Explanation: Gorgeous spiral galaxy Messier 33 seems to have more than its fair share of glowing hydrogen gas. A prominent member of the local group of galaxies, M33 is also known as the Triangulum Galaxy and lies a mere 3 million light-years away. The galaxy's central 30,000 light-years or so are shown in this sharp galaxy portrait. The portrait features M33's reddish ionized hydrogen clouds or HII regions. Sprawling along loose spiral arms that wind toward the core, M33's giant HII regions are some of the largest known stellar nurseries, sites of the formation of short-lived but very massive stars. Intense ultraviolet radiation from the luminous, massive stars ionizes the surrounding hydrogen gas and ultimately produces the characteristic red glow. In this image, broadband data were combined with narrowband data recorded through a hydrogen-alpha filter. That filter transmits the light of the strongest visible hydrogen emission line.
APOD 13 October 2023 detail.png (214.31 KiB) Viewed 18441 times
And just check out the spiral arm at lower left! It's full of bubbles.
The "bubble nebulas" that we see in M33 are mature. Their gas is dispersing, and star formation in the center of these particular nebulas have (in most cases at least) come to an end (although low-mass star formation may possibly continue along the nebula's perimeter).
We may compare the Rosette Nebula with the Orion Nebula, where the Rosette Nebula has exhausted its gas in the center, whereas the Orion Nebula is still "full of gas" and very bright in its center:
I really appreciate today's APOD, where bright blue-white stars are seen scattered like grains of sand all over the galaxy in the full resolution image. And as I've said, all the details seen in all those emission nebulas are fascinating indeed.
Or, to be precise, not being able to see the really bright nebulas for all the scattered nebulosity seen all over the place. So I recommend a picture by Adam Block, where the bright nebulas really stand out!
Triangulum Galaxy (Messier 33). Image: Adam Block/Mount Lemmon SkyCenter/
University of Arizona
Note two really bright nebulas in M33: NGC 604 at upper right, and NGC 595 to the lower right of the yellow center of M33. A closeup of NGC 604 shows us that there are bubbles in NGC 604 as well:
I wonder if those large bubble nebulae are closer in nature to Barnard's Loop rather than something like the Rosette?
Re: APOD: Hydrogen Clouds of M33 (2023 Oct 13)
Posted: Fri Oct 13, 2023 1:20 pm
by Chris Peterson
Knight of Clear Skies wrote: ↑Fri Oct 13, 2023 12:52 pm
I wonder if those large bubble nebulae are closer in nature to Barnard's Loop rather than something like the Rosette?
Yes. Unlike the Rosette (or the Bubble), these are not planetary nebulas, created by the expansion of gases off of an exploding or bursting star, but complex regions of hydrogen (vastly larger) that are being sculpted by gravity and stellar winds.
Knight of Clear Skies wrote: ↑Fri Oct 13, 2023 12:52 pm
I wonder if those large bubble nebulae are closer in nature to Barnard's Loop rather than something like the Rosette?
Yes. Unlike the Rosette (or the Bubble), these are not planetary nebulas, created by the expansion of gases off of an exploding or bursting star, but complex regions of hydrogen (vastly larger) that are being sculpted by gravity and stellar winds.
Correct, Chris. My bad.The bubbles in M33 are like Barnard's Loop, not like relatively small emission nebulas like the Rosette Nebula.
And they are not planetary nebulas either. Sorry. I couldn't resist.
Explanation: Gorgeous spiral galaxy Messier 33 seems to have more than its fair share of glowing hydrogen gas. A prominent member of the local group of galaxies, M33 is also known as the Triangulum Galaxy and lies a mere 3 million light-years away. The galaxy's central 30,000 light-years or so are shown in this sharp galaxy portrait. The portrait features M33's reddish ionized hydrogen clouds or HII regions. Sprawling along loose spiral arms that wind toward the core, M33's giant HII regions are some of the largest known stellar nurseries, sites of the formation of short-lived but very massive stars. Intense ultraviolet radiation from the luminous, massive stars ionizes the surrounding hydrogen gas and ultimately produces the characteristic red glow. In this image, broadband data were combined with narrowband data recorded through a hydrogen-alpha filter. That filter transmits the light of the strongest visible hydrogen emission line.
Where NGC 604 is located (using the image from the M33's giant HII regions link (I think I have the orientation mostly correct):
Knight of Clear Skies wrote: ↑Fri Oct 13, 2023 12:52 pm
I wonder if those large bubble nebulae are closer in nature to Barnard's Loop rather than something like the Rosette?
Yes. Unlike the Rosette (or the Bubble), these are not planetary nebulas, created by the expansion of gases off of an exploding or bursting star, but complex regions of hydrogen (vastly larger) that are being sculpted by gravity and stellar winds.
The Rosette Nebula is not a planetary nebula but, as an open star cluster, is also a former star-forming region. I think this is relatively small but basically comparable to the sometimes also very small bubbles in M33.
Knight of Clear Skies wrote: ↑Fri Oct 13, 2023 12:52 pm
I wonder if those large bubble nebulae are closer in nature to Barnard's Loop rather than something like the Rosette?
Yes. Unlike the Rosette (or the Bubble), these are not planetary nebulas, created by the expansion of gases off of an exploding or bursting star, but complex regions of hydrogen (vastly larger) that are being sculpted by gravity and stellar winds.
The Rosette Nebula is not a planetary nebula but, as an open star cluster, is also a former star-forming region. I think this is relatively small but basically comparable to the sometimes also very small bubbles in M33.
Yeah, I sort of remembered that when I typed it, but just carried on...
The "bubble nebulas" that we see in M33 are mature. Their gas is dispersing, and star formation in the center of these particular nebulas have (in most cases at least) come to an end (although low-mass star formation may possibly continue along the nebula's perimeter).
We may compare the Rosette Nebula with the Orion Nebula, where the Rosette Nebula has exhausted its gas in the center, whereas the Orion Nebula is still "full of gas" and very bright in its center:
...
Note two really bright nebulas in M33: NGC 604 at upper right, and NGC 595 to the lower right of the yellow center of M33. A closeup of NGC 604 shows us that there are bubbles in NGC 604 as well:
Upon closer inspection, I think that comparing NGC 595 with the Rossette Nebula (Caldwell 49) makes sense.
For NGC 604, I would compare it more to the Tarantula Nebula (30 Doradus).
Discovered by Edwin Hubble (USA). M33 variable C is an LBV (Luminour Blue Variable). It was initially discovered by the great Edwin Hubble in 1953. This object, almost invisible for many years suddenly flared back to life in 2013. An LBV in outburst like this have been known flare into supernovae. We have a Photometry reference image made by Odd Trondal. This supernova is in the Constellation Triangulum.
Well, I'm unimpressed. If you go the the Rochester page, you'll see the "rise" of this supernova. It wasn't much of a rise! So the thing in question is an LBV and very possibly a future supernova, but not a supernova yet.
According to ResearchGate, the total number of known supernova remnants in M33 is about 50.
Discovered by Edwin Hubble (USA). M33 variable C is an LBV (Luminour Blue Variable). It was initially discovered by the great Edwin Hubble in 1953. This object, almost invisible for many years suddenly flared back to life in 2013. An LBV in outburst like this have been known flare into supernovae. We have a Photometry reference image made by Odd Trondal. This supernova is in the Constellation Triangulum.
Well, I'm unimpressed. If you go the the Rochester page, you'll see the "rise" of this supernova. It wasn't much of a rise! So the thing in question is an LBV and very possibly a future supernova, but not a supernova yet.
According to ResearchGate, the total number of known supernova remnants in M33 is about 50.
Ann
Luminour Blue Variable? I'm not impressed by Rochester Astronomy's editors.
Discovered by Edwin Hubble (USA). M33 variable C is an LBV (Luminour Blue Variable). It was initially discovered by the great Edwin Hubble in 1953. This object, almost invisible for many years suddenly flared back to life in 2013. An LBV in outburst like this have been known flare into supernovae. We have a Photometry reference image made by Odd Trondal. This supernova is in the Constellation Triangulum.
Well, I'm unimpressed. If you go the the Rochester page, you'll see the "rise" of this supernova. It wasn't much of a rise! So the thing in question is an LBV and very possibly a future supernova, but not a supernova yet.
According to ResearchGate, the total number of known supernova remnants in M33 is about 50.
Ann
Luminour Blue Variable? I'm not impressed by Rochester Astronomy's editors.
I saw it too. (Kind of hard to miss.)
But I decided not to correct other people's spelling mistakes!
That may or may not be known, but I have found no easily accessible data on it.
I did find this rather curious entry on an M33 recent "supernova":
Well, I'm unimpressed. If you go the the Rochester page, you'll see the "rise" of this supernova. It wasn't much of a rise! So the thing in question is an LBV and very possibly a future supernova, but not a supernova yet.
According to ResearchGate, the total number of known supernova remnants in M33 is about 50.
Ann
Luminour Blue Variable? I'm not impressed by Rochester Astronomy's editors.
I saw it too. (Kind of hard to miss.)
But I decided not to correct other people's spelling mistakes!
Ann
Well, I did briefly think it might have been a new term that my ignorant self didn't yet know. Hey, aren't The Luminours a musical group? Oh, wait, that's the Lumineers:
Hydrogen Clouds of M33
Sorry. I couldn't resist.
