APOD: Spiral Galaxy M83: The Southern Pinwheel (2014 Jan 28)

[APOD Robot]

Spiral Galaxy M83: The Southern Pinwheel

Explanation: M83 is one of the closest and brightest spiral galaxies on the sky. Visible with binoculars in the constellation of Hydra, majestic spiral arms have prompted its nickname as the Southern Pinwheel. Although discovered 250 years ago, only much later was it appreciated that M83 was not a nearby gas cloud, but a barred spiral galaxy much like our own Milky Way Galaxy. M83, pictured above by the Hubble Space Telescope in a recently released image, is a prominent member of a group of galaxies that includes Centaurus A and NGC 5253, all of which lie about 15 million light years distant. Several bright supernova explosions have been recorded in M83. An intriguing double circumnuclear ring has been discovered at the center of of M83.

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[Ann]

http://heritage.stsci.edu/2014/04/caption.html wrote:

This image is being used to support a citizen science project titled STAR DATE: M83. The primary goal is to estimate ages for approximately 3,000 star clusters. Amateur scientists will use the presence or absence of the pink hydrogen emission, the sharpness of the individual stars, and the color of the clusters to estimate ages. Participants will measure the sizes of the star clusters and any associated emission nebulae. Finally, the citizen scientists will "explore" the image, identifying a variety of objects ranging from background galaxies to supernova remnants to foreground stars.

STAR DATE: M83 is a joint collaborative effort between the Space Telescope Science Institute and Zooniverse, creators of several citizen science projects including Galaxy Zoo, Planet Hunters, and the Andromeda Project (go to www.zooniverse.org to see the full list). The M83 project is scheduled to launch on Monday, January 13, 2014. People interested in exploring this remarkable image in more detail, and in directly participating in a science project, can visit http://www.projectstardate.org.

Ann

[Nitpicker]

With two nuclei, does this allow the possibility of two supermassive black holes orbiting each other?

And given that there appears to be a relationship between the mass of a central SMBH and its galaxy (based on a BBC doco I saw on the box last night: "Swallowed by a Black Hole") is there a relationship between their orientations? I'm guessing this has been discussed before on the Starship, so apologies if I'm boring anyone. But are galaxies which appear face on to us, like M83, more likely to have SMBHs with jets pointed in our direction? (Not that I'm worried about that -- I expect other galaxies are too far away to pose a threat.)

[Ann]

Watch out, Nitpicker! There is something to worry about much closer to home. WR 104 just might send something nasty our way in the not-too-distant future! Talk about a spiral! Read more about that pinwheel here.

Ann

[Nitpicker]

Watch out, Nitpicker! There is something to worry about much closer to home. WR 104 just might send something nasty our way in the not-too-distant future! Talk about a spiral! Read more about that pinwheel here.

Ann

Sure, sure. I think I've mentioned before that I only really care/worry about the Milky Way.

[starsurfer]

The M83 group has some very interesting galaxies that seem to have some sort of kinematical peculiarity. M83 has a large tidal loop structure, which is rarely seen. In the optical, Centaurus A has many tidal shells as well as a radio jet. NGC 5253, which is lesser known but no less interesting is a dwarf irregular galaxy with an ionized outflow like the ones in M82 and M106!

[Mulsar11]

This may be far fetched, but with star arms crossing in this picture and comments in a previous APofD about the center of M83 having two possible "centers", couldn't we just seeing two galaxies "laying on top of each other" from our point of view?

[neufer]

---

<<The Centaurus A/M83 Group is a complex group of galaxies in the constellations Hydra, Centaurus, and Virgo. The group may be roughly divided into two subgroups. The Cen A Subgroup, at a distance of 11.9 Mly, is centered on Centaurus A, a nearby radio galaxy. The M83 Subgroup, at a distance of 14.9 Mly, is centered on the Messier 83 (M83), a face-on spiral galaxy. This group is sometimes identified as one group and sometimes identified as two groups. Hence, some references will refer to two objects named the Centaurus A Group and the M83 Group. However, the galaxies around Centaurus A and the galaxies around M83 are physically close to each other, and both subgroups appear not to be moving relative to each other. The Centaurus A/M83 Group is part of the Virgo Supercluster of which the Local Group is an outlying member.>>

http://asterisk.apod.com/viewtopic.php? ... 10#p218810

[BDanielMayfield]

This may be far fetched, but with star arms crossing in this picture and comments in a previous APofD about the center of M83 having two possible "centers", couldn't we just seeing two galaxies "laying on top of each other" from our point of view?

Were do you see “star arms crossing”? There are numerous spurs coming off the major arms, but I don’t any crossed arms in today’s APOD.

Spurs of spiral galaxy arms are very common. Don’t we presently live in one?

Bruce

[neufer]

This may be far fetched, but with star arms crossing in this picture and comments in a previous APofD about the center of M83 having two possible "centers", couldn't we just seeing two galaxies "laying on top of each other" from our point of view?

Were do you see “star arms crossing”? There are numerous spurs coming off the major arms, but I don’t any crossed arms in today’s APOD.

Spurs of spiral galaxy arms are very common. Don’t we presently live in one?

Our galaxy DOES have four arms, not two.

http://asterisk.apod.com/viewtopic.php? ... 97#p196538
http://asterisk.apod.com/viewtopic.php? ... 85#p200139

[Ron-Astro Pharmacist]

So if M83 has moved transversely (et. al.) at some time over the15-25 million years into a position that a jet from its active galactic nucleus is pointing in our direction, could we know it?

http://en.wikipedia.org/wiki/Proper_motion

It’s strange to know something is currently a position we are not able to observe it.

[Chris Peterson]

So if M83 has moved transversely (et. al.) at some time over the15-25 million years into a position that a jet from its active galactic nucleus is pointing in our direction, could we know it?

No galaxy displays significant proper motion in such a short time. It could be precessing slightly, but I doubt enough to redirect its rotational axis towards us. And finally, M83 doesn't have a particularly active nucleus, and doesn't have jets.

It’s strange to know something is currently a position we are not able to observe it.

That describes everything in the Universe, even a spider you are watching walk across the ceiling. In order to determine the coordinates of planets in the sky, you have to correct for where they "really" are, given the minutes or hours of light travel time.

[Ann]

Crossed arms are quite photogenic! See here, here and here.

But I couldn't find any really crossed-arms galaxies, although this pair, at least. looks a bit crossed.

Ann

[Beyond]

Crossed arms are quite photogenic! See here, here and here.

But I couldn't find any really crossed-arms galaxies, although this pair, at least. looks a bit crossed.

Ann

What's behind door here #3, has a look that sorta translates to... you really don't wanna 'cross' me.

[Cousin Ricky]

Is M83 really a barred spiral, or is it just a regular spiral whose arms are unusually straight near the center? In images of all other barred spirals I've seen, the bar structure is distinct from the arms, but this does not seem to be the case with M83.

[Chris Peterson]

Is M83 really a barred spiral, or is it just a regular spiral whose arms are unusually straight near the center? In images of all other barred spirals I've seen, the bar structure is distinct from the arms, but this does not seem to be the case with M83.

Isn't any barred spiral just a spiral whose arms are unusually straight near the center?

[Anthony Barreiro]

Is M83 really a barred spiral, or is it just a regular spiral whose arms are unusually straight near the center? In images of all other barred spirals I've seen, the bar structure is distinct from the arms, but this does not seem to be the case with M83.

Isn't any barred spiral just a spiral whose arms are unusually straight near the center?

Morphological classifications of galaxies seem to have at least as much to do with our human desire to have everything fit neatly into one and only one taxonomic box as with the shapes and dynamic processes of galaxies. There are real differences between, say, spiral and elliptical galaxies, but galaxies seem to exist along a morphological continuum (or several continua), with no clear, objective boundary between one type and another, and many intermediate cases. They're not like finches, where you can distinguish one species from another by observing breeding habits.

[Ron-Astro Pharmacist]

Ron-Astro Pharmacist wrote:
So if M83 has moved transversely (et. al.) at some time over the15-25 million years into a position that a jet from its active galactic nucleus is pointing in our direction, could we know it?
No galaxy displays significant proper motion in such a short time. It could be precessing slightly, but I doubt enough to redirect its rotational axis towards us. And finally, M83 doesn't have a particularly active nucleus, and doesn't have jets.

Thanks for keeping me on track Chris. In reading some previous posts and clicking on the Centaurus A link, I had misinterpreted the caption's information. Cosmology is a tough thing to wrap your head around. Nice to have a place to interact as humbling as it can be at times. Ron

[quigley]

I'm having trouble seeing the structure of the "double circumnuclear ring." Will someone give me some description so that I may better understand what I am looking at? The link didn't help me much. Thanks.

[geckzilla]

I'm having trouble seeing the structure of the "double circumnuclear ring." Will someone give me some description so that I may better understand what I am looking at? The link didn't help me much. Thanks.

Here is an annotated image of the nuclear rings in M83's core. It's blurry and inverted but you should be able to match it up with more recent color images. For more information you can try to read the paper this image is originally from: http://iopscience.iop.org/1538-3881/116/6/2834/ (Warning: Extreme astro-nerdery contained within. Brain melting may occur. )