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APOD: NGC 6357: Cathedral to Massive Stars (2020 Aug 30)
Posted: Sun Aug 30, 2020 4:06 am
by APOD Robot
NGC 6357: Cathedral to Massive Stars
Explanation: How massive can a normal star be? Estimates made from distance, brightness and standard
solar models had given one star in the
open cluster Pismis 24 over 200 times the mass of our
Sun, making it one of the most massive stars known. This
star is the brightest object
located just above the gas front in the
featured image. Close inspection of
images taken with the
Hubble Space Telescope, however, have shown that Pismis 24-1 derives its brilliant luminosity
not from a single star but from
three at least.
Component stars would still remain near 100 solar masses, making them among the more
massive stars currently on record. Toward the bottom of the image,
stars are still forming in the associated
emission nebula NGC 6357. Appearing perhaps like a
Gothic cathedral, energetic stars near the center appear to be
breaking out and illuminating a
spectacular cocoon.
Re: APOD: NGC 6357: Cathedral to Massive Stars (2020 Aug 30)
Posted: Sun Aug 30, 2020 4:32 am
by steve case
Looks like a giant alligator snapper from the bayou:
https://i.postimg.cc/s2sPrmk2/image.png
Re: APOD: NGC 6357: Cathedral to Massive Stars (2020 Aug 30)
Posted: Sun Aug 30, 2020 6:17 am
by Ann
Today's APOD is a fascianting portrait of one of the most remarkable sites of high-mass star formation in our galaxy.
Can't stand the colors, though. There is no way that the star near the bottom of the image, which is deeper embedded in nebulosity that the cluster "above" it, should look bluer than the stars in the upper parts of the image.
No way.
Ann
Re: APOD: NGC 6357: Cathedral to Massive Stars (2020 Aug 30)
Posted: Sun Aug 30, 2020 12:11 pm
by orin stepanek
I really like the photo!
![Cool 8-)](./images/smilies/icon_cool.gif)
I'm going to tip
it on it's side and use it as a wallpaper! A
person could easily have two photos; the
stars on top; or the nebula
![Very Happy :D](./images/smilies/icon_biggrin.gif)
Re: APOD: NGC 6357: Cathedral to Massive Stars (2020 Aug 30)
Posted: Sun Aug 30, 2020 1:59 pm
by BDanielMayfield
Ann wrote: ↑Sun Aug 30, 2020 6:17 am
Today's APOD is a fascianting portrait of one of the most remarkable sites of high-mass star formation in our galaxy.
Can't stand the colors, though. There is no way that the star near the bottom of the image, which is deeper embedded in nebulosity that the cluster "above" it, should look bluer than the stars in the upper parts of the image.
No way.
Ann
Ann's comment made me look again, and I note that many stars surrounding the brightest central stars of this cluster have the blue affect, whereas all the central stars are nothing but white.
My initial view of this image was 'oh, that's nice'. But knowing what we've learned about the most massive stars being brilliantly blue, Ann's opinion is well founded.
I'd like to see other views of this scene for scientific comparison. What do the brightest stars here really look like?
Re: APOD: NGC 6357: Cathedral to Massive Stars (2020 Aug 30)
Posted: Sun Aug 30, 2020 2:08 pm
by Sa Ji Tario
Also in the constellation of the Auriga, in the Heart Nebula, in the Northern Cross, in Carina among others there are massive stars
Re: APOD: NGC 6357: Cathedral to Massive Stars (2020 Aug 30)
Posted: Sun Aug 30, 2020 2:32 pm
by orin stepanek
BDanielMayfield wrote: ↑Sun Aug 30, 2020 1:59 pm
Ann wrote: ↑Sun Aug 30, 2020 6:17 am
Today's APOD is a fascianting portrait of one of the most remarkable sites of high-mass star formation in our galaxy.
Can't stand the colors, though. There is no way that the star near the bottom of the image, which is deeper embedded in nebulosity that the cluster "above" it, should look bluer than the stars in the upper parts of the image.
No way.
Ann
Ann's comment made me look again, and I note that many stars surrounding the brightest central stars of this cluster have the blue affect, whereas all the central stars are nothing but white.
My initial view of this image was 'oh, that's nice'. But knowing what we've learned about the most massive stars being brilliantly blue, Ann's opinion is well founded.
I'd like to see other views of this scene for scientific comparison. What do the brightest stars here really look like?
Ann's views are mostly spot on; and I'm not smart enough to ? any of them! I wonder about the blue star at the bottom! Does it get some of it's color from all the dust in it's surroundings?
largest star Pismis-1 from Aug 30, 2020
Posted: Sun Aug 30, 2020 9:03 pm
by ta152h0
I thought canis majoris was the biggest star in the heavens. I remember on APOD sometime ago, when you started out showing the sun, then went on a movie showing stars as they were bigger, showing stars to scale. pass the ice cold one.
Re: largest star Pismis-1 from Aug 30, 2020
Posted: Sun Aug 30, 2020 9:41 pm
by Chris Peterson
ta152h0 wrote: ↑Sun Aug 30, 2020 9:03 pm
I thought canis majoris was the biggest star in the heavens. I remember on APOD sometime ago, when you started out showing the sun, then went on a movie showing stars as they were bigger, showing stars to scale. pass the ice cold one.
Alpha CMa (Sirius) is the
brightest star we see in our sky. But it's not very big- about twice the mass of the Sun, and not even twice the diameter. It is bright because of a fairly high intrinsic luminosity, about 25 times that of the Sun, but also because it is one of the closest stars.
Re: largest star Pismis-1 from Aug 30, 2020
Posted: Sun Aug 30, 2020 10:12 pm
by orin stepanek
ta152h0 wrote: ↑Sun Aug 30, 2020 9:03 pm
I thought canis majoris was the biggest star in the heavens. I remember on APOD sometime ago, when you started out showing the sun, then went on a movie showing stars as they were bigger, showing stars to scale. pass the ice cold one.
Cheers!
![🥃](//cdn.jsdelivr.net/gh/twitter/twemoji@latest/assets/svg/1f943.svg)
Re: largest star Pismis-1 from Aug 30, 2020
Posted: Sun Aug 30, 2020 10:30 pm
by bystander
ta152h0 wrote: ↑Sun Aug 30, 2020 9:03 pm
I thought canis majoris was the biggest star in the heavens. I remember on APOD sometime ago, when you started out showing the sun, then went on a movie showing stars as they were bigger, showing stars to scale. pass the ice cold one.
Chris Peterson wrote: ↑Sun Aug 30, 2020 9:41 pm
Alpha CMa (Sirius) is the
brightest star we see in our sky. But it's not very big- about twice the mass of the Sun, and not even twice the diameter. It is bright because of a fairly high intrinsic luminosity, about 25 times that of the Sun, but also because it is one of the closest stars.
I think he was referring to
VY Canis Majoris, but even in the
2018 June 12 APOD
UY Scuti has a larger radius, although it is not as massive. For the most massive star (and the most luminous) known star, we look to
R136a1 in the LMC, but its radius is only some 30 times that of the Sun.
Re: APOD: NGC 6357: Cathedral to Massive Stars (2020 Aug 30)
Posted: Sun Aug 30, 2020 11:58 pm
by De58te
This just makes me curious. Is Prismis 24-1 real color white or blue? In this APOD they do look white. Yet in this animation from ESA where Prismis 24-1 are actually binary stars, they look incredibly blue.
https://www.spacetelescope.org/videos/heic0619b/
Re: APOD: NGC 6357: Cathedral to Massive Stars (2020 Aug 30)
Posted: Mon Aug 31, 2020 12:48 am
by geckzilla
fwiw there isn't complete coverage over the entire image with wideband filters to portray accurate star colors relative to one another from the top half to the bottom half. Only the narrowband data cover the whole image. this is just based on me looking at the footprints in the archive search result. I'm not entirely sure how it's composed, but it doesn't look like a complete mosaic to me.
Re: APOD: NGC 6357: Cathedral to Massive Stars (2020 Aug 30)
Posted: Mon Aug 31, 2020 12:54 am
by geckzilla
ps that's me trying to say "go easy on whoever made this image they did the best they could with what they had"
Re: APOD: NGC 6357: Cathedral to Massive Stars (2020 Aug 30)
Posted: Mon Aug 31, 2020 3:03 am
by BDanielMayfield
geckzilla wrote: ↑Mon Aug 31, 2020 12:54 am
ps that's me trying to say "go easy on whoever made this image they did the best they could with what they had"
Roger on that geck. After looking at several of the links in the explanation I noticed that this very same image is featured on NASA webpages. (hey Orin, if you really like it you can buy a poster!) So the work on this image is high quality, even if some artistic license on the star coloring
MIGHT have been employed here.
I say that there might have been some creative expertise applied here due to the location of the subject, deep inside the central dust band of the galaxy, near its center where the dust is very thick. Hubble had to peer long and hard to pull data out of this area, I'd guess. So there would have to have been a great deal of signal loss, what astronomers call extinction or interstellar reddening in this image. The producer came up with a picture that looks good, so 'nuf said.