Click here for a full full resoluton image of M31
Designations: M31, NGC224, Andromeda Galaxy Designations: M32, NGC221 Designations: M110, NGC205
Visual
Magnitude: 3.4
Size: 3 deg x 1 deg
Distance: 2.3 million light
years
Discoverer: Persian astronomer
Al-Sufi, tenth century
Visual Description: To the true romantic of astronomy, M31 will always be known as the "Great Nebula in Andromeda" - a name bestowed upon it before spectroscopy revealed that this luminous mist was not the protoplasmic soup of a solar system in formation but a distant island universe like our own Milky Way Galaxy. An enormous pinwheel of dust and gas, the Andromeda Galaxy contains some 300 billion suns spread across 130,000 light years. It is rushing toward us at 185 miles per second. M31 is among the largest galaxies known and is by far the largest member of the Local Group of galaxies, which includes our Milky Way and some two dozen smaller systems. The Andromeda and Milky Way galaxies dominate the Local Group with their size, with M31 being twice as massive as our Milky Way. And though we see the Andromeda Galaxy nearly edge on, astronomers see enough structure to speculate that the Milky Way is similar in shape and structure. If you were in the Andromeda Galaxy looking at the Milky Way, the Milky Way would appear much the same way as M31 does to us. At 2.3 million light years distant, M31 is also one of the farthest objects visible to the naked eye. Under reasonably dark skies it appears as a cocoon of nebulous vapor 1º west of 4.5-magnitude Nu(υ) Andromedae in the Chained Maiden’s belt. M31 stretches 3º, or nearly 6 moon diameters, on the most transparent nights. A good pair of binoculars will show some of the galaxy’s subtle details. Even 7X35 binoculars will reveal its elliptical disk, whose surface brightness gradually fades away from a star like core. The billions of suns in the core are so tightly packed that astronomers believe there may be a black hole at the center.
The galaxy's northwestern rim has a sharp edge to it, which mark the location of a prominent dark lane slicing through that part of the galaxy; in contrast, the galaxy's southeastern rim diffuses gradually into the sky background. Binoculars will also reveal two of M31's companion galaxies: M32 and M110. M32 looks like a slightly swollen 8th-magnitude star on M3l's outermost bright rim, roughly 1/2° south and slightly east of the nucleus. M110 is a similarly bright, though larger, elliptical haze 37 northwest of M31's nucleus.
In the 4-inch at 23 x, a bright yellow "star" marks the very center o the Andromeda Galaxy. It lies inside several tightly wrapped pale yellow haloes, which start out circular close to the core but become progressively more elliptical and more skewed toward the southwest farther away from the nucleus. This teardrop-shaped patch of golden light is surrounded by an enormous ashen elliptical halo grooved with faint dust lanes.
The arms in M31's outer halo contain some bright concentrations, which, with imagination, look like spits of gray sand between streams of dark matter. Jones said these show best in photographs sensitive to blue light. Interestingly, my eyes appear to be sensitive to blue light, so I can see these concentrations well. English nova and comet discoverer George Alcock is also believed to have blue-sensitive eyes. Other observing friends, like Michael Mattel of Harvard, Massachusetts, have red-sensitive eyes. One way you can test your eyes for color sensitivity is to observe astronomical objects with blue or red features and see how you fare. You can start with these blue concentrations in M3l's spiral arms. Another good one is NGC 206 close to the galaxy's southwestern rim. This 1' X2' patch of fuzzy light is actually an enormous star cloud within the galaxy that measures 700 X 1,300 light years.
M32 is easy to mistake for a bright star in binoculars. At low and moderate powers in the telescope, M32 is essentially a featureless circular glow. But take the time to look for a faint outer envelope that gives seemingly round galaxy its elliptical shape. At 130 x, I could discern a definite starlike core with an odd vertical extension running northeast southwest through the entire galaxy. Is this a real feature or an illusion created by a peculiar alignment of faint, unresolved foreground stars?' southeastern side of the nucleus seems to be bordered by an arc of bright haze, while the same distance away to the northeast, there appears to be; faint star that flickers in and out of view. I like to see it as a beacon, friendly message from a distant neighbor.
Like M31, M32 is believed to harbor a black hole, but one perhaps times smaller than the one at the heart of M31. Also like M31, M32's light is blue-shifted, but this system appears to be approaching us at a slower speed of 126 miles per second.
M110 - We now turn our attention to the final addition to the Messier catalogue an object recommended for inclusion by Kenneth Glyn Jones as recently as 1967. M110 is the larger of the two prominent elliptical satellite galaxies that flank the majestic Andromeda Galaxy (M31), the smaller and closer one being M32. M110 hovers northwest of M31, appearing as a fuzzy oval glow with a total visual magnitude of 8.0 but a much fainter actual surface brightness of 13.9 because of its large size (21'.9x ll'.0).
High magnification reveals a highly mottled nucleus, with the portion closest to M31 detached by an obvious dust lane! A starlike object lies just south of M110's compact nucleus, and it too seems detached by dark matter, but this might simply be a contrast illusion. Furthermore, the east and west sides of the inner halo exhibit concentrations that are clearly separated from the nucleus. Thus, M110's nucleus appears ringed by arcs of diffuse starlight, which makes the following description of Ml10 by Heber Curtis of Lick Observatory very intriguing: "The bright central portion . . . [shows] traces of rather irregular spiral structure. Nucleus almost stellar. Two small dark patches near brighter central portion."
Although this peculiar galaxy does not have spiral structure, the dark patches do exist and show on photographs made with large-aperture telescopes. But it is possible for you to see them from a dark sky with a 4-inch telescope and high magnification! And M110 tolerates high powers well. See if you get the impression that, like M32, this galaxy has a faint extension or bar running north-south through it.
Telescope: Stellarvue
SV80S with
0.8X focal reducer/field flatener
Focal
Length: 384mm (480mm * 0.8 )
Mount: Takahashi NJP 160
Camera:
SBIG
ST10XME
Exposure:
15 6-minute exposures for Luminance. 6 6-minute exposures for each color
(Red, Green and Blue). Total Exposure 3 hours and 18 minutes
Other: SBIG ST402ME autoguider
using a Stellarvue AT1010 guide scope
Image Processing: Image Acquisition with CCDSoft version 5. Processed with CCDStack and Photoshop CS2
The Visual description of the M31 Andromeda Galaxy was writen by Steven James O'Meara in the book "The Messier Objects" by Stephen James O'Meara. Page. 110 - 114 and 282-283. ISBN number 0-521-55332-6.
Copyright(c) 2007 Doug Sanqunetti. All rights reserved
