Wednesday, August 31, 2016

NASA Team Probes Peculiar Age-Defying Star

An age-defying star designated as IRAS 19312+1950 (arrow) exhibits features characteristic of a very young star and a very old star. The object stands out as extremely bright inside a large, chemically rich cloud of material, as shown in this image from NASA’s Spitzer Space Telescope. A NASA-led team of scientists thinks the star – which is about 10 times as massive as our sun and emits about 20,000 times as much energy – is a newly forming protostar. That was a big surprise because the region had not been known as a stellar nursery before. But the presence of a nearby interstellar bubble, which indicates the presence of a recently formed massive star, also supports this idea. Credits: NASA/JPL-Caltech. For an unannotated version of this image, click here.

CL J1001: Record-breaking Galaxy Cluster Discovered

CL J1001+0220
Credit: X-ray: NASA/CXC/Université Paris/T.Wang et al; 


This image contains the most distant galaxy cluster, a discovery made using data from NASA's Chandra X-ray Observatory and several other telescopes. The galaxy cluster, known as CL J1001+0220, is located about 11.1 billion light years from Earth and may have been caught right after birth, a brief, but important stage of cluster evolution never seen before.

The remote galaxy cluster was found in data from the COSMOS survey, a project that observes the same patch of sky in many different kinds of light ranging from radio waves to X-rays. This composite shows CL J1001+0220 (CL J1001, for short) in X-rays from Chandra (purple), infrared data from ESO's UltraVISTA survey (red, green, and blue), and radio waves from the Atacama Large Millimeter/submillimeter Array (ALMA) (green). The diffuse X-ray emission comes from a large amount of hot gas, one of the defining elements of a galaxy cluster, as described in the press release.

In addition to its extraordinary distance, CL J1001 is remarkable because of its high levels of star formation in galaxies near the center of the cluster. Within about 250,000 light years of the center of the cluster (its core), eleven massive galaxies are found and nine of those display high rates of formation. Specifically, stars are forming in the cluster core at a rate equivalent to about 3,400 Suns per year.

The large amount of growth through star formation in the galaxies in CL J1001 distinguishes it from other galaxy clusters found at distances of about 10 billion light years and closer, where little growth is occurring. These results suggest that elliptical galaxies in clusters may form their stars through more violent and shorter bursts of star formation than elliptical galaxies outside clusters.

The latest study shows that CL 1001 galaxy cluster may be undergoing a transformation from a galaxy cluster that is still forming, known as a "protocluster," to a mature one. Astronomers have never found a galaxy cluster at this precise stage. These results may also imply that star formation slows down in large galaxies within clusters after the galaxies have already come together during the development of a galaxy cluster.

A paper describing these results appeared in The Astrophysical Journal on August 30, 2016 and is available online. The authors were Tao Wang (French Alternative Energies and Atomic Energy Commission, or CEA), David Elbaz (CEA), Emanuele Daddi (CEA), Alexis Finoguenov (University of Helsinki), Daizhong Liu (Purple Mountain Observatory, China), Veronica Strazzullo (Ludwig Maximillian University of Munich), Francesco Valentino (CEA), Remco van der Burg (CEA), Anita Zanella (CEA), Laure Ciesla (CEA), Raphael Gobat (Korean Institute for Advanced Study), Amandine Le Brun (CEA), Maurillio Pannella (Ludwig Maximillian University), Mark Sargent (University of Sussex), Xinwen Shu (Anhui Normal University), Qinghua Tan (University of Helsinki), Nico Cappelluti (Yale), and Yanxia Li (University of Hawaii).

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 CL J1001:

Scale: Image is 2.17 arcmin across (about 4.36 million light years)
Category: Groups & Clusters of Galaxies, Cosmology/Deep Fields/X-ray Background
Coordinates (J2000): RA 10h 00m 56.96s | Dec +02° 20' 09.32"
Constellation: Sextans
Observation Date: 7 pointings between 19 Dec 2006 and 07 Apr 2007
Observation Time: 66 hours 7 min (2 days 18 hours 7 min)
Obs. ID: 7997, 8001, 8002, 8503, 8006, 8496, 8123
Instrument: ACIS
References: Wang, T. et al, 2016, ApJ (accepted); arXiv:1604.07404
Color Code: X-ray (Purple), Infrared (Red, Green, Blue), Radio (Green)
Distance Estimate: About 11.1 billion light years (z=2.506)

Tuesday, August 30, 2016

Milky Way Had a Blowout Bash 6 Million Years Ago

Measurements show that the Milky Way galaxy weighs about 1-2 trillion times as much as our Sun.

About five-sixths of that is in the form of invisible and mysterious dark matter. The remaining one-sixth of our galaxy's heft, or 150-300 billion solar masses, is normal matter. However, if you count up all the stars, gas and dust we can see, you only find about 65 billion solar masses. The rest of the normal matter - stuff made of neutrons, protons, and electrons - seems to be missing.

"We played a cosmic game of hide-and-seek. And we asked ourselves, where could the missing mass be hiding?" says lead author Fabrizio Nicastro, a research associate at the Harvard-Smithsonian Center for Astrophysics (CfA) and astrophysicist at the Italian National Institute of Astrophysics (INAF).

"We analyzed archival X-ray observations from the XMM-Newton spacecraft and found that the missing mass is in the form of a million-degree gaseous fog permeating our galaxy. That fog absorbs X-rays from more distant background sources," Nicastro continues.

The astronomers used the amount of absorption to calculate how much normal matter was there, and how it was distributed. They applied computer models but learned that they couldn't match the observations with a smooth, uniform distribution of gas. Instead, they found that there is a "bubble" in the center of our galaxy that extends two-thirds of the way to Earth.

Clearing out that bubble required a tremendous amount of energy. That energy, the authors surmise, came from the feeding black hole. While some infalling gas was swallowed by the black hole, other gas was pumped out at speeds of 2 million miles per hour (1,000 km/sec).

Six million years later, the shock wave created by that phase of activity has crossed 20,000 light-years of space. Meanwhile, the black hole has run out of nearby food and gone into hibernation.
This timeline is corroborated by the presence of 6-million-year-old stars near the galactic center.

Those stars formed from some of the same material that once flowed toward the black hole.

"The different lines of evidence all tie together very well," says Smithsonian co-author Martin Elvis (CfA). "This active phase lasted for 4 to 8 million years, which is reasonable for a quasar."

The observations and associated computer models also show that the hot, million-degree gas can account for up to 130 billion solar masses of material. Thus, it just might explain where all of the galaxy's missing matter was hiding: it was too hot to be seen.

More answers may come from the proposed next-generation space mission known as X-ray Surveyor. It would be able to map out the bubble by observing fainter sources, and see finer detail to tease out more information about the elusive missing mass. The European Space Agency's Athena X-ray Observatory, planned for launch in 2028, offers similar promise.

These results have been accepted for publication in The Astrophysical Journal and are available online.

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

Monday, August 29, 2016

Jupiter's Extended Family? A Billion or More

Comparing Jupiter with Jupiter-like planets that orbit other stars can teach us about those distant worlds, and reveal new insights about our own solar system's formation and evolution. (Illustration) Credit: NASA/JPL-Caltech. › Larger image

Our galaxy is home to a bewildering variety of Jupiter-like worlds: hot ones, cold ones, giant versions of our own giant, pint-sized pretenders only half as big around.

Astronomers say that in our galaxy alone, a billion or more such Jupiter-like worlds could be orbiting stars other than our sun. And we can use them to gain a better understanding of our solar system and our galactic environment, including the prospects for finding life.

It turns out the inverse is also true -- we can turn our instruments and probes to our own backyard, and view Jupiter as if it were an exoplanet to learn more about those far-off worlds. The best-ever chance to do this is now, with Juno, a NASA probe the size of a basketball court, which arrived at Jupiter in July to begin a series of long, looping orbits around our solar system's largest planet. Juno is expected to capture the most detailed images of the gas giant ever seen. And with a suite of science instruments, Juno will plumb the secrets beneath Jupiter's roiling atmosphere.

It will be a very long time, if ever, before scientists who study exoplanets -- planets orbiting other stars -- get the chance to watch an interstellar probe coast into orbit around an exo-Jupiter, dozens or hundreds of light-years away. But if they ever do, it's a safe bet the scene will summon echoes of Juno.

"The only way we're going to ever be able to understand what we see in those extrasolar planets is by actually understanding our system, our Jupiter itself," said David Ciardi, an astronomer with NASA's Exoplanet Science Institute (NExSci) at Caltech.

Not all Jupiters are created equal

Juno's detailed examination of Jupiter could provide insights into the history, and future, of our solar system. The tally of confirmed exoplanets so far includes hundreds in Jupiter's size-range, and many more that are larger or smaller.

The so-called hot Jupiters acquired their name for a reason: They are in tight orbits around their stars that make them sizzling-hot, completing a full revolution -- the planet's entire year -- in what would be a few days on Earth. And they're charbroiled along the way.

But why does our solar system lack a "hot Jupiter?" Or is this, perhaps, the fate awaiting our own Jupiter billions of years from now -- could it gradually spiral toward the sun, or might the swollen future sun expand to engulf it?

Not likely, Ciardi says; such planetary migrations probably occur early in the life of a solar system.

"In order for migration to occur, there needs to be dusty material within the system," he said. 

"Enough to produce drag. That phase of migration is long since over for our solar system."

Jupiter itself might already have migrated from farther out in the solar system, although no one really knows, he said.

Looking back in time

If Juno's measurements can help settle the question, they could take us a long way toward understanding Jupiter's influence on the formation of Earth -- and, by extension, the formation of other "Earths" that might be scattered among the stars.

"Juno is measuring water vapor in the Jovian atmosphere," said Elisa Quintana, a research scientist at the NASA Ames Research Center in Moffett Field, California. "This allows the mission to measure the abundance of oxygen on Jupiter. Oxygen is thought to be correlated with the initial position from which Jupiter originated."

If Jupiter's formation started with large chunks of ice in its present position, then it would have taken a lot of water ice to carry in the heavier elements which we find in Jupiter. But a Jupiter that formed farther out in the solar system, then migrated inward, could have formed from much colder ice, which would carry in the observed heavier elements with a smaller amount of water. If Jupiter formed more directly from the solar nebula, without ice chunks as a starter, then it should contain less water still. Measuring the water is a key step in understanding how and where Jupiter formed.

That's how Juno's microwave radiometer, which will measure water vapor, could reveal Jupiter's ancient history.

"If Juno detects a high abundance of oxygen, it could suggest that the planet formed farther out," Quintana said.

A probe dropped into Jupiter by NASA's Galileo spacecraft in 1995 found high winds and turbulence, but the expected water seemed to be absent. Scientists think Galileo's one-shot probe just happened to drop into a dry area of the atmosphere, but Juno will survey the entire planet from orbit.

The chaotic early years

Where Jupiter formed, and when, also could answer questions about the solar system's "giant impact phase," a time of crashes and collisions among early planet-forming bodies that eventually led to the solar system we have today.

Our solar system was extremely accident-prone in its early history -- perhaps not quite like billiard balls caroming around, but with plenty of pileups and fender-benders.

"It definitely was a violent time," Quintana said. "There were collisions going on for tens of millions of years. For example, the idea of how the moon formed is that a proto-Earth and another body collided; the disk of debris from this collision formed the moon. And some people think Mercury, because it has such a huge iron core, was hit by something big that stripped off its mantle; it was left with a large core in proportion to its size."

Part of Quintana's research involves computer modeling of the formation of planets and solar systems. Teasing out Jupiter's structure and composition could greatly enhance such models, she said. 

Quintana already has modeled our solar system's formation, with Jupiter and without, yielding some surprising findings.

"For a long time, people thought Jupiter was essential to habitability because it might have shielded Earth from the constant influx of impacts [during the solar system's early days] which could have been damaging to habitability," she said. "What we've found in our simulations is that it's almost the opposite. When you add Jupiter, the accretion times are faster and the impacts onto Earth are far more energetic. Planets formed within about 100 million years; the solar system was done growing by that point," Quintana said.

"If you take Jupiter out, you still form Earth, but on timescales of billions of years rather than hundreds of millions. Earth still receives giant impacts, but they're less frequent and have lower impact energies," she said.

Getting to the core

Another critical Juno measurement that could shed new light on the dark history of planetary formation is the mission's gravity science experiment. Changes in the frequency of radio transmissions from Juno to NASA's Deep Space Network will help map the giant planet's gravitational field.

Knowing the nature of Jupiter's core could reveal how quickly the planet formed, with implications for how Jupiter might have affected Earth's formation.

And the spacecraft's magnetometers could yield more insight into the deep internal structure of Jupiter by measuring its magnetic field.

"We don't understand a lot about Jupiter's magnetic field," Ciardi said. "We think it's produced by metallic hydrogen in the deep interior. Jupiter has an incredibly strong magnetic field, much stronger than Earth's."

Mapping Jupiter's magnetic field also might help pin down the plausibility of proposed scenarios for alien life beyond our solar system.

Earth's magnetic field is thought to be important to life because it acts like a protective shield, channeling potentially harmful charged particles and cosmic rays away from the surface.

"If a Jupiter-like planet orbits its star at a distance where liquid water could exist, the Jupiter-like planet itself might not have life, but it might have moons which could potentially harbor life," he said.

An exo-Jupiter's intense magnetic field could protect such life forms, he said. That conjures visions of Pandora, the moon in the movie "Avatar" inhabited by 10-foot-tall humanoids who ride massive, flying predators through an exotic alien ecosystem.

Juno's findings will be important not only to understanding how exo-Jupiters might influence the formation of exo-Earths, or other kinds of habitable planets. They'll also be essential to the next generation of space telescopes that will hunt for alien worlds. The Transiting Exoplanet Survey Satellite (TESS) will conduct a survey of nearby bright stars for exoplanets beginning in June 2018, or earlier. The James Webb Space Telescope, expected to launch in 2018, and WFIRST (Wide-Field Infrared Survey Telescope), with launch anticipated in the mid-2020s, will attempt to take direct images of giant planets orbiting other stars.

"We're going to be able to image planets and get spectra," or light profiles from exoplanets that will reveal atmospheric gases, Ciardi said. Juno's revelations about Jupiter will help scientists to make sense of these data from distant worlds.

"Studying our solar system is about studying exoplanets," he said. "And studying exoplanets is about studying our solar system. They go together."
To learn more about a few of the known exo-Jupiters, visit:

News Media Contact

Preston Dyches
Jet Propulsion Laboratory, Pasadena, Calif.

Written by Pat Brennan
NASA Exoplanet Program 

Source: JPL-Caltech

Sunday, August 28, 2016

Gemini Images Galaxy That Is 99.99 Percent Dark Matter

The dark galaxy Dragonfly 44. The image on the left is a wide view of the galaxy taken with the Gemini North telescope using the Gemini Multi-Object Spectrograph (GMOS). The close-up on the right is from the same very deep image, revealing the large, elongated galaxy, and halo of spherical clusters of stars around the galaxy’s core, similar to the halo that surrounds our Milky Way Galaxy. Dragonfly 44 is very faint for its mass, and consists almost entirely of Dark Matter. Credit: Pieter van Dokkum, Roberto Abraham, Gemini, Sloan Digital Sky Survey. PNG image

MAUNAKEA, Hawaii — Using the world's most powerful telescopes, an international team of astronomers has discovered a massive galaxy that consists almost entirely of Dark Matter. Using the W. M. Keck Observatory and the Gemini North telescope – both on Maunakea, Hawaii – the team found a galaxy whose mass is almost entirely Dark Matter. The findings are being published in The Astrophysical Journal Letters today.

Even though it is relatively nearby, the galaxy, named Dragonfly 44, had been missed by astronomers for decades because it is very dim. It was discovered just last year when the Dragonfly Telephoto Array observed a region of the sky in the constellation Coma. Upon further scrutiny, the team realized the galaxy had to have more than meets the eye: it has so few stars that it quickly would be ripped apart unless something was holding it together.

To determine the amount of Dark Matter in Dragonfly 44, astronomers used the DEIMOS instrument installed on Keck II to measure the velocities of stars for 33.5 hours over a period of six nights so they could determine the galaxy’s mass. The team then used the Gemini Multi-Object Spectrograph (GMOS) on the 8-meter Gemini North telescope on Maunakea in Hawaii to reveal a halo of spherical clusters of stars around the galaxy’s core, similar to the halo that surrounds our Milky Way Galaxy.
“Motions of the stars tell you how much matter there is, van Dokkum said. “They don’t care what form the matter is, they just tell you that it’s there. In the Dragonfly galaxy stars move very fast. So there was a huge discrepancy: using Keck Observatory, we found many times more mass indicated by the motions of the stars, then there is mass in the stars themselves.”

The mass of the galaxy is estimated to be a trillion times the mass of the Sun – very similar to the mass of our own Milky Way galaxy. However, only one hundredth of one percent of that is in the form of stars and "normal" matter; the other 99.99 percent is in the form of dark matter. The Milky Way has more than a hundred times more stars than Dragonfly 44.

Finding a galaxy with the mass of the Milky Way that is almost entirely dark was unexpected. "We have no idea how galaxies like Dragonfly 44 could have formed,” Roberto Abraham, a co-author of the study, said. "The Gemini data show that a relatively large fraction of the stars is in the form of very compact clusters, and that is probably an important clue. But at the moment we're just guessing."
“This has big implications for the study of Dark Matter,” van Dokkum said. “It helps to have objects that are almost entirely made of Dark Matter so we don’t get confused by stars and all the other things that galaxies have. The only such galaxies we had to study before were tiny. This finding opens up a whole new class of massive objects that we can study.

“Ultimately what we really want to learn is what Dark Matter is,” van Dokkum said. “The race is on to find massive dark galaxies that are even closer to us than Dragonfly 44, so we can look for feeble signals that may reveal a Dark Matter particle.”

Additional co-authors are Shany Danieli, Allison Merritt, and Lamiya Mowla of Yale, Jean Brodie of the University of California Observatories, Charlie Conroy of Harvard, Aaron Romanowsky of San Jose State University, and Jielai Zhang of the University of Toronto.

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

DEIMOS (DEep Imaging Multi-Object Spetrograph) boasts the largest field of view (16.7 arcmin by 5 arcmin) of any of the Keck Observatory instruments, and the largest number of pixels (64 Mpix). It is used primarily in its multi-object mode, obtaining simultaneous spectra of up to 130 galaxies or stars. Astronomers study fields of distant galaxies with DEIMOS, efficiently probing the most distant corners of the universe with high sensitivity.

Keck Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.

Science Contact:

Pieter van Dokkum
Yale University
New Haven, Connecticut, USA
Tel: +1-203-432-3000

Media Contact:

Steve Jefferson
W. M. Keck Observatory
(808) 881-3827

Saturday, August 27, 2016

Rosetta captures comet outburst

In unprecedented observations made earlier this year, Rosetta unexpectedly captured a dramatic comet outburst that may have been triggered by a landslide.

Nine of Rosetta’s instruments, including its cameras, dust collectors, and gas and plasma analysers, were monitoring the comet from about 35 km in a coordinated planned sequence when the outburst happened on 19 February.

“Over the last year, Rosetta has shown that although activity can be prolonged, when it comes to outbursts, the timing is highly unpredictable, so catching an event like this was pure luck,” says Matt Taylor, ESA’s Rosetta project scientist.

“By happy coincidence, we were pointing the majority of instruments at the comet at this time, and having these simultaneous measurements provides us with the most complete set of data on an outburst ever collected.”

Copyright image: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA; all data from Grün et al (2016)

Location of the outburst
Copyright: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0

 Copyright: ESA/ATG medialab

The data were sent to Earth only a few days after the outburst, but subsequent analysis has allowed a clear chain of events to be reconstructed, as described in a paper led by Eberhard Grün of the Max-Planck-Institute for Nuclear Physics, Heidelberg, accepted for publication in Monthly Notices of the Royal Astronomical Society.
Over the next two hours, Rosetta recorded outburst signatures that exceeded background levels in some instruments by factors of up to a hundred. For example, between about 10:00–11:00 GMT, ALICE saw the ultraviolet brightness of the sunlight reflected by the nucleus and the emitted dust increase by a factor of six, while ROSINA and RPC detected a significant increase in gas and plasma, respectively, around the spacecraft, by a factor of 1.5–2.5.

In addition, MIRO recorded a 30ºC rise in temperature of the surrounding gas.

Shortly after, Rosetta was blasted by dust: GIADA recorded a maximum hit count at around 11:15 GMT. Almost 200 particles were detected in the following three hours, compared with a typical rate of 3–10 collected on other days in the same month.

At the same time, OSIRIS narrow-angle camera images began registering dust grains emitted during the blast. Between 11:10 GMT and 11:40 GMT, a transition occurred from grains that were distant or slow enough to appear as points in the images, to those either close or fast enough to be captured as trails during the exposures.

In addition, the startrackers, which are used to navigate and help control Rosetta’s attitude, measured an increase in light scattered from dust particles as a result of the outburst.

The startrackers are mounted at 90º to the side of the spacecraft that hosts the majority of science instruments, so they offered a unique insight into the 3D structure and evolution of the outburst. 
Astronomers on Earth also noted an increase in coma density in the days after the outburst.

By examining all of the available data, scientists believe they have identified the source of the outburst.

“From Rosetta’s observations, we believe the outburst originated from a steep slope on the comet’s large lobe, in the Atum region,” says Eberhard.

The fact that the outburst started when this area just emerged from shadow suggests that thermal stresses in the surface material may have triggered a landslide that exposed fresh water ice to direct solar illumination. The ice then immediately turned to gas, dragging surrounding dust with it to produce the debris cloud seen by OSIRIS.

“Combining the evidence from the OSIRIS images with the long duration of the GIADA dust impact phase leads us to believe that the dust cone was very broad,” says Eberhard.

“As a result, we think the outburst must have been triggered by a landslide at the surface, rather than a more focused jet bringing fresh material up from within the interior, for example.”

“We’ll continue to analyse the data not only to dig into the details of this particular event, but also to see if it can help us better understand the many other outbursts witnessed over the course of the mission,” adds Matt.

“It’s great to see the instrument teams working together on the important question of how cometary outbursts are triggered.”

Notes for Editors
“The 19 Feb. 2016 outburst of comet 67P/CG: A Rosetta multi-instrument study,” by E. Grün et al is published in the Monthly Notices of the Royal Astronomical Society. doi: 10.1093/mnras/stw2088

For further information, please contact:
Eberhard Grün
Max-Planck-Institute for Nuclear Physics, Heidelberg, Germany

Matt Taylor
ESA Rosetta project scientist

Markus Bauer 

ESA Science and Robotic Exploration Communication Officer

Tel: +31 71 565 6799

Mob: +31 61 594 3 954



Friday, August 26, 2016

An irregular island

Credit: ESA/Hubble & NASA

This image, courtesy of the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), captures the glow of distant stars within NGC 5264, a dwarf galaxy located just over 15 million light-years away in the constellation of Hydra (The Sea Serpent).

Dwarf galaxies like NGC 5264 typically possess around a billion stars — just one per cent of the number of stars found within the Milky Way. They are usually found orbiting other, larger, galaxies such as our own, and are thought to form from the material left over from the messy formation of their larger cosmic relatives.

NGC 5264 clearly possesses an irregular shape — unlike the more common spiral or elliptical galaxies — with knots of blue star formation. Astronomers believe that this is due to the gravitational interactions between NGC 5264 and other galaxies nearby. These past flirtations sparked the formation of new generations of stars, which now glow in bright shades of blue.

Thursday, August 25, 2016

NASA's WISE, Fermi Missions Reveal a Surprising Blazar Connection

An analysis of blazar properties observed by the Wide-field Infrared Survey Explorer (WISE) and Fermi's Large Area Telescope (LAT) reveal a correlation in emissions from the mid-infrared to gamma rays, an energy range spanning a factor of 10 billion. When plotted by gamma-ray and mid-infrared colors, confirmed Fermi blazars (gold dots) form a unique band not shared by other sources beyond our galaxy. A blue line marks the best fit of these values. The relationship allows astronomers to identify potential new gamma-ray blazars by studying WISE infrared data.
Credits: NASA's Goddard Space Flight Center/Francesco Massaro, University of Turin

Black-hole-powered galaxies called blazars are the most common sources detected by NASA's Fermi Gamma-ray Space Telescope. As matter falls toward the supermassive black hole at the galaxy's center, some of it is accelerated outward at nearly the speed of light along jets pointed in opposite directions. When one of the jets happens to be aimed in the direction of Earth, as illustrated here, the galaxy appears especially bright and is classified as a blazar. Credits: M. Weiss/CfA. Hi-res image

Astronomers studying distant galaxies powered by monster black holes have uncovered an unexpected link between two very different wavelengths of the light they emit, the mid-infrared and gamma rays. The discovery, which was accomplished by comparing data from NASA’s Wide-field Infrared Survey Explorer (WISE) and Fermi Gamma-ray Space Telescope, has enabled the researchers to uncover dozens of new blazar candidates.

Francesco Massaro at the University of Turin in Italy and Raffaele D’Abrusco at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, show for the first time that the mid-infrared colors of blazars in WISE data correlate to an equivalent measurement of their gamma-ray output.

"This connection links two vastly different forms of light over an energy range spanning a factor of 10 billion," said Massaro. "Ultimately, it will help us decipher how supermassive black holes in these galaxies manage to convert the matter around them into vast amounts of energy."

Blazars constitute more than half of the discrete gamma-ray sources seen by Fermi's Large Area Telescope (LAT). At the heart of a blazar lies a supersized black hole with millions of times the sun's mass surrounded by a disk of hot gas and dust. As material in the disk falls toward the black hole, some of it forms dual jets that blast subatomic particles straight out of the disk in opposite directions at nearly the speed of light. A blazar appears bright to Fermi for two reasons. Its jets produce many gamma rays, the highest-energy form of light, and we happen to be viewing the galaxy face on, which means one of its jets is pointing in our direction.

From January to August 2010, NASA's WISE mapped the entire sky in four infrared wavelengths, cataloging more than half a billion sources. In 2011, Massaro, D’Abrusco and their colleagues began using WISE data to investigate Fermi blazars.

"WISE made it possible to explore the mid-infrared colors of known gamma-ray blazars," said D’Abrusco. "We found that when we plotted Fermi blazars by their WISE colors in a particular way, they occupied a distinctly different part of the plot than other extragalactic gamma-ray sources."
The scientists detail new aspects of the infrared/gamma-ray connection in a paper published in The Astrophysical Journal on Aug. 9. They say the electrons, protons and other particles accelerated in blazar jets leave a specific "fingerprint" in the infrared light they emit. This same pattern is also clearly evident in their gamma rays. The relationship effectively connects the dots for blazars across an enormous swath of the electromagnetic spectrum.

About a thousand Fermi sources remain unassociated with known objects at any other wavelength. Astronomers suspect many of these are blazars, but there isn't enough information to classify them. The infrared/gamma-ray connection led the authors to search for new blazar candidates among WISE infrared sources located within the positional uncertainties of Fermi's unidentified gamma-ray objects. When the researchers applied this relationship to Fermi's unknown sources, they quickly found 130 potential blazars. Efforts are now under way to confirm the nature of these objects through follow-up studies and to search for additional candidates using the WISE connection.

"About a third of the gamma-ray objects seen by Fermi remained unknown in the most recent catalog, and this result represents an important advance in understanding their natures," said David Thompson, a Fermi deputy project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

NASA's Jet Propulsion Laboratory in Pasadena, California, manages and operates WISE for NASA's Science Mission Directorate in Washington. The spacecraft was put into hibernation mode in 2011 after twice scanning the entire sky, thereby completing its main objectives. In September 2013, WISE was reactivated, renamed NEOWISE and assigned a new mission to assist NASA's efforts to identify potentially hazardous near-Earth objects.

NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

For more information on Fermi, visit:
For more information on WISE, visit:

For additional information, please contact:

Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.

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

Wednesday, August 24, 2016

Planet Found in Habitable Zone Around Nearest Star

Artist's impression of the planet orbiting Proxima Centauri

The location of Proxima Centauri in the southern skies

Proxima Centauri and its planet compared to the Solar System

The motion of Proxima Centauri in 2016, revealing the fingerprints of a planet

Artist's impression of the planet orbiting Proxima Centauri

The sky around Alpha Centauri and Proxima Centauri (annotated)

Proxima Centauri in the southern constellation of Centaurus

Relative Sizes of the Alpha Centauri Components and other Objects (artist’s impression)

The sky around Alpha Centauri and Proxima Centauri

Artist's impression of the planet orbiting Proxima Centauri (annotated)

Angular apparent size comparison

The brilliant southern Milky Way

The Pale Red Dot Campaign

Press Conference

Press Conference at ESO HQ 

Press Conference at ESO HQ
Press Conference at ESO HQ

Press Conference at ESO HQ
Press Conference at ESO HQ

Press Conference at ESO HQ
Press Conference at ESO HQ

Press Conference at ESO HQ
Press Conference at ESO HQ

Press Conference at ESO HQ
Press Conference at ESO HQ

Press Conference at ESO HQ
Press Conference at ESO HQ


ESOcast 87: Pale Red Dot Results
ESOcast 87: Pale Red Dot Results

Artist's impression of the planet orbiting Proxima Centauri
Artist's impression of the planet orbiting Proxima Centauri

Artist's impression of the planet orbiting Proxima Centauri
Artist's impression of the planet orbiting Proxima Centauri

A journey to Proxima Centauri and its planet
A journey to Proxima Centauri and its planet

A fly-through of the Proxima Centauri system
A fly-through of the Proxima Centauri system

A fly-through of the Proxima Centauri system
A fly-through of the Proxima Centauri system

Numerical simulation of possible surface temperatures on Proxima b (synchronous rotation)
Numerical simulation of possible surface temperatures on Proxima b (synchronous rotation)

Numerical simulation of possible surface temperatures on Proxima b (3:2 resonance)
Numerical simulation of possible surface temperatures on Proxima b (3:2 resonance)

Interviews with Pale Red Dot scientists
Interviews with Pale Red Dot scientists

Press Conference at ESO HQ
Press Conference at ESO HQ

 Pale Red Dot campaign reveals Earth-mass world in orbit around Proxima Centauri

Astronomers using ESO telescopes and other facilities have found clear evidence of a planet orbiting the closest star to Earth, Proxima Centauri. The long-sought world, designated Proxima b, orbits its cool red parent star every 11 days and has a temperature suitable for liquid water to exist on its surface. This rocky world is a little more massive than the Earth and is the closest exoplanet to us — and it may also be the closest possible abode for life outside the Solar System. A paper describing this milestone finding will be published in the journal Nature on 25 August 2016.

Just over four light-years from the Solar System lies a red dwarf star that has been named Proxima Centauri as it is the closest star to Earth apart from the Sun. This cool star in the constellation of Centaurus is too faint to be seen with the unaided eye and lies near to the much brighter pair of stars known as Alpha Centauri AB.

During the first half of 2016 Proxima Centauri was regularly observed with the HARPS spectrograph on the ESO 3.6-metre telescope at La Silla in Chile and simultaneously monitored by other telescopes around the world [1]. This was the Pale Red Dot campaign, in which a team of astronomers led by Guillem Anglada-Escudé, from Queen Mary University of London, was looking for the tiny back and forth wobble of the star that would be caused by the gravitational pull of a possible orbiting planet [2].

As this was a topic with very wide public interest, the progress of the campaign between mid-January and April 2016 was shared publicly as it happened on the Pale Red Dot website and via social media.

The reports were accompanied by numerous outreach articles written by specialists around the world.
Guillem Anglada-Escudé explains the background to this unique search: “The first hints of a possible planet were spotted back in 2013, but the detection was not convincing. Since then we have worked hard to get further observations off the ground with help from ESO and others. The recent Pale Red Dot campaign has been about two years in the planning.”

The Pale Red Dot data, when combined with earlier observations made at ESO observatories and elsewhere, revealed the clear signal of a truly exciting result. At times Proxima Centauri is approaching Earth at about 5 kilometres per hour — normal human walking pace — and at times receding at the same speed. This regular pattern of changing radial velocities repeats with a period of 11.2 days. Careful analysis of the resulting tiny Doppler shifts showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about 7 million kilometres from Proxima Centauri — only 5% of the Earth-Sun distance [3].

Guillem Anglada-Escudé comments on the excitement of the last few months: "I kept checking the consistency of the signal every single day during the 60 nights of the Pale Red Dot campaign. The first 10 were promising, the first 20 were consistent with expectations, and at 30 days the result was pretty much definitive, so we started drafting the paper!"

Red dwarfs like Proxima Centauri are active stars and can vary in ways that would mimic the presence of a planet. To exclude this possibility the team also monitored the changing brightness of the star very carefully during the campaign using the ASH2 telescope at the San Pedro de Atacama Celestial Explorations Observatory in Chile and the Las Cumbres Observatory telescope network. Radial velocity data taken when the star was flaring were excluded from the final analysis.

Although Proxima b orbits much closer to its star than Mercury does to the Sun in the Solar System, the star itself is far fainter than the Sun. As a result Proxima b lies well within the habitable zone around the star and has an estimated surface temperature that would allow the presence of liquid water. Despite the temperate orbit of Proxima b, the conditions on the surface may be strongly affected by the ultraviolet and X-ray flares from the star — far more intense than the Earth experiences from the Sun [4].

Two separate papers discuss the habitability of Proxima b and its climate. They find that the existence of liquid water on the planet today cannot be ruled out and, in such case, it may be present over the surface of the planet only in the sunniest regions, either in an area in the hemisphere of the planet facing the star (synchronous rotation) or in a tropical belt (3:2 resonance rotation). Proxima b's rotation, the strong radiation from its star and the formation history of the planet makes its climate quite different from that of the Earth, and it is unlikely that Proxima b has seasons.

This discovery will be the beginning of extensive further observations, both with current instruments [5] and with the next generation of giant telescopes such as the European Extremely Large Telescope (E-ELT). Proxima b will be a prime target for the hunt for evidence of life elsewhere in the Universe. Indeed, the Alpha Centauri system is also the target of humankind’s first attempt to travel to another star system, the StarShot project.

Guillem Anglada-Escudé concludes: "Many exoplanets have been found and many more will be found, but searching for the closest potential Earth-analogue and succeeding has been the experience of a lifetime for all of us. Many people’s stories and efforts have converged on this discovery. The result is also a tribute to all of them. The search for life on Proxima b comes next..."


[1] Besides data from the recent Pale Red Dot campaign, the paper incorporates contributions from scientists who have been observing Proxima Centauri for many years. These include members of the original UVES/ESO M-dwarf programme (Martin Kürster and Michael Endl), and exoplanet search pioneers such as R. Paul Butler. Public observations from the HARPS/Geneva team obtained over many years were also included.

[2] The name Pale Red Dot reflects Carl Sagan’s famous reference to the Earth as a pale blue dot. As Proxima Centauri is a red dwarf star it will bathe its orbiting planet in a pale red glow.

[3] The detection reported today has been technically possible for the last 10 years. In fact, signals with smaller amplitudes have been detected previously. However, stars are not smooth balls of gas and Proxima Centauri is an active star. The robust detection of Proxima b has only been possible after reaching a detailed understanding of how the star changes on timescales from minutes to a decade, and monitoring its brightness with photometric telescopes.

[4] The actual suitability of this kind of planet to support water and Earth-like life is a matter of intense but mostly theoretical debate. Major concerns that count against the presence of life are related to the closeness of the star. For example gravitational forces probably lock the same side of the planet in perpetual daylight, while the other side is in perpetual night. The planet's atmosphere might also slowly be evaporating or have more complex chemistry than Earth’s due to stronger ultraviolet and X-ray radiation, especially during the first billion years of the star’s life. However, none of the arguments has been proven conclusively and they are unlikely to be settled without direct observational evidence and characterisation of the planet’s atmosphere. Similar factors apply to the planets recently found around TRAPPIST-1.

[5] Some methods to study a planet’s atmosphere depend on it passing in front of its star and the starlight passing through the atmosphere on its way to Earth. Currently there is no evidence that Proxima b transits across the disc of its parent star, and the chances of this happening seem small, but further observations to check this possibility are in progress.

More Information

This research is presented in a paper entitled “A terrestrial planet candidate in a temperate orbit around Proxima Centauri”, by G. Anglada-Escudé et al., to appear in the journal Nature on 25 August 2016.

The team is composed of Guillem Anglada-Escudé (Queen Mary University of London, London, UK), Pedro J. Amado (Instituto de Astrofísica de Andalucía - CSIC, Granada, Spain), John Barnes (Open University, Milton Keynes, UK), Zaira M. Berdiñas (Instituto de Astrofísica de Andalucia - CSIC, Granada, Spain), R. Paul Butler (Carnegie Institution of Washington, Department of Terrestrial Magnetism, Washington, USA), Gavin A. L. Coleman (Queen Mary University of London, London, UK), Ignacio de la Cueva (Astroimagen, Ibiza, Spain), Stefan Dreizler (Institut für Astrophysik, Georg-August-Universität Göttingen, Göttingen, Germany), Michael Endl (The University of Texas at Austin and McDonald Observatory, Austin, Texas, USA), Benjamin Giesers (Institut für Astrophysik, Georg-August-Universität Göttingen, Göttingen, Germany), Sandra V. Jeffers (Institut für Astrophysik, Georg-August-Universität Göttingen, Göttingen, Germany), James S. Jenkins (Universidad de Chile, Santiago, Chile), Hugh R. A. Jones (University of Hertfordshire, Hatfield, UK), Marcin Kiraga (Warsaw University Observatory, Warsaw, Poland), Martin Kürster (Max-Planck-Institut für Astronomie, Heidelberg, Germany), María J. López-González (Instituto de Astrofísica de Andalucía - CSIC, Granada, Spain), Christopher J. Marvin (Institut für Astrophysik, Georg-August-Universität Göttingen, Göttingen, Germany), Nicolás Morales (Instituto de Astrofísica de Andalucía - CSIC, Granada, Spain), Julien Morin (Laboratoire Univers et Particules de Montpellier, Université de Montpellier & CNRS, Montpellier, France), Richard P. Nelson (Queen Mary University of London, London, UK), José L. Ortiz (Instituto de Astrofísica de Andalucía - CSIC, Granada, Spain), Aviv Ofir (Weizmann Institute of Science, Rehovot, Israel), Sijme-Jan Paardekooper (Queen Mary University of London, London, UK), Ansgar Reiners (Institut für Astrophysik, Georg-August-Universität Göttingen, Göttingen, Germany), Eloy Rodriguez (Instituto de Astrofísica de Andalucía - CSIC, Granada, Spain), Cristina Rodriguez-Lopez (Instituto de Astrofísica de Andalucía - CSIC, Granada, Spain), Luis F. Sarmiento (Institut für Astrophysik, Georg-August-Universität Göttingen, Göttingen, Germany), John P. Strachan (Queen Mary University of London, London, UK), Yiannis Tsapras (Astronomisches Rechen-Institut, Heidelberg, Germany), Mikko Tuomi (University of Hertfordshire, Hatfield, UK) and Mathias Zechmeister (Institut für Astrophysik, Georg-August-Universität Göttingen, Göttingen, 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”.



Guillem Anglada-Escudé (Lead Scientist)
Queen Mary University of London
London, United Kingdom
Tel: +44 (0)20 7882 3002

Pedro J. Amado (Scientist)
Instituto de Astrofísica de Andalucía - Consejo Superior de Investigaciones Cientificas (IAA/CSIC)
Granada, Spain
Tel: +34 958 23 06 39

Ansgar Reiners (Scientist)
Institut für Astrophysik, Universität Göttingen
Göttingen, Germany
Tel: +49 551 3913825

James S. Jenkins (Scientist)
Departamento de Astronomia, Universidad de Chile
Santiago, Chile
Tel: +56 (2) 2 977 1125

Michael Endl (Scientist)
McDonald Observatory, The University of Texas at Austin
Austin, Texas, USA
Tel: +1 512 471 8312

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

Martin Archer (Public Information Officer)
Queen Mary University of London
London, United Kingdom
Tel: +44 (0) 20 7882 6963

Silbia López de Lacalle (Public Information Officer)
Instituto de Astrofísica de Andalucía
Granada, Spain
Tel: +34 958 23 05 32

Romas Bielke (Public Information Officer)
Georg August Universität Göttingen
Göttingen, Germany
Tel: +49 551 39-12172

Natasha Metzler (Public Information Officer)
Carnegie Institution for Science
Washington DC, USA
Tel: +1 (202) 939 1142

David Azocar (Public Information Officer)
Departamento de Astronomia, Universidad de Chile
Santiago, Chile

Rebecca Johnson (Public Information Officer)
McDonald Observatory, The University of Texas at Austin
Austin, Texas, USA
Tel: +1 512 475 6763

Hugh Jones (Scientist)
University of Hertfordshire
Hatfield, United Kingdom
Tel: +44 (0)1707 284426

Jordan Kenny (Public Information Officer)
University of Hertfordshire
Hatfield, United Kingdom
Tel: +44 1707 286476
Cell: +44 7730318371

Yiannis Tsapras (Scientist)
Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg
Heidelberg, Germany
Tel: +49 6221 54-181

Source: ESO