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APOD: At the Edge of NGC 891 (2012 May 26)

Posted: Sat May 26, 2012 4:07 am
by APOD Robot
Image At the Edge of NGC 891

Explanation: This sharp cosmic portrait features NGC 891. The spiral galaxy spans about 100 thousand light-years and is seen almost exactly edge-on from our perspective. In fact, about 30 million light-years distant in the constellation Andromeda, NGC 891 looks a lot like our Milky Way. At first glance, it has a flat, thin, galactic disk and a central bulge cut along the middle by regions of dark obscuring dust. The combined image data also reveals the galaxy's young blue star clusters and telltale pinkish star forming regions. And remarkably apparent in NGC 891's edge-on presentation are filaments of dust that extend hundreds of light-years above and below the center line. The dust has likely been blown out of the disk by supernova explosions or intense star formation activity. Faint neighboring galaxies can also been seen near this galaxy's disk.

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Re: APOD: At the Edge of NGC 891 (2012 May 26)

Posted: Sat May 26, 2012 5:41 am
by Boomer12k
Think it has a suitable Life Zone for suitable stars and planets with maybe life??? :?:

Awesome pic, thanks.
:---[===] *

Re: APOD: At the Edge of NGC 891 (2012 May 26)

Posted: Sat May 26, 2012 6:54 am
by Ann
Beautiful picture! Thanks, Robert Gendler (and Hubble)!

NGC 891 is a very interesting galaxy. It is one of the rare few which we seem to see exactly edge-on. Personally I'm fascinated by the fact that we can see no trace of the nucleus, although it "ought to " be situated just where the dust lane crossing the bulge is at its narrowest, as if it was being "pinched" by a cosmic clothespin!

Other characteristics is that NGC 891 seems to be father flat, with a relatively small bulge. Note, however, that it has a very extensive yellow disk. Its dust lane is somewhat active, but not very active. Note how some of the most prominent "smoke chimneys" seem to rise from the most active regions of star formation in the left part of the dust lane. Note the small galaxy right below the most active regions in the disk. The small galaxy is so featureless that it's hard to say if it's a satellite galaxy or a more distant galaxy, but its non-reddened color suggests that it is nearby. If so, it might influence the star formation in NGC 891.

Fascinatingly, there is also a small round satellite galaxy just "above" the bulge of NGC 891. So NGC 891 has one small round satellite galaxy near its disk, and one slightly larger, elongated satellite galaxy slightly farther away from its disk. This actually makes NGC 891 somewhat similar to the Andromeda galaxy, with its two prominent satellite galaxies, M32 and NGC 205!

If you check out this picture of NGC 891 by Adam Block, you can more clearly see the colors of this galaxy. The large yellow disk becomes very apparent, and you can also see the relatively neutral-colored "envelope", possibly a very flattened halo. This "envelope" is either made up of intermediate-aged stars or else of old metal-poor stars. You can see how the dust being blown into this envelope forms elongated dust clouds mostly aligned with the disk, although the dust clouds also show wavy patterns.

You can see, too, that the only place where we find really young blue stars is in parts of the dust lane.

If you compare today's APOD with Adam Block's image, you can see that some of the features seen in Adam Block's image seem to disappear. On the other hand, Adam Block's image, seen at lower resolution and therefore showing "average structures" rather than details, helps us see the average structures in Robert Gendler's Hubble image.

I want to thank both these "heroes of astrophotogarphy", robert Gendler and Adam Block, for their continuing efforts.

Ann

Re: APOD: At the Edge of NGC 891 (2012 May 26)

Posted: Sat May 26, 2012 10:47 am
by Galaxian
Ann wrote: The small galaxy is so featureless that it's hard to say if it's a satellite galaxy or a more distant galaxy, but its non-reddened color suggests that it is nearby. If so, it might influence the star formation in NGC 891.

Fascinatingly, there is also a small round satellite galaxy just "above" the bulge of NGC 891. So NGC 891 has one small round satellite galaxy near its disk, and one slightly larger, elongated satellite galaxy slightly farther away from its disk. This actually makes NGC 891 somewhat similar to the Andromeda galaxy, with its two prominent satellite galaxies, M32 and NGC 205!

Ann
Not to start an argument, but to my eyes those are spiral galaxies and there is a third one just above where the Core would be, almost hidden in the starmist of the nearer galaxy. If you imagine the three bright stars "above" NGC 891 as a triangle, with the distant spiral as part of the base, the top star points to the third, very faint galaxy.
I am sure there are many more in the picture, but to have three nearly identical spiral galaxies in the same background with that huge spiral in the foreground illustrates how *many* of those things there are.
The Universe is full of giant spiral clouds of stars.
Near the centre of APOD's image at the top as the image is orientated is a bright, foreground, Milky Way star with spikies. Just below that is a fourth even fainter spiral galaxy. Between the triangle of bright stars near 891 that I used as a pointer and the brighter star above it are at least four other spirals.
Some of those look to be about 1/50th of the linear dimension of the image of NGC 891 as seen from Earth. Assuming mediocrity, assuming all spirals are much the same size, that makes them anything up to 1500 million light years away. Of course, I'm just guessing at the relative sizes so they are possibly a lot closer.
Still, that one image has captured stars mere dozens of light years away and galaxies tens of millions times those distances.
Someone once said "Space is big".
It is also full of wonder.

Re: APOD: At the Edge of NGC 891 (2012 May 26)

Posted: Sat May 26, 2012 12:57 pm
by geckzilla
Galaxian - I think Ann was referring to the elliptical galaxy that is at the 11 o'clock position to the core (orient 3 and 9 o'clock to the dust lane)

Re: APOD: At the Edge of NGC 891 (2012 May 26)

Posted: Sat May 26, 2012 2:19 pm
by NoelC
I noticed the satellite galaxy near the central bulge (which I do see hints of), at 11 o'clock as geckzilla puts it.

Is the one further away at 8 o'clock really a satellite, or a coincidental alignment of a distant spiral? That's a good question. Surely someone must have spectral data for these, so that their distances are known.

-Noel

Re: APOD: At the Edge of NGC 891 (2012 May 26)

Posted: Sun May 27, 2012 11:11 am
by starsurfer
APOD Robot wrote:Image At the Edge of NGC 891

extend hundreds of light-years above and below the center line.
Shouldn't it say central "lane"?

Re: APOD: At the Edge of NGC 891 (2012 May 26)

Posted: Sun May 27, 2012 11:51 am
by geckzilla
Lane may be more appropriate, but line doesn't seem wrong to me, either. It does form a distinct line. Don't think it's an error.

Re: APOD: At the Edge of NGC 891 (2012 May 26)

Posted: Mon May 28, 2012 1:13 pm
by Galaxian
geckzilla wrote:Galaxian - I think Ann was referring to the elliptical galaxy that is at the 11 o'clock position to the core (orient 3 and 9 o'clock to the dust lane)
The bright thing between the two really tiny spirals? I though that was a foreground star. Sorry. Even on the largest sized image available it looks stellar to me. I can see why it would look like an elliptical, but I am not entirely convinced. I wonder why not?
Anyone got a better image of all of those background (or foreground?) objects we can refer to?
I suppose I could check the catalogues but I'm too tired. Anyone know if those spirals and my foreground star or Ann's elliptical are listed anywhere?
This is one of the absolutely magical things about APoD, the endless opportunities to learn from people who vastly more knowledgeable, more learned, more expert and less tired than me.
Thank you to all the APod Team.

Re: APOD: At the Edge of NGC 891 (2012 May 26)

Posted: Mon May 28, 2012 1:14 pm
by neufer
[img3="Nash Rambler Convertible "Landau" Coupe c.1950, with retracting roof and rigid doors, featured car of Lois Lane of the 1950s television series The Adventures of Superman"]http://upload.wikimedia.org/wikipedia/c ... sh-001.jpg[/img3]
geckzilla wrote:
Lane may be more appropriate, but line doesn't seem wrong to me, either. It does form a distinct line. Don't think it's an error.
Lane, n. [OE. lane, lone, AS. lone, lone; akin to D. laan, OFries. lana, lona.] A passageway between fences or hedges which is not traveled as a highroad; an alley between buildings; a narrow way among trees, rcks, and other natural obstructions; hence, in a general sense, a narrow passageway; as, a lane between lines of men, or through a field of ice.
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Lone, n. A lane. [Local.]
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Lene, n. [L. lenis smooth.] (Phonetics) (a) The smooth breathing (spiritus lenis). (b) Any one of the lene consonants, as p, k, or i (or Gr. π, κ, τ.). W. E. Jelf.
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Lune, n. [L. luna moon: cf. F. lune. See Luna.]

1. Anything in the shape of a half moon. [R.]

2. (Geom.) A figure in the form of a crescent, bounded by two intersecting arcs of circles.

3. A fit of lunacy or madness; a period of frenzy; a crazy or unreasonable freak. [Obs.]

. "These dangerous, unsafe lunes i' the king." Shak.
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Lyne, n. Linen. [Obs.] Spenser.
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Line, n. [OE. line, AS. līne cable, hawser, prob. from L. linea a linen thread, string, line, fr. linum flax, thread, linen, cable; but the English word was influenced by F. ligne line, from the same L. word linea. See Linen.]

1. linen thread or string; a slender, strong cord; also, a cord of any thickness; a rope; a hawser; as, a fishing line; a line for snaring birds; a clothesline; a towline.

. "Who so layeth lines for to latch fowls. Piers Plowman.

2. A more or less threadlike mark of pen, pencil, or graver; any long mark; as, a chalk line.

3. The course followed by anything in motion; hence, a road or route; as, the arrow descended in a curved line; the place is remote from lines of travel.

4. Direction; as, the line sight or vision.

5. A row of letters, words, etc., written or printed; esp., a row of words extending across a page or column.

6. A short letter; a note; as, a line from a friend.

7. (Poet.) A verse, or the words which form a certain number of feet, according to the measure.

. "In the preceding line Ulysses speaks of Nausicaa. Broome.

8. Course of conduct, thought, occupation, or policy; method of argument; department of industry, trade, or intellectual activity.

. "He is uncommonly powerful in his own line, but it is not the line of a first-rate man. Coleridge.

9. (Math.) That which has length, but not breadth or thickness.

10. The exterior limit of a figure, plat, or territory; boundary; contour; outline.

. "Eden stretched her line From Auran eastward to the royal towers Of great Seleucia. Milton.

11. A threadlike crease marking the face or the hand; hence, characteristic mark.

. "Though on his brow were graven lines austere. Byron.

. "He tipples palmistry, and dines On all her fortune-telling lines. Cleveland.

12. Lineament; feature; figure. The lines of my boy's face." Shak.

13. A straight row; a continued series or rank; as, a line of houses, or of soldiers; a line of barriers.

. "Unite thy forces and attack their lines. Dryden.

14. A series or succession of ancestors or descand ants of a given person; a family or race; as, the ascending or descending line; the line of descent; the male line; a line of kings.

. "Of his lineage am I, and his offspring By very line, as of the stock real. Chaucer.

15. A connected series of public conveyances, and hence, an established arrangement for forwarding merchandise, etc. ; as, a line of stages; an express line.

16. (Geog.) (a) A circle of latitude or of longitude, as represented on a map. (b) The equator; -- usually called the line, or equinoctial line; as, to cross the line.

17. A long tape, or a narrow ribbon of steel, etc., marked with subdivisions, as feet and inches, for measuring; a tapeline.

18. (Script.) (a) A measuring line or cord.

. "He marketh it out with a line. Is. xliv. 13.

(b) That which was measured by a line, as a field or any piece of land set apart; hence, allotted place of abode.

. "The lines are fallen unto me in pleasant places; yes. I have a goodly heritage. Ps. xvi. 6.

(c) Instruction; doctrine.

. "Their line is gone out through all the earth. Ps. xix. 4.

19. (Mach.) The proper relative position or adjustment of parts, not as to design or proportion, but with reference to smooth working; as, the engine is in line or out of line or out of line.

20. The track and roadbed of a railway; railroad.

21. (Mil.) (a) A row of men who are abreast of one another, whether side by side or some distance apart; -- opposed to column. (b) The regular infantry of an army, as distinguished from militia, guards, volunteer corps, cavalry, artillery, etc.

22. (Fort.) (a) A trench or rampart. (b) pl. Dispositions made to cover extended positions, and presenting a front in but one direction to an enemy.

23. pl. (Shipbuilding) form of a vessel as shown by the outlines of vertical, horizontal, and obique sections.

24. (Mus.) One of the straight horizontal and parallel prolonged strokes on and between which the notes are placed.

25. (Stock Exchange) A number of shares taken by a jobber.

26. (Trade) A series of various qualities and values of the same general class of articles; as, a full line of hosiery; a line of merinos, etc. McElrath.

27. The wire connecting one telegraphic station with another, or the whole of a system of telegraph wires under one management and name.

28. pl. The reins with which a horse is guided by his driver. [U. S.]

29. A measure of length; one twelfth of an inch. Hard lines, hard lot. C. Kingsley.
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