Discoveries Dec 5'11: biggest blackholes (10+20 billionx mass of our sun); Earthlike Planet Kepler-22b first in inhabitable zone

(quote)

Astrophysicists find biggest black holes yet - two monsters, one of which may be about 20 billion times the mass of our sun, could provide important clues to the formation of galaxies.
Astrophysicists scanning the heavens have clocked a new cosmological record: the two biggest black holes ever detected — one about 10 billion times the mass of our sun and the second as much as twice the size of the first.

To be described in Thursday's edition of the journal Nature, these behemoth black holes are nearly double the size of the previous record-holder and — strangely — are far more massive than they should be given the size of the galaxies they reside within. For that reason, they stand to teach scientists much about how galaxies form and grow, astronomers said.

One of the finds, which were made using telescopes in Hawaii, Texas and in space, sits 320 million light-years away in a huge elliptical galaxy within the Leo galaxy cluster. It contains a mass equivalent to 9.7 billion suns. The second resides 336 million light-years away at the center of a galaxy within the Coma galaxy cluster, in the direction of the constellation Coma Berenices. It may be far more massive than the first — in the neighborhood of 20 billion solar masses.

The excitement at the find goes beyond the two black holes' record size and the weirdness of entities so massive that even light cannot escape their pull. "Black holes are not just curiosities," said Michele Cappellari, an astrophysicist at the University of Oxford who was not involved in the study and wrote a commentary accompanying the report. "They're really a part of the theory of how we think galaxies form."

Astronomers are fairly certain that every galaxy — including our own — has a supermassive black hole at its center. These black holes' existence was proposed four decades ago to account for the high-energy bursts of radiation, known as quasars, from distant and ancient galaxies.

In recent years, the search for supermassive black holes has heated up and scientists have thus far uncovered more than five dozen of the cosmic behemoths. The two newly discovered black holes dwarf the recent former record-holder, a heavyweight of 6.3 billion solar masses in the M87 galaxy, about 50 million light-years from Earth.

The largest black holes are most likely to be found at the center of very large galaxies. That's because as a black hole's gravity pulls gas toward it, gobbling the gas and growing larger, the process allows the galaxy to grow too, from gas pulled into the galactic sphere from space.

But finding extremely large black holes is difficult because such massive galaxies — prime places to fish for the most massive black holes — are rare and often far away at the center of a cluster of galaxies. And even though such galaxies may be large and bright enough to be seen, astronomers need to be able to peer at the part of the galaxy very close to the black hole itself — hard to do from so far away.

Because they emit no light, black holes must be detected indirectly. As material moves in toward a black hole, it speeds up, and astrophysicists can use the speed of the material as a measure of how massive the black hole must be. "There was no guarantee we could actually measure anything, so it was very exciting that we found something," said study coauthor Chung-Pei Ma, an astrophysicist at UC Berkeley.

Scientists discover largest black holes ever recorded
Astronomers have recorded the biggest black holes ever detected — a pair of stellar monsters that somehow have managed to swallow the equivalent of 10 billion suns each. “That’s a fairly healthy diet,” said James Graham of the University of Toronto, who is at a loss to explain how they grew so massive.

One of the black holes has a mass of 9.7 billion suns and lurks in the elliptical galaxy NGC 3842, the brightest galaxy near the Leo constellation 320 million light-years away. The second one is even bigger and resides in galaxy NGC 4889, the brightest galaxy in the direction of the Coma Berenices constellation about 336 million light-years from Earth.

“They are the most massive directly-measured black holes in the local universe,” said Graham, director of the U of T’s Dunlap Institute for Astronomy and Astrophysics, who is on the international team that reported the find Monday in the journal Nature.

“The underlying question is how did these black (holes) get to be so big, how did they eat so much stuff over the age of the universe,” said Graham. “In a universe that is billions of years old and you grow something to billions of solar masses, that means eating one sun a year. “There is some really interesting physics going on, in how these galaxies are built up, that we haven’t understood yet.”

'We are a universe crowded with life': NASA astronomers discover ANOTHER blue planet... but this time it's habitable
Astronomers have discovered the first habitable blue planet orbiting in the habitable zone of a star similar to the Sun.

NASA’s Kepler Mission has been finding new worlds at an incredible rate over the past year but this is the first discovery of what could be a habitable super-earth as it appears to be large, rocky planet with a surface temperature of about 72 degrees Fahrenheit, similar to spring day on Earth.

A team of researchers, including Carnegie Institute's Alan Boss, made the discovery which will be published in The Astrophysical Journal. The discovery team, led by William Borucki of the NASA Ames Research Center, used photometric data from the NASA Kepler space telescope, which monitors the brightness of 155,000 stars. Earth-size planets whose orbital planes are aligned such that they periodically pass in front of their stars result in tiny dimmings of their host star’s light, dimmings that can only be measured by a highly specialized space telescope like Kepler.

This discovery is the first detection of a possibly habitable world in orbit around a Sun-like star. The host star lies about 600 light-years away from us toward the constellations of Lyra and Cygnus.

The star, a G5 star, has a mass and a radius only slightly smaller than that of our Sun. As a result, the host star is about 25 per cent less luminous than the Sun.

The planet orbits the G5 star with an orbital period of 290 days, compared to 365 days for the Earth, at a distance about 15 per cent closer to its star than the Earth from the Sun. This results in the planet’s balmy temperature.

It orbits in the middle of the star’s habitable zone, where liquid water is expected to be able to exist on the surface of the planet. Liquid water is necessary for life as we know it, and this new planet might well be not only habitable, perhaps even inhabited.

Numerous large, massive gas giant planets have been detected previously in habitable-zone orbits around solar-type stars, but gas giants are not thought to be capable of supporting life. This new exoplanet is the smallest-radius planet discovered in the habitable zone of any star to date. It is about 2.4 times larger than that of the Earth, putting it in the class of exoplanets known as super-Earths.

While the mass of this new planet is not known, it must be less than about 36 times that of the Earth, based on the absence of a measurable Doppler (radial velocity) wobble in the host star. The masses of several other super-Earths have been measured with the Doppler technique and determined to lie in the range of about 5 to 10 times that of the Earth. Some appear to be rocky, while others probably contain major fractions of ice and water. Either way, the new planet appears to be habitable.

'This discovery supports the growing belief that we live in a universe crowded with life,' Boss said. 'Kepler is on the verge of determining the actual abundance of habitable, Earth-like planets in our galaxy'.

New planet discovered to be first in habitable zone... New planet discovery excites scientists: the discovery of a new planet 600 light years away with roughly the right temperature for plant and animal habitation is causing a buzz in the science community. Though much larger than Earth, scientists haven't ruled out the possibility of life being discovered.
Kepler-22b, the most Earth-like planet ever discovered is circling a star 600 light years away, a key finding in an ongoing quest to learn if life exists beyond Earth, scientists said on Monday. Kepler-22b joins a list of more than 500 planets found to orbit stars beyond our solar system. It is the smallest and the best positioned to have liquid water on its surface - among the ingredients necessary for life on Earth.

A newly discovered planet is eerily similar to Earth and is sitting outside Earth's solar system in what seems to be the ideal place for life, except for one hitch. It is a bit too big. The planet is smack in the middle of what astronomers call the Goldilocks zone, that hard to find place that is not too hot, not too cold, where water, which is essential for life, does not freeze or boil. And it has a shopping mall-like surface temperature of near 72 degrees, scientists say.

The planet's confirmation was announced Monday by NASA along with other discoveries by its Kepler telescope, which was launched on a planet-hunting mission in 2009. That is the first planet confirmed in the habitable zone for Kepler, which already had found Earth-like rockyplanets elsewhere. Twice before astronomers have announced a planet found in that zone, but neither has been as promising.

"This is a phenomenal discovery in the course of human history," Geoff Marcy of University of California, Berkeley, one of the pioneers of planet-hunting outside Earth's solar system, said in an email. "This discovery shows that we Homo sapiens are straining our reach into the universe to find planets that remind us of home. We are almost there."

Kepler cannot find life itself, just where the conditions might be right for it to thrive. And when astronomers look for life elsewhere, they are talking about everything ranging from microbes to advanced intelligence that can be looking back at us.

The planet is 600 light years away. Each light year is 5.9 trillion miles. It would take a space shuttle about 22 million years to get there.

Kepler spots a planet when it passes in front of its star. NASA requires three of those sightings before it begins to confirm it as a planet. Borucki said the third sighting for 22b happened a year ago, just before the telescope shut down for a while. It took several months to finish the confirmation. "It's a great gift," Borucki said. "We consider this sort of our Christmas planet."

*Update August 4, 2012*

Astronomers hear 'death cry' of star shredded by black hole
A team of astronomers has detected the "death cry" of a star being devoured by a supermassive black hole. The black hole had been sitting quietly -- almost lying in wait, as it were -- until its gravity reached out and shredded a passing star, pulling the star into its death grip and causing it to emit a characteristic signal. "You can think of it as hearing the star scream as it gets devoured, if you like," said astronomer Jon Miller of the University of Michigan, lead author of a report appearing in Science Express.

The black hole, identified as Swift J1644+57, lies 3.9 billion light-years away in the constellation Draco. That name arises from its discovery on March 28, 2011, by NASA's Swift satellite, which searches the universe for gamma-ray bursts. At first, astronomers thought the signal was a common gamma-ray burst, but the gradual fade-out of the signal matched nothing that had ever been seen before from such a source. Closer observation of the object with the orbiting Suzaku and XMM-Newton X-ray telescopes ultimately revealed a faint, periodic signal that, Miller said, corresponds in frequency to an ultra-low D-sharp.

Such signals have been detected from smaller black holes and they are thought to emanate from material that is about to be sucked in, said co-author Rubens Reis of the University of Michigan. But a similar signal had previously been detected only once from a supermassive black hole -- one with a mass more than a million times that of the sun -- in a galaxy just576 million light-years away. "This discovery extends our reach to the innermost edge of a black hole located billions of light-years away, which is really amazing," Reis said. "This gives us an opportunity to explore the nature of black holes and test Einstein's relativity at a time when the universe was very different than it is today."

The wandering star experienced powerful tidal forces as it neared the black hole and was torn apart. Some of its gas fell toward the black hole and formed a disk around it, a so-called accretion disk. The innermost part of this disk was heated to temperatures of millions of degrees, hot enough to emit X-rays. At the same time, through processes that are only dimly understood, the disk emitted oppositely directed jets of matter perpendicular to the disk. These jets blasted matter outward at speeds near 90% that of light along the black hole's spin axis. One of these jets happened to point straight at Earth.

(unquote)

Images courtesy Pete Marenfeld / Nature, University of Warwick / Mark Garlick Handout, Daily Mail, Getty Images, Ames / JPL-Caltech / NASA / Reuters, and NASA Goddard Space Flight Center