Analysis of the galaxy ESO 243-49 in multiple wavelengths has detected the signature of hot stars swirling around a midsize black hole, highlighted by the white circle on this Hubble Space Telescope image. Astronomers say the readings suggest that the black hole is actually part of the leftovers from a dwarf galaxy that crashed into the bigger galaxy and disintegrated.

Astronomers have reconstructed what they think is a galactic crash scene, with a rare breed of black hole left behind amid a dwarf galaxy's wreckage. The Hubble Space Telescope played a key role in the accident investigation.

The black hole was detected three years ago in the edge-on spiral galaxy ESO 243-49, about 290 million light-years from Earth, and raised a question that's been bugging astronomers ever since.

The theoretical scenario for creating black holes through the collapse of stars is well-known. But scientists are just beginning to figure out how galaxy formation can lead to the creation of supermassive black holes that are millions or billions of times heavier than the sun. This particular black hole, designated HLX-1, was even more of a puzzler: It's about 20,000 times as massive as our sun, a kind of midsize monster that's rarely seen in our celestial neighborhood.

The astronomer who led the HLX-1 search effort, Sean Farrell of the University of Leicester and the Sydney Institute for Astronomy, took a closer look at the black hole with the aid of imagery in ultraviolet, visible and infrared wavelengths from Hubble, as well as X-ray imagery from NASA's Swift satellite. Now he and his colleagues are suggesting that the midsize black hole is a leftover from a dwarf galaxy's unfortunate encounter with the much bigger galaxy less than 200 million years earlier.

They came to that conclusion based on observations of light toward the reddish side of the spectrum — so much red light that it can't be explained just by the blaze of material falling into the black hole. Farrell and his colleagues think the light is coming from a cluster of hot stars surrounding the black hole.

"The fact that there’s a very young cluster of stars indicates that the intermediate-mass black hole may have originated as the central black hole in a very low-mass dwarf galaxy," Farrell said in a news release from the European Space Agency's Hubble team. "The dwarf galaxy was then swallowed by the more massive galaxy."

As the dwarf galaxy was ripped apart, the black hole and some of its surrounding material would have survived.

The researchers say it's not yet clear what will happen to the black hole. It might spiral into the center of ESO 243-49, merging with the supermassive black hole that's already there. Or it might settle into a stable orbit in the bigger galaxy's outer environs. Either way, the X-ray emissions that brought the black hole to light in the first place will eventually fade away.

The findings from Farrell and his colleagues were published today by The Astrophysical Journal, and the team will continue watching HLX-1 for more clues.

Looking beyond just one intermediate-mass black hole, the astronomers say the case of HLX-1 sheds light on the bigger mysteries surrounding the formation of those supermassive, galaxy-scale black holes. Most theorists surmise that big galaxies — and the big black holes at their centers — are built up gradually through the merger of smaller galaxies. This research supports that view.

Our own Milky Way galaxy might well go through the next phase of the merger process in a few billion years, when it's due to mix it up with Andromeda and create a bigger behemoth nicknamed "Milkomeda."

More about galaxy mergers:

• Twisted galaxy warped by 'stealth merger'
• Almost every galaxy has had a major collision
• Galactic merger could boot our solar system
• NASA spots most crowded space collision ever
• Black hole knocked off its axis by galaxy collision
• Cosmic Log archive on galaxies | black holes

In addition to Farrell, authors of "A Young Stellar Population Around the Intermediate Mass Black Hole ESO 243-49 HLX-1" include M. Servillat, J. Pforr, T.J. Maccarone, C. Knigge, O. Godet, C. Maraston, N.A. Webb, D. Barret, A. Gosling, R. Belmont and K. Wiersema.

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.

Scott Noble / RIT

A simulation shows superheated plasma swirling around the black hole at the center of our galaxy.

Astronomers are setting up a virtual telescope as wide as our planet to capture the first picture outlining our galaxy's monstrous black hole. 

"Everybody's super-excited," one of the leaders of the effort, astrophysicist Dimitrios Psaltis of the University of Arizona's Steward Observatory, told me today. "A couple of years ago, this was science fiction. Now it's becoming a reality."

Psaltis and his colleagues are calling together researchers from around the world for a conference in Tucson starting Wednesday, with the aim of combining up to 50 radio telescopes from Taiwan to the Netherlands to the South Pole into one big observing instrument they call the "Event Horizon Telescope."

The observations have to be done by radio telescopes sensitive to millimeter-scale wavelengths, because that's the ideal range for seeing through "the dust and the mess" at the center of our Milky Way galaxy, Psaltis said.

By combining millimeter-wave radio readings from widely separated antennas, astronomers can produce an unparalleled picture of the region around our Milky Way's central black hole. "We expect to see the swirling of matter going into the black hole in real time," Psaltis said. "What we're really hoping to see is how the black hole is fed."

Black hole in the neighborhood
A black hole is an object so massive that nothing, not even light, can escape its gravitational grip within a boundary known as the event horizon. Black holes can be created by the catastrophic collapse of massive stars, and a much larger breed can take root at the center of galaxy during its formation. The black hole at the center of the Milky Way is relatively frugal in its dining habits, and that's probably a good thing for us: Scientists have suggested that the violent galactic environment associated with more ravenous supermassive black holes wouldn't be conducive to life as we know it.

Even though our galaxy's black hole is thought to have the mass of 4 million suns, and even though astronomers have determined its location by charting its gravitational effect, astronomers have never seen it directly. The black hole itself would be nothing more than a black spot, surrounded by a blazing swirl of inward-falling matter. Its extent is said to be no more than the width of Mercury's orbit around the sun, and astronomers would be watching it from a distance of 26,000 light-years. Actually seeing the "shadow" or silhouette of the black hole's event horizon would be as challenging as spotting a grapefruit on the moon, according to a University of Arizona news release.

Despite those challenges, the astronomers behind the Event Horizon Telescope believe the observation can at last be made, in part because of promising results from a pilot study conducted using the Steward Observatory's Submillimeter Telescope in Arizona, the James Clerk Maxwell Telescope on Mauna Kea in Hawaii and the Combined Array for Research in Millimeter-wave Astronomy in California.

"Those three telescopes told us that we can actually observe all the way to the black hole," Psaltis told me.

Testing Einstein
Now more telescopes will be brought into the network, including the 50-antenna Atacama Large Millimeter Array in Chile, also known as ALMA. Sheperd Doeleman of MIT's Haystack Observatory, who is the principal investigator for the Event Horizon Telescope, says ALMA's participation will be a "real game-changer."

"We will be able to actually see what happens very close to the horizon of a black hole, which is the strongest gravitational field you can find in the universe," he said in the news release. "No one has ever tested Einstein's general theory of relativity at such strong fields."

Observing the bright outline that defines the black hole's shadow could serve as an unprecedented test of general relativity, Psaltis said. If the outline is precisely circular, that would be in line with what Einstein's theory predicts. But if the outline turns out to be elliptical, the theory "must be flawed" in some way, he said.

Psaltis emphasized that the black hole picture would not take shape all at once. Instead, the details would emerge gradually as more and more readings are sent to the project's central data processing center at MITs' Haystack Observatory.

"In perhaps three years, we'll be able to have the first complete picture of the black hole," he said.

More about black holes:

• How a black hole throws fastballs
• Zoom in on the black hole next door
• Our monster black hole will get a colossal feast
• Cygnus X-1 provides answers to black hole questions
• KVOA: Scientists meet in Tucson to get set for black hole picture

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds. 

T. Lauer / NOAO / NASA / ESA

A new Hubble Space Telescope image centers on the 100-million-solar-mass black hole at the hub of the neighboring spiral galaxy M31, or the Andromeda Galaxy, one of the few galaxies outside the Milky Way visible to the naked eye and the only other giant galaxy in the Local Group. This is the sharpest visible-light image ever made of the nucleus of an external galaxy.

The Hubble Space Telescope has captured the best view yet of the Andromeda Galaxy's nucleus — which is actually a double nucleus, thanks to the galaxy's supermassive black hole.

Andromeda is the nearest spiral galaxy to our own Milky Way, and the only galaxy outside our own that's visible to the naked eye. But it's not easy to see what's going on at the bright center of the spiral. Astronomer Tod Lauer of the National Optical Astronomy Observatory put together several exposures in blue and ultraviolet wavelengths from Hubble's Advanced Camera for Surveys to produce this ultra-sharp view.

The inset photograph tells the story: The black hole itself can't be seen, but it's near the center of a compact cluster of blue stars at the center of the inset. That cluster is surrounded by the double nucleus, an elliptical ring of older reddish stars in orbit around the black hole.

"When the stars are at the farthest point in their orbit they move slower, like cars on a crowded freeway," NASA says in its image advisory. "This gives the illusion of a second nucleus."

NASA notes that the blue stars in the cluster are no more than 200 million years old, and had to have formed close to where they are now. Such stars wouldn't last long enough to form somewhere else and move inward.

So how can stars form so deep within the black hole's gravitational field? That's what Lauer and other astronomers are trying to figure out.

Lauer presented the Hubble observations this week in Austin, Texas, at a meeting of the American Astronomical Society.

More from the astronomy meeting:

• Astronomers share galactic glories
• Hubble spots primordial galaxy cluster
• Three newfound worlds are smaller than Earth
• Scientists find most distant supernova of its kind

X-ray and radio observations have revealed how a black hole winds up and pitches fastballs made of ionized gas at a quarter of the speed of light. That's about 1.6 million times faster than the fastest fastball ever pitched on Earth.

The pitches were clocked during an outburst from the black hole system H1743-322 in mid-2009. using NASA's Rossi X-Ray Timing Explorer and the National Science Foundation's Very Long Baseline Array. The binary system, 28,000 light-years from Earth in the constellation Scorpius, consists of a normal star and a black hole that are gravitationally bound together. The black hole sucks material in a continuous stream from the star, drawing it down in a swirling disk.

Some of the superheated material radiates away from the black hole's surroundings in two jets that point in opposite directions. Every once in a while, hot ionized gas bunches up into huge "bullets" that are wound up and flung out from the disk. RXTE and the VLBA spotted a couple of the bullets as they sped away in early June 2009.

"Like a referee at a sports game, we essentially rewound the footage on the bullets' progress, pinpointing when they were launched," Gregory Sivakoff of the University of Alberta said Tuesday in a NASA news release. "With the unique capabilities of RXTE and the VLBA, we can associate their ejection with changes that likely signaled the start of the process."

By comparing the X-ray observations of H1743-322 and the radio emissions from the blobs of gas, astronomers were able to figure a timeline for the interactions in the disk and the ejection of the fastballs. Sivakoff presented the research team's findings this week in Austin, Texas, at a meeting of the American Astronomical Society, and a paper on the observations will be published in the Monthly Notices of the Royal Astronomical Society.

"This research provides new clues about the conditions needed to initiate a jet and can guide our thinking about how it happens," said Chris Done, an astrophysicist at the University of Durham in England who was not involved in the study.

Rest in peace, Rossi
The study serves as a sendoff of sorts for the Rossi X-Ray Timing Explorer, which was decommissioned last week after 16 years of science operations. "The spacecraft and its instruments had been showing their age, and in the end RXTE had accomplished everything we put it up there to do, and much more," Tod Strohmayer, RXTE project scientist at NASA's Goddard Space Flight Center, said in the space agency's obituary for the probe.

RXTE played a part in mapping the space-time shift around spinning black holes and neutron stars, detecting a black hole's X-ray "heartbeat," figuring out what's behind our galaxy's X-ray glow, studying a superflare blasted out from the Crab Nebula and observing many other extreme phenomena.

NASA says the 7,000-pound satellite is expected to re-enter the atmosphere and burn up sometime between 2014 and 2023, depending largely on how solar activity affects the decay of its orbit.

More from this week's astronomy meeting:

• Zoom in on the black hole next door
• Astronomers share galactic glories
• Hubble spots primordial galaxy cluster
• Three newfound worlds are smaller than Earth
• Scientists find most distant supernova of its kind

A network of radio telescopes scattered around the Southern Hemisphere has produced the best-ever view of cosmic jets erupting from a supermassive black hole at the center of another galaxy.

The new image shows a region of space less than 4.2 light-years across at the heart of Centaurus A, 12 million light-years away in the constellation Centaurus (of course). The galaxy, also known as NGC 5128 is anchored by a black hole as massive as 55 million suns. It's a huge radio source. In fact, if our eyes could see radio waves, Centaurus A would look nearly 20 times as big as the full moon, due to the giant lobes of radio-emitting matter spreading out from the galaxy itself.

The matter is streaming into the lobes via the particle jets that emanate from the black hole.

"These jets arise as infalling matter approaches the black hole, but we don't yet know the details of how they form and maintain themselves," Cornelia Müller, a doctoral student at the University of Erlangen-Nuremberg in Germany, said in a NASA image advisory released today.

Müller is the lead author of a study about the jets, appearing in the June issue of Astronomy and Astrophysics. She and her colleagues targeted Centaurus A with a network of nine radio telescopes in Africa, South America and Australia, known collectively as the Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry project, or TANAMI. The telescopes joined forces to zoom in on the heart of the galaxy.

NASA

Left: The giant elliptical galaxy NGC 5128 is the radio source known as Centaurus A. Vast radio-emitting lobes (shown as orange in this optical/radio composite) extend nearly a million light-years from the galaxy. Right: The radio image from the TANAMI project provides the sharpest-ever view of a supermassive black hole's jets. This view reveals the inner 4.16 light-years of the jet and counterjet, a span less than the distance between our sun and the nearest star. Undetected between the jets is the galaxy's 55-million-solar-mass black hole.

"Advanced computer techniques allow us to combine data from the individual telescopes to yield images with the sharpness of a single giant telescope, one nearly as large as Earth itself," Roopesh Ojha of NASA's Goddard Space Flight Center explained.

The radio image shows features as small as 15 light-days across, which makes it the highest-resolution view of galactic jets ever made. Studying the jets in such detail should help astronomers figure out how they form — which would make Müller very happy.

More about Centaurus A and black hole jets:

• See a black hole's blast
• Giant cannibal galaxy caught in mid-gobble
• Black hole spews jets in telescope's first image
• Inside a celestial super-volcano

In addition to Müller and Ojha, the authors of "Dual Frequency VLBI Study of Centaurus A on Sub-parsec Scales" include M. Kadler, J. Wilms, M. Böck, P.G. Edwards, C.M. Fromm, H. Hase, S. Horiuchi, U. Katz, J.E.J. Lovell, C. Plötz, T. Pursimo, S. Richers, E. Ros, R.E. Rothschild, G.B. Taylor, S.J. Tingay and J.A. Zensus.

Connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. You can also check out "The Case for Pluto," Alan's book about the controversial dwarf planet and the search for new worlds. 

Lynette Cook / Gemini Observatory / AURA

An artist's concept of what a future telescope might see in looking at the black hole at the heart of the galaxy M87. Clumpy gas swirls around the black hole in an accretion disk, feeding the central beast. The black area at center is the black hole itself, defined by the event horizon, beyond which nothing can escape.

Astronomers say they've come up with the definitive estimate for the mass and size of the biggest black hole in our celestial neighborhood, using a method that can now be applied to even bigger monsters beyond.

It's long been known that the supermassive black hole at the center of the galaxy M87 was a big one, but over the years, there's been some debate over just how big it was. Some of the estimates have ranged down toward a mass equivalent to 3 billion suns. In 2009, however, Karl Gebhardt of the University of Texas' McDonald Observatory took a fresh look at old data and came up with an estimate of 6.4 billion suns.

"That had a large uncertainty," Gebhardt told me. Today, Gebhardt and his colleagues announced a new estimate that's based on high-accuracy observations from the Gemini Observatory in Hawaii as well as the McDonald Observatory. The bottom line: M87's black hole is equal to 6.6 billion solar masses, plus or minus 400 million solar masses.

Not bad for a galaxy that's a mere 50 milllion light-years away.

"It is remarkable to have a galaxy of this size and a black hole of this mass so close to us," Gebhardt told journalists at the American Astronomical Society's winter meeting in Seattle. "It really is in our backyard."

The study has been accepted for publication in the Astrophysical Journal.

How they did it
Gebhardt's team used an instrument on the Gemini telescope known as the Near-Infrared Field Spectrograph to measure the speed of the stars orbiting the black hole. The telescope couldn't spot the individual stars — but thanks to adaptive optics, a technique that compensates for atmospheric distortions, the spectral measurements were fine enough to give the astronomers a sense of the average speed for bunches of stars.

One of Gebhardt's colleagues, graduate student Jeremy Murphy, used a different instrument on McDonald's Harlan J. Smith Telescope to track the motions of stars on the outskirts of M87. The VIRUS-P spectrograph gathered light from a "huge chunk of the sky" and come up with an estimate for the galaxy's total mass, including the mass of the dark matter halo surrounding the visible parts of the galaxy. The total came to 5.7 trillion solar masses, Murphy said.

All those observations were fed into a computer model, which spit out the black hole mass of 6.6 billion suns, spread across a distance of about 20 billion kilometers. "This is three times the size of Pluto's orbit," said Gebhardt, who went on to note that M87's monster "could swallow our solar system whole."

Gebhardt said his team's efforts demonstrated that it was possible to weigh black holes in distant galaxies by measuring stellar motions with high-resolution instruments. "It gives us the confidence to be able to probe the galaxies that are much farther away," he said.

One such galaxy, 3.5 billion light-years away, is said to contain a black hole that's 18 billion times as massive as our sun. That would make even M87's black hole look like a pipsqueak. But the current estimate is based on indirect observations. Gebhardt would love to use more direct methods to confirm the estimate.

"It gives me fodder for future observing proposals," he told me.

To see a black hole
As any science-fiction fan knows, black holes are strange objects so dense that nothing, not even light, can escape its gravitational pull within a boundary known as the "event horizon." They may result from the catastrophic collapse of a dying star, or they may develop as the supermassive core of an entire galaxy. Astronomers have observed jets and bubbles of radiation that appear to emanate from black holes, and they've even spotted the whirling disks of hot material that surround active black holes. But no one has yet seen the black holes themselves.

"There's no direct evidence yet that black holes exist ... zero, absolutely zero observational evidence," Gebhardt said in a Gemini Observatory news release. "To infer a black hole currently, we choose the 'none of above' option. This is basically because alternative explanations are increasingly being ruled out."

Gebhardt would love to see a black hole, or at least the shadow of its event horizon, and he thinks M87 is the best candidate for that because it's so massive. Our own Milky Way's central black hole is much closer, of course — but it's also much smaller, weighing in at a mere 4 million solar masses. (That's 1 percent of the margin of error for the mass estimate of M87.)

Believe it or not, some astronomers already have a plan to look for the Milky Way's black hole, as part of a project called the Event Horizon Telescope. The plan calls for outfitting the radio telescopes of the Very Long Baseline Interferometer with submillimeter-wave receivers, which just might be able to produce an image of the event horizon when they're linked together.

"It's probably two or three years that we'll need to get there," Gebhardt said. And when the Event Horizon Telescope is ready to go, he hopes that M87 will be on the list of targets. "It is by far our cleanest and best case for a black hole," he said.

Other black hole news from the AAS meeting:

Caltech

These images show one of the newly discovered black-hole pairs. On the left is an image from the Sloan Digital Sky Survey. On the right is a Keck image that resolves two active galactic nuclei, which are powered by massive black holes.

• Astronomers have discovered 16 close-knit pairs of supermassive black holes in merging galaxies, using imagery from the W.M. Keck Observatory in Hawaii. Caltech astronomer S. George Djorgovski said in a news release that the close pairs "are a missing link between the wide binary systems seen previously and the merging black-hole pairs at even smaller separations that we believe must be there." The 16 pairs were found among an array of 50 targets checked with the Keck 10-meter telescopes, with adaptive optics once again playing a crucial role.

The observations support the view that structures in the universe are assembled "through a hierarchy of mergers," Djorgovski told reporters. He joked that it would have been more interesting if the results contradicted theory, "but unfortunately, our understanding seems to be correct."

• Another team of astronomers observed the "heartbeats" seen in the light from a black hole system, using the space-based Chandra X-ray Observatory and the Rossi X-ray Timing Explorer. The study focused on GRS 1915+105, a binary system in the Milky Way galaxy thought to contain a black hole 14 times more massive than the sun. X-ray pulses emanated from the disk of material surrounding the black hole approximately every 50 seconds. By analyzing variations in the X-ray heartbeat, the astronomers could trace the flow of material into the black hole — and away from it.

"Each heartbeat blasts a new blob of material into the line of sight," Harvard's Joey Neilsen explained. "Ninety-five percent of the material coming in from the outside is actually being blown away by the black hole wind." The matter blown away from the accretion disk every day amounts to a third of the mass of the moon, Neilsen said.

More about black holes:

• See a black hole's blast
• PlayStation 3 tackles black-hole vibrations
• Instrument spots potential twin of Milky Way's black hole
• Supernovas starve supermassive black holes
• Which came first, black holes or galaxies?
• Stars form within black hole's destructive reach
• Search for more black holes at msnbc.com

In addition to Gebhardt and Murphy, co-authors of "The Black-Hole Mass in M87 From Gemini/NIFS Adaptive Optics Observations" include Joshua Adams, Douglas Richstone, Tod R. Lauer, S.M. Faber, Kayhan Gultekin and Scott Tremaine. Murphy, Gebhardt and Adams are the co-authors of "Galaxy Kinematics With VIRUS-P: The Dark Matter Halo of M87."

In addition to Djorgovski, co-authors of "Hierarchical Assembly of Supermassive Black Holes: Adaptive Optics Imaging of Double-Peaked [O III] Active Galactic Nuclei" include Hai Fu, Adam D. Myers and Lin Yan. The paper has been submitted to Astrophysical Journal Letters.

In addition to Neilsen, co-authors of "The Physics of Disk Winds, Jets, and X-ray Variability in GRS 1915+105" include Julia Lee and Ron Remillard.

Connect with the Cosmic Log community by "liking" our Facebook page, or by following msnbc.com's science editor, Alan Boyle, on Twitter (@boyle).