SMBH Mass Calculation Update
On February 1 I posted how the mass for a black hole can be calculated. The example in the post uses the star with the name S2 for the Milky Way black hole mass calculation.
Today I discovered that the orbit of S2, used to calculate the mass of the SMBH at the center of our galaxy does not conform to Kepler's third law. It should not be used.
There are a few other references on the web for the problem with the S2 orbit but even wikipedia has an oblique reference.
The motion of S2 is also useful for detecting the presence of other objects near to Sagittarius A*. It is believed that there are thousands of stars, as well as dark stellar remnants (stellar black holes, neutron stars, white dwarfs) distributed in the volume through which S2 moves. These objects will perturb S2's orbit, causing it to deviate gradually from the Keplerian ellipse that characterizes motion around a single point mass.
I immediately notice: 'It is believed...'
I had somehow missed this critical detail about thousands of objects affecting S2. At the time of that earlier post I was under the belief there was only one SMBH for our galaxy and the site I used did not question that assumption. Apparently the status of S2 changed very recently.
Simply: S2 does not move as required by Kepler's third law so we should not use it.
Wiki also says '. By 2008, S2 had been observed for one complete orbit. ' Did astronomers jump the gun?
From what I see astronomers must find a star with a valid orbit before there can be any confidence in the calculation of the mass claimed to be at the center of the Milky Way. Right now there is no orbital confirmation for a black hole. Until such a star is found there is no justification to claim there is a black hole there.
I totally missed the transition of one SMBH to thousands of black holes.There are even high res pictures showing where the one was. Wikipedia still has this:
The complex astronomical radio source Sagittarius A appears to be located almost exactly at the Galactic Center, and contains an intense compact radio source, Sagittarius A*, which coincides with a supermassive black hole at the center of the Milky Way.
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