June 18, 2016

Carina Nebula above ALMA Telescope

Carina Nebula above ALMA Telescope

In this wonderful high definition, singe-exposure image taken during the ESO Ultra HD Expedition, three deep sky objects seem to shine in front of the dish of one of the Atacama Large Millimeter/submillimeter Array (ALMA) high-precision antennas.

The most striking feature is the reddish Carina Nebula, also known as NGC 3372. It is a large cloud of gas, mostly hydrogen, in which star formation has recently taken place. The short-lived massive blue stars forged within the nebula emit copious amounts of ultraviolet radiation, which then ionises the surrounding gas and causes the hydrogen atoms to glow with a characteristic red colour. Eventually supernova explosions and strong stellar winds from the most massive stars will disperse the gas of the Carina Nebula, leaving behind one or more clusters of stars.

Two such star clusters, known as NGC 3532 and IC 2602, can be seen respectively to the top right and top left of the Carina Nebula in this image.

The three celestial objects belong to the constellation of Carina (The Keel) and were first catalogued by the French astronomer Nicolas Louis de Lacaille. They look close to one another in this image, but actually their distances from us are very different. IC 2602 lies less than 500 light-years from Earth, NGC 3532 is around 1300 light-years away and the Carina Nebula is thought to lie up to 10 000 light-years away.

Image Credit: ESO/B. Tafreshi
Explanation from: http://www.eso.org/public/images/potw1548a/

Radio Galaxy Centaurus A

Centaurus A

The FORS2 image of Centaurus A, also known as NGC 5128, is an example of how frontier science can be combined with esthetic aspects. This galaxy is a most interesting object for the present attempts to understand active galaxies. It is being investigated by means of observations in all spectral regions, from radio via infrared and optical wavelengths to X- and gamma-rays. It is one of the most extensively studied objects in the southern sky. FORS2, with its large field-of-view and excellent optical resolution, makes it possible to study the global context of the active region in Centaurus A in great detail. Note for instance the great number of massive and luminous blue stars that are well resolved individually, in the upper right and lower left in ESO Press Photo eso0005b.

Centaurus A is one of the foremost examples of a radio-loud active galactic nucleus (AGN). On images obtained at optical wavelengths, thick dust layers almost completely obscure the galaxy's centre. This structure was first reported by Sir John Herschel in 1847. Until 1949, NGC 5128 was thought to be a strange object in the Milky Way, but it was then identified as a powerful radio galaxy and designated Centaurus A.

The distance is about 10-13 million light-years (3-4 Mpc) and the apparent visual magnitude is about 8, or 5 times too faint to be seen with the unaided eye.There is strong evidence that Centaurus A is a merger of an elliptical with a spiral galaxy, since elliptical galaxies would not have had enough dust and gas to form the young, blue stars seen along the edges of the dust lane. The core of Centaurus A is the smallest known extragalactic radio source, only 10 light-days across. A jet of high-energy particles from this centre is observed in radio and X-ray images. The core probably contains a supermassive black hole with a mass of about 100 million solar masses.

This image is a composite of three exposures in B (300 sec exposure, image quality 0.60 arcsec; here rendered in blue colour), V (240 sec, 0.60 arcsec; green) and R (240 sec, 0.55 arcsec; red). The full-resolution version of this photo retains the original pixels.

Image Credit: ESO
Explanation from: https://www.eso.org/public/images/eso0005b/

Hubble Image of NGC 3324

NGC 3324

Located in the Southern Hemisphere, NGC 3324 is at the northwest corner of the Carina Nebula (NGC 3372), home of the Keyhole Nebula and the active, outbursting star Eta Carinae. The entire Carina Nebula complex is located at a distance of roughly 7,200 light-years, and lies in the constellation Carina.

This image is a composite of data taken with two of Hubble's science instruments. Data taken with the Advanced Camera for Surveys (ACS) in 2006 isolated light emitted by hydrogen. More recent data, taken in 2008 with the Wide Field Planetary Camera 2 (WFPC2), isolated light emitted by sulfur and oxygen gas. To create a color composite, the data from the sulfur filter are represented by red, from the oxygen filter by blue, and from the hydrogen filter by green.

Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)
Explanation from: https://www.spacetelescope.org/images/opo0834a/

June 17, 2016

H II Region RCW 120

H II Region RCW 120

Colour composite image of RCW120. It reveals how an expanding bubble of ionised gas about ten light-years across is causing the surrounding material to collapse into dense clumps where new stars are then formed. The 870-micron submillimetre-wavelength data were taken with the LABOCA camera on the 12-m Atacama Pathfinder Experiment (APEX) telescope. Here, the submillimetre emission is shown as the blue clouds surrounding the reddish glow of the ionised gas (shown with data from the SuperCosmos H-alpha survey). The image also contains data from the Second Generation Digitized Sky Survey (I-band shown in blue, R-band shown in red).

Image Credit: ESO/APEX/DSS2/ SuperCosmos/ Deharveng(LAM)/ Zavagno(LAM)
Explanation from: https://www.eso.org/public/images/eso0840a/

Globular Cluster Messier 12

Globular Cluster Messier 12

The high concentration of stars within globular clusters, like Messier 12, shown here in an image from the NASA/ESA Hubble Space Telescope, makes them beautiful photographic targets. But the cramped living quarters in these clusters also makes them home to exotic binary star systems where two stars are locked in tight orbits around each other and matter from one is gobbled up by its companion, releasing X-rays. It is thought that such X-ray binaries form from very close encounters between stars in crowded regions, such as globular clusters, and even though Messier 12 is fairly diffuse by globular cluster standards, such X-ray sources have been spotted there.

Astronomers have also discovered that Messier 12 is home to far fewer low-mass stars than was previously expected. In a recent study, astronomers used the European Southern Observatory’s Very Large Telescope at Cerro Paranal, Chile, to measure the brightness and colours of more than 16 000 of the globular’s 200 000 stars. They speculate that nearly one million low-mass stars have been ripped away from Messier 12 as the globular has passed through the densest regions of the Milky Way during its orbit around the galactic centre.

It seems that the serenity of this view of Messier 12 is misleading and the object has had a violent and disturbed past.

Messier 12 lies about 23 000 light-years away in the constellation of Ophiuchus (The Serpent Bearer). This image was taken using the Wide Field Channel of Hubble’s Advanced Camera for Surveys. The colour image was created from exposures through a blue filter (F435W, coloured blue), a red filter (F625W, coloured green) and a filter that passes near-infrared light (F814W coloured red). The total exposure times were 1360 s, 200 s and 364 s, respectively. The field of view is about 3.2 x 3.1 arcminutes.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1113a/

The Flame Nebula

Flame Nebula

This VISTA image shows the spectacular star-forming region known as the Flame Nebula, or NGC 2024, in the constellation of Orion (the Hunter) and its surroundings. In views of this evocative object in visible light the core of the nebula is completely hidden behind obscuring dust, but in this VISTA view, taken in infrared light, the cluster of very young stars at the object’s heart is revealed. The wide-field VISTA view also includes the glow of the reflection nebula NGC 2023, just below centre, and the ghostly outline of the Horsehead Nebula (Barnard 33) towards the lower right. The bright bluish star towards the right is one of the three bright stars forming the Belt of Orion. The image was created from VISTA images taken through J, H and Ks filters in the near-infrared part of the spectrum. The image shows the full area of the VISTA field and is one degree by 1.5 degrees in extent. The total exposure time was 14 minutes.

Image Credit: ESO/J. Emerson/VISTA
Explanation from: https://www.eso.org/public/images/eso0949n/

June 16, 2016

British Isles seen from the International Space Station

British Isles seen from the International Space Station

ISS, Orbit of the Earth
June 2016

Image Credit: ESA/NASA

Artist's Impression of Dimming of FU Orionis

FU OrionisDimming of FU Orionis

This artist's concept illustrates how the brightness of outbursting star FU Orionis has been slowly fading since its initial flare-up in 1936. The star is pictured with the disk of material that surrounds it. Researchers found that it has dimmed by about 13 percent at short infrared wavelengths from 2004 (left) to 2016 (right).

The 2004 data were collected with NASA's Spitzer Space Telescope, and the 2016 data were collected with the Stratospheric Observatory for Infrared Astronomy (SOFIA).

FU Orionis is a few hundred thousand years old. It is possible that when our sun was younger, it also went through a period of intense brightening followed by dimming.

Image Credit: NASA/JPL-Caltech
Explanation from: http://photojournal.jpl.nasa.gov/catalog/PIA20689

IC 349: the Barnard's Merope Nebula

IC 349: the Barnard's Merope Nebula

NASA's Hubble Space Telescope has caught the eerie, wispy tendrils of a dark interstellar cloud being destroyed by the passage of one of the brightest stars in the Pleiades star cluster. Like a flashlight beam shining off the wall of a cave, the star is reflecting light off the surface of pitch black clouds of cold gas laced with dust. These are called reflection nebulae.

The famous cluster is easily visible in the evening sky during the winter months as a small grouping of bright blue stars, named after the "Seven Sisters" of Greek mythology. Resembling a small dipper, this star cluster lies in the constellation Taurus at a distance of about 380 light-years from Earth. The unaided eye can discern about half a dozen bright stars in the cluster, but a small telescope will reveal that the Pleiades contains many hundreds of fainter stars.

In many cases, the nebulae surrounding star clusters represent material from which the stars have formed recently. However the Pleiades nebulosity is actually an independent cloud, drifting through the cluster at a relative speed of about 6.8 miles/second (11 kilometers/second).

In 1890, American astronomer E. E. Barnard, observing visually with the Lick Observatory 36-inch telescope in California, discovered an exceptionally bright nebulosity adjacent to the bright Pleiades star Merope. It is now cataloged as IC 349, or "Barnard's Merope Nebula." IC 349 is so bright because it lies extremely close to Merope—only about 3,500 times the separation of the Earth from the Sun, or about 0.06 light-year—and thus is strongly illuminated by the star's light.

In the new Hubble image, Merope itself is just outside the frame on the upper right. The colorful rays of light at the upper right, pointing back to the star, are an optical phenomenon produced within the telescope, and are not real. However, the remarkable parallel wisps extending from lower left to upper right are real features, revealed for the first time through Hubble's high-resolution imaging capability. Astronomers George Herbig and Theodore Simon of the University of Hawaii obtained these broadband observations with Hubble's Wide Field and Planetary Camera 2 on September 19, 1999.

Herbig and Simon propose that, as the Merope Nebula approaches Merope, the strong starlight shining on the dust decelerates the dust particles. Physicists call this phenomenon "radiation pressure."

Smaller dust particles are slowed down more by the radiation pressure than the larger particles. Thus, as the cloud approaches the star, there is a sifting of particles by size, much like grain thrown in the air to separate wheat from chaff. The nearly straight lines pointing toward Merope are thus streams of larger particles, continuing on toward the star while the smaller decelerated particles are left behind at the lower left of the picture.

Over the next few thousand years, the nebula—if it survives the close passage without being completely destroyed—will move on past Merope, somewhat like a comet swinging past our Sun. This chance collision allows astronomers to study interstellar material under very rare conditions, and thus learn more about the structure of the dust lying between the stars.

Image Credit: NASA and The Hubble Heritage Team (STScI/AURA)
Explanation from: http://hubblesite.org/newscenter/archive/releases/2000/36/image/a/

June 15, 2016

Gluttonous Star May Hold Clues to Planet Formation

Planet Formation

In 1936, the young star FU Orionis began gobbling material from its surrounding disk of gas and dust with a sudden voraciousness. During a three-month binge, as matter turned into energy, the star became 100 times brighter, heating the disk around it to temperatures of up to 12,000 degrees Fahrenheit (7,000 Kelvin). FU Orionis is still devouring gas to this day, although not as quickly.

This brightening is the most extreme event of its kind that has been confirmed around a star the size of the sun, and may have implications for how stars and planets form. The intense baking of the star's surrounding disk likely changed its chemistry, permanently altering material that could one day turn into planets.

"By studying FU Orionis, we're seeing the absolute baby years of a solar system," said Joel Green, a project scientist at the Space Telescope Science Institute, Baltimore, Maryland. "Our own sun may have gone through a similar brightening, which would have been a crucial step in the formation of Earth and other planets in our solar system."

Visible light observations of FU Orionis, which is about 1,500 light-years away from Earth in the constellation Orion, have shown astronomers that the star's extreme brightness began slowly fading after its initial 1936 burst. But Green and colleagues wanted to know more about the relationship between the star and surrounding disk. Is the star still gorging on it? Is its composition changing? When will the star's brightness return to pre-outburst levels?

To answer these questions, scientists needed to observe the star’s brightness at infrared wavelengths, which are longer than the human eye can see and provide temperature measurements.

Green and his team compared infrared data obtained in 2016 using the Stratospheric Observatory for Infrared Astronomy, SOFIA, to observations made with NASA's Spitzer Space Telescope in 2004. SOFIA, the world's largest airborne observatory, is jointly operated by NASA and the German Aerospace Center and provides observations at wavelengths no longer attainable by Spitzer. The SOFIA data were taken using the FORCAST instrument (Faint Object infrared Camera for the SOFIA Telescope).

"By combining data from the two telescopes collected over a 12-year interval, we were able to gain a unique perspective on the star's behavior over time," Green said.

Using these infrared observations and other historical data, researchers found that FU Orionis had continued its ravenous snacking after the initial brightening event: The star has eaten the equivalent of 18 Jupiters in the last 80 years.

The recent measurements provided by SOFIA inform researchers that the total amount of visible and infrared light energy coming out of the FU Orionis system decreased by about 13 percent over the 12 years since the Spitzer observations. Researchers determined that this decrease is caused by dimming of the star at short infrared wavelengths, but not at longer wavelengths. That means up to 13 percent of the hottest material of the disk has disappeared, while colder material has stayed intact.

"A decrease in the hottest gas means that the star is eating the innermost part of the disk, but the rest of the disk has essentially not changed in the last 12 years," Green said. "This result is consistent with computer models, but for the first time we are able to confirm the theory with observations."

Astronomers predict, partly based on the new results, that FU Orionis will run out of hot material to nosh on within the next few hundred years. At that point, the star will return to the state it was in before the dramatic 1936 brightening event. Scientists are unsure what the star was like before or what set off the feeding frenzy.

"The material falling into the star is like water from a hose that's slowly being pinched off," Green said. "Eventually the water will stop."

If our sun had a brightening event like FU Orionis did in 1936, this could explain why certain elements are more abundant on Mars than on Earth. A sudden 100-fold brightening would have altered the chemical composition of material close to the star, but not as much farther from it. Because Mars formed farther from the sun, its component material would not have been heated up as much as Earth's was.

At a few hundred thousand years old, FU Orionis is a toddler in the typical lifespan of a star. The 80 years of brightening and fading since 1936 represent only a tiny fraction of the star's life so far, but these changes happened to occur at a time when astronomers could observe.

"It's amazing that an entire protoplanetary disk can change on such a short timescale, within a human lifetime," said Luisa Rebull, study co-author and research scientist at the Infrared Processing and Analysis Center (IPAC), based at Caltech, Pasadena, California.

Green plans to gain more insight into the FU Orionis feeding phenomenon with NASA's James Webb Space Telescope, which will launch in 2018. SOFIA has mid-infrared high-resolution spectrometers and far-infrared science instrumentation that complement Webb’s planned near- and mid-infrared capabilities. Spitzer is expected to continue exploring the universe in infrared light, and enabling groundbreaking scientific investigations, into early 2019.

Image Credit: NASA/JPL-Caltech
Explanation from: https://www.nasa.gov/feature/jpl/gluttonous-star-may-hold-clues-to-planet-formation

Scattered stars in Sagittarius

stars in Sagittarius

This colourful and star-studded view of the Milky Way galaxy was captured when the NASA/ESA Hubble Space Telescope pointed its cameras towards the constellation of Sagittarius (The Archer). Blue stars can be seen scattered across the frame, set against a distant backdrop of red-hued cosmic companions. This blue litter most likely formed at the same time from the same collapsing molecular cloud.

The colour of a star can reveal many of its secrets. Shades of red indicate a star much cooler than the Sun, so either at the end of its life, or much less massive. These lower-mass stars are called red dwarfs and are thought to be the most common type of star within the Milky Way. Similarly, brilliant blue hues indicate hot, young, or massive stars, many times the mass of the Sun.

A star’s mass decides its fate; more massive stars burn brightly over a short lifespan, and die young after only tens of millions of years. Stars like the Sun typically have more sedentary lifestyles and live longer, burning for approximately ten billion years. Smaller stars, on the other hand, live life in the slow lane and are predicted to exist for trillions of years, well beyond the current age of the Universe.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1624a/

WFPC2 Mosaic of NGC 604 in M33

NGC 604

This full mosaic WFPC2 image shows a slightly larger area around NGC 604. The scale of this image is 2.5 arcminutes along the bottom.

Image Credit: NASA/ESA and The Hubble Heritage Team (AURA/STScI)

June 14, 2016

Hubble finds Universe may be expanding faster than expected

expansion of space

Astronomers have used Hubble to measure the distances to stars in nineteen galaxies more accurately than previously possible. They found that the Universe is currently expanding faster than the rate derived from measurements of the Universe shortly after the Big Bang. If confirmed, this apparent inconsistency may be an important clue to understanding three of the Universe’s most elusive components: dark matter, dark energy and neutrinos.

A team of astronomers, led by Nobel Laureate Adam Riess and using the NASA/ESA Hubble Space Telescope, have discovered that the Universe is expanding between five and nine percent faster than previously calculated. This is in clear discrepancy with the rate predicted from measurements of the infant Universe.

“This surprising finding may be an important clue to understanding those mysterious parts of the Universe that make up 95 percent of everything and don’t emit light, such as dark energy, dark matter, and dark radiation,” explains Adam Riess of the Space Telescope Science Institute and the Johns Hopkins University, both in Baltimore, USA.

One possible explanation for this unexpectedly fast expansion of the Universe is a new type of subatomic particle that may have changed the balance of energy in the early Universe, so called dark radiation.

The team made the discovery by refining the measurement of how fast the Universe is expanding, a value called the Hubble constant, to unprecedented accuracy, reducing the uncertainty to only 2.4 percent.

This new measurement presents a puzzle because it does not agree with the expansion rate found by looking at the moments shortly after the Big Bang. Measurements of the afterglow from the Big Bang from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) and the European Space Agency’s Planck satellite mission yield smaller predictions for the Hubble constant.

Comparing the Universe’s expansion rate as calculated by WMAP and Planck (for the time after the Big Bang) and Hubble (for our modern Universe) is like building a bridge, Riess explains: “You start at two ends, and you expect to meet in the middle if all of your drawings are right and your measurements are right. But now the ends are not quite meeting in the middle and we want to know why.”

This refined determination of the Hubble constant was made possible by making precise measurements of the distances to both nearby and faraway galaxies using Hubble. The improved distance measurements were made by streamlining and strengthening the cosmic distance ladder, which astronomers use to measure accurate distances to galaxies. The team compared these measured distances with the expansion of space as measured by the stretching of light from receding galaxies and these two values were then used to calculate the Hubble constant.

The team is continuing to use Hubble with the aim of reducing the uncertainty in the Hubble constant even further, their goal being to reach an uncertainty of just 1 percent. Current telescopes such as the European Space Agency’s Gaia satellite, and future telescopes such as the NASA/ESA/CSA James Webb Space Telescope (JWST) and the European Extremely Large Telescope (E-ELT) could also help astronomers make better measurements of the expansion rate and lead to a better understanding of our Universe and the laws that govern it.

Image Credit: NASA,ESA, A. Feild (STScI), and A. Riess (STScI/JHU)
Explanation from: https://www.spacetelescope.org/news/heic1611/

Dragonfish Nebula in the Infrared

Dragonfish Nebula in the Infrared

This infrared image from NASA's Spitzer Space Telescope shows the nebula nicknamed "the Dragonfish." This turbulent region, jam-packed with stars, is home to some of the most luminous massive stars in our Milky Way galaxy. It is located approximately 30,000 light-years away in the Crux constellation.

The massive stars have blown a bubble in the gas and dust, carving out a shell of more than 100 light-years across (seen in lower, central part of image). This shell forms the "toothy mouth" of the Dragonfish, and the two bright spots make it up its beady eyes.

The infrared light in this region is coming from the gas and dust that are being heated up by the unseen central cluster of massive stars. The bright spots along the shell, including the "eyes," are possible smaller regions of newly formed stars, triggered by the compression of the gas and dust by winds from the central, massive stars.

Infrared light in this image was captured by the infrared array camera on Spitzer, at wavelengths of 3.6 microns (blue); 4.5 microns (green); and 8.0 microns (red). The data were captured before Spitzer ran out of its liquid coolant in 2009, and began its "warm" mission.

Image Credit: NASA/JPL-Caltech/Univ. of Toronto
Explanation from: http://www.spitzer.caltech.edu/images/4838-sig11-018-Dragonfish-Coming-At-You-in-Infrared

Artist’s impression of cold intergalactic rain

cold intergalactic rain

Deep in the heart of the Abell 2597 Brightest Cluster Galaxy, astronomers see a small cluster of giant gas clouds raining in on the central black hole. They were revealed by the billion light-year-long shadows they cast toward Earth. These ALMA data present the first observational evidence for predicted chaotic cold accretion onto a supermassive black hole.

Image Credit: NRAO/AUI/NSF; Dana Berry/SkyWorks; ALMA (ESO/NAOJ/NRAO)
Explanation from: http://www.eso.org/public/images/eso1618b/

June 13, 2016

Earth seen from the International Space Station

Earth seen from the International Space Station

ISS, Orbit of the Earth
April 2016

Image Credit: ESA/NASA

The IC 2560 Galaxy

The IC 2560 Galaxy

Lying over 110 million light-years away from Earth in the constellation of Antlia (The Air Pump) is the spiral galaxy IC 2560, shown here in an image from NASA/ESA Hubble Space Telescope. At this distance it is a relatively nearby spiral galaxy, and is part of the Antlia cluster — a group of over 200 galaxies held together by gravity. This cluster is unusual; unlike most other galaxy clusters, it appears to have no dominant galaxy within it.

In this image, it is easy to spot IC 2560's spiral arms and barred structure. This spiral is what astronomers call a Seyfert-2 galaxy, a kind of spiral galaxy characterised by an extremely bright nucleus and very strong emission lines from certain elements — hydrogen, helium, nitrogen, and oxygen. The bright centre of the galaxy is thought to be caused by the ejection of huge amounts of super-hot gas from the region around a central black hole.

There is a story behind the naming of this quirky constellation — Antlia was originally named antlia pneumatica by French astronomer Abbé Nicolas Louis de Lacaille, in honour of the invention of the air pump in the 17th century.

Image Credit: ESA/Hubble, NASA, Nick Rose
Explanation from: https://www.spacetelescope.org/images/potw1335a/

Black Hole Fed by Cold Intergalactic Delug

cold intergalactic rain

An international team of astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) has witnessed a cosmic weather event that has never been seen before — a cluster of towering intergalactic gas clouds raining in on the supermassive black hole at the centre of a huge galaxy one billion light-years from Earth. The results will appear in the journal Nature on 9 June 2016.

The new ALMA observation is the first direct evidence that cold dense clouds can coalesce out of hot intergalactic gas and plunge into the heart of a galaxy to feed its central supermassive black hole. It also reshapes astronomers’ views on how supermassive black holes feed, in a process known as accretion.

Previously, astronomers believed that, in the largest galaxies, supermassive black holes fed on a slow and steady diet of hot ionised gas from the galaxy’s halo. The new ALMA observations show that, when the intergalactic weather conditions are right, black holes can also gorge on a clumpy, chaotic downpour of giant clouds of very cold molecular gas.

“Although it has been a major theoretical prediction in recent years, this is one of the first unambiguous pieces of observational evidence for a chaotic, cold rain feeding a supermassive black hole,” said Grant Tremblay, an astronomer with Yale University in New Haven, Connecticut, USA, former ESO Fellow, and lead author on the new paper. “It’s exciting to think we might actually be observing this galaxy-spanning rainstorm feeding a black hole whose mass is about 300 million times that of the Sun.”

Tremblay and his team used ALMA to peer into an unusually bright cluster of about 50 galaxies, collectively known as Abell 2597. At its core is a massive elliptical galaxy, descriptively named the Abell 2597 Brightest Cluster Galaxy. Suffusing the space between these galaxies is a diffuse atmosphere of hot ionised gas, which was previously observed with NASA’s Chandra X-ray Observatory.

"This very, very hot gas can quickly cool, condense, and precipitate in much the same way that warm, humid air in Earth's atmosphere can spawn rain clouds and precipitation," Tremblay said. "The newly condensed clouds then rain in on the galaxy, fueling star formation and feeding its supermassive black hole."

Near the centre of this galaxy the researchers discovered just this scenario: three massive clumps of cold gas are careening toward the supermassive black hole in the galaxy’s core at about a million kilometres per hour. Each cloud contains as much material as a million Suns and is tens of light-years across.

Normally, objects on that scale would be difficult to distinguish at these cosmic distances, even with ALMA’s amazing resolution. They were revealed, however, by the billion-light-year-long “shadows” they cast toward Earth.

Additional data from the National Science Foundation’s Very Long Baseline Array indicate that the gas clouds observed by ALMA are only about 300 light-years from the central black hole, essentially teetering on the edge of being devoured, in astronomical terms.

While ALMA was only able to detect three clouds of cold gas near the black hole, the astronomers speculate that there may be thousands like them in the vicinity, setting up the black hole for a continuing downpour that could fuel its activity for a long time.

The astronomers now plan to use ALMA to search for these "rainstorms" in other galaxies in order to determine whether such cosmic weather is as common as current theory suggests it might be.

Image Credit: NRAO/AUI/NSF; Dana Berry/SkyWorks; ALMA (ESO/NAOJ/NRAO)
Explanation from: http://www.eso.org/public/news/eso1618/

June 12, 2016

Scotland, Northern Ireland and Isle of Man seen from the International Space Station

Scotland, Northern Ireland and Isle of Man seen from the International Space Station

ISS, Orbit of the Earth
May 2016

Image Credit: ESA/NASA

Star-Forming Region NGC 6334

Star-Forming Region NGC 6334

This image of the star formation region NGC 6334 is one of the first scientific images from the ArTeMiS instrument on APEX. The picture shows the glow detected at a wavelength of 0.35 millimetres coming from dense clouds of interstellar dust grains. The new observations from ArTeMiS show up in orange and have been superimposed on a view of the same region taken in near-infrared light by ESO’s VISTA telescope at Paranal.

Image Credit: ArTeMiS team/Ph. André, M. Hennemann, V. Revéret et al./ESO/J. Emerson/VISTA
Explanation from: https://www.eso.org/public/images/eso1341a/

The NGC 524 Galaxy

The NGC 524 Galaxy

This striking cosmic whirl is the centre of galaxy NGC 524, as seen with the NASA/ESA Hubble Space Telescope. This galaxy is located in the constellation of Pisces, some 90 million light-years from Earth.

NGC 524 is a lenticular galaxy. Lenticular galaxies are believed to be an intermediate state in galactic evolution — they are neither elliptical nor spiral. Spirals are middle-aged galaxies with vast, pinwheeling arms that contain millions of stars. Along with these stars are large clouds of gas and dust that, when dense enough, are the nurseries where new stars are born. When all the gas is either depleted or lost into space, the arms gradually fade away and the spiral shape begins to weaken. At the end of this process, what remains is a lenticular galaxy — a bright disc full of old, red stars surrounded by what little gas and dust the galaxy has managed to cling on to.

This image shows the shape of NGC 524 in detail, formed by the remaining gas surrounding the galaxy’s central bulge. Observations of this galaxy have revealed that it maintains some spiral-like motion, explaining its intricate structure.

Image Credit: ESA/Hubble, NASA, Nick Rose
Explanation from: https://www.spacetelescope.org/images/potw1329a/