by Ann » Fri Dec 01, 2023 6:58 am
Milky Way rising. Image Credit & Copyright: José Rodrigues
What I find most interesting about this APOD is the gray color of the main dust lane of the Milky Way. The color is due to a magnificent sprinkling of stars in front of the dark dust lane. Many of these stars may be just foreground stars, unrelated to the dust lane, but it seems very likely that many of these stars were actually born here. Then again, what do we mean by "here"? The major dust lane of the Milky Way is thousands of light-years deep. Or rather, the major Milky Way dust lane that we see in projection is likely made up of large numbers of overlapping segments.
Beautiful barred spiral galaxy NGC 4535 has two major spiral arms, but also armlets and various dust structures located between the major arms. So if we see stars that appear to have formed in the dust lane of an edge-on galaxy, in which of the dust (and gas) structures were they actually born? Naturally, we can't see very deep into the Milky Way at all, because of the heavy dust extinction, so I find it likely that the dust lane we can see should have played a role in creating the stars that we see in front of it.
An old picture of edge-on spiral galaxy NGC 891 really demonstrates how parts of a galaxy's major dust lane may be sparkling with new stars, while an equally large part of it may seem all "dark and dead":
Note that the "left half" of the central dust lane of NGC 891 is blue with recent star formation, whereas the "right side" is mostly "dark and dead". (Or it may just possibly be "pregnant" with a lot of unborn stars, but if so, we can't see it in Jean-Charles Cuillandre's picture.)
Let's look at the Milky Way from another angle (so to speak):
The region of the Milky Way that we saw in the APOD was about this part of Akira Fuji's picture:
- A small part of the Milky Way Akira Fuji.png (144.02 KiB) Viewed 2937 times
It is starry! And it's likely that this small part of the Milky Way dust lane really has given birth to a lot of stars.
Ann
[float=left][attachment=1]APOD 1 December 2023 annotated.png[/attachment][c][size=85][color=#0040FF]Milky Way rising. Image Credit & Copyright: José Rodrigues[/color][/size][/c][/float]
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What I find most interesting about this APOD is the gray color of the main dust lane of the Milky Way. The color is due to a magnificent sprinkling of stars in front of the dark dust lane. Many of these stars may be just foreground stars, unrelated to the dust lane, but it seems very likely that many of these stars were actually born here. Then again, what do we mean by "here"? The major dust lane of the Milky Way is thousands of light-years deep. Or rather, the major Milky Way dust lane that we see in projection is likely made up of large numbers of overlapping segments.
[img3="NGC 4535. Credit: ESA/Hubble & NASA, J. Lee and the PHANGS-HST Team"]https://upload.wikimedia.org/wikipedia/commons/thumb/e/e3/Colours_of_the_Lost_Galaxy.jpg/1004px-Colours_of_the_Lost_Galaxy.jpg[/img3]
Beautiful barred spiral galaxy NGC 4535 has two major spiral arms, but also armlets and various dust structures located between the major arms. So if we see stars that appear to have formed in the dust lane of an edge-on galaxy, in which of the dust (and gas) structures were they actually born? Naturally, we can't see very deep into the Milky Way at all, because of the heavy dust extinction, so I find it likely that the dust lane we can see should have played a role in creating the stars that we see in front of it.
An old picture of edge-on spiral galaxy NGC 891 really demonstrates how parts of a galaxy's major dust lane may be sparkling with new stars, while an equally large part of it may seem all "dark and dead":
[img3="NGC 891. Credit: Jean-Charles Cuillandre (CFHT), Hawaiian Starlight, CFHT"]https://apod.nasa.gov/apod/image/0207/ngc891_cfht.jpg[/img3]
Note that the "left half" of the central dust lane of NGC 891 is blue with recent star formation, whereas the "right side" is mostly "dark and dead". (Or it may just possibly be "pregnant" with a lot of unborn stars, but if so, we can't see it in Jean-Charles Cuillandre's picture.)
Let's look at the Milky Way from another angle (so to speak):
[float=left][img3="The northern Milky Way from Cygnus to Sagittarius. The very dark long dust lane in the image is called the Great Rift. There are no signs of obvious star formation in the Great Rift. Credit: Akira Fuji"]https://upload.wikimedia.org/wikipedia/commons/thumb/7/78/Dark_Rift_2012.jpg/1280px-Dark_Rift_2012.jpg[/img3][/float]
[clear][/clear]
The region of the Milky Way that we saw in the APOD was about this part of Akira Fuji's picture:
[attachment=0]A small part of the Milky Way Akira Fuji.png[/attachment]
It is starry! And it's likely that this small part of the Milky Way dust lane really has given birth to a lot of stars.
Ann