NASA, ESA Telescopes Give Shape to Furious Black Hole Winds

Supermassive black holes at the cores of galaxies blast radiation and ultra-fast winds outward, as illustrated in this artist's conception. Image credit: NASA/JPL-Caltech.  › Full image and caption

This plot of data from two space telescopes, NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Space Agency's (ESA's) XMM-Newton determines for the first time the shape of ultra-fast winds from supermassive black holes, or quasars. Image credit: NASA/JPL-Caltech/Keele Univ.  › Full image and caption

NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and ESA's (European Space Agency) XMM-Newton telescope are showing that fierce winds from a supermassive black hole blow outward in all directions -- a phenomenon that had been suspected, but difficult to prove until now.

This discovery has given astronomers their first opportunity to measure the strength of these ultra-fast winds and prove they are powerful enough to inhibit the host galaxy's ability to make new stars.

"We know black holes in the centers of galaxies can feed on matter, and this process can produce winds. This is thought to regulate the growth of the galaxies," said Fiona Harrison of the California Institute of Technology (Caltech) in Pasadena, California. Harrison is the principal investigator of NuSTAR and a co-author on a new paper about these results appearing in the journal Science. "Knowing the speed, shape and size of the winds, we can now figure out how powerful they are."

Supermassive black holes blast matter into their host galaxies, with X-ray-emitting winds traveling at up to one-third the speed of light. In the new study, astronomers determined PDS 456, an extremely bright black hole known as a quasar more than 2 billion light-years away, sustains winds that carry more energy every second than is emitted by more than a trillion suns.

"Now we know quasar winds significantly contribute to mass loss in a galaxy, driving out its supply of gas, which is fuel for star formation," said the study's lead author, Emanuele Nardini of Keele University in England.

NuSTAR and XMM-Newton simultaneously observed PDS 456 on five separate occasions in 2013 and 2014. The space telescopes complement each other by observing different parts of the X-ray light spectrum: XMM-Newton views low-energy and NuSTAR views high-energy.

Previous XMM-Newton observations had identified black-hole winds blowing toward us, but could not determine whether the winds also blew in all directions. XMM-Newton had detected iron atoms, which are carried by the winds along with other matter, only directly in front of the black hole, where they block X-rays. The scientists combined higher-energy X-ray data from NuSTAR with observations from XMM-Newton. By doing this, they were able to find signatures of iron scattered from the sides, proving the winds emanate from the black hole not in a beam, but in a nearly spherical fashion.

"This is a great example of the synergy between XMM-Newton and NuSTAR," said Norbert Schartel, XMM-Newton project scientist at ESA. "The complementarity of these two X-ray observatories is enabling us to unveil previously hidden details about the powerful side of the universe."

With the shape and extent of the winds known, the researchers could then determine the strength of the winds and the degree to which they can inhibit the formation of new stars.

Astronomers think supermassive black holes and their home galaxies evolve together and regulate each other's growth. Evidence for this comes in part from observations of the central bulges of galaxies -- the more massive the central bulge, the larger the supermassive black hole.

This latest report demonstrates a supermassive black hole and its high-speed winds greatly affect the host galaxy. As the black hole bulks up in size, its winds push vast amounts of matter outward through the galaxy, which ultimately stops new stars from forming.

Because PDS 456 is relatively close, by cosmic standards, it is bright and can be studied in detail. This black hole gives astronomers a unique look into a distant era of our universe, around 10 billion years ago, when supermassive black holes and their raging winds were more common and possibly shaped galaxies as we see them today.

"For an astronomer, studying PDS 456 is like a paleontologist being given a living dinosaur to study," said study co-author Daniel Stern of NASA's Jet Propulsion Laboratory in Pasadena. "We are able to investigate the physics of these important systems with a level of detail not possible for those found at more typical distances, during the 'Age of Quasars.'"

NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington.

For more information, visit: http://www.nasa.gov/nustar  -  http://www.nustar.caltech.edu/

Media Contact

Whitney Clavin
Jet Propulsion Laboratory, Pasadena, California
818-354-4673
whitney.clavin@jpl.nasa.gov

Felicia Chou
NASA Headquarters, Washington
202-358-0257
felicia.chou@nasa.gov

Source: JPL-Caltech/News

For the first time, spacecraft catch a solar shockwave in the act

Earth’s magnetosphere is depicted with the high-energy particles of the Van Allen radiation belts (shown in red) and various processes responsible for accelerating these particles to relativistic energies indicated. The effects of an interplanetary shock penetrate deep into this system, energizing electrons to ultra-relativistic energies in a matter of seconds. Courtesy of NASA

Solar storm found to produce “ultrarelativistic, killer electrons” in 60 seconds

On Oct. 8, 2013, an explosion on the sun’s surface sent a supersonic blast wave of solar wind out into space. This shockwave tore past Mercury and Venus, blitzing by the moon before streaming toward Earth. The shockwave struck a massive blow to the Earth’s magnetic field, setting off a magnetized sound pulse around the planet.

NASA’s Van Allen Probes, twin spacecraft orbiting within the radiation belts deep inside the Earth’s magnetic field, captured the effects of the solar shockwave just before and after it struck.

Now scientists at MIT’s Haystack Observatory, the University of Colorado, and elsewhere have analyzed the probes’ data, and observed a sudden and dramatic effect in the shockwave’s aftermath: The resulting magnetosonic pulse, lasting just 60 seconds, reverberated through the Earth’s radiation belts, accelerating certain particles to ultrahigh energies.

“These are very lightweight particles, but they are ultrarelativistic, killer electrons — electrons that can go right through a satellite,” says John Foster, associate director of MIT’s Haystack Observatory. “These particles are accelerated, and their number goes up by a factor of 10, in just one minute. We were able to see this entire process taking place, and it’s exciting: We see something that, in terms of the radiation belt, is really quick.”

The findings represent the first time the effects of a solar shockwave on Earth’s radiation belts have been observed in detail from beginning to end. Foster and his colleagues have published their results in the Journal of Geophysical Research.

Catching a shockwave in the act

Since August 2012, the Van Allen Probes have been orbiting within the Van Allen radiation belts. The probes’ mission is to help characterize the extreme environment within the radiation belts, so as to design more resilient spacecraft and satellites.

One question the mission seeks to answer is how the radiation belts give rise to ultrarelativistic electrons — particles that streak around the Earth at 1,000 kilometers per second, circling the planet in just five minutes. These high-speed particles can bombard satellites and spacecraft, causing irreparable damage to onboard electronics.

The two Van Allen probes maintain the same orbit around the Earth, with one probe following an hour behind the other. On Oct. 8, 2013, the first probe was in just the right position, facing the sun, to observe the radiation belts just before the shockwave struck the Earth’s magnetic field. The second probe, catching up to the same position an hour later, recorded the shockwave’s aftermath.

Dealing a “sledgehammer blow”

Foster and his colleagues analyzed the probes’ data, and laid out the following sequence of events: As the solar shockwave made impact, according to Foster, it struck “a sledgehammer blow” to the protective barrier of the Earth’s magnetic field. But instead of breaking through this barrier, the shockwave effectively bounced away, generating a wave in the opposite direction, in the form of a magnetosonic pulse — a powerful, magnetized sound wave that propagated to the far side of the Earth within a matter of minutes.

In that time, the researchers observed that the magnetosonic pulse swept up certain lower-energy particles. The electric field within the pulse accelerated these particles to energies of 3 to 4 million electronvolts, creating 10 times the number of ultrarelativistic electrons that previously existed.

Taking a closer look at the data, the researchers were able to identify the mechanism by which certain particles in the radiation belts were accelerated. As it turns out, if particles’ velocities as they circle the Earth match that of the magnetosonic pulse, they are deemed “drift resonant,” and are more likely to gain energy from the pulse as it speeds through the radiation belts. The longer a particle interacts with the pulse, the more it is accelerated, giving rise to an extremely high-energy particle.

Foster says solar shockwaves can impact Earth’s radiation belts a couple of times each month. The event in 2013 was a relatively minor one.

“This was a relatively small shock. We know they can be much, much bigger,” Foster says. “Interactions between solar activity and Earth’s magnetosphere can create the radiation belt in a number of ways, some of which can take months, others days. The shock process takes seconds to minutes. This could be the tip of the iceberg in how we understand radiation-belt physics.”

Barry Mauk, a project scientist at Johns Hopkins University’s Applied Physics Laboratory, views the group’s findings as “the most comprehensive analysis of shock-induced acceleration within Earth’s space environment ever achieved.”

“Significant shock-induced acceleration of Earth’s radiation belts occur only occasionally, but these events are important because they have the potential of suddenly generating the most intense and energetic electrons, and therefore the most dangerous conditions for astronauts and satellites,” says Mauk, who did not contribute to the study. “Earth’s space environment serves as a wonderful laboratory for studying the nature of shock acceleration that is occurring elsewhere in the solar system and universe.”

Source: MIT - Massachusetts Institute of Technology/News

Hubble Gets Best View of a Circumstellar Debris Disk Distorted by a Planet Release Images

Hubble Views of Beta Pictoris (1997 and 2012)

Credit: NASA, ESA, and D. Apai and G. Schneider (University of Arizona)

 Release Images

Astronomers have used NASA's Hubble Space Telescope to take the most detailed picture to date of a large, edge-on, gas-and-dust disk encircling the 20-million-year-old star Beta Pictoris.

Beta Pictoris remains the only directly imaged debris disk that has a giant planet (discovered in 2009). Because the orbital period is comparatively short (estimated to be between 18 and 22 years), astronomers can see large motion in just a few years. This allows scientists to study how the Beta Pictoris disk is distorted by the presence of a massive planet embedded within the disk.

The new visible-light Hubble image traces the disk in closer to the star to within about 650 million miles of the star (which is inside the radius of Saturn's orbit about the Sun).

"Some computer simulations predicted a complicated structure for the inner disk due to the gravitational pull by the short-period giant planet. The new images reveal the inner disk and confirm the predicted structures. This finding validates models, which will help us to deduce the presence of other exoplanets in other disks," said Daniel Apai of the University of Arizona. The gas-giant planet in the Beta Pictoris system was directly imaged in infrared light by the European Southern Observatory's Very Large Telescope six years ago.

When comparing the latest Hubble images to Hubble images taken in 1997, astronomers find that the disk's dust distribution has barely changed over 15 years despite the fact that the entire structure is orbiting the star like a carousel. This means the disk's structure is smoothly continuous in the direction of its rotation on the timescale, roughly, of the accompanying planet's orbital period.

In 1984 Beta Pictoris was the very first star discovered to host a bright disk of light-scattering circumstellar dust and debris. Ever since then Beta Pictoris has been an object of intensive scrutiny with Hubble and with ground-based telescopes. Hubble spectroscopic observations in 1991 found evidence for extrasolar comets frequently falling into the star.

The disk is easily seen because it is tilted edge-on and is especially bright due to a very large amount of starlight-scattering dust. What's more, Beta Pictoris is closer to Earth (63 light-years) than most of the other known disk systems.

Though nearly all of the approximately two-dozen known light-scattering circumstellar disks have been viewed by Hubble to date, Beta Pictoris is the first and best example of what a young planetary system looks like, say researchers.

One thing astronomers have recently learned about circumstellar debris disks is that their structure, and amount of dust, is incredibly diverse and may be related to the locations and masses of planets in those systems. "The Beta Pictoris disk is the prototype for circumstellar debris systems, but it may not be a good archetype," said co-author Glenn Schneider of the University of Arizona.

For one thing the Beta Pictoris disk is exceptionally dusty. This may be due to recent major collisions among unseen planetary-sized and asteroid-sized bodies embedded within it. In particular, a bright lobe of dust and gas on the southwestern side of the disk may be the result of the pulverization of a Mars-sized body in a giant collision.

Both the 1997 and 2012 images were taken in visible light with Hubble's Space Telescope Imaging Spectrograph in its coronagraphic imaging mode. A coronagraph blocks out the glare of the central star so that the disk can be seen. 

Contact

Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
villard@stsci.edu

Daniel Apai / Glenn Schneider
University of Arizona, Tucson, Ariz.
520-621-6534 / 520-621-5865
apai@arizona.edu / gschneider@as.arizona.edu

Source: HubbleSite

   

Panta rhei — motion in the Milky Way

Palomar 12

Credit:  ESA/Hubble & NASA

Panta rhei is a simplified version of the famous greek philosopher Heraclitus' teachings. It basically means, everything flows. And everything in the Universe is indeed continually on the move, spiralling and shifting through space.

Some cosmic objects move a little further than others — take the subject of this NASA/ESA Hubble Space Telescope image, a globular cluster of stars known as Palomar 12.

Although it currently lies on the outskirts of the Milky Way’s halo, Palomar 12 was not born here. When astronomers first studied this cluster, they were puzzled by its strangely young age when compared to the other clusters in the galaxy. It appeared to be around 30% younger than other Milky Way globulars. Surely if it had been born within our galaxy, it would have sprung to life at a similar time to its cluster companions?

A bit more digging revealed that Palomar 12 was actually ripped from its initial home, the Sagittarius Dwarf Elliptical galaxy, around 1.7 billion years ago via tidal interactions between its former home and our galaxy. The dwarf galaxy that Palomar 12 once called home is a satellite galaxy to ours, and closely orbits around us — even occasionally passing through the plane of our galaxy. In fact, it is being slowly torn apart and consumed by the Milky Way.

The sparkling stars in this picture were imaged by Hubble’s Advanced Camera for Surveys.

Source: ESA/Hubble - Space Telescope

Dust to dust: a disintegrating rocky exoplanet could unlock secrets to how our solar system was formed

Exoplanet KIC 1255 b orbits its parent star followed by a comet-like dust tail.

Credit: Artists impression by Maciej Szyszko)

Exciting new research has opened up the chance to find out what distant planets are made of. A team of astronomers from The Open University (OU) and the Universities of Warwick and Sheffield, has made observations which can help reveal the chemical makeup of a small rocky world orbiting a distant star about 1500 light years away from Earth, increasing our understanding of how planets, including ours, were formed.

Using an advanced, ultra-fast camera known as ULTRACAM, located on the William Herschel Telescope (WHT), part of the Isaac Newton Group of Telescopes (ING) in the Canary Islands, the researchers have observed an extraordinary exoplanet named ‘KIC 1255 b’. The ING is owned by STFC and is operated in collaboration with the Netherlands and Spain.

"A single year on KIC 1255b lasts only 16 hours on Earth and the whole planet seems to be slowly boiling away under intense heat of its sun" said Jakub Bochinski, research student at the OU, and lead author of the study.

The planet’s surface is heated to over 2100K (over 1800°C), hot enough to vaporise rock. As a result, the planet’s outer layers are continuously destroyed, with the evaporating rock creating a comet-like dust tail following the planet in its orbit.

The ULTRACAM measurements were the most sensitive yet made, and revealed that the dust cloud, when visible, blocks a slightly larger fraction of the star’s blue light than red light. A similar effect is seen at sunset on Earth when the Sun’s light is scattered by dust in the Earth’s atmosphere, making the remaining light appear reddened. The exact colour-dependence of the scattering by dust (measured by carrying out simultaneous, multi-colour measurements with ULTRACAM) can reveal the size and composition of the dust grains. Ultimately, a series of measurements of KIC 1255b’s dust cloud could reveal the chemical composition of the dust.

Since the dust is made from the rocky surface of the disintegrating planet, the same technique will allow the chemical makeup of the planet’s surface to be measured.

The research was funded by STFC.  

More Information

Marion O'Sullivan
STFC Press Office
Tel: 01235 445627
Mob: 07824 888990 


Notes for editors:

1. The full press release and image is available from the Open University website.
2. The paperDirect evidence for an evolving dust cloud from the exoplanet KIC12557548 bis published in The Astrophysical Journal Letters.
   
   
3. ULTRACAM is an ultra-fast, triple-beam CCD camera designed to study astrophysics on the fastest timescales. The instrument was designed and built by a consortium including Professor Dhillon from the University of Sheffield, Professor Tom Marsh from the University of Warwick and the Science and Technology Facilities Council (STFC’s) UK Astronomy Technology Centre

Source: Science and Technology Facilities Council (STFC)

Stars akin to the sun also explode when they die sll@iaa.es

Radio and infrared image of IRAS 15103-5754 showing the velocity of the material in the jet. 

 IRAS 15103-5754, a star observed as it was turning into a planetary nebula, yields new clues as to the death of stars akin to the sun

The birth of planetary nebulae, resulting from the death of low and intermediate mass stars, is usually thought of as a slow process, in contrast with the intense supernovae that massive stars produce. But a recent study led by researchers at the Institute of Astrophysics of Andalusia (IAA-CSIC) in collaboration with the Center for Astrobiology (CAB, CSIC/INTA) has revealed the fact that explosive phenomena also intervene in the formation of planetary nebulae.

"In a few thousand million years, the sun will exhaust its nuclear fuel, expand into a red giant and eject a major part of its mass. The final result will be a white dwarf surrounded by a glowing planetary nebula.  Even though every star with a mass below ten solar masses goes through this short but important final transition, many details of the process still evade us”, says José Francisco Gómez, IAA-CSIC researcher in charge of the project.

The study of IRAS 15103-5754, part of a group of sixteen objects known as ‘water fountains’, has yielded important clues concerning this final stage. ‘Water fountains’ are  mature stars in a state of transition from red giants to planetary nebulae which display jets of ejected material that can be detected from intense radiation produced by water vapor molecules (water maser emission).

IRAS 15103-5754 stands out within the small group under study because it has been observed that the velocity of the material inside the jet increases in proportion to the distance from the central star.  "Water molecules are generally destroyed soon after the planetary nebula is formed, and in the rare cases where a maser emission has been detected, the velocity has always been very low”, says Luis F. Miranda (IAA-CSIC, University of Vigo). “In IRAS 15103-5754 we are seeing for the first time a water maser emission at velocities of hundreds of kilometers per second.  We are witnessing the transition of a star into a planetary nebula in real time".

“The high velocity can only be explained by the occurrence of an explosion”. Our results show that, contrary to the most widespread theories, when a star turns into a planetary nebula an enormous explosion is produced – short-lived but highly energetic – which will determine the evolution of the star in its last phases of life”, says  José Francisco Gómez (IAA-CSIC).

This study has established the importance of ‘water fountains’ in understanding how the symmetry of stars is broken in the final stages of their lives, and thus to shed light on the outstanding variety of planetary nebulae that we encounter.

Reference:

José F. Gómez et al. "The first water fountain collimated outflow in a planetary nebula". The Astrophysical Journal. DOI: 10.1088/0004-637X/799/2/186

Contact:

Instituto de Astrofísica de Andalucía (IAA-CSIC)

Unidad de Divulgación y Comunicación:  http://www-divulgacion.iaa.es
Silbia López de Lacalle - sll@iaa.es - 958230532

 Source: Instituto de Astrofísica de Andalucía (IAA-CSIC)

The Strange Case of the Missing Dwarf New SPHERE instrument shows its power

 PR Image eso1506a

The SPHERE instrument attached to the VLT 

PR Image eso1506b

The unusual binary star V471 Tauri in the constellation of Taurus 

PR Image eso1506c

Wide-field view of the sky around the unusual binary star V471 Tauri 

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Videos

PR Video eso1506a

Zooming in on the unusual binary star V471 Tauri

New SPHERE instrument shows its power

The new SPHERE instrument on ESO’s Very Large Telescope has been used to search for a brown dwarf expected to be orbiting the unusual double star V471 Tauri. SPHERE has given astronomers the best look so far at the surroundings of this intriguing object and they found — nothing. The surprising absence of this confidently predicted brown dwarf means that the conventional explanation for the odd behaviour of V471 Tauri is wrong. This unexpected result is described in the first science paper based on observations from SPHERE.

Some pairs of stars consist of two normal stars with slightly different masses. When the star of slightly higher mass ages and expands to become a red giant, material is transferred to other star and ends up surrounding both stars in a huge gaseous envelope. When this cloud disperses the two move closer together and form a very tight pair with one white dwarf, and one more normal star [1].

One such stellar pair is called V471 Tauri [2]. It is a member of the Hyades star cluster in the constellation of Taurus and is estimated to be around 600 million years old and about 163 light-years from Earth. The two stars are very close and orbit each other every 12 hours. Twice per orbit one star passes in front of the other — which leads to regular changes in the brightness of the pair observed from Earth as they eclipse each other.

A team of astronomers led by Adam Hardy (Universidad Valparaíso, Valparaíso, Chile) first used the ULTRACAM system on ESO’s New Technology Telescope to measure these brightness changes very precisely. The times of the eclipses were measured with an accuracy of better than two seconds — a big improvement on earlier measurements.

The eclipse timings were not regular, but could be explained well by assuming that there was a brown dwarf orbiting both stars whose gravitational pull was disturbing the orbits of the stars. They also found hints that there might be a second small companion object.

Up to now however, it has been impossible to actually image a faint brown dwarf so close to much brighter stars. But the power of the newly installed SPHERE instrument on ESO’s Very Large Telescope allowed the team to look for the first time exactly where the brown dwarf companion was expected to be. But they saw nothing, even though the very high quality images from SPHERE should have easily revealed it [3].

“There are many papers suggesting the existence of such circumbinary objects, but the results here provide damaging evidence against this hypothesis,” remarks Adam Hardy.

If there is no orbiting object then what is causing the odd changes to the orbit of the binary? Several theories have been proposed, and, while some of these have already been ruled out, it is possible that the effects are caused by magnetic field variations in the larger of the two stars [4], somewhat similar to the smaller changes seen in the Sun.

“A study such as this has been necessary for many years, but has only become possible with the advent of powerful new instruments such as SPHERE. This is how science works: observations with new technology can either confirm, or as in this case disprove, earlier ideas. This is an excellent way to start the observational life of this amazing instrument,” concludes Adam Hardy.

Notes

[1] Such pairs are known as post-common-envelope binaries.

[2] This name means that the object is the 471st variable star (or as closer analysis shows, pair of stars) to be identified in the constellation of Taurus.

[3] The SPHERE images are so accurate that they would have been able to reveal a companion such as a brown dwarf that is 70 000 times fainter than the central star, and only 0.26 arcseconds away from it. The expected brown dwarf companion in this case was predicted to be much brighter.

[4] This effect is called the Applegate mechanism and results in regular changes in the shape of the star, which can lead to changes in the apparent brightness of the double star seen from Earth.

More Information

This research was presented in a paper entitled “The First Science Results from SPHERE: Disproving the Predicted Brown Dwarf around V471 Tau” by A. Hardy et al., to appear in the Astrophysical Journal Letters on 18 February 2015.

The team is composed of A. Hardy (Universidad Valparaíso, Valparaíso, Chile; Millennium Nucleus "Protoplanetary Disks in ALMA Early Science", part of the Millennium Science Initiative Program, Universidad Valparaíso), M.R. Schreiber (Universidad Valparaíso), S.G. Parsons (Universidad Valparaíso), C. Caceres (Universidad Valparaíso), G. Retamales (Universidad Valparaíso), Z. Wahhaj (ESO, Santiago, Chile), D. Mawet (ESO, Santiago, Chile), H. Canovas (Universidad Valparaíso), L. Cieza (Universidad Diego Portales, Santiago, Chile; Universidad Valparaíso), T.R. Marsh (University of Warwick, Coventry, United Kingdom), M.C.P. Bours (University of Warwick), V.S. Dhillon (University of Sheffield, Sheffield, United Kingdom) and A. Bayo (Universidad Valparaíso).

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”.

Links 

• Research paper
• Photos of the VLT

Contacts

Adam Hardy
Universidad Valparaíso
Valparaíso, Chile
Tel: +56 32 2508457
Email: adam.hardy@postgrado.uv.cl

Matthias Schreiber
Universidad de Valparaíso
Valparaíso, Chile
Tel: +56 32 2399279
Email: matthias@dfa.uv.cl 

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

Source: ESO

Why Do Starburst Galaxies 'Burst'? ALMA Sees Super Stellar Nurseries at Heart of Sculptor Galaxy

What is the recipe for starburst? Astronomers studied NGC 253 with ALMA to find out. These new ALMA data reveal a diffuse envelope of carbon monoxide gas (shown in red), which surrounds stellar nurseries -- regions of active star formation (in yellow). By dissecting these regions with ALMA, astronomers are uncovering clues to the processes and conditions that drive furious star formation. The ALMA data are superimposed on a Hubble image that covers part of the same region. Credit: B. Saxton (NRAO/AUI/NSF); ALMA (NRAO/ESO/NAOJ); A. Leroy; STScI/NASA, ST-ECF/ESA, CADC/NRC/CSA

NGC253 -- Why Starburst Galaxies "Burst" from NRAO Outreach on Vimeo.

Animation of ALMA data reveals a diffuse envelope of carbon monoxide gas (shown in red), which surrounds stellar nurseries -- regions of active star formation (in yellow). By dissecting these regions with ALMA, astronomers are uncovering clues to the processes and conditions that drive furious star formation. The ALMA data are superimposed on a Hubble image that covers part of the same region. Credit: B. Saxton (NRAO/AUI/NSF); ALMA (NRAO/ESO/NAOJ); A. Leroy; STScI/NASA, ST-ECF/ESA, CADC/NRC/CSA

ALMA image of starbursting clouds inside NGC 253. The red region is the lower density CO gas surrounding higher density star-forming regions in yellow.Credit: B. Saxton (NRAO/AUI/NSF); ALMA (NRAO/ESO/NAOJ); A. Leroy;

ALMA antennas at night. Credit: NRAO/AUI/NSF

Starburst galaxies transmute gas into new stars at a dizzying pace – up to 1,000 times faster than typical spiral galaxies like the Milky Way. To help understand why some galaxies "burst" while others do not, an international team of astronomers used the Atacama Large Millimeter/submillimeter Array (ALMA) to dissect a cluster of star-forming clouds at the heart of NGC 253, one of the nearest starburst galaxies to the Milky Way.

"All stars form in dense clouds of dust and gas," said Adam Leroy, an astronomer formerly with the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia, and now with The Ohio State University in Columbus. "Until now, however, scientists struggled to see exactly what was going on inside starburst galaxies that distinguished them from other star-forming regions."

ALMA changes that by offering the power to resolve individual star-forming structures, even in distant systems. As an early demonstration of this capability, Leroy and his colleagues mapped the distributions and motions of multiple molecules in clouds at the core of NGC 253, also known as the Sculptor Galaxy.

Sculptor, a disk-shape galaxy currently undergoing intense starburst, is located approximately 11.5 million light-years from Earth, which is remarkably nearby for such an energetic star factory. This proximity makes Sculptor an excellent target for detailed study.

“There is a class of galaxies and parts of galaxies, we call them starbursts, where we know that gas is just plain better at forming stars,” noted Leroy. “To understand why, we took one of the nearest such regions and pulled it apart – layer by layer – to see what makes the gas in these places so much more efficient at star formation.”

ALMA’s exceptional resolution and sensitivity allowed the researchers to first identify ten distinct stellar nurseries inside the heart of Sculptor, something that was remarkably hard to accomplish with earlier telescopes, which blurred the different regions together.

The team then mapped the distribution of about 40 millimeter-wavelength “signatures” from different molecules inside the center of the galaxy. This was critically important since different molecules correspond to different conditions in and around star-forming clouds. For example, carbon monoxide (CO) corresponds to massive envelopes of less dense gas that surround stellar nurseries. Other molecules, like hydrogen cyanide (HCN), reveal dense areas of active star formation. Still rarer molecules, like H13CN and H13CO+, indicate even denser regions.

By comparing the concentration, distribution, and motion of these molecules, the researchers were able to peel apart the star-forming clouds in Sculptor, revealing that they are much more massive, ten times denser, and far more turbulent than similar clouds in normal spiral galaxies.

These stark differences suggest that it’s not just the number of stellar nurseries that sets the throttle for a galaxy to create new stars, but also what kind of stellar nurseries are present. Because the star-forming clouds in Sculptor pack so much material into such a small space, they are simply better at forming stars than the clouds in a galaxy like the Milky Way. Starburst galaxies, therefore, show real physical changes in the star-formation process, not just a one-to-one scaling of star formation with the available reservoir of material.

“These differences have wide-ranging implications for how galaxies grow and evolve,” concluded Leroy. “What we would ultimately like to know is whether a starburst like Sculptor produces not just more stars, but different types of stars than a galaxy like the Milky Way. ALMA is bringing us much closer to that goal.”

These results are accepted for publication in the Astrophysical Journal and are being presented February 15, 2015, at a news conference at the American Association for the Advancement of Science (AAAS) meeting in San Jose, California.

                                                       

#   #   # 

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

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

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

Contact: 

Charles E. Blue, 
NRAO Public Information Officer
434-296-0314; 
Email: cblue@nrao.edu

Source:  National Radio Astronomy Observatory (NRAO)

Embryos of Stars

A far-infrared image of the cold pre-stellar cloud L1544 (the cloud is at the lower left, with other clouds of gas and dust nearby). The cloud is about 450 light-years from Earth in the nearest large region of star formation. New studies of the gas motions in the core show that the stellar embryo is slowly collapsing in a manner that agrees well with some models and excludes others. Credit: ESA/Herschel/SPIRE 

Stars like the Sun begin their lives as cold, dense cores of dust and gas that gradually collapse under the influence of gravity until nuclear fusion is ignited. Exactly how the critical collapse process occurs in these embryos, however, is poorly understood, with several competing ideas having been advanced. Material might just freely fall to the center, although in more likely scenarios the infall is inhibited by pressure from warm gas, turbulent motions, magnetic fields, or even perhaps by some combination of them. It might be possible to distinguish between these alternative collapse hypotheses by examining how the core's density varies with radius, but it turns out that (at least for spherical clouds) the predicted density distributions all look about the same. The predicted distributions of velocity for the infalling gas, however, are quite different.

The dust in these cores makes them completely opaque in the optical, and so studying their behaviors requires techniques at other wavelengths. One of the most exciting developments in astronomy over the past decade has been the development of far-infrared and millimeter wavelength tools for the tasks of identifying pre-stellar cores as such, and determining their properties. CfA astronomer Eric Keto and two colleagues used observations of emission lines from water and carbon monoxide at both wavelength regimes to measure the velocity distribution of the gas in a pre-stellar, dense core. Each of these gas molecules traces a sightly different density of gas (the typical value in these clouds is about one hundred thousand particles per cubic centimeter).

The data clearly prefer the scenario in which the gas temperature is nearly constant throughout the cloud with just enough total mass present for gravity to drive slow contraction. Actually, the paper's authors were the first to advocate and describe just such a possibility, and these observations of this particular core bring a satisfying confirmation that no magnetic fields or turbulence is present or needed. The new results highlight the dramatic modern successes in unraveling the earliest stages of stellar birth, and the power of new technology. More cores now need to be measured in order to determine if these particular conclusions have general validity.

Reference(s): 

 

"The Dynamics of Collapsing Cores and Star Formation," Eric Keto, Paola Caselli, and Jonathan Rawlings, MNRAS 446, 3731, 2015.

Source: Smithsonian Astrophysical Observatory

 

Mystery Mars plume baffles scientists

Mystery plume on Mars

Observations of a mysterious plume-like feature (marked with yellow arrow) at the limb of the Red Planet on 20 March 2012. The observation was made by astronomer W. Jaeschke. The image is shown with the north pole towards the bottom and the south pole to the top.  Copyright: W. Jaeschke

Plumes seen reaching high above the surface of Mars are causing a stir among scientists studying the atmosphere on the Red Planet. 

On two separate occasions in March and April 2012, amateur astronomers reported definite plume-like features developing on the planet. 

The plumes were seen rising to altitudes of over 250 km above the same region of Mars on both occasions. By comparison, similar features seen in the past have not exceeded 100 km. 

“At about 250 km, the division between the atmosphere and outer space is very thin, so the reported plumes are extremely unexpected,” says Agustin Sanchez-Lavega of the Universidad del País Vasco in Spain, lead author of the paper reporting the results in the journal Nature.

High-altitude plume on Mars

The top image shows the location of the mysterious plume on Mars, identified within the yellow circle (top image, south is up), along with different views of the changing plume morphology taken by W. Jaeschke and D. Parker on 21 March 21 2012. Copyright: W. Jaeschke and D. Parker

The features developed in less than 10 hours, covering an area of up to 1000 x 500 km, and remained visible for around 10 days, changing their structure from day to day.

None of the spacecraft orbiting Mars saw the features because of their viewing geometries and illumination conditions at the time.

However, checking archived Hubble Space Telescope images taken between 1995 and 1999 and of databases of amateur images spanning 2001 to 2014 revealed occasional clouds at the limb of Mars, albeit usually only up to 100 km in altitude.

But one set of Hubble images from 17 May 1997 revealed an abnormally high plume, similar to that spotted by the amateur astronomers in 2012.

Scientists are now working on determining the nature and cause of the plumes by using the Hubble data in combination with the images taken by amateurs.

Hubble spies mystery plume on Mars

A curious plume-like feature was observed on Mars on 17 May 1997 by the Hubble Space Telescope. It is similar to the features detected by amateur astronomers in 2012, although appeared in a different location. The Hubble image is extracted from this publicly available image.  Copyright: JPL/NASA/STScI

“One idea we’ve discussed is that the features are caused by a reflective cloud of water-ice, carbon dioxide-ice or dust particles, but this would require exceptional deviations from standard atmospheric circulation models to explain cloud formations at such high altitudes,” says Agustin. 

“Another idea is that they are related to an auroral emission, and indeed auroras have been previously observed at these locations, linked to a known region on the surface where there is a large anomaly in the crustal magnetic field,” adds Antonio Garcia Munoz, a research fellow at ESA’s ESTEC and co-author of the study. 

The jury is still out on the nature and genesis of these curious high-altitude martian plumes. Further insights should be possible following the arrival of ESA’s ExoMars Trace Gas Orbiter at the Red Planet, scheduled for launch in 2016.

Notes for Editors
 

“An extremely high altitude plume seen at Mars morning terminator,” by A. Sánchez-Lavega et al. is published in the 16 February 2015 issue of the journal Nature.

 

The ground-based images were provided by astronomers W. Jaeschke, D. Parker, J. Phillips and D. Peach. 

For further information, please contact:
 
Markus Bauer






ESA Science and Robotic Exploration Communication Officer







Tel: +31 71 565 6799







Mob: +31 61 594 3 954







Email: markus.bauer@esa.int

Agustin Sanchez-Lavega
Universidad del País Vasco UPV/EHU
Email: agustin.sanchez@ehu.es
Antonio Garcia Munoz
ESA-ESTEC
Email: agarcia@cosmos.esa.int

Source: ESA

NOAO: NASA Solicits Proposals for a World-class Precision Doppler Spectrometer at Kitt Peak National Observatory

Figure 1: Very high velocity precision is needed to measure the mass of low mass planets through the subtle motion, the “wobble”, that a planet induces in its host star. The extreme precision radial velocity spectrometer (EPDS) destined for Kitt Peak will measure stellar motions with a precision of 0.1 - 0.5 m/s (or 0.2 - 1 mph), velocities comparable to the running speed of a desert tortoise or gila monster. With such high precision, the spectrometer will be able to detect and characterize Jupiter- and Neptune-sized gas giant planets as well as super-Earth and Earth-sized rocky planets.

Kitt Peak National Observatory is the future home of a state-of-the-art instrument that will be used to detect and characterize other worlds. The new instrument, an extreme precision radial velocity spectrometer, will measure the subtle motion of stars produced by their orbiting planets. The spectrometer, funded by NASA, will be deployed on an existing telescope at Kitt Peak, the 3.5-meter WIYN telescope. The National Optical Astronomy Observatory (NOAO), which is funded by NSF, is a partner in the telescope and operates Kitt Peak. 

The spectrometer is the cornerstone of a newly established partnership between NSF and NASA focused on exoplanet research (NASA-NSF Exoplanet Observational Research; NN-EXPLORE), which aims to advance exoplanet science through the use of the NOAO share of the WIYN telescope. 

As an initial step in the partnership, NASA announced on 2015 January 22 a request for proposals to build an Extreme Precision Doppler Spectrometer (EPDS) for use by the astronomical community. The spectrometer will measure stellar radial velocities with a precision sufficient to characterize Jupiter- and Neptune-sized gas giant planets as well as super-Earth and Earth-sized rocky planets. 

The new spectrometer will be a world-class precision radial velocity instrument, with a minimum velocity precision of better than 0.5 m/s (1 mph) and a goal of 0.1 m/s (0.2 mph). For context, the leisurely speed of 0.2 mph is close to the top speed of a desert tortoise; and 1 mph is similar to the sprint speed of a gila monster. 

Such extreme precision is needed to measure the mass of an orbiting planet through the slight motion that the planet induces in the star. As a planet orbits a star, it causes the star to move, or “wobble”, as both objects orbit their gravitational center of mass. Lower mass planets induce subtler motions in the star, and correspondingly higher velocity precision is needed to characterize them. Jupiter causes a 13 m/s (29 mph) amplitude wobble in the Sun, whereas the Earth induces a much smaller wobble (about 0.1 m/s). As a result, extreme precision is needed to characterize rocky Earth-sized planets. 

The new spectrometer is expected to play a critical role in characterizing high-priority exoplanet targets identified by current and future NASA missions, in particular Kepler, K2, and TESS. The Kepler mission has found more than 1000 confirmed exoplanets and more than 3000 unconfirmed planet candidates to date. K2, Kepler’s extended mission survey of selected fields in the ecliptic plane, is currently underway. The future Transiting Exoplanet Survey Satellite (TESS) will conduct an all-sky survey of transiting exoplanet systems around relatively bright and nearby stars. 

Achieving the scientific potential of these missions requires supporting ground-based observations.

High-resolution imaging and spectroscopy are used to rule out astronomical false positives. Precise radial velocity measurements are needed to confirm the planetary nature of the companions and to measure their masses. As Kitt Peak Director Lori Allen explains, “Once we measure a planet’s mass, we can use what we know about the planet’s size, as measured by Kepler and TESS, to infer whether the planet is rocky like the Earth or gaseous like Jupiter.” 

NASA has established an aggressive development schedule for the new spectrometer in order to make the instrument available for use by the astronomical community on a timescale relevant to the availability of data from the TESS mission (mid-FY18). 

“NASA and the NSF are excited to team up to advance humankind’s understanding of planets around other stars,” said Doug Hudgins, Program Scientist for NASA’s Exoplanet Exploration Program. “The new EPDS spectrometer will give the US science community access to a world-class instrument for years to come.”

Although the new spectrometer is its cornerstone, the NSF-NASA partnership will be launched much in advance of its arrival. Beginning this year, the partnership will establish an exoplanet-related Guest Observer research program on the WIYN telescope using existing WIYN instrumentation. The new spectrometer will be included in the Guest Observer program beginning in 2018.

The National Optical Astronomy Observatory is operated by Association of Universities for Research in Astronomy Inc. under a cooperative agreement with the National Science Foundation.

Media Contact:

Dr. Joan Najita
National Optical Astronomy Observatory
950 N Cherry Ave
Tucson AZ 85719 USA
+1 520-318-8416
E-mail: najita@noao.edu

Source:  National Optical Astronomy Observatory (NOAO)

VLA Finds Unexpected "Storm" at Galaxy's Core

In this composite image of the Teacup Galaxy, the green colors show the starlight, the blue colors show the gas and the red/yellow colors show the radio emission. The bright yellow blobs in the center of the image show where the radio “jets,” launched by the black hole, are driving into the gas and accelerating it to 1,000 km/s (200,000 miles per hour). The giant bubbles also are being inflated by the central black hole. This demonstrates that the central black hole is having a catastrophic effect on its home galaxy. CREDIT: C. Harrison, A. Thomson; Bill Saxton, NRAO/AUI/NSF; NASA.

Astronomers using the National Science Foundation's Very Large Array (VLA) found surprisingly energetic activity in what they otherwise considered a "boring" galaxy, and their discovery provides important insight on how supermassive black holes can have a catastrophic effect on the galaxies in which they reside.

"It appears that a supermassive black hole is explosively heating and blasting around the gas in this galaxy and, as a result, is transforming it from an actively star-forming galaxy into one devoid of gas that can no longer form stars," said Chris Harrison, the lead-author of the study, from The Centre for Extragalactic Astronomy at Durham University in the U.K.

Two major types of galaxies are spirals, rich in gas and actively forming stars, and ellipticals, gas-poor and with very little star formation. The massive ellipticals, astronomers think, started life as actively star-forming galaxies. Powerful jets and winds of material, powered by supermassive black holes at the galaxies' centers, are believed to remove or destroy the raw material needed for continued star formation.

"For many years, we've seen direct evidence of this happening in galaxies that are extremely bright when viewed through radio telescopes. These, rare, radio-bright galaxies harbor powerful jets, launched at the black hole, that plow into the surrounding gas," Harrison said. "However, to understand how all of galaxies in our Universe formed, we needed to know if these same processes occur in less extreme galaxies that better represent the majority. This was the focus of our study," he added.

As part of an ongoing investigation, Harrison and his colleagues used the VLA to study a galaxy labelled J1430+1339, also known as the "Teacup," because of its appearance. About 1.1 billion light-years from Earth, the galaxy had been identified as having characteristics typical of galaxies with a central black hole actively consuming material. Follow-on observations with NASA's Hubble Space Telescope also revealed evidence that the Teacup has the appearance of a elliptical-type galaxy, but is surrounded by gas that suggests it is still in the process of transforming from a star-forming galaxy.

The VLA observations showed that the galaxy has "bubbles" extending from 30,000 to 40,000 light-years on each side of its core, along with smaller jet-like structures, about 2,000 light-years in size. These jet-like structures are located at the position where visible-light observations indicate gas is being accelerated to speeds up to about 1,000 kilometers per second.

Alasdair Thomson, another Durham astronomer involved in the study, said, "These radio observations have revealed that the central black hole is whipping up a storm at the center of this galaxy, by launching powerful jets that are accelerating the gas in the host galaxy and are colliding with the gas on larger scales. This is the same kind of powerful process we'd previously seen in rare, extremely radio-luminous galaxies. The incredible capabilites of the VLA have allowed us to discover that these processes can occur in the more-common, radio-faint galaxies, as long as you look hard enough."

"This 'storm' in the 'Teacup' means that the jet-driven process in which a black hole is removing or destroying star-forming material may be much more typical than we knew before, and could be a crucial piece in the puzzle of understanding how the galaxies we see around us were formed," Harrison said. Harrison and his collaborators now have observed eight more such objects with the VLA and are analyzing their data to see if the others show similar characteristics.

Harrison worked with a team of astronomers from the U.K., the U.S., and Chile. They presented their findings in the Astrophysical Journal.

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

Contact:

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

Source: National Radio Astronomy Observatory

'Pale Blue Dot' Images Turn 25

These six narrow-angle color images were made from the first ever "portrait" of the solar system taken by Voyager 1, which was more than 4 billion miles from Earth and about 32 degrees above the ecliptic. Image credit: NASA/JPL-Caltech.  › Full image and caption

 

The cameras of Voyager 1 on Feb. 14, 1990, pointed back toward the sun and took a series of pictures of the sun and the planets, making the first ever "portrait" of our solar system as seen from the outside. Image credit: NASA/JPL-Caltech.  › Full image and caption

 

This narrow-angle color image of the Earth, dubbed "Pale Blue Dot," is a part of the first ever "portrait" of the solar system taken by Voyager 1. Image credit: NASA/JPL-Caltech. › Full image and caption

Valentine's Day is special for NASA's Voyager mission. It was on Feb. 14, 1990, that the Voyager 1 spacecraft looked back at our solar system and snapped the first-ever pictures of the planets from its perch at that time beyond Neptune.

This "family portrait" captures Neptune, Uranus, Saturn, Jupiter, Earth and Venus from Voyager 1's unique vantage point. A few key members did not make it in: Mars had little sunlight, Mercury was too close to the sun, and dwarf planet Pluto turned out too dim. 

Taking these images was not part of the original plan, but the late Carl Sagan, a member of the Voyager imaging team at the time, had the idea of pointing the spacecraft back toward its home for a last look. The title of his 1994 book, "Pale Blue Dot," refers to the image of Earth in this series.

"Twenty-five years ago, Voyager 1 looked back toward Earth and saw a 'pale blue dot,' " an image that continues to inspire wonderment about the spot we call home," said Ed Stone, project scientist for the Voyager mission, based at the California Institute of Technology, Pasadena. 

The image of Earth contains scattered light that resembles a beam of sunlight, which is an artifact of the camera itself that makes the tiny Earth appear even more dramatic. Voyager 1 was 40 astronomical units from the sun at this moment. One astronomical unit is 93 million miles, or 150 million kilometers.

These family portrait images are the last that Voyager 1, which launched in 1977, returned to Earth. Mission specialists subsequently turned the camera off so that the computer controlling it could be repurposed. The spacecraft is still operating, but no longer has the capability to take images. 

"After taking these images in 1990, we began our interstellar mission. We had no idea how long the spacecraft would last," Stone said.

Today, Voyager 1, at a distance of 130 astronomical units, is the farthest human-made object from Earth, and it still regularly communicates with our planet. In August 2012, the spacecraft entered interstellar space - the space between the stars -- and has been delivering data about this uncharted territory ever since. Its twin, Voyager 2, also launched in 1977, is also journeying toward interstellar space. 

Voyager 1 is more than three times farther from Earth than it was on Valentine's Day 25 years ago. Today, Earth would appear about 10 times dimmer from Voyager's vantage point.

Sagan wrote in his "Pale Blue Dot" book: "That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. ... There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world."

A video clip of Ann Druyan, Carl Sagan's co-author and widow, discussing the pale blue dot image, is available at:  http://www.jpl.nasa.gov/video/details.php?id=1363

NASA's Jet Propulsion Laboratory, Pasadena, California, built and operates the twin Voyager spacecraft. The Voyagers Interstellar Mission is a part of NASA's Heliophysics System Observatory, sponsored by the Heliophysics Division of NASA's Science Mission Directorate in Washington.

For more information about Voyager, visit: http://voyager.jpl.nasa.gov

Media Contact

Elizabeth Landau
NASA's Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6425
Elizabeth.Landau@jpl.nasa.gov

 

 

  Source: JPL-Caltech/News