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APOD Robot wrote: NGC 2683: Edge On Spiral Galaxy

Does spiral galaxy NGC 2683 have a bar across its center?
Being so nearly like our own barred Milky Way Galaxy, one might guess it has.

• . http://www.criticalcommons.org/Members/ ... e-iv-a-new

Ann wrote:
NGC 2683 has been called the UFO galaxy, and it really has a shape reminiscent of a classic flying saucer.

Cousin Ricky wrote:The other day on another forum, someone asked if there were any atheists who lent credence to astrology. Of course, the answer is “yes” (however few). If you look at my avatar, you’ll know what my astrological (tropical?) sign is. However, you’ll also know what I think of astrology.

Someone mentioned Chinese astrology, and I responded that if I had a Chinese background, I might use an image of Lepus, although it wouldn’t have the built-in clever pun. But I found myself wondering what constellation I would use if my background were Vietnamese.

Today’s APOD possibly answers that question.

Tumbleweed wrote:A very slow clockwise tumble to this galaxy.

Tumbleweed wrote:

Tumbleweed wrote:A very slow clockwise tumble to this galaxy.

P.S. Comparing the mass of the galaxy, the rate of tumble, and the deflection of the leading and trailing edges will give the density of the medium the galaxy is tumbling in. Mathematicians, do your stuff.

Ann wrote: . . . This galaxy is somewhat bland and poor in star formation. Or, to put it somewhat differently, this flying saucer lacks its red nebulae brake lights.

MarkBour wrote:

Ann wrote: . . . This galaxy is somewhat bland and poor in star formation. Or, to put it somewhat differently, this flying saucer lacks its red nebulae brake lights.

Ann --
Just wondering. Do edge-on galaxies show us less nebulae in general, or can we see them fine in most edge-on galaxies? I'm wondering if this galaxy is perhaps more rich in them than we can see, just that the dust lanes block our view.

Beyond wrote:

Cousin Ricky wrote:The other day on another forum, someone asked if there were any atheists who lent credence to astrology. Of course, the answer is “yes” (however few). If you look at my avatar, you’ll know what my astrological (tropical?) sign is. However, you’ll also know what I think of astrology.

Someone mentioned Chinese astrology, and I responded that if I had a Chinese background, I might use an image of Lepus, although it wouldn’t have the built-in clever pun. But I found myself wondering what constellation I would use if my background were Vietnamese.

Today’s APOD possibly answers that question.

When i first saw your avatar, i didn't know what it was. After what you've just said, i still don't. At least I'm consistent.

geckzilla wrote:

MarkBour wrote:

Ann wrote: . . . This galaxy is somewhat bland and poor in star formation. Or, to put it somewhat differently, this flying saucer lacks its red nebulae brake lights.

Ann --
Just wondering. Do edge-on galaxies show us less nebulae in general, or can we see them fine in most edge-on galaxies? I'm wondering if this galaxy is perhaps more rich in them than we can see, just that the dust lanes block our view.

Puffs of hydrogen alpha typically extend beyond dust lanes, ballooning out over time. I'm not sure they're not there. I think this image may simply lack narrowband data.

APOD Robot wrote: NGC 2683: Edge On Spiral Galaxy

Explanation: Does spiral galaxy NGC 2683 have a bar across its center? Being so nearly like our own barred Milky Way Galaxy, one might guess it has. Being so nearly edge-on, however, it is hard to tell.....

FloridaMike wrote:
If we can detect a bar in our own galay which is almost perfectly edge-on why is it hard to tell if near edge-on NGC 2683 has a bar?

conversely...

If we cannot tell if near edge-on NGC 2683 has a bar how do we detect a bar in our own galaxy which is almost perfectly edge-on ?

http://en.wikipedia.org/wiki/Galactic_Center wrote:
<<The nature of the Milky Way's bar which extends across the Galactic Center is actively debated, with estimates for its half-length and orientation spanning between 1–5 kpc (short or a long bar) and 10–50°. Certain authors advocate that the Milky Way features two distinct bars, one nestled within the other. The bar is delineated by red-clump stars (see also red giant), however, RR Lyr variables do not trace a prominent Galactic bar. The bar may be surrounded by a ring called the "5-kpc ring" that contains a large fraction of the molecular hydrogen present in the Milky Way, as well as most of the Milky Way's star formation activity. Viewed from the Andromeda Galaxy, it would be the brightest feature of the Milky Way.>>

Cousin Ricky wrote:The other day on another forum, someone asked if there were any atheists who lent credence to astrology. Of course, the answer is “yes” (however few). If you look at my avatar, you’ll know what my astrological (tropical?) sign is. However, you’ll also know what I think of astrology.

Someone mentioned Chinese astrology, and I responded that if I had a Chinese background, I might use an image of Lepus, although it wouldn’t have the built-in clever pun. But I found myself wondering what constellation I would use if my background were Vietnamese.

Today’s APOD possibly answers that question.

FloridaMike wrote:If we can detect a bar in our own galay which is almost perfectly edge-on why is it hard to tell if near edge-on NGC 2683 has a bar?

Tumbleweed wrote:

Tumbleweed wrote:A very slow clockwise tumble to this galaxy.

P.S. Comparing the mass of the galaxy, the rate of tumble, and the deflection of the leading and trailing edges will give the density of the medium the galaxy is tumbling in. Mathematicians, do your stuff.

geckzilla wrote:Yes, what Art said, and for galaxies like NGC 2683 the stars stop becoming measurable when they blob together. If you can figure out what isovelocity contours and kinematics are you might be able to understand the paper linked to in the APOD description. Hmm, what are these mystical and arcane words? Astronomers are a little magical.

geckzilla wrote: ... you might be able to understand the paper linked to in the APOD description. Hmm, what are these mystical and arcane words?

Rachel, Matthew & Stacy wrote:We present optical long-slit and SparsePak Integral Field Unit emission line spectroscopy along with optical broadband and near-IR images of the edge-on spiral galaxy NGC 2683. We find a multi-valued, figure-of-eight velocity structure in the inner 45'' of the long-slit spectrum and twisted isovelocity contours in the velocity field. We also find, regardless of wavelength, that the galaxy isophotes are boxy. We argue that taken together, these kinematic and photometric features are evidence for the presence of a bar in NGC 2683. We use our data to constrain the orientation and strength of the bar.

Chris Peterson wrote:

Tumbleweed wrote:

Tumbleweed wrote:A very slow clockwise tumble to this galaxy.

P.S. Comparing the mass of the galaxy, the rate of tumble, and the deflection of the leading and trailing edges will give the density of the medium the galaxy is tumbling in. Mathematicians, do your stuff.

Galaxies move in the intergalactic medium, which is far too tenuous to have any effect on the motion of any part of any galaxy. So there's nothing to see along the edges, and galaxies don't tumble at all.

Tumbleweed wrote:So you don't believe that the vast majority of the universe (Dark Matter) through which the galaxies move, or in which the galaxies move, is a reality?