Starship Asterisk*

http://ay201b.wordpress.com/spitzer-infrared-nearby-galaxies-survey/ wrote:
[c]Harvard Astronomy 201B : ISM and Star Formation[/c]
<<The Spitzer Space Telescope has three instruments on-board:

• IRAC (Infrared Array Camera) is an infrared camera operating on four wavelengths (3.6 µm, 4.5 µm, 5.8 µm and 8 µm).
  
  IRS (Infrared Spectrograph) is an infrared spectrometer with four sub-modules operating at the wavelengths 5.3-14 µm (low resolution), 10-19.5 µm (high resolution), 14-40 µm (low resolution), and 19-37 µm (high resolution).
  
  MIPS (Multiband Imaging Photometer for Spitzer) has three detector arrays in the far infrared (128 × 128 pixels at 24 µm, 32 × 32 pixels at 70 µm, 2 × 20 pixels at 160 µm).

Dust Distribution in M31 Showing Evidence of a Galactic Collision

[b][color=#FF0000]Fig.10: The Andromeda Galaxy (M31) at 24-micron by MIPS[/color][/b] (Image Credit: http://www.spitzer.caltech.edu/&#41 )

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[b][color=#0000FF]Fig.11: M31 Inner Dust Ring at 8-micron by IRAC[/color][/b] (Image Credit: http://www.spitzer.caltech.edu/&#41 )

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<<Here is an image of M31 at 24-micron. An outer ring of dust is prominent. This picture is constructed from 11,000 separate snapshots by MIPS. Asymmetrical features are seen in the prominent ring of star formation. The ring appears to be split into two pieces, forming the hole to the lower right. These features may have been caused by interactions with satellite galaxies (such as M32 and M110) around M31 (The Andromeda Galaxy) as they plunge through its disk. This image also reveals tracings of spiral arms within this ring that reach into the very center of the galaxy.

With a further imaging using IRAC onboard Spitzer, new evidence was found that the Andromeda Galaxy was probably involved in a violent head-on collision with the neighboring dwarf galaxy Messier 32 (M32) more than 200 million years ago. The following image (Fig.11) reveals an inner dust ring deep within the Andromeda galaxy in addition to the outer prominent dust ring visible in the 24-micron image (Fig.10). When combined with a previously observed outer ring, the presence of both dust rings suggests that M32 plunged through the disk of the Andromeda Galaxy along Andromeda’s polar axis approximately 210 million years ago. (Ref: http://www.spitzer.caltech.edu/)

What is most interesting is that the centers of those rings (outer ring center is number 1 with red color, inner ring center is number 2 with green color) are offset from the galactic center (number 3 with purple color in the upper diagram (Fig.11)). The outer ring of star formation is offset from the galactic center by about 1kpc, which is about 10% of the radius of the outer ring. The inner ring of star formation is offset from the galactic center by about 0.5kpc, which is about 40% of the radius of the inner ring.>>

Psnarf wrote:The structure of the black hole at the center of the galaxy appears strange to me on the large images. http://www.herschel.caltech.edu/media/i ... 3-004b.jpg Perhaps it is an optical illusion.

Psnarf wrote:
I was looking for the color codes when I found these wavelengths on the ESA Hershel site: blue is 70 mm, green is 100 mm, and red is combined 160 mm and 250 mm. Blue is hotter than green; red is colder than green, only a few degrees above 0-kelvin. Just for fun, I reached for my 32-cm ruler. Seven centimeters is about the length of my index finger. It is difficult for me to imagine infrared waves that long, much too large to get past the pupils of our eyeballs.

drollere wrote:the "ring" structure, known as a circumnuclear ring, seems to occur in about 20% of spiral galaxies (in a small sample) and is associated with an active galactic nucleus. computer simulations suggest that the rings would result from the near collision of two galactic nuclei; the ring is compressed from the nucleus outward as a massive shock wave. the shock wave rolls up the interstellar medium to create large and very active star forming regions, which are indicated by the brightest areas in the infrared.

this is a beautiful image, and it is fascinating that beauty often goes with the analytical content of an image, so that beauty is the affective experience of insight into fundamental structure or process.

anon wrote:"making it more the twice the size" Good grief. It always pains me to see APOD explanations with grammar and spelling errors.

• O beautiful spiral in the sky
  How far away from us you lie
  Yet drawing closer, someday to be
  Merging with us... well, not me
  
  'cause I'm definitely not going to be around for that.

emc wrote:

anon wrote:"making it more the twice the size" Good grief. It always pains me to see APOD explanations with grammar and spelling errors.

It pains me to see my own errors... I feel relief when I see other's.

emc wrote:
In referring to another person besides me, “other’s” is correct.

emc wrote:In referring to another person besides me, “other’s” is correct.

MikeJ wrote:While there is no up or down in space, every time I see the Andromeda or other galaxy at a steep angle like this I wonder are we looking up at the bottom or down at the top. In other words is the edge to the right top closer to us or is it the bottom left and at that distance can we really know for sure?