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Post Info TOPIC: Andromeda galaxy (M31)


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M31 galaxy
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Title: Spiral arm structures revealed in the M31 galaxy
Authors: Yu.N.Efremov

Striking regularities are found in the northwestern arm of the M31 galaxy. Star complexes located in this arm are all spaced 1.2 kpc apart and have similar sizes of about 0.6 kpc. Within the same arm region Beck et al. (1989) detected a regular magnetic field, and we found that its wavelength is the spacing between the complexes. In this arm, groups of HII regions lie inside star complexes, which, in turn, are located inside the gas and dust lane. In contrast, the southwestern arm of M31 splits into a gas and dust lane upstream and a dense stellar arm downstream, with HII regions located mostly along the boundary between these components of the arm. The stellar density in the southwestern arm is much higher than in the northwestern arm, and the former is not fragmented into star complexes. The age gradient across this arm have been found in earlier observations. According the classical SDW theory, these drastic differences may be due to their different pitch angles: about 0 degree for northwestern part of the arm and about 30 degree for the southwestern segment. Data on M31, M51, M74, and some other galaxies suggest that star complexes are mostly located in the arm segments that are not accompanied by a dust lane upstream, i.e. do not host spiral shock wave. The regularities in the distribution of complexes along a density wave spiral arm are most probably due to the development of the Parker-Jeans instability, which builds up star complexes if the initial SFR in the arm is low and, as a sequence, magnetic field is regular along the arm.

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RE: Andromeda galaxy (M31)
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NASA's Swift satellite takes a sensational image of our galaxy's nearest neighbour
Andromeda is certainly one of the most photographed celestial objects, being the largest and nearest galaxy to our own Milky Way. Nobody, however, has seen it quite like this before. NASA's Swift satellite, in its tireless pursuit of cosmic explosions, has taken a sensational image of Andromeda in all its ultraviolet beauty. The picture is commendable because it is the sharpest high resolution image in this wavelength of M31, as Andromeda is frequently known due to its position at number 31 in Charles Messier's famous catalogue.

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An international team of astronomers led from the National Research Council Herzberg Institute of Astrophysics (NRC-HIA) has discovered that our near cosmic neighbour, the Andromeda Galaxy, is swallowing smaller galaxies as it continues to grow. Results published this week in the science journal Nature show the discovery of giant structures in its outer parts, relics of smaller galaxies that have already been absorbed by Andromeda. The finding has come to light from the broadest and deepest image of a galaxy ever made, spanning a volume with a diameter nearly 1,000,000 light years around Andromeda.

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Astronomers watch 'galaxy cannibalism'
The collision of two galaxies relatively close to our own Milky Way is giving astronomers insights into how galaxies like ours develop.
Initial results of a new research paper show that even though the Triangulum Galaxy dwarfs the Andromeda Galaxy at one-tenth its size, the two galaxies are coming together in a cosmic collision.


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Swift Makes Best-ever Ultraviolet Portrait of Andromeda Galaxy
In a break from its usual task of searching for distant cosmic explosions, NASA's Swift satellite has acquired the highest-resolution view of a neighbouring spiral galaxy ever attained in the ultraviolet. The galaxy, known as M31 in the constellation Andromeda, is the largest and closest spiral galaxy to our own.

"Swift reveals about 20,000 ultraviolet sources in M31, especially hot, young stars and dense star clusters. Of particular importance is that we have covered the galaxy in three ultraviolet filters. That will let us study M31's star-formation processes in much greater detail than previously possible" - Stefan Immler, a research scientist on the Swift team at NASA's Goddard Space Flight Centre in Greenbelt, Md.



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Queen's physicist unlocking the mysteries of neighbouring galaxies
An international team of astronomers, including Queen's University physicist Larry Widrow, have uncovered evidence of a nearby cosmic encounter. Their study indicates that the Andromeda and Triangulum galaxies, the two galaxies closest to our own, collided about two to three billion years ago.

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The vast Andromeda galaxy appears to have expanded by digesting stars from other galaxies, research has shown.
When an international team of scientists mapped Andromeda, they discovered stars that they said were "remnants of dwarf galaxies".
The astronomers report their findings in the journal Nature.


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Cosmic cannibalism seen in action
Stars and giant structures around the Andromeda Galaxy - many seen for the first time - are probably the remnants of smaller galaxies that have been cannibalised by Andromeda, finds a new study published online today in Nature.
The new images, captured by an international team of astronomers including the University of Bristol, are from the largest panoramic survey of Andromeda ever made. The survey covers a region nearly a million light years across.


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The Andromeda galaxy, the closest neighbour to our own Milky Way, has been growing by scooping up stars from smaller surrounding galaxies, a Canadian-led team of astronomers has found.

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Astronomers have been able to witness a feature of galaxy evolution that they have long suspected but have been unable to visualise whereby one swirling mass of stars devours another that happens to have come within its gravitational sphere of influence.
A telescopic study of the Andromeda galaxy some 2.3 million light years away, the nearest spiral galaxy to our own Milky Way that can be seen with the naked eye, has exposed the galaxy's immense gravitational tides that are eating away at the smaller Triangulum galaxy as it slowly orbits its galactic master.

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Andromeda Galaxy Exoplanet
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The first ever discovery of a planet outside our galaxy has left a local astronomy expert stunned.
The breakthrough find was made by foreign researchers, who claim to have witnessed evidence of a new planet in the Andromeda galaxy 2.5 million light years away.
Professor Michael Smith, director of astrophysics and planetary science at the University of Kent, spoke to Kent on Saturday of his awe at what he called the most exciting space discovery for years.


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