Observation history of Andromeda galaxy

The earliest observation record of Andromeda galaxy may come from Persian astronomer Al Su Fei, who described it as "Xiao Yun", and the mark on the map was also "Xiao Yun" at that time. The first person to observe and record with a telescope was Simon Marius in 16 12.

1764, messier catalogued him as M3 1, mistakenly thinking that Simon Marius was the discoverer and didn't realize Al Su Fei's earlier work.

1785, astronomer William Herschel noticed a red spot in the core region of the galaxy, which convinced him that it was the nearest "big nebula" among all the nebulae, and estimated (wrongly) that the distance should be within 2000 times of Sirius according to the color and brightness of the nebula.

1786, F. W. Herschel first listed it as a nebula that can be decomposed into stars.

1864, william huggins observed the spectrum of Andromeda galaxy, and noticed that the spectrum of Andromeda galaxy was superimposed with dark lines on a continuous spectrum with continuous frequency, which was very similar to a single star, so he inferred that Andromeda galaxy had the essence of a star.

1885, a supernova appeared in Andromeda galaxy (Andromeda s), which was the first time to see a star in such a distant galaxy. At that time, he underestimated his brightness and only thought he was a new star, so he was called 1885.

19 14, pease found that M3 1 has rotating motion.

19 17, a new star in M3 1 was observed in Heber Curtis, and 1 1 was found in the photographic records. Curtis noticed that the average luminosity of these new stars is about 10, which is much lower than the magnitude in the Milky Way. This result raised the estimated distance to 500,000 light-years and made him a supporter of the "island universe" hypothesis. This hypothesis holds that spiral nebulae are also independent galaxies.

During the period of 1920, there was a big debate between harlow shapley and Heber Curtis about the Milky Way, spiral nebula and the scale of the universe. In order to support his statement that M3 1 is an alien galaxy, Curtis proposed that there are dust clouds in our own Milky Way galaxy, which cause similar black paths and have obvious Doppler frequency shift.

From 1924 to 1925, Hubble recognized the Cepheid variable on the spiral arm of Andromeda galaxy on photographic film, calculated the distance according to the period-luminosity relationship, and confirmed that it was a star system outside the Milky Way, and the debate subsided. The distance of M3 1 is confirmed by the photos taken in reflecting telescope, which is 2.5m (100 inch). Hubble's measurements finally confirmed that these stars and gases are not in our galaxy, but a galaxy far away from our galaxy as a whole.

1939, through the research of babcock and others, the rotation speed curve from the center to the edge was measured, from which the mass of the Milky Way was known. It is estimated that the mass of M3 1 is not less than 3./kloc-0 /×101solar mass, which is more than twice that of the Milky Way and the largest in this galaxy group. M3 1 has a star-like core with a diameter of only 25 light years, and its mass is equivalent to 107 solar mass, that is, 1500 stars gather in a cubic parsec. The infrared radiation of the star-like core is very strong, which is about equal to the radiation of the whole core area of the Milky Way. But the radio there is only 1/20 of Silver Heart Radio. Radio observation shows that neutral hydrogen is mostly concentrated in a wide ring with a radius of 10 kiloparsec. The content of hydrogen is 1% of the total mass, which is less than 1.4 ~ 7% of the Milky Way. It can be considered that most of the gases in M3 1 have formed stars.

From 1943 to 1944, Walter Baade?? Distinguish the celestial bodies in the core of Andromeda galaxy and identify the clusters and stars in it. According to his observation of this galaxy, he distinguished two different star groups. He called the young and fast-moving stars in the silver disk the first star group, and the old and reddish stars in the nuclear sphere the second star group. This naming principle was later quoted in our galaxy and other occasions. (Otter previously noticed the phenomenon that stars are divided into two star groups) and pointed out the spatial distribution of star groups. Dr Budd also found that there are two different types of Cepheid Variables, which double the distance estimate of M3 1 and affect the rest of the universe. On the spiral arm of M3 1 is the extreme constellation I, including O-B star, bright Supergiant star, OB star and ionized hydrogen region. Classical Cepheid Variables, novas, Red Giant Stars, Planetary Nebulae and other diskpopulation celestial bodies were observed on the silver disk. In the central area, there is Cepheid Variable Star II. The globular clusters of halo members can reach 30,000 parsec from the main plane of the galaxy. It was also found that the content of heavy elements in M3 1 segment increased gradually from the periphery to the center. This phenomenon shows that the process of heavy elements in interstellar matter caused by stellar ejection is much more frequent in the central region of the galaxy than in the peripheral region.

19 In 1950s, the first radio map of Andromeda galaxy was jointly completed by john baldwin and Cambridge Radio Astronomy Group. The core of Andromeda galaxy is listed as 2C 56 in the radio astronomical catalog of 2C catalog.

In 2006, nine galaxies were found to extend along a plane across the core of Andromeda galaxy, rather than being randomly dispersed. This may explain that these satellite galaxies have a common origin.

M3 1 plays an important role in the history of astronomy, and also plays an important role in the study of galaxies, because it is a giant spiral galaxy closest to us, although it is not the latest.