APOD: In the Arms of M83 (2011 Nov 11)

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APOD: In the Arms of M83 (2011 Nov 11)

Post by APOD Robot » Fri Nov 11, 2011 5:06 am

Image In the Arms of M83

Explanation: Big, bright, and beautiful, spiral galaxy M83 lies a mere twelve million light-years away, near the southeastern tip of the very long constellation Hydra. This cosmic close-up, a mosaic based on data from the Hubble Legacy Archive, traces dark dust and young, blue star clusters along prominent spiral arms that lend M83 its nickname, The Southern Pinwheel. Typically found near the edges of the thick dust lanes, a wealth of reddish star forming regions also suggest another popular moniker for M83, The Thousand-Ruby Galaxy. Dominated by light from older stars, the bright yellowish core of M83 lies at the upper right. The core is also bright at x-ray energies that reveal a high concentration of neutron stars and black holes left from an intense burst of star formation. In fact, M83 is a member of a group of galaxies that includes active galaxy Centaurus A. The close-up field of view spans over 25,000 light-years at the estimated distance of M83.

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by Ann » Fri Nov 11, 2011 5:23 am

This is an incredibly beautiful galaxy, and it is an incredibly beautiful APOD. This image demonstrates how stunningly beautiful Hubble galaxy images can be when the choice of filters allows a creation of RGB images, where old stellar populations show up as yellow, young stellar populations show up as blue, and emission nebulae are red.
Image
The Hubble filters used for this image are F336W (U), F555W (V), F814W (I), F502N ([O III]), and F657N (H-alpha). The original Hubble image looked like this. As you can see, the color balance is not the same as it is in today's APOD. Today's APOD got its final look thanks to the processing of Robert Gendler, and it is no secret that I love his "color scheme" for his galaxies.

Check out this page to get a better look at the original Hubble image.

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by starstruck » Fri Nov 11, 2011 7:36 am

Inspirational image! Makes me wish I could paint!

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by Boomer12k » Fri Nov 11, 2011 9:02 am

Awesome!

"And look there's a Camel walking across it" -- Benny Hill episode.

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by neufer » Fri Nov 11, 2011 1:15 pm

http://en.wikipedia.org/wiki/11-11-11 wrote:
Click to play embedded YouTube video.
<<11-11-11 is a 2011 film written and directed by Darren Lynn Bousman. The film is a horror-thriller set on 11:11 on the 11th day of the 11th month and concerning an entity from another world that enters the earthly realm through Heaven's 11th gate. The film is set to be released on November 11, 2011.

After the tragic death of his wife and child, famed American author Joseph Crone travels from the United States to Barcelona, Spain to reunite with his estranged brother Samuel and dying father, Richard. However, fate has a different plan for Joseph as his life becomes plagued with strange happenings, and the constant sightings of the number 11. Curiosity quickly turns to obsession, and Joseph soon realizes that this number holds a horrific meaning not only to himself but possibly to all of religion. Isolated in a foreign country with only the support of his companion, Sadie, Joseph soon realizes that 11/11/11 is more than just a date, it’s a warning.>>
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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by biddie67 » Fri Nov 11, 2011 1:57 pm

The APOD description mentions that a galaxy can have more than one black hole? Wouldn''t a galaxy appear more irregular with multiple black holes?

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by neufer » Fri Nov 11, 2011 2:01 pm

biddie67 wrote:
The APOD description mentions that a galaxy can have more than one black hole?
Wouldn''t a galaxy appear more irregular with multiple black holes?
I know that I certainly would.
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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by Psnarf » Fri Nov 11, 2011 2:17 pm

[Thanks, Master Neufer, I needed that!]
Now I have change all that galactic-center wiring in my brain. Multiple black holes, multiple neutron stars. I still don't understand what a spiral arm is. It remains static wrt the center while orbiting stars passing through it slow down like a traffic jam, then speed up again on the other side of the arm. Whoops, I'd better head on over to another forum. Meanwhile, I'm going to print that view of M83 on photo paper and hang it on the wall where I can see it from my desk. I rarely get such a close-up view of a galaxy.

Goodbye,
Ruby Thursday [Apologies to the Rolling Stones]
(Meanwhile, I'm hiding under my bed until this whole 111111111111 business blows over: 0xFFF)

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by orin stepanek » Fri Nov 11, 2011 2:21 pm

I like the thousand rubies definition; seems to fit! 8-)
Orin

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by biddie67 » Fri Nov 11, 2011 2:24 pm

(( laughing )) OK for you, neufer!!!!

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by GuyWithAQuestion » Fri Nov 11, 2011 3:58 pm

The image description talked about older stars (as well as black holes and neutron stars) near the galaxy center and younger stars further out along the spiral arms. Should I imagine the galaxy (and it's central black hole) as a type of gravity sink that is collecting dust and gas from it's surroundings... that when the dust and gas reaches a certain concentration it begins to form stars (young stars on the spiral arms)? And that over the millions and billions of years these young stars are pulled by gravity closer to the central black hole and take the place of the "current" older stars? And that as these old stars become even older they supernova, resulting in neutron stars and/or smaller black holes... all of which is streaming into the central black hole?

If so, I guess I've never been taught or thought about the central black hole working like a gigantic vacuum (vacuum yes, but I always thought of it as more localilzed) and creating spiral arms of young stars that slowly move towards the center of the galaxy like on a conveyor belt... kinda cool if I'm thinking correctly :)

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by neufer » Fri Nov 11, 2011 4:38 pm

Psnarf wrote:
I still don't understand what a spiral arm is. It remains static wrt the center while orbiting stars passing through it slow down like a traffic jam, then speed up again on the other side of the arm. Whoops, I'd better head on over to another forum. Meanwhile, I'm going to print that view of M83 on photo paper and hang it on the wall where I can see it from my desk. I rarely get such a close-up view of a galaxy.
http://en.wikipedia.org/wiki/Spiral_galaxies wrote:
Image
<<The first acceptable theory for the spiral structure was devised by C. C. Lin and Frank Shu in 1964. They suggested that the spiral arms were manifestations of spiral density waves, they assumed that the stars travel in slightly elliptical orbits, and that the orientations of their orbits is correlated i.e. the ellipses vary in their orientation (one to another) in a smooth way with increasing distance from the galactic center. This is illustrated in the diagram. It is clear that the elliptical orbits come close together in certain areas to give the effect of arms. Stars therefore do not remain forever in the position that we now see them in, but pass through the arms as they travel in their orbits.>>
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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by neufer » Fri Nov 11, 2011 5:09 pm

GuyWithAQuestion wrote:
The image description talked about older stars (as well as black holes and neutron stars) near the galaxy center and younger stars further out along the spiral arms. Should I imagine the galaxy (and it's central black hole) as a type of gravity sink that is collecting dust and gas from it's surroundings... that when the dust and gas reaches a certain concentration it begins to form stars (young stars on the spiral arms)? And that over the millions and billions of years these young stars are pulled by gravity closer to the central black hole and take the place of the "current" older stars? And that as these old stars become even older they supernova, resulting in neutron stars and/or smaller black holes... all of which is streaming into the central black hole?
I'm not sure that anyone really knows precisely the why concerning the distribution of old (Population II) & new (Population I) stars.

However, new (high metallicity Population I) stars do NOT (and CAN NOT) evolve into (old low metallicity Population II) stars; only the reverse, in fact, can happen.

Rather new (high metallicity Population I) stars explode and evolve into even newer (high metallicity Population I) stars, white dwarfs, neutron stars and black holes.
http://en.wikipedia.org/wiki/Population_I_stars#Population_I_stars wrote:
Image
<<In astronomy and physical cosmology, the metallicity (also called Z) of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium. Since stars, which comprise most of the visible matter in the universe, are composed mostly of hydrogen and helium, astronomers use for convenience the blanket term "metal" to describe all other elements collectively. Thus, a nebula rich in carbon, nitrogen, oxygen, and neon would be "metal-rich" in astrophysical terms even though those elements are non-metals in chemistry. This term should not be confused with the usual definition of "metal"; metallic bonds are impossible within stars, and the very strongest chemical bonds are only possible in the outer layers of cool K and M stars.

The metallicity of an astronomical object may provide an indication of its age. When the universe first formed, according to the Big Bang theory, it consisted almost entirely of hydrogen which, through primordial nucleosynthesis, created a sizeable proportion of helium and only trace amounts of lithium and beryllium and no heavier elements. Therefore, older stars have lower metallicities than younger stars such as our Sun.

Stellar populations are categorized as I, II, and III, with each group having decreasing metal content and increasing age. The populations were named in the order they were discovered, which is the reverse of the order they were created. Thus, the first stars in the universe (low metal content) were population III, and recent stars (high metallicity) are population I.

While older stars do have fewer heavy elements, the fact that all stars observed have some heavier elements poses something of a puzzle, and the current explanation for this proposes the existence of hypothetical metal-free Population III stars in the early universe. Soon after the Big Bang, without metals, it is believed that only stars with masses hundreds of times that of the Sun could be formed; near the end of their lives these stars would have created the first 26 elements up to iron in the periodic table via nucleosynthesis.

It has been proposed that recent supernovae SN 2006gy and SN 2007bi may have been pair-instability supernovae in which such super-massive Population III stars exploded. It has been speculated that these stars could have formed relatively recently in dwarf galaxies containing primordial metal-free interstellar matter; past supernovae in these galaxies could have ejected their metal-rich contents at speeds high enough for them to escape the galaxy, keeping the metal content of the galaxy very low.

The next generation of stars was born out of those materials left by the death of the first. The oldest observed stars, known as Population II, have very low metallicities; as subsequent generations of stars were born they became more metal-enriched, as the gaseous clouds from which they formed received the metal-rich dust manufactured by previous generations. As those stars died, they returned metal-enriched material to the interstellar medium via planetary nebulae and supernovae, enriching the nebulae out of which the newer stars formed ever further. These youngest stars, including the Sun, therefore have the highest metal content, and are known as Population I stars.

Across the Milky Way, metallicity is higher in the galactic centre and decreases as one moves outwards. The gradient in metallicity is attributed to the density of stars in the galactic centre: there are more stars in the centre of the galaxy and so, over time, more metals have been returned to the interstellar medium and incorporated into new stars. By a similar mechanism, larger galaxies tend to have a higher metallicity than their smaller counterparts. In the case of the Magellanic Clouds, two small irregular galaxies orbiting (see note about newest research) the Milky Way, the Large Magellanic Cloud has a metallicity of about forty per cent of the Milky Way, while the Small Magellanic Cloud has a metallicity of about ten per cent of the Milky Way.>>
Art Neuendorffer

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by Chris Peterson » Fri Nov 11, 2011 5:46 pm

biddie67 wrote:The APOD description mentions that a galaxy can have more than one black hole? Wouldn''t a galaxy appear more irregular with multiple black holes?
Galaxies have millions of black holes. Since these are stellar mass (ordinary) black holes, they interact with the galaxy no differently than stars. Some galaxies have two supermassive black holes- presumably the result of a galactic merger. They are normally close together in orbit about one another, and therefore don't have a major influence on the overall galactic structure. But since these are recently merged galaxies, their structure tends to be somewhat jumbled anyway.
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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by Chris Peterson » Fri Nov 11, 2011 5:51 pm

GuyWithAQuestion wrote:And that over the millions and billions of years these young stars are pulled by gravity closer to the central black hole and take the place of the "current" older stars? And that as these old stars become even older they supernova, resulting in neutron stars and/or smaller black holes... all of which is streaming into the central black hole?
There is no mechanism by which a central black hole can attract material from the galaxy towards it. It has only a very local influence- the material in orbit must be dense enough to undergo hydrodynamic or electrodynamic drag. Otherwise, the material will simply remain in a stable orbit. Drag forces in the majority of a galaxy are extremely small. And of course, the mass of a central supermassive black hole is also tiny compared with the mass of the entire galaxy, so it doesn't have much effect on the overall orbits of galactic stars, either.
Chris

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xuxa

Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by xuxa » Fri Nov 11, 2011 6:57 pm

everytime i look at a shot like this or of other galaxys, it reassures me that we as beings are not alone in this or any other universe...and yes for every star in our universe ,i belive there is another universe out there x10..

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by Ann » Fri Nov 11, 2011 9:50 pm

http://en.wikipedia.org/wiki/Population ... on_I_stars wrote:

While older stars do have fewer heavy elements, the fact that all stars observed have some heavier elements poses something of a puzzle, and the current explanation for this proposes the existence of hypothetical metal-free Population III stars in the early universe. Soon after the Big Bang, without metals, it is believed that only stars with masses hundreds of times that of the Sun could be formed; near the end of their lives these stars would have created the first 26 elements up to iron in the periodic table via nucleosynthesis.
Astronomers find pristine gas from the big bang

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by Ann » Fri Nov 11, 2011 10:07 pm

Image
By the way... people were looking for an APOD which could be described as "62". Perhaps today's APOD is the one. Today's image is M83, and 83 is 62 + 21, and 21 is half of 42, which is the meaning of Life, the Universe and Everything. On 11-11-11, which contains the figure 1 six times, that's got to be significant. If we add that one of the "elevens" should have "twenty" before it, we get, sort of, a figure 2, too. Note that 2011-11-11 can be thought of as 2+0+1+1+1+1+1+1, which is 8, and that there are 3 "elevens", and 8+3 is both 11 and, sort of, 83. I'm sure 62 is in there somewhere, too.

This globular cluster, by the way, is M62. To my knowledge M62 is not in M83, but you never know. The picture is by Hubble.

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stephen

Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by stephen » Sat Nov 12, 2011 12:51 am

Could someone please answer this for a complete layman? In M83 and other such galaxies, which look "crowded" as hell, is the "space between stars" as huge as it is in our own Milky Way? If one could materialize at random in M83, would there be black space and distant stars only? Seems impossible looking from the outside. Thanks.

saturn2

Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by saturn2 » Sat Nov 12, 2011 12:57 am

I think that this Galaxy is very compact, the center is very bright.
Beautiful Spiral Galaxy.
The Universe is beautiful, indeed.

saturn2

Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by saturn2 » Sat Nov 12, 2011 1:24 am

Ann
Your explanation is very interesting.

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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by Chris Peterson » Sat Nov 12, 2011 1:31 am

stephen wrote:Could someone please answer this for a complete layman? In M83 and other such galaxies, which look "crowded" as hell, is the "space between stars" as huge as it is in our own Milky Way? If one could materialize at random in M83, would there be black space and distant stars only? Seems impossible looking from the outside. Thanks.
In a typical galaxy, like M83 or the Milky Way, stellar densities range from one star per cubic parsec or less to perhaps 100 stars per cubic parsec in the core. That core density is high, and if you were to materialize in such a region you'd certainly have an impressive sky around you, but that still represents essentially empty space.

Images can't help but to make galaxies look vastly more crowded than they actually are, because diffraction and other optical phenomena bloat the size of stars thousands of times. If you could see an undistorted image of M83, individual stars would only be a tiny fraction of the size of a pixel on your screen- perhaps the size of bacteria!
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Re: APOD: In the Arms of M83 (2011 Nov 11)

Post by stephen » Sat Nov 12, 2011 1:47 am

To Chris Peterson. Thank you for the very clear explanation.
Stephen