A cosmic megamaser

IRAS 16399-0937

Credit: ESA/Hubble & NASA

Acknowledgement: Judy Schmidt (geckzilla)

This galaxy has a far more exciting and futuristic classification than most — it is a megamaser. Megamasers are intensely bright, around 100 million times brighter than the masers found in galaxies like the Milky Way. The entire galaxy essentially acts as an astronomical laser that beams out microwave emission rather than visible light (hence the ‘m’ replacing the ‘l’).

This megamaser is named IRAS 16399-0937, and is located over 370 million light-years from Earth. This NASA/ESA Hubble Space Telescope image belies the galaxy’s energetic nature, instead painting it as a beautiful and serene cosmic rosebud. The image comprises observations captured across various wavelengths by two of Hubble’s instruments: the Advanced Camera for Surveys (ACS), and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS).

NICMOS’s superb sensitivity, resolution, and field of view gave astronomers the unique opportunity to observe the structure of IRAS 16399-0937 in detail. They found that IRAS 16399-0937 hosts a double nucleus — the galaxy’s core is thought to be formed of two separate cores in the process of merging. The two components, named IRAS 16399N and IRAS 16399S for the northern and southern parts respectively, sit over 11 000 light-years apart. However, they are both buried deep within the same swirl of cosmic gas and dust and are interacting, giving the galaxy its peculiar structure.

The nuclei are very different. IRAS 16399S appears to be a starburst region, where new stars are forming at an incredible rate. IRAS 16399N, however, is something known as a LINER nucleus (Low Ionization Nuclear Emission Region), which is a region whose emission mostly stems from weakly-ionised or neutral atoms of particular gases. The northern nucleus also hosts a black hole with some 100 million times the mass of the Sun!

Source: ESA/Hubble/images

NASA's NEOWISE Mission Spies One Comet, Maybe Two

An artist's rendition of 2016 WF9 as it passes Jupiter's orbit inbound toward the sun. 

Image credit: NASA/JPL-Caltech.  

Full image and caption

NASA's NEOWISE mission has recently discovered some celestial objects traveling through our neighborhood, including one on the blurry line between asteroid and comet. Another--definitely a comet--might be seen with binoculars through next week.

An object called 2016 WF9 was detected by the NEOWISE project on Nov. 27, 2016. It's in an orbit that takes it on a scenic tour of our solar system. At its farthest distance from the sun, it approaches Jupiter's orbit. Over the course of 4.9 Earth-years, it travels inward, passing under the main asteroid belt and the orbit of Mars until it swings just inside Earth's own orbit. After that, it heads back toward the outer solar system. Objects in these types of orbits have multiple possible origins; it might once have been a comet, or it could have strayed from a population of dark objects in the main asteroid belt.

2016 WF9 will approach Earth's orbit on Feb. 25, 2017. At a distance of nearly 32 million miles (51 million kilometers) from Earth, this pass will not bring it particularly close. The trajectory of 2016 WF9 is well understood, and the object is not a threat to Earth for the foreseeable future.

A different object, discovered by NEOWISE a month earlier, is more clearly a comet, releasing dust as it nears the sun. This comet, C/2016 U1 NEOWISE, "has a good chance of becoming visible through a good pair of binoculars, although we can't be sure because a comet's brightness is notoriously unpredictable," said Paul Chodas, manager of NASA's Center for Near-Earth Object (NEO) Studies at the Jet Propulsion Laboratory in Pasadena, California.

As seen from the northern hemisphere during the first week of 2017, comet C/2016 U1 NEOWISE will be in the southeastern sky shortly before dawn. It is moving farther south each day and it will reach its closest point to the sun, inside the orbit of Mercury, on Jan. 14, before heading back out to the outer reaches of the solar system for an orbit lasting thousands of years. While it will be visible to skywatchers at Earth, it is not considered a threat to our planet either.

NEOWISE is the asteroid-and-comet-hunting portion of the Wide-Field Infrared Survey Explorer (WISE) mission. After discovering more than 34,000 asteroids during its original mission, NEOWISE was brought out of hibernation in December of 2013 to find and learn more about asteroids and comets that could pose an impact hazard to Earth. If 2016 WF9 turns out to be a comet, it would be the 10th discovered since reactivation. If it turns out to be an asteroid, it would be the 100th discovered since reactivation.

What NEOWISE scientists do know is that 2016 WF9 is relatively large: roughly 0.3 to 0.6 mile (0.5 to 1 kilometer) across.

It is also rather dark, reflecting only a few percent of the light that falls on its surface. This body resembles a comet in its reflectivity and orbit, but appears to lack the characteristic dust and gas cloud that defines a comet.

"2016 WF9 could have cometary origins," said Deputy Principal Investigator James "Gerbs" Bauer at JPL. "This object illustrates that the boundary between asteroids and comets is a blurry one; perhaps over time this object has lost the majority of the volatiles that linger on or just under its surface."

Near-Earth objects (NEOs) absorb most of the light that falls on them and re-emit that energy at infrared wavelengths. This enables NEOWISE's infrared detectors to study both dark and light-colored NEOs with nearly equal clarity and sensitivity.

"These are quite dark objects," said NEOWISE team member Joseph Masiero, "Think of new asphalt on streets; these objects would look like charcoal, or in some cases are even darker than that."

NEOWISE data have been used to measure the size of each near-Earth object it observes. Thirty-one asteroids that NEOWISE has discovered pass within about 20 lunar distances from Earth's orbit, and 19 are more than 460 feet (140 meters) in size but reflect less than 10 percent of the sunlight that falls on them.

The Wide-field Infrared Survey Explorer (WISE) has completed its seventh year in space after being launched on Dec. 14, 2009.

Data from the NEOWISE mission are available on a website for the public and scientific community to use. A guide to the NEOWISE data release, data access instructions and supporting documentation are available at:  http://wise2.ipac.caltech.edu/docs/release/neowise/

Access to the NEOWISE data products is available via the on-line and API services of the NASA/IPAC Infrared Science Archive.

A list of peer-reviewed papers using the NEOWISE data is available at:  http://neowise.ipac.caltech.edu/publications.html


News Media Contact

DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-5011
agle@jpl.nasa.gov

Laurie Cantillo / Dwayne Brown
NASA Headquarters, Washington
202-358-1077 / 202-358-1726
laura.l.cantillo@nasa.gov / dwayne.c.brown@nasa.gov

Source: JPL-Caltech

A Deficit of Dark Matter in Elliptical Galaxies

Figure1: The line-of-sight velocity distribution of 214 PNe in the NGC 3379 galaxy relative to the centre. Circles represent receding PNe and boxes approaching PNe. Dotted circles denote distance from the centre of the galaxy in units of one effective radius. Velocity is proportional to the symbol size, and ranges from -400 to +400 km/s^-1. Credit: Yong Tian. Large format: JPEG. 

The 'missing mass problem' is a long-standing issue in astrophysics, being present in galaxies, cluster of galaxies and even at the cosmological scale. Astronomers from Taiwan have used archival data from PN.S and SAURON to study the internal dynamics of seven nearby elliptical galaxies, and report finding a dearth of dark matter. They conclude that the dynamics of these galaxies are well explained by MOdified Newtonian Dynamics (MOND).

In the dark matter halo scenario, one expects that close to the centre of a galaxy ordinary matter dominates dark matter, while at large distances from the centre dark matter becomes dominant. Thus measurement of the dynamics at the outskirts of galaxies is crucial to the dark matter scenario. As an alternative to the dark matter scenario, MOND predicts the dynamics at the outskirts solely from the ordinary, luminous matter of the galaxy.

Elliptical galaxies commonly have their stars concentrated at the centre, and gas content is low. This makes the study of dynamics by stars at large distance from the centre very difficult. Due to their strong emission lines, Planetary Nebulae (PNe) are potentially good probes for studying the kinematics and dynamics at the outskirts of elliptical galaxies. The Planetary Nebulae Spectrograph (PN.S) on the William Herschel Telescope (WHT) can detect and measure the velocity of PNe, and in recent years has been obtaining velocity measurements of several hundreds of PNe in several nearby galaxies (see Figure 1).

The first results of the analysis of the observations were reported by Romanowsky et al. in 2003. They found a 'dearth' of dark matter in three elliptical galaxies and that the data are modelled well by Newtonian dynamics. However, the 'lack of dark matter' in these galaxies can be explained by another view of the 'missing mass problem' — MOND.

The 'missing mass problem' is, in fact, the mismatch between the measured gravitational acceleration and the inferred Newtonian gravitational acceleration produced by the observed luminous matter of the system. The mismatch can be accounted for by the existence of non-luminous matter ('dark matter'), a modified law of inertia or a modified theory of gravity. The latter was proposed in the 80s as a modification of Newton's second law when the acceleration is smaller than a small constant, a₀=1.2x10^-10 m/s².

Milgrom & Sanders (2003) showed that the luminous elliptical galaxies reported by Romanowsky et al. can be well explained by MOND. They pointed out that in MOND the acceleration discrepancy is small in these systems.

With refined stellar and planetary nebula velocity measurements obtained using the SAURON integral-field spectrograph and PN.S on the WHT, the Romanowsky sample could be enlarged to seven elliptical galaxies.

Tian and Ko (2016) find that, again, all galaxies in the new sample have a deficit of dark matter. The data can be fit by adding a singular isothermal dark matter halo but the required amount of dark matter does not dominate the mass in the halos, contrary to expectation. They show, however, that MOND naturally explains the dynamics of these seven galaxies out to six effective radii.

More information:

• Milgrom M., Sanders R. H., 2003, "Modified Newtonian Dynamics and the ``Dearth of Dark Matter in Ordinary Elliptical Galaxies", ApJ, 599, L25 [ ADS ].
• Romanowsky et al., 2003, "A Dearth of Dark Matter in Ordinary Elliptical Galaxies", Science, 301, 1696 [ ADS ].
• Yong Tian, and Chung-Ming Ko, 2016, "Dynamics of elliptical galaxies with planetary nebulae in modified Newtonian dynamics", MNRAS, 462, 1092 [ ADS ].
• Planetary Nebula Spectrograph (PN.S) web site.
• SAURON web site.

Contact: 

Javier Méndez
(Public Relations Officer)

Source:   Isaac Newton Group of Telescopes

NGC 6357: Cosmic 'Winter' Wonderland

NGC 6357

Credit X-ray: NASA/CXC/PSU/L.Townsley et al;

 Optical: UKIRT; Infrared: NASA/JPL-Caltech 

JPEG (1000.4 kb) - Large JPEG (9.1 MB) - Tiff (18.8 MB) - 4K JPG (6.9 MB) - More Images

Tour of NGC 6357

More Animations

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Although there are no seasons in space, this cosmic vista invokes thoughts of a frosty winter landscape. It is, in fact, a region called NGC 6357 where radiation from hot, young stars is energizing the cooler gas in the cloud that surrounds them.

This composite image contains X-ray data from NASA's Chandra X-ray Observatory and the ROSAT telescope (purple), infrared data from NASA's Spitzer Space Telescope (orange), and optical data from the SuperCosmos Sky Survey (blue) made by the United Kingdom Infrared Telescope.

Located in our galaxy about 5,500 light years from Earth, NGC 6357 is actually a "cluster of clusters," containing at least three clusters of young stars, including many hot, massive, luminous stars. The X-rays from Chandra and ROSAT reveal hundreds of point sources, which are the young stars in NGC 6357, as well as diffuse X-ray emission from hot gas. There are bubbles, or cavities, that have been created by radiation and material blowing away from the surfaces of massive stars, plus supernova explosions.

Astronomers call NGC 6357 and other objects like it "HII" (pronounced "H-two") regions. An HII region is created when the radiation from hot, young stars strips away the electrons from neutral hydrogen atoms in the surrounding gas to form clouds of ionized hydrogen, which is denoted scientifically as "HII".

Researchers use Chandra to study NGC 6357 and similar objects because young stars are bright in X-rays. Also, X-rays can penetrate the shrouds of gas and dust surrounding these infant stars, allowing astronomers to see details of star birth that would be otherwise missed.

A recent paper on Chandra observations of NGC 6357 by Leisa Townsley of Pennsylvania State University appeared in The Astrophysical Journal Supplement Series and is available online.

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

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Fast Facts for NGC 6357:

Scale: Image is about 44 arcmin across (70 light years)
Category: Normal Stars & Star Clusters
Coordinates (J2000): RA 17h 25m 34.2s | Dec -34° 23' 12"
Constellation: Scorpius
Observation Date: 7 pointings between July 2004 and July 2016
Observation Time: 72 hours 13 min. (3 days 13 min)
Obs. ID: 4477, 10987, 10988, 13267, 13622, 18453
Instrument: ACIS
References: Townsley, L. et al, 2014, ApJS, 213, 1; arXiv:1403.2576
Color Code: X-ray (Purple); Optical (Blue); Infrared (Orange)
Distance Estimate: About 5,500 light years

Source: NASA’s Chandra X-ray Observatory

VLA, ALMA Team Up to Give First Look at Birthplaces of Most Current Stars

Radio/Optical combination images of distant galaxies as seen with NSF's Very Large Array and NASA's Hubble Space Telescope. Their distances from Earth are indicated in the top set of images. Below, the same images, without labels. Credit: K. Trisupatsilp, NRAO/AUI/NSF, NASA.

Astronomers have gotten their first look at exactly where most of today's stars were born. To do so, they used the National Science Foundation's Karl G. Jansky Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array (ALMA) to look at distant galaxies seen as they were some 10 billion years ago.

At that time, the Universe was experiencing its peak rate of star formation. Most stars in the present Universe were born then.

"We knew that galaxies in that era were forming stars prolifically, but we didn't know what those galaxies looked like, because they are shrouded in so much dust that almost no visible light escapes them," said Wiphu Rujopakam, of the Kavli Institute for the Physics and Mathematics of the Universe at the University of Tokyo and Chulalongkorn University in  Bangkok, who was lead author on the research paper.

Radio waves, unlike visible light, can get through the dust. However, in order to reveal the details of such distant -- and faint -- galaxies, the astronomers had to make the most sensitive images ever made with the VLA.

The new observations, using the VLA and ALMA, have answered longstanding questions about just what mechanisms were responsible for the bulk of star formation in those galaxies. They found that intense star formation in the galaxies they studied most frequently occured throughout the galaxies, as opposed to much smaller regions in present-day galaxies with similar high star-formation rates.

The astronomers used the VLA and ALMA to study galaxies in the Hubble Ultra Deep Field, a small area of sky observed since 2003 with NASA's Hubble Space Telescope (HST). The HST made very long exposures of the area to detect galaxies in the far-distant Universe, and numerous observing programs with other telescopes have followed up on the HST work.

"We used the VLA and ALMA to see deeply into these galaxies, beyond the dust that obscured their innards from Hubble," said Kristina Nyland, of the National Radio Astronomy Observatory (NRAO). "The VLA showed us where star formation was occurring, and ALMA revealed the cold gas that is the fuel for star formation," she added.

"In this study, we made the most sensitive image ever made with the VLA," said Preshanth Jagannathan, also of NRAO. "If you took your cellphone, which transmits a weak radio signal, and put it at more than twice the distance to Pluto, near the outer edge of the solar system, its signal would be roughly as strong as what we detected from these galaxies," he added.

The study of the galaxies was done by an international team of astronomers. Others involved include James Dunlop of the University of Edinburgh and Rob Ivison of the University of Edinburgh and the European Southern Observatory. The researchers reported their findings in the Dec. 1 issue of the Astrophysical Journal.

ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of South Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.

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

Media Contact:  

Dave Finley, Public Information Officer
(575) 835-7302
dfinley@nrao.edu

Source: National Radio Astronomy Observatory (NRAO)

Milky-Way-Like Galaxies Seen in their Awkward Adolescent Years

Four Milky-Way-like progenitor galaxies as seen as they would have appeared 9 billion years ago. ALMA observations of carbon monoxide (red) is superimposed on images taken with the Hubble Space Telescope. The carbon monoxide would most likely be suffused throughout the young galaxies. Credit. ALMA (ESO/NAOJ/NRAO) C. Papovich; A. Angelich (NRAO/AUI/NSF); NASA/ESA Hubble Space Telescope

Spiral galaxies like our own Milky Way were not always the well-ordered, pinwheel-like structures we see in the universe today. Astronomers believe that about 8-10 billion years ago, progenitors of the Milky Way and similar spiral galaxies were smaller, less organized, but amazingly rich in star-forming material; so much so, that they would have been veritable star factories, churning out new stars faster than at any other point in their lifetimes. Now, astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have found evidence to support this view. By studying four very young versions of galaxies like the Milky Way as they were seen approximately 9 billion years ago, the astronomers discovered that each galaxy was incredibly rich in carbon monoxide gas, a well-known tracer of star-forming gas. “We used ALMA to detect adolescent versions of the Milky Way and found that such galaxies do indeed have much higher amounts of molecular gas, which would fuel rapid star formation," said Casey Papovich, an astronomer at Texas A&M University in College Station and lead author on a paper appearing in Nature Astronomy. “I liken these galaxies to an adolescent human who consumes prodigious amounts of food to fuel their own growth during their teenage years.” Though the relative abundance of star-forming gas is extreme in these galaxies, they are not yet fully formed and rather small compared to the Milky Way as we see it today. The new ALMA data indicate that the vast majority of the mass in these galaxies is in cold molecular gas rather than in stars. These observations, the astronomers note, are helping build a complete picture of how matter in Milky-Way-size galaxies evolved and how our own galaxy formed.

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

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The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of 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 National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

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

The galaxies in this study and shown in the accompanying image are identified as ZFOURGE CDFS 467 (top left), ZFOURGE CDFS 4409 (top right), ZFOURGE CDFS 8193 (bottom left), and ZFOURGE CDFS 6497 (bottom right).

This research is presented in a paper titled "Large molecular gas reservoirs in ancestors of Milky Way-mass galaxies nine billion years ago," by Papovich et al., published in Nature Astronomy. [http://www.nature.com/articles/s41550-016-0003]

Contact:

Charles Blue
NRAO Public Information Officer
+1 434.296.0314; cblue@nrao.edu

Source: National Radio Astronomy Observatory (NRAO)

Astro-pointillism

NGC 4707

Credit: ESA/Hubble & NASA

On a clear evening in April of 1789, the renowned astronomer William Herschel continued his unrelenting survey of the night sky, hunting for new cosmic objects — and found cause to celebrate! Lengthening his impressive list of cosmic discoveries yet again, the astronomer spotted this bright spiral galaxy, named NGC 4707, lurking in the constellation of Canes Venatici (The Hunting Dog). NGC 4707 lies roughly 22 million light-years from Earth.

Over two centuries later, the NASA/ESA Hubble Space Telescope is able to view the same galaxy in far greater detail than Herschel could, allowing us to appreciate the intricacies and characteristics of NGC 4707 as never before. This striking image comprises observations from Hubble’s Advanced Camera for Surveys (ACS), one of a handful of high-resolution instruments currently aboard the space telescope.

Herschel himself reportedly described NGC 4707 as a “small, stellar” galaxy; while it is classified as a spiral (type Sm), its overall shape, centre, and spiral arms are very loose and undefined, and its central bulge is either very small or non-existent. It instead appears as a rough sprinkling of stars and bright flashes of blue on a dark canvas, as if a pointillist painter had dotted the cosmos with small pinpricks of bright paint.

The blue smudges seen across the frame highlight regions of recent or ongoing star formation, with newborn stars glowing in bright, intense shades of cyan and turquoise.

Source: ESA/Hubble/Images

First Light for Band 5 at ALMA

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The merging galaxy system Arp 220 from ALMA and Hubble

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Band 5 ALMA receiver

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One of the Band 5 receivers for ALMA

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One of the Band 5 receivers for ALMA 

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New receivers improve ALMA’s ability to search for water in the Universe 

The Atacama Large Millimeter/submillimeter Array (ALMA) in Chile has begun observing in a new range of the electromagnetic spectrum. This has been made possible thanks to new receivers installed at the telescope’s antennas, which can detect radio waves with wavelengths from 1.4 to 1.8 millimetres — a range previously untapped by ALMA. This upgrade allows astronomers to detect faint signals of water in the nearby Universe.

ALMA observes radio waves from the Universe, at the low-energy end of the electromagnetic spectrum. With the newly installed Band 5 receivers, ALMA has now opened its eyes to a whole new section of this radio spectrum, creating exciting new observational possibilities.

The European ALMA Programme Scientist, Leonardo Testi, explains the significance: “The new receivers will make it much easier to detect water, a prerequisite for life as we know it, in our Solar System and in more distant regions of our galaxy and beyond. They will also allow ALMA to search for ionised carbon in the primordial Universe.”

It is ALMA’s unique location, 5000 metres up on the barren Chajnantor plateau in Chile, that makes such an observation possible in the first place. As water is also present in Earth’s atmosphere, observatories in less elevated and less arid environments have much more difficulty identifying the origin of the emission coming from space. ALMA’s great sensitivity and high angular resolution mean that even faint signals of water in the local Universe can now be imaged at this wavelength [1].

The Band 5 receiver, which was developed by the Group for Advanced Receiver Development (GARD) at Onsala Space Observatory, Chalmers University of Technology, Sweden, has already been tested at the APEX telescope in the SEPIA instrument. These observations were also vital to help select suitable targets for the first receiver tests with ALMA.

The first production receivers were built and delivered to ALMA in the first half of 2015 by a consortium consisting of the Netherlands Research School for Astronomy (NOVA) and GARD in partnership with the National Radio Astronomy Observatory (NRAO), which contributed the local oscillator to the project. The receivers are now installed and being prepared for use by the community of astronomers.

To test the newly installed receivers observations were made of several objects including the colliding galaxies Arp 220, a massive region of star formation close to the centre of the Milky Way, and also a dusty red supergiant star approaching the supernova explosion that will end its life [2].

To process the data and check its quality, astronomers, along with technical specialists from ESO and the European ALMA Regional Centre (ARC) network, gathered at the Onsala Space Observatory in Sweden, for a "Band 5 Busy Week" hosted by the Nordic ARC node [3]. The final results have just been made freely available to the astronomical community worldwide.

Team member Robert Laing at ESO is optimistic about the prospects for ALMA Band 5 observations: “It's very exciting to see these first results from ALMA Band 5 using a limited set of antennas. In the future, the high sensitivity and angular resolution of the full ALMA array will allow us to make detailed studies of water in a wide range of objects including forming and evolved stars, the interstellar medium and regions close to supermassive black holes.”

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Notes

[1] A key spectral signature of water lies in this expanded range — at a wavelength of 1.64 millimetres.

[2] The observations were performed and made possible by the ALMA Extension of Capabilities team in Chile.

[3] The ESO Band 5 Science Verification team includes: Elizabeth Humphreys, Tony Mroczkowski, Robert Laing, Katharina Immer, Hau-Yu (Baobab) Liu, Andy Biggs, Gianni Marconi and Leonardo Testi. The team working on processing the data included: Tobia Carozzi, Simon Casey, Sabine König, Ana Lopez-Sepulcre, Matthias Maercker, Iván Martí-Vidal, Lydia Moser, Sebastien Muller, Anita Richards, Daniel Tafoya and Wouter Vlemmings.

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More Information

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of 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 National Science Council of Taiwan (NSC) 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.

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

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Links

• Photos of ALMA 

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Contacts

Leonardo Testi
European ALMA Programme Scientist, ESO
Garching bei München, Germany
Tel: +49 89 3200 6541
Email: ltesti@eso.org

Robert Laing
ESO ALMA Scientist
Garching bei München, Germany
Tel: +49 89 3200 6625
Email: rlaing@eso.org

Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org

Source: ESO

Festive nebulae light up Milky Way Galaxy satellite

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Festive nebulae

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Wide-field image of Magellanic clouds (ground-based image)

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Globular cluster 47 Tucanae and the Small Magellanic Cloud (ground-based image)

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Small Magellanic Cloud (ground-based image)

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Small Magellanic Cloud and SMIDGE survey 

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Videos 

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Zoom in on NGC 248Videos

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The sheer observing power of the NASA/ESA Hubble Space Telescope is rarely better illustrated than in an image such as this. This glowing pink nebula, named NGC 248, is located in the Small Magellanic Cloud, just under 200 000 light-years away and yet can still be seen in great detail.

Our home galaxy, the Milky Way, is part of a collection of galaxies known as the Local Group. Along with the Andromeda Galaxy, the Milky Way is one of the Group’s most massive members, around which many smaller satellite galaxies orbit. The Magellanic Clouds are famous examples, which can easily be seen with the naked eye from the southern hemisphere.

Within the smaller of these satellite galaxies, the Small Magellanic Cloud, the NASA/ESA Hubble Space Telescope captured two festive-looking emission nebulae, conjoined so they appear as one. Intense radiation from the brilliant central stars is causing hydrogen in the nebulae to glow pink.

Together the nebulae are called NGC 248. They were discovered in 1834 by the astronomer Sir John Herschel. NGC 248 is about 60 light-years long and 20 light-years wide. It is among a number of glowing hydrogen nebulae in the Small Magellanic Cloud, which lies in the southern constellation of Tucana (The Toucan), about 200 000 light-years away.

The nebula was observed as part of a Hubble survey, the Small Magellanic cloud Investigation of Dust and Gas Evolution (SMIDGE). In this survey astronomers are using Hubble to probe the Small Magellanic Cloud to understand how its dust — an important component of many galaxies and related to star formation — is different from the dust in the Milky Way.

Thanks to its relative proximity, the Small Magellanic Cloud is a valuable target. It also turns out to have only between a fifth and a tenth of the amount of heavy elements that the Milky Way has, making the dust similar to what we expect to see in galaxies in the earlier Universe.

This allows astronomers to use it as a cosmic laboratory to study the history of the Universe in our cosmic backyard. These observations also help us to understand the history of our own galaxy as most of the star formation happened earlier in the Universe, at a time when the percentage of heavy elements in the Milky Way was much lower than it is now.

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The data used in this image were taken with Hubble’s Advanced Camera for Surveys in September 2015.

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More information

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Image credit: NASA, ESA, STScI, K. Sandstrom (University of California, San Diego), and the SMIDGE team.

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Links

• Images of Hubble
• Link to hubblesite release

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Contacts

Karin Sandstrom
University of California
San Diego, USA
Tel: +1 858-246-0552
Email: kmsandstrom@ucsd.edu

Mathias Jäger
ESA/Hubble, Public Information Officer
Garching bei München, Germany
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Pan-STARRS Releases Largest Digital Sky Survey to the World

This compressed view of the entire sky visible from Hawai'i by the Pan-STARRS1 Observatory is the result of half a million exposures, each about 45 seconds in length, taken over a period of 4 years. The shape comes from making a map of the celestial sphere, like a map of the Earth, but leaving out the southern quarter. The disk of the Milky Way looks like a yellow arc, and the dust lanes show up as reddish brown filaments. The background is made up of billions of faint stars and galaxies. If printed at full resolution, the image would be 1.5 miles long, and you would have to get close and squint to see the detail. Danny Farrow, Pan-STARRS1 Science Consortium and Max Planck Institute for Extraterrestial Physics. Low Resolution (jpg)

The Pan-STARRS1 Observatory on Halealakala, Maui, opens at sunset to begin a night of mapping the sky. Photo by Rob Ratkowski.   Low Resolution (jpg)

Cambridge, MA - The Pan-STARRS project at the University of Hawai'i Institute for Astronomy (UH IfA) is publicly releasing the world's largest digital sky survey today from the Space Telescope Science Institute (STScI) in Baltimore, Md. The Harvard-Smithsonian Center for Astrophysics (CfA) is among the partners who contributed to the Pan-STARRS1 Surveys.

"The Pan-STARRS1 Surveys allow anyone to access millions of images and use the database and catalogs containing precision measurements of billions of stars and galaxies," said Dr. Ken Chambers, Director of the Pan-STARRS Observatories. "Pan-STARRS has made discoveries from Near Earth Objects and Kuiper Belt Objects in the solar system to lonely planets between the stars; it has mapped the dust in three dimensions in our galaxy and found new streams of stars; and it has found new kinds of exploding stars and distant quasars in the early universe."

"With this release we anticipate that scientists - as well as students and even casual users - around the world will make many new discoveries about the universe from the wealth of data collected by Pan-STARRS," Chambers added.

The four years of data comprise 3 billion separate sources, including stars, galaxies, and various other objects. The immense collection contains 2 petabytes of data, which is equivalent to one billion selfies, or one hundred times the total content of Wikipedia.

The first Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) observatory is a 1.8-meter telescope at the summit of Haleakala, on Maui. In May 2010, it embarked on a digital sky survey of the sky in visible and near infrared light. This was the first survey to observe the entire sky visible from Hawaii multiple times in many colors of light, with the goal of finding moving, transient, and variable objects, including asteroids that could potentially threaten the Earth. The survey took approximately four years to complete, and scanned the sky 12 times in each of five filters.

"Achieving the high quality of the Pan-STARRS1 measurements and maintaining it over such an enormous quantity of data was a unique computational challenge and the results are a tribute to the dedicated efforts of our small team of scientists at the UH IfA and our collaborators who worked to process and calibrate the extraordinary volume of raw image data," said Dr. Eugene Magnier, lead of the Pan-STARRS Image Processing team.

A number of CfA scientists were involved in analyzing Pan-STARRS data and extracting groundbreaking results. For example, Dr. Douglas Finkbeiner and students Edward Schlafly and Gregory Green led the effort to map the interstellar dust in the Milky Way in three dimensions. They used the colors of nearly 1 billion stars, requiring photometric calibration at a level unprecedented for ground-based surveys.

"The tiny particles in dust clouds make background stars fainter and redder, for the same reason the sky turns red at sunset," said Dr. Finkbeiner. "In order to measure the subtle color shifts, we must know the brightnesses and colors of the stars at the percent level. With vastly more data than any human could ever look at directly, this required serious effort, and I'm proud of everyone who contributed."

"Pan-STARRS also has given us an unprecedented view of the dynamic and transient nature of astronomical phenomena," said CfA astronomer Dr. Edo Berger. "Our group discovered and studied new types of supernova explosions and the disruptions of stars by supermassive black holes from the Pan-STARRS data."

The Pan-STARRS1 Surveys program was undertaken by the PS1 Science Consortium - a collaboration among 10 research institutions in four countries with support from NASA and the National Science Foundation (NSF). Consortium observations for the sky survey, mapping everything visible from Hawaii, were completed in April 2014. This data is now being released publicly.

"The cooperation between STScI and the Pan-STARRS team at the University of Hawaii has been essential to ensuring that this initial data release is successful," explained Dr. Marc Postman, Head of the Community Missions office at STScI, and liaison between STScI and the PS1 Consortium.

"STScI was a natural partner to host the Pan-STARRS public archive given its extensive experience serving astronomy data to the international community. In advance of the release of the Pan-STARRS data, STScI staff helped perform checks of data quality, helped write archive user documentation, tested and installed the local data storage and database query system, and designed, built and deployed the web-based user interfaces to the archive system."

The rollout is being done in two stages. Today's release is the "Static Sky," which is the average of each of those individual epochs. For every object, there's an average value for its position, its brightness, and its colors. In 2017, the second set of data will be released, providing a catalog that gives the information and images for each individual epoch.

The Space Telescope Science Institute provides the storage hardware, the computers that handle the database queries, and the user-friendly interfaces to access the data.

The survey data resides in the Mikulski Archive for Space Telescopes (MAST), which serves as NASA's repository for all of its optical and ultraviolet-light observations, some of which date to the early 1970s. It includes all of the observational data from such space astrophysics missions as Hubble, Kepler, GALEX, and a wide variety of other telescopes, as well as several all-sky surveys. Pan-STARRS marks the nineteenth mission to be archived in MAST.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

For more information, contact:

Christine Pulliam
Media Relations Manager
Harvard-Smithsonian Center for Astrophysics
617-495-7463
cpulliam@cfa.harvard.edu

Source: Harvard-Smithsonian Center for Astrophysics

Fluctuations in extragalactic gamma rays reveal two source classes but no dark matter

This view shows the entire sky in gamma ray radiation, at energies greater than 1 GeV, based on five years of data from the Large Area Telescope instrument on NASA's Fermi Gamma-ray Space Telescope. Brighter colours indicate brighter gamma-ray emission. The large bright band in the middle is the emission from our own Galaxy. Credit: NASA/DOE/Fermi LAT Collaboration

Researchers from the Max Planck Institute for Astrophysics and the University of Amsterdam GRAPPA Center of Excellence just published the most precise analysis so far of the fluctuations in the gamma-ray background. They used more than six years of data gathered by the Fermi Large Area Telescope and found two different source classes contributing to the gamma-ray background. No traces of a contribution of dark matter particles were found in the analysis. The study was performed with an international collaboration of researchers and is published in the journal Physical Review D.

Gamma rays are particles of light, or photons, with the highest energy in the universe, invisible to the human eye. The most common emitters of gamma rays are blazars: supermassive black holes at the centres of galaxies. In smaller numbers, gammy rays are also produced by a certain kind of stars called pulsars and in huge stellar explosions such as supernovae.

In 2008 NASA launched the Fermi satellite to map the gamma-ray universe with extreme accuracy. The Large Area Telescope, mounted on the Fermi satellite, has been taking data ever since. It continuously scans the whole sky every three hours. The majority of the detected gamma rays is produced in our own Galaxy (the Milky Way), but the Fermi telescope also managed to detect more than 3000 extragalactic sources (according to the latest count performed in January 2016). However, these individual sources are not enough to explain the total amount of gamma-ray photons coming from outside our Galaxy. In fact, about 75% of them are unaccounted for.

Isotropic gamma-ray background

As far back as the late 1960’s, orbiting observatories have found a diffuse background of gamma rays streaming from all directions in the universe. If you had gamma-ray vision, and looked at the sky, there would be no place that would be dark.

The source of this so-called isotropic gamma-ray background is hitherto unknown. This radiation could be produced by unresolved blazars, or other astronomical sources too faint to be detected with the Fermi telescope. Parts of the gamma-ray background might also hold the fingerprint of the illustrious dark matter particle, a so-far undetected particle held responsible for the missing 80% of the matter in our universe. If two dark matter particles collide, they can annihilate and produce a signature of gamma-ray photons.

Fluctuations in the isotropic gamma-ray background, based on 81 months of data. Emission from our own Galaxy, the Milky Way, is masked in grey. Credit: Mattia Fornasa, UvA/Grappa

Fluctuations

“The analysis and interpretation of fluctuations of the diffuse gamma-ray background is a new research area in high-energy astrophysics,” explains Eiichiro Komatsu at the Max Planck Institute for Astrophysics, who developed the necessary analysis tools for fluctuations in this radiation. He was also part of the team that for the first time reported fluctuations in the gamma ray background in 2012. For this latest analysis, the researchers used 81 months of data gathered by the Fermi Large Area Telescope – much more data and with a larger energy range than in previous studies.

The scientists were able to distinguish two different contributions to the gamma-ray background. One class of gamma-ray sources is needed to explain the fluctuations at low energies (below 1 GeV), and another type of sources is needed to generate the fluctuations at higher energy – the signatures of these two contributions is markedly different.

The gamma rays in the high-energy ranges – from a few GeV up – are likely originating from unresolved blazars, the researchers suggest in their paper. Further investigation of these potential sources is currently under way. However, it seems much harder to pinpoint a source for the fluctuations with energies below 1 GeV. None of the known gamma-ray emitters have a behaviour that is consistent with the new data.

Constraints on dark matter 

So far, the Fermi telescope has not detected any conclusive indication of gamma-ray emission originating from dark-matter particles. Also this latest study showed no indication of a signal associated with dark matter. “Our measurement complements other search campaigns that used gamma rays to look for dark matter,” says lead author Mattia Fornasa from the University of Amsterdam. “It confirms that there is little room left for dark matter induced gamma-ray emission in the isotropic gamma-ray background.”

The precision of the fluctuation measurement has improved markedly since the first result in 2012. “I am glad to see that our measurements provide significant new insights into the origin of the gamma-ray background,” says Komatsu.  

“My original motivation to do this analysis in 2006 was to find evidence for gamma-rays from dark matter particles. Well, we have not found gamma-rays from dark matter yet,” Komatsu concedes, “but I am still excited about our measurements leading to a new understanding of populations of astrophysical gamma-ray sources such as blazars. I have not given up hope on finding gamma-rays from dark matter yet though, and we have some new ideas on how to improve our method.”

Contact

Komatsu, Eiichiro
Managing director
Phone:2208
Email: ekomatsu@mpa-garching.mpg.de

Website: personal homepage (the institute is not responsible for the contents of personal homepages)

Hämmerle, Hannelore
Press officer
Phone: 3980gas
Email: hanne@mpa-garching.mpg.de

Original Publication

Mattia Fornasa, Alessandro Cuoco, Jesús Zavala, Jennifer M. Gaskins, Miguel A. Sánchez-Conde, German Gomez-Vargas, Eiichiro Komatsu, Tim Linden, Francisco Prada, Fabio Zandanel and Aldo Morselli

 

The angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its Dark Matter interpretation

Phys. Rev. D 94, 123005, 9 December 2016

Source DOI

M. Ackermann et al.

Anisotropies in the diffuse gamma-ray background measured by the Fermi LAT

Phys. Rev. D 85, 083007, 2012

Source DOI

 Source: Max Planck Institute for Astrophysics

A closer look at IC 5201

IC 5201

Credit: ESA/Hubble & NASA

In 1900, astronomer Joseph Lunt made a discovery: Peering through a telescope at Cape Town Observatory, the British–South African scientist spotted this beautiful sight in the southern constellation of Grus (The Crane): a barred spiral galaxy now named IC 5201.

Over a century later, the galaxy is still of interest to astronomers. For this image, the NASA/ESA Hubble Space Telescope used its Advanced Camera for Surveys (ACS) to produce a beautiful and intricate image of the galaxy. Hubble’s ACS can resolve individual stars within other galaxies, making it an invaluable tool to explore how various populations of stars have sprung to life, evolved, and died throughout the cosmos.

IC 5201 sits over 40 million light-years away from us. As with two thirds of all the spirals we see in the Universe — including the Milky Way, the galaxy has a bar of stars slicing through its centre.

Source: ESA/Hubble/Images

Microlensing Study Suggests Most Common Outer Planets Likely Neptune-mass

A new statistical study of planets found by a technique called gravitational microlensing suggests that Neptune-mass worlds are likely the most common type of planet to form in the icy outer realms of planetary systems. The study provides the first indication of the types of planets waiting to be found far from a host star, where scientists suspect planets form most efficiently.

Neptune-mass worlds are likely the most common type in the outer realms of planetary system

Credits: NASA's Goddard Space Flight Center.  
This video can be downloaded from the Scientific Visualization Studio

This graph plots 4,769 exoplanets and planet candidates according to their masses and relative distances from the snow line, the point where water and other materials freeze solid (vertical cyan line). Gravitational microlensing is particularly sensitive to planets in this region. Planets are shaded according to the discovery technique listed at right. Masses for unconfirmed planetary candidates from NASA's Kepler mission are calculated based on their sizes. For comparison, the graph also includes the planets of our solar system. Credits: NASA's Goddard Space Flight Center. Hi-res image

"We've found the apparent sweet spot in the sizes of cold planets. Contrary to some theoretical predictions, we infer from current detections that the most numerous have masses similar to Neptune, and there doesn't seem to be the expected increase in number at lower masses," said lead scientist Daisuke Suzuki, a post-doctoral researcher at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland Baltimore County. "We conclude that Neptune-mass planets in these outer orbits are about 10 times more common than Jupiter-mass planets in Jupiter-like orbits."

Gravitational microlensing takes advantage of the light-bending effects of massive objects predicted by Einstein's general theory of relativity. It occurs when a foreground star, the lens, randomly aligns with a distant background star, the source, as seen from Earth. As the lensing star drifts along in its orbit around the galaxy, the alignment shifts over days to weeks, changing the apparent brightness of the source. The precise pattern of these changes provides astronomers with clues about the nature of the lensing star, including any planets it may host.

"We mainly determine the mass ratio of the planet to the host star and their separation," said team member David Bennett, an astrophysicist at Goddard. "For about 40 percent of microlensing planets, we can determine the mass of the host star and therefore the mass of the planet."

More than 50 exoplanets have been discovered using microlensing compared to thousands detected by other techniques, such as detecting the motion or dimming of a host star caused by the presence of planets. Because the necessary alignments between stars are rare and occur randomly, astronomers must monitor millions of stars for the tell-tale brightness changes that signal a microlensing event.

However, microlensing holds great potential. It can detect planets hundreds of times more distant than most other methods, allowing astronomers to investigate a broad swath of our Milky Way galaxy. The technique can locate exoplanets at smaller masses and greater distances from their host stars, and it's sensitive enough to find planets floating through the galaxy on their own, unbound to stars.

NASA's Kepler and K2 missions have been extraordinarily successful in finding planets that dim their host stars, with more than 2,500 confirmed discoveries to date. This technique is sensitive to close-in planets but not more distant ones. Microlensing surveys are complementary, best probing the outer parts of planetary systems with less sensitivity to planets closer to their stars.

"Combining microlensing with other techniques provides us with a clearer overall picture of the planetary content of our galaxy," said team member Takahiro Sumi at Osaka University in Japan.

From 2007 to 2012, the Microlensing Observations in Astrophysics (MOA) group, a collaboration between researchers in Japan and New Zealand, issued 3,300 alerts informing the astronomical community about ongoing microlensing events. Suzuki's team identified 1,474 well-observed microlensing events, with 22 displaying clear planetary signals. This includes four planets that were never previously reported.

To study these events in greater detail, the team included data from the other major microlensing project operating over the same period, the Optical Gravitational Lensing Experiment (OGLE), as well as additional observations from other projects designed to follow up on MOA and OGLE alerts.

From this information, the researchers determined the frequency of planets compared to the mass ratio of the planet and star as well as the distances between them. For a typical planet-hosting star with about 60 percent the sun's mass, the typical microlensing planet is a world between 10 and 40 times Earth's mass. For comparison, Neptune in our own solar system has the equivalent mass of 17 Earths.

The results imply that cold Neptune-mass worlds are likely to be the most common types of planets beyond the so-called snow line, the point where water remained frozen during planetary formation. In the solar system, the snow line is thought to have been located at about 2.7 times Earth's mean distance from the sun, placing it in the middle of the main asteroid belt today.

Neptune-mass exoplanets like the one shown in this artist's rendering may be the most common in the icy regions of planetary systems. Beyond a certain distance from a young star, water and other substances remain frozen, leading to an abundant population of icy objects that can collide and form the cores of new planets. In the foreground, an icy body left over from this period drifts past the planet. Credits: NASA/Goddard/Francis Reddy.  Hi-res image

A paper detailing the findings was published in The Astrophysical Journal on Dec. 13.

"Beyond the snow line, materials that were gaseous closer to the star condense into solid bodies, increasing the amount of material available to start the planet-building process," said Suzuki. "This is where we think planetary formation was most efficient, and it's also the region where microlensing is most sensitive."

NASA's Wide Field Infrared Survey Telescope (WFIRST), slated to launch in the mid-2020s, will conduct an extensive microlensing survey. Astronomers expect it will deliver mass and distance determinations of thousands of planets, completing the work begun by Kepler and providing the first galactic census of planetary properties.

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

WFIRST is managed at Goddard, with participation by JPL, the Space Telescope Science Institute in Baltimore, the Infrared Processing and Analysis Center, also in Pasadena, and a science team comprising members from U.S. research institutions across the country.

For more information on how NASA’s Kepler is working with ground-based efforts, including the MOA and OGLE groups, to search for planets using microlensing, please visit:  https://www.nasa.gov/feature/ames/kepler/searching-for-far-out-and-wandering-worlds/


By Francis Reddy
NASA's Goddard Space Flight Center in Greenbelt, Maryland

Editor: Karl Hille

Source: NASA/Exoplanets

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