APOD: M31: The Andromeda Galaxy (2018 Dec 17)

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APOD: M31: The Andromeda Galaxy (2018 Dec 17)

Post by APOD Robot » Mon Dec 17, 2018 5:07 am

Image M31: The Andromeda Galaxy

Explanation: What is the nearest major galaxy to our own Milky Way Galaxy? Andromeda. In fact, our Galaxy is thought to look much like Andromeda. Together these two galaxies dominate the Local Group of galaxies. The diffuse light from Andromeda is caused by the hundreds of billions of stars that compose it. The several distinct stars that surround Andromeda's image are actually stars in our Galaxy that are well in front of the background object. Andromeda is frequently referred to as M31 since it is the 31st object on Messier's list of diffuse sky objects. M31 is so distant it takes about two million years for light to reach us from there. Although visible without aid, the featured image of M31 is a digital mosaic of 20 frames taken with a small telescope. Much about M31 remains unknown, including exactly how long it will before it collides with our home galaxy.

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Re: APOD: M31: The Andromeda Galaxy (2018 Dec 17)

Post by Ann » Mon Dec 17, 2018 7:09 am

Today's APOD doesn't make my sense of aesthetics shout with delight.

But I do admire the "respect" it pays to M31 by portraying it in a way that I would describe as accurate. I will never forget the time when I first saw Andromeda through my parents' binoculars. I saw a fuzzy, yellowish patch, whose yellowish hue looked almost exactly the same as the yellow color of the central bulge in today's APOD.

Since I'm a diehard fan of everything that is blue, it pains me just a little that the blue parts of Andromeda don't look more bold and bright. But how can I complain? The outer parts of Andromeda are sparsely populated by blue and non-blue main sequence stars and red giants. I do think that there really is star formation going on in these parts of Andromeda and some blue stars are born here, but I have no reason to believe that the outer parts of Andromeda are strongly dominated by blue light. They aren't.

And these parts of our sister galaxy are faint too, which can be seen very clearly in Robert Gendler's APOD. But they are large, and they contribute to the impression that Andromeda is a galaxy of impressive size. It is, too.

We can also see that there are reddish Hα nebulas scattered in the disk. But these emission nebulas are neither bright nor very numerous. This too is correct, because there is not a lot of star formation going on in M31.

So while this APOD doesn't make me jump for joy, I do appreciate the "respect" it pays to our mighty sister galaxy.

Ann
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heehaw

Re: APOD: M31: The Andromeda Galaxy (2018 Dec 17)

Post by heehaw » Mon Dec 17, 2018 9:50 am

Hi, neighbor!

sunson

Re: APOD: M31: The Andromeda Galaxy (2018 Dec 17)

Post by sunson » Mon Dec 17, 2018 3:01 pm

Do I see a tail from the small galaxy as if running away from the monster behind?

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Re: APOD: M31: The Andromeda Galaxy (2018 Dec 17)

Post by neufer » Mon Dec 17, 2018 4:31 pm

sunson wrote:
Mon Dec 17, 2018 3:01 pm

Do I see a tail from the small galaxy as if running away from the monster behind?
https://videos.files.wordpress.com/fSDd ... me_dvd.mp4
https://www.messier-objects.com/messier ... oung-star/

Messier 110: Edward Young Star
September 26, 2015 by admin


<<Messier 110 (M110), also known as NGC 205 an the Edward Young Star. Messier 110 is often catalogued as a dwarf spheroidal galaxy, which makes it the only galaxy of this type listed in the Messier Catalogue. It is, however, much brighter than other galaxies of this kind and is sometimes classified simply as a spheroidal galaxy. M110 has an estimated mass of between 4 and 15 billion solar masses. Messier 110 shows evidence of recent star forming activity as it contains a population of young blue stars at its centre. It also has some dust, which is unusual for a galaxy of this type and likely a result of interaction with its large neighbour, M31. M110 is classified as a peculiar elliptical galaxy because of its unusual dark structures and signs of recent star formation. The galaxy does not appear to have a supermassive black hole at its centre.

M110 is a satellite of the much larger Andromeda Galaxy (M31). It lies at a distance of 2.69 million light years from Earth and has an apparent magnitude of 8.92. It has the designation NGC 205 in the New General Catalogue.

Messier 110 occupies an area of 21.9 by 11 arc minutes of apparent sky, corresponding to an actual diameter of 17,000 light years. In spite of its size, the galaxy is difficult to observe with binoculars because it has a low surface brightness. To be seen in small telescopes, it requires exceptionally clear, dark skies. In 3-inch telescopes, M110 appears as a faint, diffuse patch of light, while 8-inch telescopes reveal a larger oval shape with a slightly brighter core.

Charles Messier never added M110 to his catalogue, but he depicted both this object and M32 on a drawing of M31, the “Great Andromeda Nebula.” He first observed M110 on August 10, 1773 and noted: On August 10, I examined, under a very good sky, the beautiful nebula of the girdle of Andromeda [M31], with my achromatic refractor, which I had made to magnify 68 times, for creating a drawing like the one of that in Orion [M42] (Mém. de l’acad. 1771, pag. 460). I saw that [nebula] which C. [Citizen] Legentil discovered on October 29, 1749 [M32]. I also saw a new, fainter one, placed north of the great [nebula], which was distant from it about 35′ in right ascension and 24′ in declination. It appeared to me amazing that this faint nebula has escaped [the discovery by] the astronomers and myself, since the discovery of the great [nebula] by Simon Marius in 1612, because when observing the great [nebula], the small is located in the same field [of view] of the telescope. I will give a drawing of that remarkable nebula in the girdle of Andromeda, with the two small which accompany it.

Caroline Herschel discovered M110 independently on August 27, 1783 and added it as No. 9 to her catalogue. She wrote: Augt 27th [1783]. About 1/2 deg preceding & a little north of Mess 31st a nebula. There are many stars besides in the field, but these two [diagram] are the largest.

Her brother William Herschel catalogued the object as H V.18 on October 5, 1784, describing it as “very bright, much extended, 30′ long, 12′ broad.

John Herschel catalogued M110 as h 44 and later included it in his General Catalogue as GC 205. He described the object as “very bright; very large; much extended in position angle 165 deg; very gradually very much brighter toward the middle.

Admiral William Henry Smyth observed the object in September 1836 and offered the following description: A large faintish nebula of an oval form, with its major axis extending north and south. It is between the left arm and robes of Andromeda, a little to the np [north preceding, NW] of 31 Messier; and was discovered by Miss Herschel in 1783, with a Newtonian 2-foot [FL] sweeper. It lies between two sets of stars, consisting of four each, and each disposed like the figure 7, the preceding group being the smallest; besides other telescopic stars to the south, This mysterious apparition was registered by H [William Herschel] as 30′ long and 12′ broad, but only half that size by his son; and there was a faint suspicion of a nucleus. This doubt must stand over for the present, – for whatever was a matter of uncertainty in the 20-foot reflector, would have no chance of definition in my instrument. It was carefully differentiated with Beta Andromedae.

Heber Curtis photographed the galaxy with the Crossley reflector at the Lick Observatory and wrote: The companion n.p. the nebula in Andromeda. The bright central portion is about 2′ in diameter, showing traces of rather irregular spiral structure; the nucleus is almost stellar. There are two small dark patches near the brighter central portion. Very much fainter matter forms the outer portions of the nebula in an oval about 8’x3′; no whorls can be made out in this outer portion; doubtless a spiral of Andromeda type. 2 s.n.

Walter Baade resolved the galaxy into stars in 1944 and confirmed that it lies at about the same distance as the Andromeda Galaxy. Messier 110 was finally included in the Messier Catalogue in 1967 by the Welsh amateur astronomer Kenneth Glyn Jones.>>
Art Neuendorffer

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Re: APOD: M31: The Andromeda Galaxy (2018 Dec 17)

Post by Fred the Cat » Mon Dec 17, 2018 11:05 pm

What a gorgeous galaxy! If we didn’t already have such a nice one of our own, I wouldn’t mind calling Andromeda home. In fact, the entire neighborhood is quite acceptable. :thumb_up: Very nice portrait of one of the family Mr. Gendler :clap:

Just wish our eyes could see it better in the night sky . 8-)
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Re: APOD: M31: The Andromeda Galaxy (2018 Dec 17)

Post by Ann » Tue Dec 18, 2018 12:16 am

sunson wrote:
Mon Dec 17, 2018 3:01 pm
Do I see a tail from the small galaxy as if running away from the monster behind?
I don't think Art answered that question in his rather lengthy answer to you! 8-) Maybe I missed it.

But, yes, you do. That tail is indeed visible in some photographs, including today's APOD.

M110, satellite of Andromeda. Credit: Jean-Charles Cuillandre (CFHT)
& Giovanni Anselmi (Coelum Astronomia), Hawaiian Starlight
Andromeda and satellites.
Credit: Giuseppe Donatiello





















Ann
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Re: APOD: M31: The Andromeda Galaxy (2018 Dec 17)

Post by neufer » Tue Dec 18, 2018 12:52 am

Ann wrote:
sunson wrote:
Do I see a tail from the small galaxy as if running away from the monster behind?
yes, you do. That tail is indeed visible in some photographs, including today's APOD.
:arrow: That's no tail... that's
a sEVEREly warped disk.
Art Neuendorffer

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Re: APOD: M31: The Andromeda Galaxy (2018 Dec 17)

Post by Joe Stieber » Tue Dec 18, 2018 12:58 am

Today's picture is a bit unusual in that it's a Monday repeat (of a repeat). It was last used on 2015-August-30, and before that, on 2009-May-10. I didn't look back beyond that.

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Re: APOD: M31: The Andromeda Galaxy (2018 Dec 17)

Post by Bird_Man » Tue Dec 18, 2018 5:30 pm

Should I be taking out galaxy collision insurance? Get it now before the rates go up.