M31, Andromeda Galaxy - spiral galaxy question (26 Nov 2006)

[orin stepanek]

http://antwrp.gsfc.nasa.gov/apod/ap061126.html

What is below Andromeda at about 4:30? Is this a cluster or a distant eliptical galaxy?
Orin

[Nereid]

NGC 205, a.k.a. M110.

[orin stepanek]

NGC 205, a.k.a. M110.

Thanks Nereid!
I noticed on some views that M110 seems to be more separated from M31 than on others. http://www.seds.org/messier/m/m031.html

http://antwrp.gsfc.nasa.gov/apod/ap991114.html

http://antwrp.gsfc.nasa.gov/apod/ap061126.html Does this represent considerable movement on these galaxies?
Orin

[BMAONE23]

I would imagine that it is probably caused by increased exposure time and better imaging equipment revealing more faint stars on the outskirts of the Andromeda galaxy.

I would like to see an image of Andromeda that overlays an eye visible star field that activates VIA curser contact with the image. You see the night stars as if you were standing outside looking at them then POOF there is actual size Andromeda with the passage of the curser.

[Galactic Groove]

If you study the pics in the links you gave, you'll see just what BMAONE23 is talking about. Each of those pictures was captured using different filters, exposure lengths, and camera/telescope qualities. In the last link you can see all that extra detail with regards to the outer ambient glow surrounding the two galaxies which isn't really visible in the first two pics. This makes it look like the gap between the 2 galaxies is less than in the first two.

[orin stepanek]

Thanks! Clears it up. Looks like the third illustration is a little more edge on; but that can't be. Must have something to do with the photography used in each picture.
Orin

[kass williams]

In images of spiral galaxies like that of Andromeda posted on Nov. 6, 2006, the galaxies look rather like terrestrial hurricanes as seen from space. Do galaxies, like hurricanes, have depth as well as width? Do they have an 'eye wall' structure? Or are they as flat as they appear in photos?

[Case]

In images of spiral galaxies like that of Andromeda posted on Nov. 6, 2006, the galaxies look rather like terrestrial hurricanes as seen from space.

APOD Nov. 6, 2006 shows 'The Ghostly Tail of Comet SWAN'.
Maybe you were thinking of November 26, 2006?

Do galaxies, like hurricanes, have depth as well as width? Do they have an 'eye wall' structure? Or are they as flat as they appear in photos?

Have a look at this edge-on galaxy, NGC 4565. The center of galaxies isn't empty at all, it's the most densely 'populated' area.

[kass williams]

NGC 4565 is undoubtedly bulgy in the middle and that answers my question about galactic depth. I still wonder, though, if the rotation of a galaxy can create an eye-wall-like effect, a vertical mass of spinning stars and gas.

And you are correct, the Andromeda photo was posted on November 26, not 06. I have gremlins in my keyboard.

[BMAONE23]

there could be something of an EYE WALL effect or tourus (doughnut) shape event horizon around the central BH. this hasn't been observed though (yet)

[starnut]

there could be something of an EYE WALL effect or tourus (doughnut) shape event horizon around the central BH. this hasn't been observed though (yet)

The event horizon of the supermassive BH at the center of the galaxy would be the "eye wall" itself, but only if there is an accretion disc around the BH.

Kass,

In an hurricane, the eyewall is formed by the rapid rotation of the storm cloud around a low pressure area. A galaxy, on the other hand, is a slow rotating mass of individual stars, gas and dust clouds, each following its own orbit at its own speed, all going roughly in the same direction. The gravitation of the BH has diminishing influence on the objects the farther the objects are from the BH.