APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 4481
Joined: Fri Dec 04, 2009 3:27 am

APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by APOD Robot » Fri Nov 12, 2021 5:05 am

Image M33: The Triangulum Galaxy

Explanation: The small, northern constellation Triangulum harbors this magnificent face-on spiral galaxy, M33. Its popular names include the Pinwheel Galaxy or just the Triangulum Galaxy. M33 is over 50,000 light-years in diameter, third largest in the Local Group of galaxies after the Andromeda Galaxy (M31), and our own Milky Way. About 3 million light-years from the Milky Way, M33 is itself thought to be a satellite of the Andromeda Galaxy and astronomers in these two galaxies would likely have spectacular views of each other's grand spiral star systems. As for the view from planet Earth, this sharp image shows off M33's blue star clusters and pinkish star forming regions along the galaxy's loosely wound spiral arms. In fact, the cavernous NGC 604 is the brightest star forming region, seen here at about the 4 o'clock position from the galaxy center. Like M31, M33's population of well-measured variable stars have helped make this nearby spiral a cosmic yardstick for establishing the distance scale of the Universe.

<< Previous APOD This Day in APOD Next APOD >>

User avatar
Ann
4725 Å
Posts: 11656
Joined: Sat May 29, 2010 5:33 am

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by Ann » Fri Nov 12, 2021 5:34 am

M33_PS1_CROP_13x13[1].jpg

Wow, that is a stunning portrait of the Triangulum Galaxy! :D

You will very rarely hear me complain that a picture is "too blue". Nevertheless, there is a lot of blue in this picture, and, well, I love it. Of course. There is also a lot of pink from Hα nebulas where brilliantly hot stars have just formed. What we really don't see in the "starry attire" of the galaxy is any yellow stuff! But the yellow stars are there - just look at the Hubble image below!


Well, that's the mysterious case of the color-changing galactic center, isn't it? 🕵️‍♀️ There can be no doubt that the small inner "bulge" of M33 - which probably isn't a bulge since it most likely isn't bulging, but you know what I mean - is yellow, today's APOD notwithstanding.

But today's APOD is so graceful! I love it! Look at the long graceful arms of our small Local Group spiral galaxy! And note the tiny, tiny little white nucleus. Astronomers say there is no central black hole there, at least not a supermassive one.
Wikipedia wrote:

The nucleus of this galaxy is an H II region, and it contains an ultraluminous X-ray source with an emission of 1.2 × 1039 erg s−1, which is the most luminous source of X-rays in the Local Group of galaxies. This source is modulated by 20% over a 106-day cycle. However, the nucleus does not appear to contain a supermassive black hole, as an upper limit of 3,000 solar masses is placed on the mass of a central black hole based upon the velocity of stars in the core region.

And then of course there is the giant site of star formation in M33, NGC 604. But that is a matter for another day! :D

Ann
You do not have the required permissions to view the files attached to this post.
Color Commentator

User avatar
XgeoX
Science Officer
Posts: 122
Joined: Tue Jun 30, 2020 12:57 pm
AKA: Idiot

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by XgeoX » Fri Nov 12, 2021 12:10 pm

Hey the NGC 604 link is dead!

Eric

User avatar
orin stepanek
Plutopian
Posts: 6993
Joined: Wed Jul 27, 2005 3:41 pm
Location: Nebraska

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by orin stepanek » Fri Nov 12, 2021 12:37 pm

APOD; M33 is itself thought to be a satellite of the Andromeda Galaxy
Hard to imagine M33 orbiting M31 at such a distance! :shock: So maybe the Milky Way could be also? :roll:
Orin

Smile today; tomorrow's another day!

NCTom

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by NCTom » Fri Nov 12, 2021 1:29 pm

One source has M31 and M33 750,000 light years apart. The view from either galaxy must be awesome.

User avatar
bystander
Apathetic Retiree
Posts: 20813
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by bystander » Fri Nov 12, 2021 2:39 pm

XgeoX wrote:
Fri Nov 12, 2021 12:10 pm
Hey the NGC 604 link is dead!

Eric
https://hubblesite.org/contents/news-re ... 03-30.html
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

User avatar
Chris Peterson
Abominable Snowman
Posts: 16228
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by Chris Peterson » Fri Nov 12, 2021 3:01 pm

NCTom wrote:
Fri Nov 12, 2021 1:29 pm
One source has M31 and M33 750,000 light years apart. The view from either galaxy must be awesome.
Probably similar to what we see in the sky when the Milky Way is overhead.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18572
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by neufer » Fri Nov 12, 2021 3:43 pm

orin stepanek wrote:
Fri Nov 12, 2021 12:37 pm
APOD; M33 is itself thought to be a satellite of the Andromeda Galaxy
Hard to imagine M33 orbiting M31 at such a distance! :shock:
  • The distance may not be quite as much as 750,000 light-years:
(At a M33 distance of ~2.73 Mly they would be ~595,000 light-years apart.)[/list]
https://www.messier.seds.org/m/m033.html wrote:
<<The results of the Hipparcos satellite have lead to a revision of the cosmic distance scale, therefore also of our distance to M33: The current value is about 3.0 million light-years. With our (3.0 Mly) distance values, the distance of M33 from M31 is about 750,000 light-years.>>
https://en.wikipedia.org/wiki/Triangulum_Galaxy#Location wrote:
<<The Triangulum Galaxy is a spiral galaxy ~2.73 million light-years from Earth. Estimates of the distance from the Milky Way to the Triangulum Galaxy range from 2.38 to 3.07 Mly, with most estimates since the year 2000 lying in the middle portion of this range, making it slightly more distant than the Andromeda Galaxy (at 2.54 Mly). At least three techniques have been used to measure distances to M 33. Using the Cepheid variable method, an estimate of 2.77 ± 0.13 Mly was achieved in 2004. In the same year, the tip of the red-giant branch (TRGB) method was used to derive a distance estimate of 2.59 ± 0.08 Mly.

In 2006, a group of astronomers announced the discovery of an eclipsing binary star in the Triangulum Galaxy. By studying the eclipses of the stars, astronomers were able to measure their sizes. Knowing the sizes and temperatures of the stars they were able to measure the absolute magnitude of the stars. When the visual and absolute magnitudes are known, the distance to the star can be measured. The stars lie at the distance of 3.07 ± 0.24 Mly. The average of 102 distance estimates published since 1987 gives a distance modulus of 2.878 Mly.>>
Art Neuendorffer

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18572
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by neufer » Fri Nov 12, 2021 3:53 pm

Chris Peterson wrote:
Fri Nov 12, 2021 3:01 pm
NCTom wrote:
Fri Nov 12, 2021 1:29 pm

One source has M31 and M33 750,000 light years apart. The view from either galaxy must be awesome.
Probably similar to what we see in the sky when the Milky Way is overhead.
Or when we view these galaxies with field glasses.
Art Neuendorffer

User avatar
Chris Peterson
Abominable Snowman
Posts: 16228
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by Chris Peterson » Fri Nov 12, 2021 3:56 pm

neufer wrote:
Fri Nov 12, 2021 3:53 pm
Chris Peterson wrote:
Fri Nov 12, 2021 3:01 pm
NCTom wrote:
Fri Nov 12, 2021 1:29 pm

One source has M31 and M33 750,000 light years apart. The view from either galaxy must be awesome.
Probably similar to what we see in the sky when the Milky Way is overhead.
Or when we view these galaxies with field glasses.
Which produces about the same effect as viewing the Milky Way.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
johnnydeep
Commander
Posts: 948
Joined: Sun Feb 20, 2011 8:57 pm

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by johnnydeep » Fri Nov 12, 2021 4:22 pm

Chris Peterson wrote:
Fri Nov 12, 2021 3:01 pm
NCTom wrote:
Fri Nov 12, 2021 1:29 pm
One source has M31 and M33 750,000 light years apart. The view from either galaxy must be awesome.
Probably similar to what we see in the sky when the Milky Way is overhead.
How so? The stars of the Milky Way are at most about 75000 ly away from us here on earth. And the Milky Way is bigger than M33. Why would something 10 times farther away look the same to an observer in M31?
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."

User avatar
Chris Peterson
Abominable Snowman
Posts: 16228
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by Chris Peterson » Fri Nov 12, 2021 4:48 pm

johnnydeep wrote:
Fri Nov 12, 2021 4:22 pm
Chris Peterson wrote:
Fri Nov 12, 2021 3:01 pm
NCTom wrote:
Fri Nov 12, 2021 1:29 pm
One source has M31 and M33 750,000 light years apart. The view from either galaxy must be awesome.
Probably similar to what we see in the sky when the Milky Way is overhead.
How so? The stars of the Milky Way are at most about 75000 ly away from us here on earth. And the Milky Way is bigger than M33. Why would something 10 times farther away look the same to an observer in M31?
The distance doesn't matter. Only the surface brightness and the size. And these would be similar in both cases.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
johnnydeep
Commander
Posts: 948
Joined: Sun Feb 20, 2011 8:57 pm

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by johnnydeep » Fri Nov 12, 2021 8:07 pm

Chris Peterson wrote:
Fri Nov 12, 2021 4:48 pm
johnnydeep wrote:
Fri Nov 12, 2021 4:22 pm
Chris Peterson wrote:
Fri Nov 12, 2021 3:01 pm


Probably similar to what we see in the sky when the Milky Way is overhead.
How so? The stars of the Milky Way are at most about 75000 ly away from us here on earth. And the Milky Way is bigger than M33. Why would something 10 times farther away look the same to an observer in M31?
The distance doesn't matter. Only the surface brightness and the size. And these would be similar in both cases.
How is the size similar? How does a smaller thing 10x away looks the same size as a larger thing 1x away?

...Oh wait, is it because the Milky Way is spread over 360 degrees of our sky, but M33 would subtend only - what, 5 degrees(*)? (as seen from M31) - so that its similar surface brightness is 10x more compacted?

(*) - not really sure how many degrees, nor if the relative orientations matter (brightness would be less if one galaxy was face-on to the other one, right)?
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."

p1gnone
Ensign
Posts: 10
Joined: Fri May 18, 2007 12:15 am

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by p1gnone » Fri Nov 12, 2021 10:16 pm

If Triangulum galaxy is 3MLY from us and perhaps orbiting Andromeda, then considering MilkyWay galaxy 2MLY from Andromeda galaxy, with this pair colliding in 2BY, what can one say about the motion and longterm prospects of collisions with the Triangulum galaxy?
Any links to 3D representations of relative positions and motions?
such as, but better than https://galnet.fandom.com/wiki/Local_Group,_List
Last edited by p1gnone on Fri Nov 12, 2021 10:20 pm, edited 1 time in total.

User avatar
Chris Peterson
Abominable Snowman
Posts: 16228
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by Chris Peterson » Fri Nov 12, 2021 10:19 pm

johnnydeep wrote:
Fri Nov 12, 2021 8:07 pm
Chris Peterson wrote:
Fri Nov 12, 2021 4:48 pm
johnnydeep wrote:
Fri Nov 12, 2021 4:22 pm


How so? The stars of the Milky Way are at most about 75000 ly away from us here on earth. And the Milky Way is bigger than M33. Why would something 10 times farther away look the same to an observer in M31?
The distance doesn't matter. Only the surface brightness and the size. And these would be similar in both cases.
How is the size similar? How does a smaller thing 10x away looks the same size as a larger thing 1x away?

...Oh wait, is it because the Milky Way is spread over 360 degrees of our sky, but M33 would subtend only - what, 5 degrees(*)? (as seen from M31) - so that its similar surface brightness is 10x more compacted?

(*) - not really sure how many degrees, nor if the relative orientations matter (brightness would be less if one galaxy was face-on to the other one, right)?
I don't mean we'd see the same structure. One is a band and the other a blob. But the general appearance would be similar- a dim gray cloud with dark patches in it.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
Ann
4725 Å
Posts: 11656
Joined: Sat May 29, 2010 5:33 am

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by Ann » Sat Nov 13, 2021 5:40 am

p1gnone wrote:
Fri Nov 12, 2021 10:16 pm
If Triangulum galaxy is 3MLY from us and perhaps orbiting Andromeda, then considering MilkyWay galaxy 2MLY from Andromeda galaxy, with this pair colliding in 2BY, what can one say about the motion and longterm prospects of collisions with the Triangulum galaxy?
Any links to 3D representations of relative positions and motions?
such as, but better than https://galnet.fandom.com/wiki/Local_Group,_List
Sky&Telescope wrote:

Both the Milky Way and Andromeda have satellite galaxies that are roughly 1/10th their mass – the Large Magellanic Cloud and the Triangulum Galaxy, respectively. It was previously thought that these satellites had been long-term companions of their bigger cousins. However, more recent work has revealed that the Large Magellanic Cloud is falling into our galaxy for the very first time. It’s a long fall — the two won’t merge for about another 2.5 billion years.
So the Milky Way will merge with the Large Magellanic Cloud in 2.5 billion years! That is going to be a light show and a shake up like our galaxy hasn't seen in billions of years!
Sharp images from the Hubble Space Telescope and radio data from the Very Long Baseline Array had suggested that Andromeda and Triangulum might have had a different history: passing close by each other 6 billion years ago and are doing so again currently.

But the new simulations reveal that this scenario cannot be true — Triangulum is only now making its first approach. Essentially, this result suggests that the Local Group came together more recently than previously thought ­– and it’s still growing today.
So M33 is approaching Andromeda for the very first time. But it is not going to hit Andromeda but be gravitationally "kicked out of the way". (At least on its current, first approach.)

So when will the Milky Way and Andromeda collide?
Van der Marel called the Hubble Space Telescope into action in 2012 to answer this question. Hubble data suggested that there was only a small sideways motion (about 17 km/s), so the two galaxies were heading for a head-on collision. But now, after averaging the Hubble results with the new Gaia measurements, van der Marel’s team finds that Andromeda is sliding sideways more quickly, at around 60 km/s. “That means the orbit [of the two galaxies] will be more of a glancing blow than a head-on collision,” he says. “But it’s still very much the case that these two galaxies will ultimately collide.”
The new result revises the predicted date of the galactic merger from 3.9 billion years’ time to 4.5 billion.
The way I read this, there will be a glancing blow rather than a head-on collision between the Milky Way and Andromeda in 4.5 billion years time.


Ann
Color Commentator

User avatar
johnnydeep
Commander
Posts: 948
Joined: Sun Feb 20, 2011 8:57 pm

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by johnnydeep » Sat Nov 13, 2021 4:10 pm

Chris Peterson wrote:
Fri Nov 12, 2021 10:19 pm
johnnydeep wrote:
Fri Nov 12, 2021 8:07 pm
Chris Peterson wrote:
Fri Nov 12, 2021 4:48 pm


The distance doesn't matter. Only the surface brightness and the size. And these would be similar in both cases.
How is the size similar? How does a smaller thing 10x away looks the same size as a larger thing 1x away?

...Oh wait, is it because the Milky Way is spread over 360 degrees of our sky, but M33 would subtend only - what, 5 degrees(*)? (as seen from M31) - so that its similar surface brightness is 10x more compacted?

(*) - not really sure how many degrees, nor if the relative orientations matter (brightness would be less if one galaxy was face-on to the other one, right)?
I don't mean we'd see the same structure. One is a band and the other a blob. But the general appearance would be similar- a dim gray cloud with dark patches in it.
Ok, but it would still be a lot dimmer, and less majestic, no? More like how the LMC looks to us? ( The LMC is ~160 kly away from us, and M33 is ~600 kly away from M31, but, per Wikipedia, LMC has a fifth the number of stars. )
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."

User avatar
Chris Peterson
Abominable Snowman
Posts: 16228
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by Chris Peterson » Sat Nov 13, 2021 4:26 pm

johnnydeep wrote:
Sat Nov 13, 2021 4:10 pm
Chris Peterson wrote:
Fri Nov 12, 2021 10:19 pm
johnnydeep wrote:
Fri Nov 12, 2021 8:07 pm


How is the size similar? How does a smaller thing 10x away looks the same size as a larger thing 1x away?

...Oh wait, is it because the Milky Way is spread over 360 degrees of our sky, but M33 would subtend only - what, 5 degrees(*)? (as seen from M31) - so that its similar surface brightness is 10x more compacted?

(*) - not really sure how many degrees, nor if the relative orientations matter (brightness would be less if one galaxy was face-on to the other one, right)?
I don't mean we'd see the same structure. One is a band and the other a blob. But the general appearance would be similar- a dim gray cloud with dark patches in it.
Ok, but it would still be a lot dimmer, and less majestic, no? More like how the LMC looks to us? ( The LMC is ~160 kly away from us, and M33 is ~600 kly away from M31, but, per Wikipedia, LMC has a fifth the number of stars. )
I don't know. I haven't figured out how large it would appear or what shape.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18572
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by neufer » Sat Nov 13, 2021 8:52 pm

johnnydeep wrote:
Sat Nov 13, 2021 4:10 pm
Chris Peterson wrote:
Fri Nov 12, 2021 10:19 pm
johnnydeep wrote:
Fri Nov 12, 2021 8:07 pm

...Oh wait, is it because the Milky Way is spread over 360 degrees of our sky, but M33 would subtend only - what, 5 degrees(*)? (as seen from M31) - so that its similar surface brightness is 10x more compacted?

(*) - not really sure how many degrees, nor if the relative orientations matter (brightness would be less if one galaxy was face-on to the other one, right)?
I don't mean we'd see the same structure. One is a band and the other a blob. But the general appearance would be similar- a dim gray cloud with dark patches in it.
Ok, but it would still be a lot dimmer, and less majestic, no? More like how the LMC looks to us? ( The LMC is ~160 kly away from us, and M33 is ~600 kly away from M31, but, per Wikipedia, LMC has a fifth the number of stars. )
The SMC is ~5 degrees long with apparent magnitude ~2.7.

This approximates what M33 would look like from M31 (sans spiral).
Art Neuendorffer

User avatar
johnnydeep
Commander
Posts: 948
Joined: Sun Feb 20, 2011 8:57 pm

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by johnnydeep » Sat Nov 13, 2021 9:12 pm

neufer wrote:
Sat Nov 13, 2021 8:52 pm
johnnydeep wrote:
Sat Nov 13, 2021 4:10 pm
Chris Peterson wrote:
Fri Nov 12, 2021 10:19 pm


I don't mean we'd see the same structure. One is a band and the other a blob. But the general appearance would be similar- a dim gray cloud with dark patches in it.
Ok, but it would still be a lot dimmer, and less majestic, no? More like how the LMC looks to us? ( The LMC is ~160 kly away from us, and M33 is ~600 kly away from M31, but, per Wikipedia, LMC has a fifth the number of stars. )
The SMC is ~5 degrees long with apparent magnitude ~2.7.

This approximates what M33 would look like from M31 (sans spiral).
Cool.
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."

VictorBorun
Science Officer
Posts: 361
Joined: Fri Oct 16, 2020 10:25 pm

Re: APOD: M33: The Triangulum Galaxy (2021 Nov 12)

Post by VictorBorun » Sun Nov 14, 2021 2:31 am

Ann wrote:
Sat Nov 13, 2021 5:40 am
The way I read this, there will be a glancing blow rather than a head-on collision between the Milky Way and Andromeda in 4.5 billion years time.
Ann
So the Triangulum Galaxy is pulling Andromeda to north and is pulled by Andromeda to south in this map.
The Triangulum Galaxy is much symmetric and not tidally deformed for now.
But its pair of arms is complemented with additional arms or spurs. Compressing the posted image by sin 36°:
The Triangulum Galaxy (2021 Nov 12)..png
Another strange thing is the subtle glow of the thicker gas/stellar disk: that disk is not round and is not cocentric
You do not have the required permissions to view the files attached to this post.