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Surprising Image Provides New Tool For Studying A Galaxy

November 15, 2013 Leave a comment

Credit: Jayanne English (U. of Manitoba), Judith Irwin (Queen's U.), Richard Rand (U. of New Mexico) and collaborators in the CHANG-ES consortium, NRAO VLA, NASA WISE & Spitzer missions, NOAO, and SDSS.

Credit: Jayanne English (U. of Manitoba), Judith Irwin (Queen’s U.), Richard Rand (U. of New Mexico) and collaborators in the CHANG-ES consortium, NRAO VLA, NASA WISE & Spitzer missions, NOAO, and SDSS.

Astronomers studying gas halos around nearby galaxies were surprised when detailed studies with the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) showed that one of their subjects is not a single galaxy, but rather two, nearly perfectly superimposed on the sky to masquerade as one. The discovery allowed them to use the alignment to learn otherwise-unobtainable facts about the nearer galaxy.

As part of a study of 35 galaxies, the astronomers observed one called UGC 10288, a spiral galaxy more than 100 million light-years distant that appears edge-on as seen from Earth. Their multiple VLA observations in 2011 and 2012 produced the best radio-telescope images of that galaxy ever made. The detailed images surprisingly revealed a more-distant galaxy, with strong radio emission, almost directly behind UGC 10288. In previous images, the two galaxies had been blended together.

The background galaxy is nearly 7 billion light-years from Earth.

“This changed the picture, quite literally,” said Judith Irwin, of Queen’s University in Ontario, Canada. “It changed our understanding of the characteristics of UGC 10288, but also gave us an unexpected new tool for learning more about that galaxy,” Irwin added. The alignment of a foreground galaxy with such a strongly-emitting background galaxy with extended jets probably is the first such alignment found, the astronomers said.

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Hubble Views An Old And Mysterious Cluster

November 15, 2013 Leave a comment

Image credit: NASA, ESA

Image credit: NASA, ESA

This multi-coloured firework display is a cluster of stars known as Messier 15, located some 35 000 light-years away in the constellation of Pegasus (The Winged Horse). It is one of the oldest globular clusters known, with an age of around 12 billion years.

Very hot blue stars and cooler golden stars are seen swarming together in this image, becoming more concentrated towards the cluster’s bright centre. Messier 15 is one of the densest globular clusters known, with most of its mass concentrated at its core.

However, this sparkling bauble has hidden secrets. Astronomers studying the cluster with Hubble in 2002 found there to be something dark and mysterious lurking at its heart. It could either be a collection of dark neutron stars, or an intermediate-mass black hole. Of the two possibilities it is more likely that Messier 15 harbours a black hole at its centre, as does the massive globular cluster Mayall II.

Intermediate-mass black holes are thought to form either from the merging of several smaller, stellar-mass black holes, or as a result of a collision between massive stars in dense clusters. A third possibility is that they were formed during the Big Bang. In terms of mass they lie between the more commonly found stellar-mass and supermassive types of black hole [3], and could tell us about how black holes grow and evolve within clusters like Messier 15, and within galaxies.

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MESSENGER Detects Comets ISON And Encke, Prepares For Closer Encounters

November 15, 2013 Leave a comment

NASA’s Mercury-orbiting MESSENGER spacecraft has captured images of two comets — 2P/Encke and C/2012 S1 (ISON) — setting the stage for observations later this month when both comets will be substantially brighter and much closer to Mercury and the Sun.

ISON was discovered in September 2012 by amateur Russian astronomers, who observed with a 16-inch telescope that is part of the International Scientific Optical Network (ISON), after which the comet was named. On November 28, ISON will fly within 700,000 miles (1.2 million kilometers) of the Sun’s photosphere, at which time it is expected either to flare brilliantly or disintegrate.

As part of an ISON observation campaign involving ground- and space-based NASA observatories, as well as many other observatories around the world, MESSENGER has been poised for several weeks to collect observations of ISON. From November 9 through November 11, the probe’s Mercury Dual Instrument System (MDIS) captured its first images of the comet.

A few days earlier, from November 6 through November 8, MESSENGER’s imagers picked up its first snapshots of Encke. Unlike ISON, Encke has been known for quite a while. It was discovered in 1786 and recognized as a periodic comet in 1819. Its orbital period is 3.3 years — the shortest period of any known comet — and November 21 will mark its 62nd recorded perihelion.

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Comet ISON On Track For Thanksgiving Roasting, Possible Pre-Dawn Views In Early December

November 15, 2013 Leave a comment

A comet that’s caused a lot of excitement is racing toward a close encounter with the Sun on Thanksgiving Day, according to the editors of StarDate magazine. Comet ISON will pass about 700,000 miles above the Sun before whipping around and heading back toward deep space — if it survives. If it does, the comet could easily be visible to the unaided eye for a few weeks after the encounter.

An automated asteroid-hunting telescope, part of the International Scientific Optical Network (ISON) in Russia, discovered Comet C/2012 S1 (ISON) on September 21, 2012. Some comet-watchers quickly suggested that it could become as bright as a full Moon late this year. Continued observations, however, show that it’s not brightening as much as those optimistic projections indicated.

However, the comet appears to be holding together as it approaches the Sun, suggesting that it could survive the solar encounter, probably its first.

The comet will get brighter as it approaches the Sun, but more difficult to see through the Sun’s glare. It will shine at its brightest as it passes the Sun, although it will be too close to the Sun to view safely.

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Young Stars Paint Spectacular Stellar Landscape

November 15, 2013 Leave a comment

Credit: ESO/G. Beccari

Credit: ESO/G. Beccari

Most stars do not form alone, but with many siblings that are created at about the same time from a single cloud of gas and dust. NGC 3572, in the southern constellation of Carina (The Keel), is one of these clusters. It contains many hot young blue-white stars that shine brightly and generate powerful stellar winds that tend to gradually disperse the remaining gas and dust from their surroundings. The glowing gas clouds and accompanying cluster of stars are the subjects of a new picture from the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile.

In the lower part of the image a big chunk of the molecular cloud that gave birth to these stellar youngsters still can be seen. It has been dramatically affected by the powerful radiation coming from its smoldering offspring. The radiation not only makes it glow with a characteristic hue, but also sculpts the clouds into amazingly convoluted shapes, including bubbles, arcs and the dark columns that astronomers call elephant trunks.

A strange feature captured in this image is the tiny ring-like nebula located slightly above the centre of the image. Astronomers still are a little uncertain about the origin of this curious feature. It is probably a dense leftover from the molecular cloud that formed the cluster, perhaps a bubble created around a very bright hot star. But some authors have considered that it may be some kind of oddly shaped planetary nebula — the remnants of a dying star.

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‘Freakish’ Asteroid Discovered, Resembles Rotating Lawn Sprinkler

November 15, 2013 1 comment

Credit: NASA, ESA, and D. Jewitt (UCLA)

Credit: NASA, ESA, and D. Jewitt (UCLA)

Astronomers have discovered a “weird and freakish object” resembling a rotating lawn sprinkler in the asteroid belt between Mars and Jupiter. The find, reported online in the Nov. 7 issue of the Astrophysical Journal Letters, has left them scratching their heads and searching for an explanation for the strange asteroid’s out-of-this-world appearance.

Normal asteroids appear simply as tiny points of light. This bizarre asteroid has six comet-like tails of dust radiating from it like spokes on a wheel.

“It’s hard to believe we’re looking at an asteroid,” said lead investigator David Jewitt, a professor in the UCLA Department of Earth and Space Sciences and the UCLA Department of Physics and Astronomy. “We were dumbfounded when we saw it. Amazingly, its tail structures change dramatically in just 13 days as it belches out dust.”

One interpretation is that the asteroid’s rotation rate increased to the point where its surface started flying apart, ejecting dust in episodic eruptions, starting last spring. The team has ruled out a recent asteroid impact scenario because a large quantity of dust would have been blasted into space all at once. This object, designated P/2013 P5, has ejected dust for at least five months, Jewitt said.

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