Hubble: Sombrero Galaxy's Halo Suggests a Turbulent Past

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Hubble: Sombrero Galaxy's Halo Suggests a Turbulent Past

Post by bystander » Thu Feb 20, 2020 6:50 pm

Beyond the Brim, Sombrero Galaxy's Halo Suggests a Turbulent Past
NASA | GSFC | STScI | HubbleSite | 2020 Feb 20
stsci-h-p2008a-f.jpg
On the left is an image of the Sombrero galaxy (M104) that includes a portion of the
much fainter halo far outside its bright disk and bulge. Hubble photographed two
regions in the halo (one of which is shown by the white box). The images on the right
zoom in to show the level of detail Hubble captured. The orange box, a small subset of
Hubble's view, contains myriad halo stars. The stellar population increases in density
closer to the galaxy's disk (bottom blue box). Credits: NASA/Digitized Sky Survey/
P. Goudfrooij (STScI)/The Hubble Heritage Team (STScI/AURA)

Surprising new data from NASA's Hubble Space Telescope suggests the smooth, settled "brim" of the Sombrero galaxy's disk may be concealing a turbulent past. Hubble's sharpness and sensitivity resolves tens of thousands of individual stars in the Sombrero's vast, extended halo, the region beyond a galaxy's central portion, typically made of older stars. These latest observations of the Sombrero are turning conventional theory on its head, showing only a tiny fraction of older, metal-poor stars in the halo, plus an unexpected abundance of metal-rich stars typically found only in a galaxy's disk, and the central bulge. Past major galaxy mergers are a possible explanation, though the stately Sombrero shows none of the messy evidence of a recent merger of massive galaxies. ...

Long a favorite of astronomers and amateur sky watchers alike for its bright beauty and curious structure, the Sombrero Galaxy (M104) now has a new chapter in its strange story — an extended halo of metal-rich stars with barely a sign of the expected metal-poor stars that have been observed in the halos of other galaxies. Researchers, puzzling over the data from Hubble, turned to sophisticated computer models to suggest explanations for the perplexing inversion of conventional galactic theory. Those results suggest the equally surprising possibility of major mergers in the galaxy's past, though the Sombrero's majestic structure bears no evidence of recent disruption. ...

The results also defied expectations, indicating that the unperturbed Sombrero had undergone major accretion, or merger, events billions of years ago. Unlike our Milky Way galaxy, which is thought to have swallowed up many small satellite galaxies in so-called "minor" accretions over billions of years, a major accretion is the merger of two or more similarly massive galaxies that are rich in later-generation, higher-metallicity stars. ...

The Strikingly Metal-Rich Halo of the Sombrero Galaxy ~ Roger E. Cohen et al
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Re: Hubble: Sombrero Galaxy's Halo Suggests a Turbulent Past

Post by neufer » Thu Feb 20, 2020 10:59 pm

Art Neuendorffer

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Re: Hubble: Sombrero Galaxy's Halo Suggests a Turbulent Past

Post by Ann » Fri Feb 21, 2020 4:31 am




















I've always thought that there is a bit of a similarity between the Sombrero Galaxy and planet Saturn. How did they acquire their equatorial extensions?


In 2012, then-recent images by the Spitzer Space Telescope prompted a new hypothesis about the cause of Saturn's disk (make that disks):
Jason Major of Universe Today wrote:

Although it might seem that the Sombrero is the result of a collision between two separate galaxies, that’s actually not thought to be the case. Such an event would have destroyed the disk structure that’s seen today; instead, it’s thought that the Sombrero accumulated a lot of extra gas billions of years ago when the Universe was populated with large clouds of gas and dust. The extra gas fell into orbit around the galaxy, eventually spinning into a flattened disk and forming new stars.
The new observations by Hubble do suggest a major collision as the cause of the formation of the Sombrero Galaxy. But how did it get so orderly?

And how did Saturn's rings become so orderly?

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Re: Hubble: Sombrero Galaxy's Halo Suggests a Turbulent Past

Post by neufer » Fri Feb 21, 2020 2:45 pm

Ann wrote:
Fri Feb 21, 2020 4:31 am
Jason Major of Universe Today wrote:

Although it might seem that the Sombrero is the result of a collision between two separate galaxies, that’s actually not thought to be the case. Such an event would have destroyed the disk structure that’s seen today; instead, it’s thought that the Sombrero accumulated a lot of extra gas billions of years ago when the Universe was populated with large clouds of gas and dust. The extra gas fell into orbit around the galaxy, eventually spinning into a flattened disk and forming new stars.
The new observations by Hubble do suggest a major collision as the cause of the formation of the Sombrero Galaxy. But how did it get so orderly?
Click to play embedded YouTube video.
A bullet cluster collision would leave:
  • 1) an accumulated disk with a lot of extra gas

    2) a pair of polar galaxies with
    lots of stars & dark matter but no gas

    3) and one very wet Neil deGrasse Tyson :arrow:
Art Neuendorffer