APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

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APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by APOD Robot » Thu Mar 22, 2018 4:11 am

Image NGC 253: Dusty Island Universe

Explanation: Shiny NGC 253 is one of the brightest spiral galaxies visible, and also one of the dustiest. Some call it the Silver Dollar Galaxy for its appearance in small telescopes, or just the Sculptor Galaxy for its location within the boundaries of the southern constellation Sculptor. Discovered in 1783 by mathematician and astronomer Caroline Herschel, the dusty island universe lies a mere 10 million light-years away. About 70 thousand light-years across, NGC 253 is the largest member of the Sculptor Group of Galaxies, the nearest to our own Local Group of Galaxies. In addition to its spiral dust lanes, tendrils of dust seem to be rising from a galactic disk laced with young star clusters and star forming regions in this sharp color image. The high dust content accompanies frantic star formation, earning NGC 253 the designation of a starburst galaxy. NGC 253 is also known to be a strong source of high-energy x-rays and gamma rays, likely due to massive black holes near the galaxy's center. Take a trip through extragalactic space in this short video flyby of NGC 253.

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Ann
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Re: APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by Ann » Thu Mar 22, 2018 6:09 am

NGC 253 is one of my least favorite galaxies. It looks kind of boring. No huge brilliant blue clusters are visible, no truly large flamboyant emission nebulas can be seen, and there are no large and obvious outflows like the ones in M82. The spiral structure of NGC 253 is indistinct.

But I don't doubt that NGC 253 looks good through a telescope.

Ann
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Re: APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by JohnD » Thu Mar 22, 2018 9:13 am

Billing that link as a "short video flyby" of NGC 253 was a bit overblown! This was nothing of the sort, just a zoom and retreat from the same photo as featured on this APOD! Compare other galactic flyby simulations, eg: https://www.youtube.com/watch?v=jSyeT6rlQz4

John

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Re: APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by neufer » Thu Mar 22, 2018 3:16 pm

https://en.wikipedia.org/wiki/Star_number wrote:
A star number is a centered figurate number that represents a centered hexagram (six-pointed star), such as the one that Chinese checkers is played on.

The nth star number is given by the formula Sn = 6n(n − 1) + 1.

The first 43 star numbers are: 1, 13, 37, 73, 121, 181, 253, 337, 433, 541, 661, 793, 937, 1093, 1261, 1441, 1633, 1837, 2053, 2281, 2521, 2773, 3037, 3313, 3601, 3901, 4213, 4537, 4873, 5221, 5581, 5953, 6337, 6733, 7141, 7561, 7993, 8437, 8893, 9361, 9841, 10333, 10837 (sequence A003154 in the OEIS).
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Re: APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by GoshOGeeOGolly » Thu Mar 22, 2018 4:55 pm

neufer wrote: Thu Mar 22, 2018 3:16 pm
https://en.wikipedia.org/wiki/Star_number wrote:
A star number is a centered figurate number that represents a centered hexagram (six-pointed star), such as the one that Chinese checkers is played on.

The nth star number is given by the formula Sn = 6n(n − 1) + 1.

The first 43 star numbers are: 1, 13, 37, 73, 121, 181, 253, 337, 433, 541, 661, 793, 937, 1093, 1261, 1441, 1633, 1837, 2053, 2281, 2521, 2773, 3037, 3313, 3601, 3901, 4213, 4537, 4873, 5221, 5581, 5953, 6337, 6733, 7141, 7561, 7993, 8437, 8893, 9361, 9841, 10333, 10837 (sequence A003154 in the OEIS).
GOGOG to NEUF .. I jump my orange front row 2cd from right .. or .. gogog .. I can't see the board using the quote, and forgot my move. You win.

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Re: APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by neufer » Thu Mar 22, 2018 5:16 pm

GoshOGeeOGolly wrote: Thu Mar 22, 2018 4:55 pm
GOGOG to NEUF .. I jump my orange front row 2cd from right .. or .. gogog ..
I can't see the board using the quote, and forgot my move. You win.
http://www.trentu.ca/faculty/jjoyce/fw-6.htm wrote:
Agog and magog and the round of them agrog.
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Re: APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by Craig Willford » Thu Mar 22, 2018 8:11 pm

"... ikely due to massive black holes near the galaxy's center."

Is there a reason to suspect that there is more than one massive black hole at the center?

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Re: APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by neufer » Thu Mar 22, 2018 10:07 pm

Craig Willford wrote: Thu Mar 22, 2018 8:11 pm
"... likely due to massive black holes near the galaxy's center."

Is there a reason to suspect that there is more than one massive black hole at the center?
https://en.wikipedia.org/wiki/Sculptor_Galaxy#Central_black_hole wrote:
<<Research suggests the presence in the center of this galaxy of a supermassive black hole, with a mass estimated to be 5 million times that of our Sun, which is slightly heavier than Sagittarius A*.>>
  • One supermassive black hole with multiple dust bunnies?
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Re: APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by Ann » Fri Mar 23, 2018 5:46 am

Craig Willford wrote: Thu Mar 22, 2018 8:11 pm "... ikely due to massive black holes near the galaxy's center."

Is there a reason to suspect that there is more than one massive black hole at the center?
There is certainly no reason to believe that there are two supermassive black holes in close proximity at the center of NGC 253. If a galaxy as close to us as NGC 253 was similarly endowed, the astronomical community, including you and me, would be sure to know about it now. And the rest of the world too, don't you think? After all, what might happen to us, if two supermassive black holes were to merge only 10 million light-years from us?

Even if absolutely nothing happened to us - which would be the far, far more likely outcome - the merging of the two supermassive black holes so close to us might still provide a spectacle for professional astronomers and amateurs alike. And NGC 253 would rise from relative obscurity to astronomical super-fame. Stephen Hawking, move over!

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Re: APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by geckzilla » Fri Mar 23, 2018 6:29 am

Ann wrote: Fri Mar 23, 2018 5:46 am
Craig Willford wrote: Thu Mar 22, 2018 8:11 pm "... ikely due to massive black holes near the galaxy's center."

Is there a reason to suspect that there is more than one massive black hole at the center?
There is certainly no reason to believe that there are two supermassive black holes in close proximity at the center of NGC 253. If a galaxy as close to us as NGC 253 was similarly endowed, the astronomical community, including you and me, would be sure to know about it now. And the rest of the world too, don't you think? After all, what might happen to us, if two supermassive black holes were to merge only 10 million light-years from us?

Even if absolutely nothing happened to us - which would be the far, far more likely outcome - the merging of the two supermassive black holes so close to us might still provide a spectacle for professional astronomers and amateurs alike. And NGC 253 would rise from relative obscurity to astronomical super-fame. Stephen Hawking, move over!
Take a look at the data and information available at the Chandra website:
http://chandra.harvard.edu/photo/2001/0012/index.html
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Re: APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by neufer » Fri Mar 23, 2018 1:35 pm

geckzilla wrote: Fri Mar 23, 2018 6:29 am
Craig Willford wrote: Thu Mar 22, 2018 8:11 pm
"... likely due to massive black holes near the galaxy's center."

Is there a reason to suspect that there is more than one massive black hole at the center?
Take a look at the data and information available at the Chandra website:
http://chandra.harvard.edu/photo/2001/0012/index.html
http://www.sciencemag.org/news/2001/06/midsized-black-holes-everywhere wrote:
Midsized Black Holes Everywhere
By Mark SincellJun. 7, 2001 , Science Magazine

PASADENA, CALIFORNIA--Like the glint of diamonds in the dust, brilliant pinpricks of x-rays have led three independent teams to a precious discovery: Nearly 100 surprisingly heavy black holes in nearby galaxies. A handful of similar objects had been seen before, but the teams never expected to find so many more. They suggest these so-called intermediate mass black holes could coalesce to form the supermassive black holes thought to inhabit nearly every galaxy.

Black holes once seemed to come in two drastically different varieties. Those in the Milky Way and nearby galaxies had about the same mass as the sun; the rest were at least a million times heavier and lived in galaxies at the distant fringes of the universe. In between, there was nothing. The gaps began to fill in 2 years ago. First, astronomers using the Hubble Space Telescope discovered that the supermassive black holes were common in nearby galaxies too, and every galaxy could harbor one of the dark beasts. Then, the ASCA x-ray satellite spotted an unusually bright x-ray source in the galaxy M82, thought to come from the superheated gas surrounding a black hole weighing about 100 solar masses. But was it a rarity?

Absolutely not, says a chorus of speakers here at this week's meeting of the American Astronomical Society. Using images of 40 nearby galaxies taken with the Chandra X-ray Observatory, three teams have brought the count to almost 100. Goddard Space Flight Center astrophysicist Kim Weaver, who led one of the teams, argues that these black holes could spiral to the center of the galaxy and coalesce into a supermassive hole. "There is definitely enough material there to do this," agrees Andrew Ptak, an astrophysicist at Carnegie Mellon University in Pittsburgh, who leads a second team.
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Re: APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by GoshOGeeOGolly » Fri Mar 23, 2018 3:32 pm

GoshOGeeOGolly wrote: Fri Mar 23, 2018 3:29 pm
neufer wrote: Fri Mar 23, 2018 1:35 pm
geckzilla wrote: Fri Mar 23, 2018 6:29 am

Take a look at the data and information available at the Chandra website:
http://chandra.harvard.edu/photo/2001/0012/index.html
http://www.sciencemag.org/news/2001/06/midsized-black-holes-everywhere wrote:
Midsized Black Holes Everywhere
By Mark SincellJun. 7, 2001 , Science Magazine

PASADENA, CALIFORNIA--Like the glint of diamonds in the dust, brilliant pinpricks of x-rays have led three independent teams to a precious discovery: Nearly 100 surprisingly heavy black holes in nearby galaxies. A handful of similar objects had been seen before, but the teams never expected to find so many more. They suggest these so-called intermediate mass black holes could coalesce to form the supermassive black holes thought to inhabit nearly every galaxy.

Black holes once seemed to come in two drastically different varieties. Those in the Milky Way and nearby galaxies had about the same mass as the sun; the rest were at least a million times heavier and lived in galaxies at the distant fringes of the universe. In between, there was nothing. The gaps began to fill in 2 years ago. First, astronomers using the Hubble Space Telescope discovered that the supermassive black holes were common in nearby galaxies too, and every galaxy could harbor one of the dark beasts. Then, the ASCA x-ray satellite spotted an unusually bright x-ray source in the galaxy M82, thought to come from the superheated gas surrounding a black hole weighing about 100 solar masses. But was it a rarity?

Absolutely not, says a chorus of speakers here at this week's meeting of the American Astronomical Society. Using images of 40 nearby galaxies taken with the Chandra X-ray Observatory, three teams have brought the count to almost 100. Goddard Space Flight Center astrophysicist Kim Weaver, who led one of the teams, argues that these black holes could spiral to the center of the galaxy and coalesce into a supermassive hole. "There is definitely enough material there to do this," agrees Andrew Ptak, an astrophysicist at Carnegie Mellon University in Pittsburgh, who leads a second team.
OOPS. Wrong button pushed, will try again.

Is there any chance even smaller undetected Black Holes could be the missing mass thought to be Dark Matter? (Boy, could THAT question push some buttons.)

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Re: APOD: NGC 253: Dusty Island Universe (2018 Mar 22)

Post by neufer » Fri Mar 23, 2018 3:47 pm

GoshOGeeOGolly wrote: Fri Mar 23, 2018 3:32 pm
Is there any chance even smaller undetected Black Holes could be the missing mass thought to be Dark Matter?
https://en.wikipedia.org/wiki/Dark_matter wrote:
<<Most scenarios involving familiar objects such as interstellar dust, large black holes, asteroids and other non-luminous or dense objects are thought to be ruled out by observations or the little present knowledge of dark matter's properties. Current models prefer a cold dark matter scenario, in which structures emerge by gradual accumulation of particles.

Multiple lines of evidence suggest the majority of dark matter is not made of baryons:
  • Astronomical searches for gravitational microlensing in the Milky Way found that at most a small fraction of the dark matter may be in dark, compact, conventional objects (MACHOs, etc.); the excluded range of object masses is from half the Earth's mass up to 30 solar masses, which covers nearly all the plausible candidates.
  • Sufficient diffuse, baryonic gas or dust would be visible when backlit by stars.
  • The theory of Big Bang nucleosynthesis predicts the observed abundance of the chemical elements. If there are more baryons, then there should also be more helium, lithium and heavier elements synthesized during the Big Bang. Agreement with observed abundances requires that baryonic matter makes up between 4–5% of the universe's critical density. In contrast, large-scale structure and other observations indicate that the total matter density is about 30% of the critical density.
  • Detailed analysis of the small irregularities (anisotropies) in the cosmic microwave background. Observations by WMAP and Planck indicate that around five-sixths of the total matter is in a form that interacts significantly with ordinary matter or photons only through gravitational effects.>>
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