Andromeda galaxy from Earth | Satellites, Mass and Brightness


Andromeda galaxy from Earth

The actual distance to the Andromeda galaxy is currently given as 2.52 ± 0.14 million light years, and by current knowledge it is way more than the milky way. Furthermore, astronomers largely agree that the Andromeda Galaxy, also known as M31 or NGC 224, is on a collision course with the Milky Way.


Andromeda galaxy Distance from our Milky Way galaxy

  • It is about 2.5 million light years away from us. A light year is 9.46 trillion kilometers.
  • However, the distance is not constant. The Andromeda Galaxy and our Milky Way are getting closer to each other – and very quickly. 
  • The two galaxies move towards each other at a speed of about 110 km per second. After all, this equates to about 400,000 kilometers per hour. 
  • Scientists believe that the Andromeda Galaxy and our Milky Way will meet in about four billion years.

If the researchers’ calculations are correct, this process would take another two billion years.

Andromeda galaxy from Earth

Andromeda is close enough that it is possible to use the Top of the Red Giant Arm (TRGB) method to measure its estimated distance. (Andromeda galaxy from Earth) Using this technique, the estimated distance of M31 obtained in 2005 is 2.56 ± 0.08 Mly (785 ± 25 kiloparsecs). 

Overall the combined distance of these distance measurements was estimated at 2.54 ± 0.06 Mly (779 ± 18 kiloparsecs). Based on the upper distance, (Andromeda’s satellites) the diameter of M31’s greatest circumference is approximately 141 ± 3 kiloparsecs (43,230 ± 920 parsecs). Using trigonometry, that figure can be obtained by increasing the unrealistic 3.18° angle to the sky.


Andromeda’s satellites 

Andromeda galaxy from Earth

The Andromeda galaxy consists of satellite galaxies consisting of 14 smaller galaxies. The best known and most commonly observed satellite galaxies are M32 and M110. Based on current evidence, it appears that M32 had a very close encounter with M31 (Andromeda). M32 may have been a very large galaxy, after which M31 removed its stellar object and a rapid increase in star formation in its core occurred, which then ended.


Andromeda’s mass and brightness estimation

The estimated mass for the Andromeda halo (including dark matter) is about 12.3×1012 million compared to the galaxy 19 million . Thus M31 is smaller than our galaxy, although the margin of error is still high enough to be sure. Although it is possible to compare the Milky Way and M31, and M31’s spheroid actually has a much higher density than the higher stellar densities.

M31 in particular is a particularly common star compared to the Milky Way, and the estimated luminosity of M31 is ~2.6×1010 L☉ 25% greater than the luminosity of our Milky Way. However, the rate of star formation in the Milky Way is comparable to that of M31. significantly more in the Milky Way, with only one solar body being produced per year compared to 3-5 solar masses in the Milky Way. The rate of supernovae in the Milky Way is almost twice that of M31. 

Andromeda galaxy from Earth

It turns out that M31 may have had a great composition phase in the past but it is quieter than before, but star formation appears to be more active than that in the Milky Way. Should this continue, the Milky Way’s brightness could be brighter than M31’s in the future.


[Andromeda galaxy from Earth | Satellites, Mass and Brightness]


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