APOD: Spiral Galaxy M66 from Hubble (2021 Feb 24)

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APOD: Spiral Galaxy M66 from Hubble (2021 Feb 24)

Post by APOD Robot » Wed Feb 24, 2021 5:05 am

Image Spiral Galaxy M66 from Hubble

Explanation: It's always nice to get a new view of an old friend. This stunning Hubble Space Telescope image of nearby spiral galaxy M66 is just that. A spiral galaxy with a small central bar, M66 is a member of the Leo Galaxy Triplet, a group of three galaxies about 30 million light years from us. The Leo Triplet is a popular target for relatively small telescopes, in part because M66 and its galactic companions M65 and NGC 3628 all appear separated by about the angular width of a full moon. The featured image of M66 was taken by Hubble to help investigate the connection between star formation and molecular gas clouds. Clearly visible are bright blue stars, pink ionized hydrogen clouds -- sprinkled all along the outer spiral arms, and dark dust lanes in which more star formation could be hiding.

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Ann
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Re: APOD: Spiral Galaxy M66 from Hubble (2021 Feb 24)

Post by Ann » Wed Feb 24, 2021 6:02 am

Are the APOD editors aware that today's image is a very, very recent repeat?

M66_Hubble_LeoShatz_Crop1024[1].jpg
M66. Astronomy Picture of the Day on January 28, 2021.
Image Credit: NASA, ESA, Hubble; Processing & Copyright: Leo Shatz


Okay. Maybe a few more people were involved in today's version of the Hubble image of Leo Triplet galaxy M66 than in the January 28 version of it. Also the framing of the two pictures is a little different. Still, for a casual observer, the difference is too small to comment on.

I wrote quite a lot about M66 in the January 24 thread, so I won't repeat myself after less than a month!

Ann
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Re: APOD: Spiral Galaxy M66 from Hubble (2021 Feb 24)

Post by orionghf » Wed Feb 24, 2021 12:13 pm

Hi I'm new here :ssmile: , I guess one of the links is broken
the one with the text investigate
that links to https://www.stsci.edu/hst/phase2-public/15654.pdf
or is it just broken for me :? :?:

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Re: APOD: Spiral Galaxy M66 from Hubble (2021 Feb 24)

Post by orin stepanek » Wed Feb 24, 2021 12:28 pm

M66_HubbleShatz_960.jpg

Bet it would be more amazing if it were a photo from James Webb! :D 8-)
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Re: APOD: Spiral Galaxy M66 from Hubble (2021 Feb 24)

Post by orin stepanek » Wed Feb 24, 2021 12:34 pm

orionghf wrote:
Wed Feb 24, 2021 12:13 pm
Hi I'm new here :ssmile: , I guess one of the links is broken
the one with the text investigate
that links to https://www.stsci.edu/hst/phase2-public/15654.pdf
or is it just broken for me :? :?:
Service temporarily unavailable! Try again later!
Orin

Smile today; tomorrow's another day!

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Re: APOD: Spiral Galaxy M66 from Hubble (2021 Feb 24)

Post by johnnydeep » Wed Feb 24, 2021 7:02 pm

orin stepanek wrote:
Wed Feb 24, 2021 12:34 pm
orionghf wrote:
Wed Feb 24, 2021 12:13 pm
Hi I'm new here :ssmile: , I guess one of the links is broken
the one with the text investigate
that links to https://www.stsci.edu/hst/phase2-public/15654.pdf
or is it just broken for me :?
Service temporarily unavailable! Try again later!
Well, it's working now. The PDF is 265 pages long, and filled with tons of graphs and tables, all of which mean little to this rank amateur :ssmile:
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."

andyg

Re: APOD: Spiral Galaxy M66 from Hubble (2021 Feb 24)

Post by andyg » Wed Feb 24, 2021 9:17 pm

Dumb question? Is all the bright light at the center reflected from haze or a heck of a lot of stars? I'm assuming the latter, but then why are they so much smaller than the new blue stars? Or are these old, small "yellow dwarf" stars that just stick around a long time?

andyg

Re: APOD: Spiral Galaxy M66 from Hubble (2021 Feb 24)

Post by andyg » Wed Feb 24, 2021 9:49 pm

andyg wrote:
Wed Feb 24, 2021 9:17 pm
Dumb question? Is all the bright light at the center reflected from haze or a heck of a lot of stars? I'm assuming the latter, but then why are they so much smaller than the new blue stars? Or are these old, small "yellow dwarf" stars that just stick around a long time?
Yup, dumb question. Nevermind!

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Re: APOD: Spiral Galaxy M66 from Hubble (2021 Feb 24)

Post by orin stepanek » Thu Feb 25, 2021 1:50 am

johnnydeep wrote:
Wed Feb 24, 2021 7:02 pm
orin stepanek wrote:
Wed Feb 24, 2021 12:34 pm
orionghf wrote:
Wed Feb 24, 2021 12:13 pm
Hi I'm new here :ssmile: , I guess one of the links is broken
the one with the text investigate
that links to https://www.stsci.edu/hst/phase2-public/15654.pdf
or is it just broken for me :?
Service temporarily unavailable! Try again later!
Well, it's working now. The PDF is 265 pages long, and filled with tons of graphs and tables, all of which mean little to this rank amateur :ssmile:
I wasn't really interested as cept to explain that the link was down instead of broken! 😉 10Q!
Orin

Smile today; tomorrow's another day!

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Ann
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Re: APOD: Spiral Galaxy M66 from Hubble (2021 Feb 24)

Post by Ann » Thu Feb 25, 2021 6:14 am

andyg wrote:
Wed Feb 24, 2021 9:17 pm
Dumb question? Is all the bright light at the center reflected from haze or a heck of a lot of stars? I'm assuming the latter, but then why are they so much smaller than the new blue stars? Or are these old, small "yellow dwarf" stars that just stick around a long time?
Hi Andy!

Cluster NGC 6231 Sergio Eguivar.png
Young blue star cluster NGC 6231. Photo: Sergio Eguivar.

The "big blue stars" in M66 are actually clusters of young bright stars, similar to cluster NGC 6231 in the picture at left.

The large blue patch just below center is a large field of young stars, with some star clusters mixed into it. It is similar to the large blue patch or field of young stars in Sagittarius, called the Small Sagittarius Star Cloud.

Large Sagittarius Star Cloud.png
The Large Sagittarius Star Cloud, made up of small old red stars.
Photo: Michael Stecker.


In the picture at left you can see the Large Sagittarius Star Cloud of the Milky Way. In the picture at right you can see the Andromeda Galaxy. As you can see, the yellow center (or bulge) of Andromeda is very much brighter than its bluish disk.

The Large Sagittarius Star Cloud is part of the bulge of the Milky Way. Basically, the stellar population in the bulge of the Milky Way (and in the bulge of Andromeda) is made up of modest (not overly bright) red giant stars like Pollux, Arcturus and Dubhe, as well as truly huge numbers of stars like the Sun, and, even more, stars fainter and redder than the Sun.


Most stars that are born are low-mass stars, lower in mass than the Sun. They are called red dwarfs, and they are redder and much fainter than the Sun, and they have extraordinarily long life spans. Not a single red dwarf that was ever born in the history of the Universe has ever died of old age! That is because they fuse their meager supply of gas so exceedingly slowly!

So when more and more stars are born in the Universe, the "supply" of small red stars just grows larger and larger. More and more of them are born, and none of them die. The sheer overwhelming numbers of them make their total light bright, even if the vast majority of the individual stars are faint. (Admittedly though, most of the light from galactic bulges comes from the red giant stars. They are also numerous in there.)

Why do they gather in the center of galaxies? The way I understand it, star formation starts in the center of galaxies, and a lot of stars are born there. But after some time the molecular gas, which is necessary for new stars to be born, is "used up" or "blown away" from the center of spiral galaxies (like the Milky Way and Andromeda), and instead, what remains of the gas gathers in the disk and in the spiral arms, where relatively small numbers of bright, blue and short-lived stars are born.

But in some former spiral galaxies, all the gas has been used up, all the bright blue stars have died, and only the small red and yellow stars remain. These galaxies are "all yellow".

Ann
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Last edited by Ann on Fri Feb 26, 2021 5:44 am, edited 1 time in total.
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andyg

Re: APOD: Spiral Galaxy M66 from Hubble (2021 Feb 24)

Post by andyg » Thu Feb 25, 2021 8:54 pm

Ann wrote:
Thu Feb 25, 2021 6:14 am
andyg wrote:
Wed Feb 24, 2021 9:17 pm
Dumb question? Is all the bright light at the center reflected from haze or a heck of a lot of stars? I'm assuming the latter, but then why are they so much smaller than the new blue stars? Or are these old, small "yellow dwarf" stars that just stick around a long time?
Hi Andy!


The "big blue stars" in M66 are actually clusters of young bright stars, similar to cluster NGC 6231 in the picture at left.

The large blue patch just below center is a large field of young stars, with some star clusters mixed into it. It is similar to the large blue patch or field of young stars in Sagittarius, called the Small Sagittarius Star Cloud.

In the picture at left you can see the Large Sagittarius Star Cloud of the Milky Way. In the picture at right you can see the Andromeda Galaxy. As you can see, the yellow center (or bulge) of Andromeda is very much brighter than its bluish disk.

The Large Sagittarius Star Cloud is part of the bulge of the Milky Way. Basically, the stellar population in the bulge of the Milky Way (and in the bulge of Andromeda) is made up of modest (not overly bright) red giant stars like Pollux, Arcturus and Dubhe, as well as truly huge numbers of stars like the Sun, and, even more, stars fainter and redder than the Sun.

Most stars that are born are low-mass stars, lower in mass than the Sun. They are called red dwarfs, and they are redder and much fainter than the Sun, and they have extraordinarily long life spans. Not a single red dwarf that was ever born in the history of the Universe has ever died of old age! That is because they fuse their meager supply of gas so exceedingly slowly!

So when more and more stars are born in the Universe, the "supply" of small red stars just grows larger and larger. More and more of them are born, and none of them die. The sheer overwhelming numbers of them make their total light bright, even if the vast majority of the individual stars are faint.

Why do they gather in the center of galaxies? The way I understand it, star formation starts in the center of galaxies, and a lot of stars are born there. But after some time the molecular gas, which is necessary for new stars to be born, is "used up" or "blown away" from the center of spiral galaxies (like the Milky Way and Andromeda), and instead, the gas gathers in the disk and in the spiral arms, where new, bright, blue and short-lived stars are born.

Ann
Thank you!!