Testing Einstein's Theory in Sagittarius A

Softpedia ^ | Monday, August 30th, 2010 | Tudor Vieru

[SunkenCiv]

The bright B spectral class star S2 has been observed by astronomers since 1995, because it is revolving around the radio source known as Sagittarius A, which most likely is the supermassive black hole at the core of the Milky Way.

Given that the object spins around the dark behemoth once every 16 years, it has already concluded a full orbit around the radio source since being discovered...

Among its most important points is the fact that the orbit of an object located close to a star or black holes exerting a strong gravitational pull do not respect the rules of classic astronomy.

Generally, Kepler's 3rd law and Newton's law of gravity can be used to predict how an object's orbit will carry on in the future. But these calculations are not true in the case of planets or stars circling around black holes or extremely massive stars.

For example, the variations t in S2's orbit that were recorded over only 16 years are a clear indicator that Einstein was right to say massive objects with excessive gravitational pulls deform the fabric of space-time around them...

What makes this system worth studying is the fact that Schwarzschild radius around the supermassive black hole extends about the same distance as the orbit of Mercury.

The radius is the rough equivalent of the black hole's surface, the limit beyond which not even light can escape the massive gravitational pull the crushed globe of matter produces.

The particular black hole at the core of the Milky Way has the mass of about four million Suns, experts say. Knowing this, and the fact that S2 travels at 5,000 kilometers per second in its orbit, allows scientists to test some actual observations against theoretical predictions.

[SunkenCiv]

What did you just say? I just got back from the bank. ;’)

[guitarplayer1953]

Keep putting your dimes in the machine and you will reach the end of the film.

[E8crossE8]

This article exhibits the pleasing characteristic of - at least - not displaying atrocious errors of scientific fact, as do far too many popular articles written about ongoing research.

Incidentally, one poster wrote above that the author of the article states without qualification with respect to the presumed black hole 'Sagittarius A' that its "Schwarzschild radius around the supermassive black hole extends about the same distance as the orbit of Mercury." This is an established fact, described in, among other publications, Schodel, R., et al., Nature 419, 694 (2002) and Ghez, A. M., et al., ApJ 586, L127 (2003).

[SunkenCiv]

Thanks E.