Starship Asterisk*

quigley wrote: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.

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.

Chris Peterson wrote:

Cousin Ricky wrote: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?

Cousin Ricky wrote: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.

Ann wrote: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

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?

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

BDanielMayfield wrote:

Mulsar11 wrote:
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?

Mulsar11 wrote: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?

http://en.wikipedia.org/wiki/Centaurus_A/M83_Group wrote:

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<<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

Ann wrote: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

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.