astronomers as "Pandora's Cluster" because all of the different structures found within it. This view of Abell 2744 contains X-ray data from Chandra (blue) showing hot gas, optical data from Subaru and the VLT (red, green and blue), and radio data from the NSF's Karl G. Jansky Very Large Array (red).

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.