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Astronomers Spot Record-Breaking Lunar Impact

February 26, 2014 Leave a comment

A meteorite with the mass of a small car crashed into the Moon last September, according to Spanish astronomers. The impact, the biggest seen to date, produced a bright flash and would have been easy to spot from the Earth. The scientists publish their description of the event in the journal Monthly Notices of the Royal Astronomical Society.

The Moon lacks the atmosphere that prevents small rocks from space from reaching the surface of the Earth. The result is very visible – vast numbers of craters large and small cover the whole of our nearest neighbour and record 4.5 billion years of collisions that span the history of the Solar system.

Although there is almost no chance of a very large object striking the Moon or planets, collisions with smaller objects are very common even today. The odds of seeing one of these by chance are pretty poor, so scientists have set up networks of telescopes that can detect them automatically.

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Detection Of Water Vapor In The Atmosphere Of A Hot Jupiter

February 26, 2014 Leave a comment

Although liquid water covers a majority of Earth’s surface, scientists are still searching for planets outside of our solar system that contain water. Researchers at Caltech and several other institutions have used a new technique to analyze the gaseous atmospheres of such extrasolar planets and have made the first detection of water in the atmosphere of the Jupiter-mass planet orbiting the nearby star tau Boötis. With further development and more sensitive instruments, this technique could help researchers learn about how many planets with water—like Earth—exist within our galaxy.

Scientists have previously detected water vapor on a handful of other planets, but these detections could only take place under very specific circumstances, says graduate student Alexandra Lockwood, the first author of the study. “When a planet transits—or passes in orbit in front of—its host star, we can use information from this event to detect water vapor and other atmospheric compounds,” she says. “Alternatively, if the planet is sufficiently far away from its host star, we can also learn about a planet’s atmosphere by imaging it.”

However, significant portions of the population of extrasolar planets do not fit either of these criteria, and there was not really a way to find information about the atmospheres of these planets. Looking to resolve this problem, Lockwood and her adviser Geoffrey Blake, professor of cosmochemistry and planetary sciences and professor of chemistry, applied a novel technique for finding water in a planetary atmosphere. Other researchers had used similar approaches previously to detect carbon monoxide in tau Boötis b.

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Bullying Black Holes Force Galaxies To Stay Red And Dead

February 26, 2014 Leave a comment

Copyright: Digitised Sky Survey/NASA Chandra/Southern Observatory for Astrophysical Research/Very Large Array (Robert Dunn et al. 2010)

Copyright: Digitised Sky Survey/NASA Chandra/Southern Observatory for Astrophysical Research/Very Large Array (Robert Dunn et al. 2010)

Giant elliptical galaxies are the most puzzling type of galaxy in the Universe. Since they mysteriously shut down their star-forming activity and remain home only to the longest-lived of their stars – which are low-mass ones and appear red – astronomers often call these galaxies ‘red and dead’.

Up until now, it was thought that red-and-dead galaxies were poor in cold gas – the vital raw material from which stars are born. While cold gas is abundant in spiral galaxies with lively star formation, the lack of it in giant ellipticals seemed to explain the absence of new stars.

Astronomers have long been debating the physical processes leading to the end of their star formation. They speculated that these galaxies somehow expelled the cold gas, or that they had simply used it all to form stars in the past. Although the reason was uncertain, one thing seemed to have been established: these galaxies are red and dead because they no longer possess the means to sustain the production of stars.

This view is being challenged by a new study based on data from ESA’s Herschel Space Observatory. The results are published in Monthly Notices of the Royal Astronomical Society.

“We looked at eight giant elliptical galaxies that nobody had looked at with Herschel before and we were delighted to find that, contrary to previous belief, six out of eight abound with cold gas”, explains Norbert Werner from Stanford University in California, USA, who led the study.
This is the first time that astronomers have seen large amounts of cold gas in red-and-dead galaxies that are not located at the centre of a massive galaxy cluster.

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