Friday, October 21, 2016

The Toucan and the cluster

Credit: ESA/Hubble & NASA

It may be famous for hosting spectacular sights such as the Tucana Dwarf Galaxy and 47 Tucanae (heic1510), the second brightest globular cluster in the night sky, but the southern constellation of Tucana (The Toucan) also possesses a variety of unsung cosmic beauties.

One such beauty is NGC 299, an open star cluster located within the Small Magellanic Cloud just under 200 000 light-years away. Open clusters such as this are collections of stars weakly bound by the shackles of gravity, all of which formed from the same massive molecular cloud of gas and dust. Because of this, all the stars have the same age and composition, but vary in their mass because they formed at different positions within the cloud.

This unique property not only ensures a spectacular sight when viewed through a sophisticated instrument attached to a telescope such as Hubble’s Advanced Camera for Surveys, but gives astronomers a cosmic laboratory in which to study the formation and evolution of stars — a process that is thought to depend strongly on a star’s mass.

Thursday, October 20, 2016

NGC 5128: Mysterious Cosmic Objects Erupting in X-rays Discovered

NGC 5128
Credit: NASA/CXC/UA/J.Irwin et al.  

A Tour of IC 2497

This image shows the location of a remarkable source that dramatically flares in X-rays unlike any ever seen. Along with another similar source found in a different galaxy, these objects may represent an entirely new phenomenon, as reported in our latest press release [link to PR].

These two objects were both found in elliptical galaxies, NGC 5128 (also known as Centaurus A) shown here and NGC 4636. In this Chandra X-ray Observatory image of NGC 5128, low, medium, and high-energy X-rays are colored red, green, and blue, and the location of the flaring source is outlined in the box to the lower left.

Both of these mysterious sources flare dramatically - becoming a hundred times brighter in X-rays in about a minute before steadily returning to their original X-ray levels about an hour later. At their X-ray peak, these objects qualify as ultraluminous X-ray sources (ULXs) that give off hundreds to thousands of times more X-rays than typical X-ray binary systems where a star is orbiting a black hole or neutron star.

Five flares were detected from the source located near NGC 5128, which is at a distance of about 12 million light years from Earth. A movie showing the average change in X-rays for the three flares with the most complete Chandra data, covering both the rise and fall, is shown in the inset.

The source associated with the elliptical galaxy NGC 4636, which is located about 47 million light years away, was observed to flare once.

The only other objects known to have such rapid, bright, repeated flares involve young neutron stars such as magnetars, which have extremely powerful magnetic fields. However, these newly flaring sources are found in populations of much older stars. Unlike magnetars, the new flaring sources are likely located in dense stellar environments, one in a globular cluster and the other in a small, compact galaxy.

When they are not flaring, these newly discovered sources appear to be normal binary systems where a black hole or neutron star is pulling material from a companion star similar to the Sun. This indicates that the flares do not significantly disrupt the binary system.

While the nature of these flares is unknown, the team has begun to search for answers. One idea is that the flares represent episodes when matter pulled away from a companion star falls rapidly onto a black hole or neutron star. This could happen when the companion makes its closest approach to the compact object in an eccentric orbit. Another explanation could involve matter falling onto an intermediate-mass black hole, with a mass of about 800 times that of the Sun for one source and 80 times that of the Sun for the other.

This result is describing in a paper appearing in the journal Nature on October 20, 2016. The authors are Jimmy Irwin (University of Alabama), Peter Maksym (Harvard-Smithsonian Center for Astrophysics), Gregory Sivakoff (University of Alberta), Aaron Romanowsky (San Jose State University), Dacheng Lin (University of New Hampshire), Tyler Speegle, Ian Prado, David Mildebrath (University of Alabama), Jay Strader (Michigan State University), Jifeng Lui (Chinese Academy of Sciences), and Jon Miller (University of Michigan).

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

Fast Facts for NGC 5128:

Scale: Main image is 16.7 arcmin across (about 58,000 light years); Inset image is 1 arcmin across (about 3,500 light years)
Category: Quasars & Active Galaxies
Coordinates (J2000): RA 13h 25m 52.7s | Dec -43° 05' 46.00"
Constellation: Centaurus
Observation Date: 21 pointings between 05 Dec 1999 and 29 Aug 2012
Observation Time: 229 hours 57 min (9 days 13 hours 57 min).
Obs. ID: 316, 962, 2978, 3965, 7797-7799, 7800, 8489, 8490, 10722, 10723, 10724-10726, 11846, 11847, 12155, 12156, 13303, 13304
Instrument: ACIS
Also Known As: Centaurus A, Cen A
References: Irwin, J. et al, 2016, Nature (in press)
Color Code: X-ray (Red, Green, Blue)
Distance Estimate: 12 million light years

Wednesday, October 19, 2016

Highest Resolution Image of Eta Carinae

Detailed look on Eta Carinae

Highest resolution image of Eta Carinae

Digitized Sky Survey Image of Eta Carinae Nebula

The Carina Nebula in the constellation of Carina 

Panoramic view of the WR 22 and Eta Carinae regions of the Carina Nebula*

One Picture, Many Stories

The Carina Nebula imaged by the VLT Survey Telescope 

Eta Carinae 


Zoom on Eta Carinae
Zoom on Eta Carinae

Animation of Eta Carinae and its surrounding
Animation of Eta Carinae and its surrounding

VLT Interferometer captures raging winds in famous massive stellar system

An international team of astronomers have used the Very Large Telescope Interferometer to image the Eta Carinae star system in the greatest detail ever achieved. They found new and unexpected structures within the binary system, including in the area between the two stars where extremely high velocity stellar winds are colliding. These new insights into this enigmatic star system could lead to a better understanding of the evolution of very massive stars.

Led by Gerd Weigelt from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, a team of astronomers have used the Very Large Telescope Interferometer (VLTI) at ESO’s Paranal Observatory to take a unique image of the Eta Carinae star system in the Carina Nebula.

This colossal binary system consists of two massive stars orbiting each other and is very active, producing stellar winds which travel at velocities of up to ten million kilometres per hour [1]. The zone between the two stars where the winds from each collide is very turbulent, but until now it could not be studied.

The power of the Eta Carinae binary pair creates dramatic phenomena. A “Great Eruption” in the system was observed by astronomers in the 1830s. We now know that this was caused by the larger star of the pair expelling huge amounts of gas and dust in a short amount of time, which led to the distinctive lobes, known as the Homunculus Nebula, that we see in the system today. The combined effect of the two stellar winds as they smash into each other at extreme speeds is to create temperatures of millions of degrees and intense deluges of X-ray radiation.

The central area where the winds collide is so comparatively tiny — a thousand times smaller than the Homunculus Nebula — that telescopes in space and on the ground so far have not been able to image them in detail. The team has now utilised the powerful resolving ability of the VLTI instrument AMBER to peer into this violent realm for the first time. A clever combination — an interferometer — of three of the four Auxiliary Telescopes at the VLT lead to a tenfold increase in resolving power in comparison to a single VLT Unit Telescope. This delivered the sharpest ever image of the system and yielded unexpected results about its internal structures.

The new VLTI image clearly depict the structure which exists between the two Eta Carinae-stars. An unexpected fan-shaped structure was observed where the raging wind from the smaller, hotter star crashes into the denser wind from the larger of the pair.

Our dreams came true, because we can now get extremely sharp images in the infrared. The VLTI provides us with a unique opportunity to improve our physical understanding of Eta Carinae and many other key objects”, says Gerd Weigelt.

In addition to the imaging, the spectral observations of the collision zone made it possible to measure the velocities of the intense stellar winds [2]. Using these velocities, the team of astronomers were able to produce more accurate computer models of the internal structure of this fascinating stellar system, which will help increase our understanding of how these kind of extremely high mass stars lose mass as they evolve.

Team member Dieter Schertl (MPIfR) looks forward: “The new VLTI instruments GRAVITY and MATISSE will allow us to get interferometric images with even higher precision and over a wider wavelength range. This wide wavelength range is needed to derive the physical properties of many astronomical objects.


[1] The two stars are so massive and bright that the radiation they produce rips off their surfaces and spews them into space. This expulsion of stellar material is referred to as stellar “wind”, and it can travel at millions of kilometres per hour.

[2] Measurements were done through the Doppler effect. Astronomers use the Doppler effect (or shifts) to calculate precisely how fast stars and other astronomical objects move toward or away from Earth. The movement of an object towards or away from us causes a slight shift in its spectral lines. The velocity of the motion can be calculated from this shift.

 More Information

This research was presented in a paper to appear in Astronomy and Astrophysics.

The team is composed of G. Weigelt (Max Planck Institute for Radio Astronomy, Germany), K.-H. Hofmann (Max Planck Institute for Radio Astronomy, Germany), D. Schertl (Max Planck Institute for Radio Astronomy, Germany), N. Clementel (South African Astronomical Observatory, South Africa) , M.F. Corcoran (Goddard Space Flight Center, USA; Universities Space Research Association, USA), A. Damineli (Universidade de São Paulo, Brazil ), W.-J. de Wit (European Southern Observatory, Chile), R. Grellmann (Universität zu Köln, Germany), J. Groh (The University of Dublin, Ireland ), S. Guieu (European Southern Observatory, Chile), T. Gull (Goddard Space Flight Center, USA), M. Heininger (Max Planck Institute for Radio Astronomy, Germany) , D.J. Hillier (University of Pittsburgh, USA), C.A. Hummel (European Southern Observatory, Germany), S. Kraus (University of Exeter, UK), T. Madura (Goddard Space Flight Center, USA), A. Mehner (European Southern Observatory, Chile), A. Mérand ( European Southern Observatory, Chile), F. Millour (Université de Nice Sophia Antipolis, France), A.F.J. Moffat (Université de Montréal, Canada), K. Ohnaka (Universidad Católica del Norte, Chile), F. Patru (Osservatorio Astrofisico di Arcetri, Italy), R.G. Petrov (Université de Nice Sophia Antipolis, France), S. Rengaswamy (Indian Institute of Astrophysics, India) , N.D. Richardson (The University of Toledo, USA), T. Rivinius (European Southern Observatory, Chile), M. Schöller (European Southern Observatory, Germany), M. Teodoro (Goddard Space Flight Center, USA) , and M. Wittkowski (European Southern Observatory, Germany)

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”.



Gerd Weigelt
Max-Planck-Institut für Radioastronomie
Bonn, Germany
Tel: +49 228 525 243

Dieter Schertl
Max-Planck-Institut für Radioastronomie
Bonn, Germany
Tel: +49 228 525 301

Norbert Junkes
Public Information Officer, Max-Planck-Institut für Radioastronomie
Bonn, Germany
Tel: +49 228 525 399

Mathias Jäger
Public Information Officer
Garching bei München, Germany
Tel: +49 176 62397500

Source: ESO

Cloudy Nights, Sunny Days on Distant Hot Jupiters

This illustration represents how hot Jupiters of different temperatures and different cloud compositions might appear to a person flying over the dayside of these planets on a spaceship, based on computer modeling. Credits: NASA/JPL-Caltech/University of Arizona/V. Parmentier. Full image and caption

The weather forecast for faraway, blistering planets called "hot Jupiters" might go something like this: Cloudy nights and sunny days, with a high of 2,400 degrees Fahrenheit (about 1,300 degrees Celsius, or 1,600 Kelvin).

These mysterious worlds are too far away for us to see clouds in their atmospheres. But a recent study using NASA's Kepler space telescope and computer modeling techniques finds clues to where such clouds might gather and what they're likely made of. The study was published in the Astrophysical Journal and is also available on the arXiv.

Hot Jupiters, among the first of the thousands of exoplanets (planets outside our solar system) discovered in our galaxy so far, orbit their stars so tightly that they are perpetually charbroiled. And while that might discourage galactic vacationers, the study represents a significant advance in understanding the structure of alien atmospheres.

Endless days, endless nights

Hot Jupiters are tidally locked, meaning one side of the planet always faces its sun and the other is in permanent darkness. In most cases, the "dayside" would be largely cloud-free and the "nightside" heavily clouded, leaving partly cloudy skies for the zone in between, the study shows.

"The cloud formation is very different from what we know in the solar system," said Vivien Parmentier, a NASA Sagan Fellow and postdoctoral researcher at the University of Arizona, Tucson, who was the lead author of the study.

A "year" on such a planet can be only a few Earth days long, the time the planet takes to whip once around its star. On a "cooler" hot Jupiter, temperatures of, say, 2,400 degrees Fahrenheit might prevail.

But the extreme conditions on hot Jupiters worked to the scientists’ advantage.

"The day-night radiation contrast is, in fact, easy to model," Parmentier said. “[The hot Jupiters] are much easier to model than Jupiter itself."

An eclipse, then blips

The scientists first created a variety of idealized hot Jupiters using global circulation models -- simpler versions of the type of computer models used to simulate Earth’s climate.

Then they compared the models to the light Kepler detected from real hot Jupiters. Kepler, which is now operating in its K2 mission, was designed to register the extremely tiny dip in starlight when a planet passes in front of its star, which is called a "transit." But in this case, researchers focused on the planets' "phase curves," or changes in light as the planet passes through phases, like Earth’s moon.

Matching the modeled hot Jupiters to phase curves from real hot Jupiters revealed which curves were caused by the planet’s heat, and which by light reflected by clouds in its atmosphere. By combining Kepler data with computer models, scientists were able to infer global cloud patterns on these distant worlds for the first time.

The new cloud view allowed the team to draw conclusions about wind and temperature differences on the hot Jupiters they studied. Just before the hotter planets passed behind their stars -- in a kind of eclipse -- a blip in the planet’s optical light curve revealed a "hot spot" on the planet’s eastern side.

And on cooler eclipsing planets, a blip was seen just after the planet re-emerged on the other side of the star, this time on the planet’s western side.

The early blip on hotter worlds reveals that powerful winds were pushing the hottest, cloud-free part of the atmosphere, normally found directly beneath its sun, to the east. Meanwhile, on cooler worlds, clouds could bunch up and reflect more light on the "colder," western side of the planet, causing the post-eclipse blip.

"We’re claiming that the west side of the planet’s dayside is more cloudy than the east side," Parmentier said.

While the puzzling pattern has been seen before, this research was the first to study all the hot Jupiters showing this behavior.

This led to another first. By figuring out how clouds are distributed, which is intimately tied to the planet’s overall temperature, scientists were able to determine what the clouds were probably made of.

Just add manganese, and stir

Hot Jupiters are far too hot for water-vapor clouds like those on Earth. Instead, clouds on these planets are likely formed as exotic vapors condense to form minerals, chemical compounds like aluminum oxide, or even metals, like iron.

The science team found that manganese sulfide clouds probably dominate on "cooler" hot Jupiters, while silicate clouds prevail at higher temperatures. On these planets, the silicates likely "rain out" into the planet’s interior, vanishing from the observable atmosphere.

In other words, a planet’s average temperature, which depends on its distance from its star, governs the kinds of clouds that can form. That leads to different planets forming different types of clouds.

"Cloud composition changes with planet temperature," Parmentier said. "The offsetting light curves tell the tale of cloud composition. It’s super interesting, because cloud composition is very hard to get otherwise."

The new results also show that clouds are not evenly distributed on hot Jupiters, echoing previous findings from NASA’s Spitzer Space Telescope suggesting that different parts of hot Jupiters have vastly different temperatures.

The new findings come as we mark the 21st anniversary of exoplanet hunting. On Oct. 6, 1995, a Swiss team announced the discovery of 51 Pegasi b, a hot Jupiter that was the first planet to be confirmed in orbit around a sun-like star. Parmentier and his team hope their revelations about the clouds on hot Jupiters could bring more detailed understanding of hot Jupiter atmospheres and their chemistry, a major goal of exoplanet atmospheric studies.

NASA Ames manages the Kepler and K2 missions for NASA's Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corporation operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado at Boulder. This work was performed in part under contract with JPL, funded by NASA through the Sagan Fellowship Program, executed by the NASA Exoplanet Science Institute.

For more information on the Kepler and the K2 mission, visit:

For more information about exoplanets, visit:

Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.

Michele Johnson
Ames Research Center, Moffett Field, Calif.

Written by Pat Brennan

Tuesday, October 18, 2016

Recently active lava flows on the eastern flank of Idunn Mons on Venus

Figure 1 – The figure displays an elevation model of Idunn Mons (46 S; 146 W), a volcano with a diameter of 200 km located at Imdr Regio on Venus. NASA/JPL-Caltech/ESA

Figure 2 – The figure displays an elevation model of Idunn Mons (46S; 146 W), overlain on VIRTIS emissivity anomaly. In red, the areas characterized by recent volcanic activity. NASA/JPL-Caltech/ESA

Figure 3 – Geologic map of the eastern flank of Idunn Mons (46 S; 146 W), displaying the five lava flow units (lfu) identified during the mapping process. Lfu are classified from a to e. Lfu-a represents the summit composite unit of Idunn Mons, while the lfu-b, lfu-c, lfu-d and lfu-e are flank units of the volcanic edifice. ESA/DLR

Press release issued by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR) and the joint 48th annual meeting of the Division for Planetary Sciences (DPS) of the American Astronomical Society (AAS) and 11th annual European Planetary Science Congress (EPSC).

The European Space Agency’s Venus Express mission has provided a great amount of data from the surface and atmosphere of Earth’s inner twin planet. Among these observations was the mapping of the southern hemisphere of Venus in the near infrared spectral range using the VIRTIS (Visible and InfraRed Thermal Imaging Spectrometer) instrument. However the thick and permanent cloud cover of Venus limits the achievable resolution, similar to observing a scene through fog. Using a numerical model, planetary researchers at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR) pushed the limits of the data resolution. With this new technique the emissivity anomalies were analyzed on the top and eastern flank of Idunn Mons, a volcano with a diameter of 200 kilometers at its base situated in the southern hemisphere of Venus. These anomalies provide an indication of geologically recent volcanism in this area.

“We could identify and map distinctive lava flows from the top and eastern flank of the volcano, which might have been recently active in terms of geologic time,” says Piero D’Incecco, planetary researcher at the DLR who is presenting these results today at the joint 48th meeting of the American Astronomical Society’s Division for Planetary Sciences (DPS) and 11th European Planetary Science Congress in Pasadena, California.

“With our new technique we could combine the infrared data with much higher-resolution radar images from the NASA Magellan mission, having been in orbit about Venus from 1990 until 1992. It is the first time that — combining the datasets from two different missions — we can perform a high resolution geologic mapping of a recently active volcanic structure from the surface of a planet other than Earth.” This study will also provide motivation for future projects focused on the exploration of Venus, as for example the NASA Discovery VERITAS mission proposal or the ESA EnVision M5 mission proposal that — in combining high-resolution radar and near-infrared mapping — will extend the frontiers of our current knowledge of the geology of Venus.

Search for Location and Extent of the Lava Flows

From 2006 until 2014 the ESA Venus Express probe was analyzing the atmosphere and surface of Earth’s twin planet. The Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS) has provided data that indicate the occurrence of recent volcanic activity on Venus. DLR scientists Piero D’Incecco, Nils Mueller, Joern Helbert and Mario D’Amore selected the eastern flank of Idunn Mons — Imdr Regio’s single large volcano — as the study area, since it was identified in VIRTIS data as one of the regions with relatively high values of thermal emissivity at 1 micron wavelength.

Using the capabilities of specific techniques developed in the Planetary Spectroscopy Laboratory group at DLR in Berlin, the study intends to identify location and extent of the sources of such anomalies, thus the lava flows responsible for the relatively high emissivity observed by VIRTIS over the eastern flank of Idunn Mons. Therefore the lava flow units on the top and eastern flank of Idunn Mons are mapped, varying the values of simulated 1 micron emissivity assigned to the mapped units. For each configuration the total mismatch as root mean square error in comparison with the VIRTIS observations is calculated. In the best-fit configuration, the flank lava flows are characterized by high values of 1 micron simulated emissivity. Hence, the lava flow units on the eastern flank on Idunn Mons are likely responsible for the relatively high 1 micron emissivity anomalies observed by VIRTIS. This result is supported by the reconstructed post-eruption stratigraphy, displaying the relative dating of the mapped lava flows, that is independent of the 1 micron emissivity modeling. Values of average microwave emissivity extracted from the lava flow units range around the global mean, which is consistent with dry basalts.

Press Contacts:

Manuela Braun
German Aerospace Center (DLR)
Corporate Communications, Editor, Human Space Flight, Space Science, Engineering
+49 2203 601-3882

Anita Heward
European Planetary Science Congress (EPSC) Press Officer
+44 (0)77 5603 4243

Science Contact:

Dr. Jörn Helbert
German Aerospace Center (DLR)
Institute of Planetary Research, Co-Investigator VIRTIS Venus Express
+49 30 67055-319

Further information:

The joint 48th meeting of the Division for Planetary Sciences (DPS) and 11th European Planetary Science Congress (EPSC) in Pasadena, California, is second time DPS and EPSC have been joined into one meeting. The goal of the joint meeting is to strengthen international scientific collaboration in all areas of planetary science. This is the first time that EPSC, which provides the dissemination platform for the Europlanet 2020 Research Infrastructure, is held outside Europe. Follow: #dpsepsc, @DPSMeeting, @europlanetmedia, and @AAS_Press on Twitter.

Source: EuroPlanet

Monday, October 17, 2016

Discovering the Treasures in Chandra’s Archives

Each year, NASA’s Chandra X-ray Observatory helps celebrate American Archive Month by releasing a collection of images using X-ray data in its archive.

The Chandra Data Archive is a sophisticated digital system that ultimately contains all of the data obtained by the telescope since its launch into space in 1999. Chandra’s archive is a resource that makes these data available to the scientific community and the general public for years after they were originally obtained.

Each of these six new images also includes data from telescopes covering other parts of the electromagnetic spectrum, such as visible and infrared light. This collection of images represents just a small fraction of the treasures that reside in Chandra’s unique X-ray archive.
From left to right, starting on the top row, the objects are:

 Westerlund 2, 3C31, PSR J1509-5850, Abell 665, RX J0603.3+4214 and CTB 37A

Westerlund 2: A cluster of young stars – about one to two million years old – located about 20,000 light years from Earth.  Data in visible light from the Hubble Space Telescope (green and blue) reveal thick clouds where the stars are forming. High-energy radiation in the form of X-rays, however, can penetrate this cosmic haze, and are detected by Chandra (purple).

3C31: X-rays from the radio galaxy 3C31 (blue), located 240 million light years from Earth, allow astronomers to probe the density, temperature, and pressure of this galaxy, long known to be a powerful emitter of radio waves. The Chandra data also reveal a jet blasting away from one side of the central galaxy, which also is known as NGC 383.  Here, the Chandra X-ray image has been combined with Hubble’s visible light data (yellow).

PSR J1509-5850: Pulsars were first discovered in 1967 and today astronomers know of over a thousand such objects. The pulsar, PSR J1509-5850, located about 12,000 light years from Earth and appearing as the bright white spot in the center of this image, has generated a long tail of X-ray emission trailing behind it, as seen in the lower part of the image. This pulsar has also generated an outflow of particles in approximately the opposite direction. In this image, X-rays detected by Chandra (blue) and radio emission (pink) have been overlaid on a visible light image from the Digitized Sky Survey of the field of view.

Abell 665: Merging galaxy clusters can generate enormous shock waves, similar to cold fronts in weather on Earth. This system, known as Abell 665, has an extremely powerful shockwave, second only to the famous Bullet Cluster. Here, X-rays from Chandra (blue) show hot gas in the cluster. The bow wave shape of the shock is shown by the large white region near the center of the image. The Chandra image has been added to radio emission (purple) and visible light data from the Sloan Digital Sky Survey showing galaxies and stars (white).

RX J0603.3+4214: The phenomenon of pareidolia is when people see familiar shapes in images. This galaxy cluster has invoked the nickname of the “Toothbrush Cluster” because of its resemblance to the dental tool. In fact, the stem of the brush is due to radio waves (green) while the diffuse emission where the toothpaste would go is produced by X-rays observed by Chandra (purple). Visible light data from the Subaru telescope show galaxies and stars (white) and a map from gravitational lensing (blue) shows the concentration of the mass, which is mostly (about 80%) dark matter.

CTB 37A: Astronomers estimate that a supernova explosion should occur about every 50 years on average in the Milky Way galaxy. The object known as CTB 37A is a supernova remnant located in our Galaxy about 20,000 light years from Earth. This image shows that the debris field glowing in X-rays (blue) and radio waves (pink) may be expanding into a cooler cloud of gas and dust seen in infrared light (orange).

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. 

Read More from NASA's Chandra X-ray Observatory.

For more Chandra images, multimedia and related materials, visit:

Molly Porter
Marshall Space Flight Center, Huntsville, Ala.

Megan Watzke
Chandra X-ray Center, Cambridge, Mass.

Editor: Lee Mohon

Sunday, October 16, 2016

Cluster’s Advanced Age in Razor-sharp Focus

Gemini Observatory GeMS image of NGC 6624 revealing individual stars to the cluster’s core. The Cluster’s age as determined with this study is between 11.5-12.5 billion years old, which confirms that it formed when the Universe was only a fraction of its current age of about 13.8 billion years. Composite color image by Travis Rector, University of Alaska Anchorage. Image Credit: Gemini Observatory/AURA.  Full resolution JPEG | TIFF 

The color-magnitude diagrams of NGC6624 obtained from the Gemini observations. All the main evolutionary sequences of the cluster are easily visible. These NIR diagrams turn out to be comparable to the HST optical ones, both in depth and in photometric accuracy. The photometric errors for each bin of Ks and J magnitudes are shown on the right side of the panels.

An international team of astronomers, using the Gemini Multi-conjugate adaptive optics System (GeMS) and the high resolution camera GSAOI, brought the ancient globular cluster NGC 6624 into razor-sharp focus and determined its age with very high accuracy - a challenging observation even from space. In addition to producing a beautiful image, this work ultimately helps astronomers to better understand the formation and evolution of our Galaxy during its earliest development when the Universe was less than two billion years old. 
Researchers using advanced adaptive optics technology at the Gemini South telescope in Chile probed the depths of the highly compact globular cluster NGC 6624, revealing pinpoint images of thousands of stars. The sharpness of the near-infrared images is competitive with that obtained from space with the Hubble Space Telescope in optical light. “With images this sharp, astronomers can do things that we never dreamed were possible from the ground,” says team member Douglas Geisler of the University of Concepción in Chile.

The team obtained the imaging data using two filters that are sensitive to specific wavelength bands of near-infrared light, then plotted them on a color-magnitude diagram – a technique that reveals details about the evolutionary history of the cluster’s stars. According to first author Sara Saracino from the University of Bologna, this is the most accurate, and deepest, near-infrared color-magnitude diagram ever produced of this cluster and indeed perhaps the best-ever made for any bulge cluster. The results of this research will be published in The Astrophysical Journal. A preprint of the paper can be found here.

The observations provide a clear detection of the so-called “main-sequence knee,” a distinctive bend in the evolutionary track of low mass main-sequence stars (those that burn hydrogen into helium at their cores). This feature is extremely faint and therefore difficult to detect, requiring very precise photometry (measuring the brightness of individual stars). Photometry is generally a problem with most adaptive optics data.

This is the first time the main-sequence knee has been identified in this globular cluster. “Analysis of these razor-sharp images, and the very deep color-magnitude diagram, allows us to determine the age of the cluster to extremely high precision,” says Saracino. In turn, this helps to better understand the formation and evolution of our Milky Way bulge, which may well be the oldest component of the Galaxy. The new Gemini data reveal that the age of NGC 6624 is between 11.5-12.5 billion years old, almost as old as the Universe itself - estimated to be about 13.8 billion years old.

NGC 6624 is also interesting because it has been classified as what astronomers call a post-core collapse cluster, meaning that this is a highly evolved system. The high quality of the data also allowed the researchers to perform a detailed study of the distribution of main-sequence stars of different masses outward from the center. As expected for such a highly evolved system, the team found evidence of a significant increase in low-mass stars at increasing distances from the cluster center.

This study is part of a much larger research program aimed at shedding new light on the still debated processes that formed the Milky Way’s bulge using its globular cluster population. Due to the large amount of absorption by material between the stars in the Milky Way Galaxy, detailed studies of bulge globular clusters have been severely hampered until now. Geisler notes that the advent of the GeMS instrument now allows astronomers to penetrate the dust and study these clusters in the great detail they deserve. “It will certainly continue to provide us with very important clues about how our Galaxy formed and evolved,” he says.

The Gemini Multi-conjugate adaptive optics System (GeMS), combined with the Gemini South Adaptive Optics Imager (GSAOI), delivers near diffraction-limited images of near-infrared light (0.9-2.5 microns), over a field nearly as large as the Hubble Space Telescope’s Wide Field Camera 3 (WFC3). Using five artificial laser guide stars, and up to three natural guide stars, GeMS/GSAOI can correct for atmospheric turbulence at an unprecedented level, making it the most powerful wide-field adaptive optics system currently available to astronomers.

Science Contacts:

Sara Saracino
Department of Physics and Astronomy
University of Bologna, Italy
Office: +39 051 2095788
Cell: +39 3201607913

Douglas Geisler
Departamento de Astronomia
Universidad de Concepción, Chile
Office: 56-41-2203092
Cell: 56-9-93078848

Media Contacts:

Peter Michaud
Gemini Observatory
Hilo, Hawai‘i
Cell: (808) 936-6643

Manuel Paredes
Gemini Observatory<
br /> La Serena, Chile 
Phone: +56 (51) 2205671

Saturday, October 15, 2016

Hubble Reveals Observable Universe Contains 10 Times More Galaxies Than Previously Thought

Credit: NASA, ESA, the GOODS Team, and M. Giavialisco (University of Massachusetts, Amherst)

The universe suddenly looks a lot more crowded, thanks to a deep-sky census assembled from surveys taken by NASA's Hubble Space Telescope and other observatories.

Astronomers came to the surprising conclusion that there are at least 10 times more galaxies in the observable universe than previously thought.

The results have clear implications for galaxy formation, and also helps shed light on an ancient astronomical paradox — why is the sky dark at night?

In analyzing the data, a team led by Christopher Conselice of the University of Nottingham, U.K., found that 10 times as many galaxies were packed into a given volume of space in the early universe than found today. Most of these galaxies were relatively small and faint, with masses similar to those of the satellite galaxies surrounding the Milky Way. As they merged to form larger galaxies the population density of galaxies in space dwindled. This means that galaxies are not evenly distributed throughout the universe's history, the research team reports in a paper to be published in The Astrophysical Journal.

"These results are powerful evidence that a significant galaxy evolution has taken place throughout the universe's history, which dramatically reduced the number of galaxies through mergers between them — thus reducing their total number. This gives us a verification of the so-called top-down formation of structure in the universe," explained Conselice.

One of the most fundamental questions in astronomy is that of just how many galaxies the universe contains. The landmark Hubble Deep Field, taken in the mid-1990s, gave the first real insight into the universe's galaxy population. Subsequent sensitive observations such as Hubble's Ultra Deep Field revealed a myriad of faint galaxies. This led to an estimate that the observable universe contained about 100 billion galaxies. The new research shows that this estimate is at least 10 times too low.

Conselice and his team reached this conclusion using deep-space images from Hubble and the already published data from other teams. They painstakingly converted the images into 3-D, in order to make accurate measurements of the number of galaxies at different epochs in the universe's history. In addition, they used new mathematical models, which allowed them to infer the existence of galaxies that the current generation of telescopes cannot observe. This led to the surprising conclusion that in order for the numbers of galaxies we now see and their masses to add up, there must be a further 90 percent of galaxies in the observable universe that are too faint and too far away to be seen with present-day telescopes. These myriad small faint galaxies from the early universe merged over time into the larger galaxies we can now observe.

"It boggles the mind that over 90 percent of the galaxies in the universe have yet to be studied. Who knows what interesting properties we will find when we discover these galaxies with future generations of telescopes? In the near future, the James Webb Space Telescope will be able to study these ultra-faint galaxies," said Conselice.

The decreasing number of galaxies as time progresses also contributes to the solution for Olbers' paradox (first formulated in the early 1800s by German astronomer Heinrich Wilhelm Olbers): Why is the sky dark at night if the universe contains an infinity of stars? The team came to the conclusion that indeed there actually is such an abundance of galaxies that, in principle, every patch in the sky contains part of a galaxy. However, starlight from the galaxies is invisible to the human eye and most modern telescopes due to the other known factors that reduce visible and ultraviolet light in the universe. Those factors are the reddening of light due to the expansion of space, the universe's dynamic nature, and the absorption of light by intergalactic dust and gas. All combined, this keeps the night sky dark to our vision.

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


Ray Villard
Space Telescope Science Institute, Baltimore, Maryland

Mathias Jäger
ESA/Hubble, Garching, Germany

Christopher Conselice
University of Nottingham, Nottingham, United Kingdom

Source: HubbleSite

Friday, October 14, 2016

Cassiopeia’s unusual resident

Credit:ESA/Hubble & NASA and S. Smartt (Queen's University Belfast) 

This image, taken by the NASA/ESA Hubble Space Telescope’s Wide Field Planetary Camera 2, shows a spiral galaxy named NGC 278. This cosmic beauty lies some 38 million light-years away in the northern constellation of Cassiopeia (The Seated Queen).

While NGC 278 may look serene, it is anything but. The galaxy is currently undergoing an immense burst of star formation. This flurry of activity is shown by the unmistakable blue-hued knots speckling the galaxy’s spiral arms, each of which marks a clump of hot newborn stars.

However, NGC 278’s star formation is somewhat unusual; it does not extend to the galaxy’s outer edges, but is only taking place within an inner ring some 6500 light-years across. This two-tiered structure is visible in this image — while the galaxy’s centre is bright, its extremities are much darker. This odd configuration is thought to have been caused by a merger with a smaller, gas-rich galaxy — while the turbulent event ignited the centre of NGC 278, the dusty remains of the small snack then dispersed into the galaxy’s outer regions. Whatever the cause, such a ring of star formation, called a nuclear ring, is extremely unusual in galaxies without a bar at their centre, making NGC 278 a very intriguing sight.

Source: ESA/Images

Thursday, October 13, 2016

Building Blocks of Life's Building Blocks Come From Starlight

The dusty side of the Sword of Orion is illuminated in this striking infrared image from ESA's Hershel Space Observatory. Within the inset image, the emission from ionized carbon atoms (C+) is overlaid in yellow. Credit: ESA/NASA/JPL-Caltech.  › Full image and caption

Life exists in a myriad of wondrous forms, but if you break any organism down to its most basic parts, it's all the same stuff: carbon atoms connected to hydrogen, oxygen, nitrogen and other elements. But how these fundamental substances are created in space has been a longstanding mystery.

Now, astronomers better understand how molecules form that are necessary for building other chemicals essential for life. Thanks to data from the European Space Agency's Herschel Space Observatory, scientists have found that ultraviolet light from stars plays a key role in creating these molecules, rather than "shock" events that create turbulence, as was previously thought.

Scientists studied the ingredients of carbon chemistry in the Orion Nebula, the closest star-forming region to Earth that forms massive stars. They mapped the amount, temperature and motions of the carbon-hydrogen molecule (CH, or "methylidyne" to chemists), the carbon-hydrogen positive ion (CH+) and their parent: the carbon ion (C+). An ion is an atom or molecule with an imbalance of protons and electrons, resulting in a net charge.

"On Earth, the sun is the driving source of almost all the life on Earth. Now, we have learned that starlight drives the formation of chemicals that are precursors to chemicals that we need to make life," said Patrick Morris, first author of the paper and researcher at the Infrared Processing and Analysis Center at Caltech in Pasadena.

In the early 1940s, CH and CH+ were two of the first three molecules ever discovered in interstellar space. In examining molecular clouds -- assemblies of gas and dust -- in Orion with Herschel, scientists were surprised to find that CH+ is emitting rather than absorbing light, meaning it is warmer than the background gas. The CH+ molecule needs a lot of energy to form and is extremely reactive, so it gets destroyed when it interacts with the background hydrogen in the cloud. Its warm temperature and high abundance are therefore quite mysterious.

Why, then, is there so much CH+ in molecular clouds such as the Orion Nebula? Many studies have tried to answer this question before, but their observations were limited because few background stars were available for studying. Herschel probes an area of the electromagnetic spectrum -- the far infrared, associated with cold objects -- that no other space telescope has reached before, so it could take into account the entire Orion Nebula instead of individual stars within. The instrument they used to obtain their data, HIFI, is also extremely sensitive to the motion of the gas clouds.

One of the leading theories about the origins of basic hydrocarbons has been that they formed in "shocks," events that create a lot of turbulence, such as exploding supernovae or young stars spitting out material. Areas of molecular clouds that have a lot of turbulence generally create shocks. Like a large wave hitting a boat, shock waves cause vibrations in material they encounter. Those vibrations can knock electrons off atoms, making them ions, which are more likely to combine. But the new study found no correlation between these shocks and CH+ in the Orion Nebula.

Herschel data show that these CH+ molecules were more likely created by the ultraviolet emission of very young stars in the Orion Nebula, which, compared to the sun, are hotter, far more massive and emit much more ultraviolet light. When a molecule absorbs a photon of light, it becomes "excited" and has more energy to react with other particles. In the case of a hydrogen molecule, the hydrogen molecule vibrates, rotates faster or both when hit by an ultraviolet photon.
It has long been known that the Orion Nebula has a lot of hydrogen gas. When ultraviolet light from large stars heats up the surrounding hydrogen molecules, this creates prime conditions for forming hydrocarbons. As the interstellar hydrogen gets warmer, carbon ions that originally formed in stars begin to react with the molecular hydrogen, creating CH+. Eventually the CH+ captures an electron to form the neutral CH molecule.

"This is the initiation of the whole carbon chemistry," said John Pearson, researcher at NASA's Jet Propulsion Laboratory, Pasadena, California, and study co-author. "If you want to form anything more complicated, it goes through that pathway."

Scientists combined Herschel data with models of molecular formation and found that ultraviolet light is the best explanation for how hydrocarbons form in the Orion Nebula.

The findings have implications for the formation of basic hydrocarbons in other galaxies as well. It is known that other galaxies have shocks, but dense regions in which ultraviolet light dominates heating and chemistry may play the key role in creating fundamental hydrocarbon molecules there, too. 

"It's still a mystery how certain molecules get excited in the cores of galaxies," Pearson said. "Our study is a clue that ultraviolet light from massive stars could be driving the excitation of molecules there, too."

Herschel is a European Space Agency mission, with science instruments provided by consortia of European institutes and with important participation by NASA. While the observatory stopped making science observations in April 2013, after running out of liquid coolant as expected, scientists continue to analyze its data. NASA's Herschel Project Office is based at NASA's Jet Propulsion Laboratory, Pasadena, California. JPL contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of IPAC, supports the U.S. astronomical community. Caltech manages JPL for NASA.

More information about Herschel is available at:

News Media Contact

Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.

Source: JPL-Caltech

Wednesday, October 12, 2016

The Milky Way’s Ancient Heart

Variable stars close to the galactic centre

RR Lyrae stars in the constellation of Sagittarius

Wide-field view of the Centre of the Milky Way

Variable RR Lyrae stars
PR Video eso1636a
Variable RR Lyrae stars 

Zoom on the galactic centre
PR Video eso1636b
Zoom on the galactic centre 

Pan across the galactic centre
Pan across the galactic centre

VISTA finds remains of archaic globular star cluster

Ancient stars, of a type known as RR Lyrae, have been discovered in the centre of the Milky Way for the first time, using ESO’s infrared VISTA telescope. RR Lyrae stars typically reside in ancient stellar populations over 10 billion years old. Their discovery suggests that the bulging centre of the Milky Way likely grew through the merging of primordial star clusters. These stars may even be the remains of the most massive and oldest surviving star cluster of the entire Milky Way.

A team led by Dante Minniti (Universidad Andrés Bello, Santiago, Chile) and Rodrigo Contreras Ramos (Instituto Milenio de Astrofísica, Santiago, Chile) used observations from the VISTA infrared survey telescope, as part of the Variables in the Via Lactea (VVV) ESO public survey, to carefully search the central part of the Milky Way. By observing infrared light, which is less affected by cosmic dust than visible light, and exploiting the excellent conditions at ESO’s Paranal Observatory, the team was able to get a clearer view of this region than ever before. They found a dozen ancient RR Lyrae stars at the heart of the Milky Way that were previously unknown.

Our Milky Way has a densely populated centre — a feature common to many galaxies, but unique in that it is close enough to study in depth. This discovery of RR Lyrae stars provides compelling evidence that helps astronomers decide between two main competing theories for how nuclear bulges form [1].

RR Lyrae stars are typically found in dense globular clusters. They are variable stars, and the brightness of each RR Lyrae star fluctuates regularly. By observing the length of each cycle of brightening and dimming in an RR Lyrae, and also measuring the star’s brightness, astronomers can calculate its distance [2].

Unfortunately, these excellent distance-indicator stars are frequently outshone by younger, brighter stars and in some regions they are hidden by dust. Therefore, locating RR Lyrae stars right in the extremely crowded heart of the Milky Way was not possible until the public VVV survey was carried out using infrared light. Even so, the team described the task of locating the RR Lyrae stars in amongst the crowded throng of brighter stars as “daunting”.

Their hard work was rewarded, however, with the identification of a dozen RR Lyrae stars. Their discovery indicate that remnants of ancient globular clusters are scattered within the centre of the Milky Way’s bulge.

Rodrigo Contreras Ramos elaborates: “This discovery of RR Lyrae Stars in the centre of the Milky Way has important implications for the formation of galactic nuclei. The evidence supports the scenario in which the nuclear bulge was originally made out of a few globular clusters that merged.”

The theory that galactic nuclear bulges form through the merging of globular clusters is contested by the competing hypothesis that these bulges are actually due to the rapid accretion of gas. The unearthing of these RR Lyrae stars — almost always found in globular clusters — is very strong evidence that part of the Milky Way's nuclear bulge did in fact form through merging. By extension, all other similar galactic bulges may have formed the same way.

Not only are these stars powerful evidence for an important theory of galactic evolution, they are also likely to be over 10 billion years old — the dim, but dogged survivors of perhaps the oldest and most massive star cluster within the Milky Way.


[1] The nuclear stellar bulge is the compact component in the innermost regions of the Milky Way (and other galaxies) extending to a size of about 400 light-years.

[2] RR Lyrae stars, like some other regular variables such as Cepheids, show a simple relationship between how quickly they change in brightness and how luminous they are. Longer periods mean brighter stars. This period-luminosity relationship can be used to deduce the distance of a star from its period of variation and its apparent brightness.

More Information

This research was presented in a paper to appear in The Astrophysical Journal Letters.

The team is composed of D. Minniti (Instituto Milenio de Astrofísica, Santiago, Chile; Departamento de Física, Universidad Andrés Bello, Santiago, Chile; Vatican Observatory, Vatican City State; Centro de Astrofisica y Tecnologias Afines - CATA), R. Contreras Ramos (Instituto Milenio de Astrofísica, Santiago, Chile;  Pontificia Universidad Católica de Chile, Instituto de Astrofísica, Santiago, Chile), M. Zoccali (Instituto Milenio de Astrofísica, Santiago, Chile; Pontificia Universidad Católica de Chile, Instituto de Astrofísica, Santiago, Chile), M. Rejkuba (European Southern Observatory, Garching bei München, Germany; Excellence Cluster Universe, Garching, Germany), O.A. Gonzalez (UK Astronomy Technology Centre, Royal Observatory, Edinburgh, UK), E. Valenti (European Southern Observatory, Garching bei München, Germany), F. Gran (Instituto Milenio de Astrofísica, Santiago, Chile;  Pontificia Universidad Católica de Chile, Instituto de Astrofísica, Santiago, Chile)

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”.



Dante Minniti
Universidad Andrés Bello
Santiago, Chile

Rodrigo Contreras Ramos
Instituto Milenio de Astrofísica
Santiago, Chile

Mathias Jäger
Public Information Officer
Garching bei München, Germany
Cell: +49 176 62397500

Source: ESO