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In the Milky Way In Andromeda (M 31) Cocorico !
Two virtual blacks holes ?
Source : HST

Here is the Andromeda Galaxy, also called M 31 in the Messier catalog.
This image was made by T.Rector and b. Wolpa (NOAO/AURA/NSF).

Andromeda is our neighbour, it is only 2.54 million al.

In this image, the centre is overexposed. So we see nothing in the nucleus.

Source : HST
Zoom vers le centre d'andromède
But January 12, 2012, is published the photograph of core M 31, taken by the HST.
Source : HST ACS/HRC
Noyau de Andromede

Two black holes ?

Of course not. This is obviously of two globular clusters in the process of merging. This does not happen peacefully. It realizes observing that in the contact zone occur rating collisions. (Collision Supernovas). It was possible to measure the speeds of stars to the surface of these two clusters. These speeds are considerable. But the announced figures differ greatly from one author to another, or when one star to another.

Are there black holes at the centers of these two globular clusters?

 Yes, it is possible but, to our knowledge, this has not been demonstrated. On the other hand, as in most globular clusters, and those in particular, large quantities are observed 'Blue straggler stars'. This confirms, if any is needed, that the two objects observed in the center of M 31 are of globular clusters.
However, the coalescence of these two objects might in the future lead to the formation of a massive black hole. But for now, we would be in the best case, only in a preliminary phase.

Let us note in passing that:

  1. the resolution of the HST can distinguish the stars of this galaxy. This is an achievement that deserves to be highlighted.

  2. the exposure time was certainly better adjusted to this galactic center is not overexposed. Which is unfortunately too often the case for the majority of galactic images taken by professional and amateur astrophotographers.



  1. Andromeda Galaxy. (WIkipédia)
  2. The Cluster of Blue Stars Surrounding the M31 Nuclear Black Hole - Tod R. Lauer, Ralf Bender, John Kormendy et Richard F. Green.
  3. Blue straggler stars. (WIkipédia)
  4. The Double Nucleus of M 31. (11 Oct 1966) KPNO/NOAO et al, HST)
  5. HST STIS Spectroscopy of the triple nucleus of M31: two nested disks in keplerian rotation around a supermassive black hole. (In this document, there would be much to discuss.)
  6. Collisions stellaires January 2003 in "Pour la Science" (French)
  7. Stellar Collisions and Blue Straggler Stars in Dense Globular Clusters

 Creation date: 27/02/2016
Last release: 08/05/18 

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