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Archive for December 14, 2011

Spectacular Sundiving Comet

December 14, 2011 Leave a comment

Comet Lovejoy is plunging toward the sun, and its ~200-meter wide core is vaporizing furiously as it approaches the hot star. So far the comet’s brightness seems to be exceeding expectations. Indeed, there is a slim chance that the sundiver will brighten enough to be seen with the naked eye in broad daylight on Dec. 15th. Check http://spaceweather.com for further discussion and the latest movies from the Solar and Heliospheric Observatory.

Full Story: http://spaceweather.com/archive.php?month=12&day=15&year=2011&view=view

(NB: Full Story link will only be active from December 15th onwards – in the meantime, go to Spaceweather’s front page at http://spaceweather.com/)

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A Black Hole’s Dinner is Fast Approaching

December 14, 2011 Leave a comment

Astronomers using ESO’s Very Large Telescope have discovered a gas cloud with several times the mass of the Earth accelerating fast towards the black hole at the centre of the Milky Way. This is the first time ever that the approach of such a doomed cloud to a supermassive black hole has been observed. The results will be published in the 5 January 2012 issue of the journal Nature.

During a 20-year programme using ESO telescopes to monitor the movement of stars around the supermassive black hole at the centre of our galaxy (eso0846), a team of astronomers led by Reinhard Genzel at the Max-Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany, has discovered a unique new object fast approaching the black hole.

Over the last seven years, the speed of this object has nearly doubled, reaching more than 8 million km/h. It is on a very elongated orbit  and in mid-2013 it will pass at a distance of only about 40 billion kilometres from the event horizon of the black hole, a distance of about 36 light-hours. This is an extremely close encounter with a supermassive black hole in astronomical terms.

This object is much cooler than the surrounding stars (only about 280 degrees Celsius), and is composed mostly of hydrogen and helium. It is a dusty, ionised gas cloud with a mass roughly three times that of the Earth. The cloud is glowing under the strong ultraviolet radiation from the hot stars around it in the crowded heart of the Milky Way.

Full Story: http://www.eso.org/public/news/eso1151/

Close Type Ia Supernova Solves Cosmic Mystery

December 14, 2011 Leave a comment

Type Ia supernovae (SN Ia’s) are the extraordinarily bright and remarkably similar “standard candles” astronomers use to measure cosmic growth, a technique that in 1998 led to the discovery of dark energy – and 13 years later to a Nobel Prize, “for the discovery of the accelerating expansion of the universe.” The light from thousands of SN Ia’s has been studied, but until now their physics – how they detonate and what the star systems that produce them actually look like before they explode – has been educated guesswork.

Peter Nugent of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) heads the Computational Cosmology Center in the Lab’s Computational Research Division and also leads the Lab’s collaboration in the multi-institutional Palomar Transient Factory (PTF). On August 24 of this year, searching data as it poured into DOE’s National Energy Research Scientific Computing Center (NERSC) from an automated telescope on Palomar Mountain in California, Nugent spotted a remarkable object. It was shortly confirmed as a Type Ia supernova in the Pinwheel Galaxy, some 21 million light-years distant. That’s unusually close by cosmic standards, and the nearest SN Ia since 1986; it was subsequently given the official name SN 2011fe.

Full Story: http://newscenter.lbl.gov/news-releases/2011/12/14/sn-2011fe/