Spiral Galaxy M-31 (NGC 224) "The Andromeda Galaxy"
There are two images of M-31 below; both taken with a Canon DSLR, the first thru Kopernik's 80mm Brandon refractor, and the second thru a 200mm telephoto lens.
Simon Marius: (Dec 15, 1612) '....like a flame of a candle seen through horn. ....whitish, irregular and faint; brighter toward the center.'
G. B. Hodierna: (before 1654) 'A very admirable nebula never seen to my knowledge by anyone. …. No multitude of close stars can be distinguished in it …. It has a glow similar to a comet.'
Charles Messier: (Aug 3, 1764) 'A beautiful nebula shaped like a spindle. No star recognized. ….resembles two cones or pyramids, base to base….. Discovered by Simon Marius and reported on the English Atlas.'
Quote from the Deep Sky Field Guide to Uranometria 2000:
Not a difficult object to the unaided eye under reasonably dark skies; darker sites will reveal a noticeable elongation in the object.
NGC 206: A star cloud in the SW part of M-31.... it is extended N-S and is best defined on the E flank.
The Great Andromeda Galaxy is the brightest and nearest of all the spiral galaxies. It is also the only one which is an obvious naked-eye object. With the naked eye it appears as a small elongated fuzzy light about 1 degree west of the star Nu Andromedae. On a really clear night a pair of 7x50 binoculars will show the full length, extending to over 4 degrees. However, even the largest telescopes show little more than an elongated misty patch which gradually brightens in the center to a nearly star-like nucleus. A sharp eyed observer using at least an 8-inch telescope under a dark and clear sky, can see both the prominent dark lane on the northwest edge of the central hub, and the bright star cloud near the south tip. However, except for these faint details, the galaxy remains a smoothly luminous glow, without a hint of resolution.
It takes a long-exposure photograph or CCD image, using a large telescope, to expose the true nature of M-31. The "Little Cloud”, in Andromeda is actually a vast galaxy, an aggregation of billions of stars like our own Milky Way. It has an elongated oval appearance because it is inclined only 15 degrees from the edge-on position. It is actually round and flat, with a spiral pattern. When looking at M-31 we are not only looking out through space across the enormous distance of about 13 thousand quadrillion miles(2.2 million light years); but we are also looking back through time, to a period about 2.2 million years ago........
Since M-31 is quite easily visible to the naked eye, ancient astronomers knew of it. The first written record is that of Al Sufi, who included it in his “Book of the Fixed Stars for AD 964” as a 'little cloud', and a familiar object which he had observed as early as AD 905.
Simon Marius, a contemporary of Galileo, was the first to examine it through the telescope on Dec. 15th, 1612 and described it in the preface to his Mundus Jovialis as, 'like the flame of a candle seen through horn'....
Erik Holmberg's Catalogue of External Galaxies, gives M 31 a total mass of 320 billion Suns. At least 300 globular clusters surround M 31. The spiral arms are mostly colored blue and most of the gas, dust, and blue stars are at the junction of the spiral arms and the nucleus. These are regions of young, Population I stars...... Nevertheless, more than 90 per cent of the mass of M-31 consists of the older stars of Population II.
THE COMPANIONS OF THE ANDROMEDA GALAXY: M-31 has four small satellite companions, dwarf systems of the elliptical type. All are apparently at the distance of the main system and are gravitationally connected with it. They are M-32(NGC 221), M-110(NGC 205), NGC 147, and NGC 185.
George Normandin, KAS
September 21st, 2008
