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Post Info TOPIC: NGC 4736


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Messier 94
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Messier 94 (also M94, NGC 4736 and PGC 43495) is a magnitude +9.0 face-on spiral galaxy located 16.0 1.3 million light-years away in the constellation Canes Venatici.

The galaxy was discovered by French astronomer Pierre Francois Andre Mechain using a 15.24 cm (6 inch) newtonian speculum reflector on the 22nd March 1781.
The galaxy was observed by Charles Messier in 1781.

Right Ascension 12h 50m 53.1s, Declination +41 07' 14"

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RE: NGC 4736
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Galaxy's Ring of Fire

burningRing-rect.jpg?1368736333

The "starburst ring" seen at center in red and yellow hues is not the product of love, as in the song, but is instead a frenetic region of star formation.
The galaxy, a spiral beauty called Messier 94, is located about 17 million light-years away. In this image from NASA's Spitzer Space Telescope, infrared light is represented in different colors, with blue having the shortest wavelengths and red, the longest.
Starburst rings like this can often be triggered by gravitational encounters with other galaxies but, in this case, may have instead been caused by the galaxy's oval shape. Gas in the ring is being converted into hot, young stars, which then warm the dust, causing it to glow with infrared light.

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Posts: 131433
Date:
Messier 94
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Astronomers have captured a new image of the island universe M94, revealing previously undetected spiral arms around its outskirts.
An international team of astrophysicists based at the Blackbird Observatory, New Mexico, spent three years looking at M94 - which is located 15 million light-years away - for evidence of the spirals.
The galaxy, which was first discovered in 1781, is a popular target for astronomers and lies in the northern constellation of the hunting dogs, Canes Venatici.

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NGC 4736
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What do you call an absence of darkness? Dark matter is supposed to be spread throughout the universe, but a new study reports a spiral galaxy that seems to be empty of the stuff, and astrophysicists cannot easily explain why.
In the outer regions of most galaxies, stars orbit around the centre so fast that they should fly away. The combined mass of all the observable inner stars and gas does not exert strong enough gravity to hold onto these speeding outliers, suggesting some mass is missing.
Most astronomers believe that the missing mass is made up of some exotic invisible substance, labelled dark matter, which forms vast spherical halos around each galaxy. Another possibility is that the force of gravity behaves in an unexpected way, a theory known as modified Newtonian dynamics, or MOND.
In the spiral galaxy NGC 4736, however, the rotation slows down as you move farther out from the crowded inner reaches of the galaxy. At first glance, that declining rotation curve is just what you would expect if there is no extended halo of dark matter, and no modification to gravity. As you move far away from the swarming stars of the inner galaxy, gravity becomes weaker, and so motions become more sedate.
The rotation measurements only stretch 35,000 light years out from the galactic centre, which is not far enough to confirm that first impression. So a team of astronomers in Poland developed a more sophisticated analysis.
Joanna Jalocha, Lukasz Bratek and Marek Kutschera of the Polish Academy of Science in Krakow have found a way to splice the rotation curve together with another measurement: the density of hydrogen gas far from the galactic centre.
According to their combined mathematical model, ordinary luminous stars and gas can indeed account for all the mass in NGC 4736.

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