May 5th, 2001
Astronomy HWK #4
1. There is evidence that supports the hypothesis that the Milky Way Galaxy has a massive black hole at its core.At the center of our very own galaxy is a mysterious source of energy. Vast amounts of radiation pour from this compact source which may be a Supermassive Black Hole. Astronomers found an intense radio source with strings of other radio sources clustered about it in the direction of the galactic center.The intense source was named Sagittarius A because the center of the galaxy lies in the direction of the constellation Sagittarius.The position of Sagittarius A as has been observed through radio telescopes around the world seems to be very near the dynamical and gravitational center of the galaxy.Based on its high luminosity and radio spectrum Sagittarius A is neither a star nor a pulsar.It has a luminosity of 5 stars but is smaller than our solar system.Also, it can't be a supernova remnant since it is not expanding. The strongest evidence that it is a!
Supermassive Black Hole comes from Doppler shift of ionized gas in its vicinity. Their observed speeds, as high as 300 km/s, can be explained as an orbital and spiral motion around the center. Therefore, a source of gravity is required to hold these high-speed gases in orbit. Such a massive object, this compact, can only be a Supermassive Black Hole.
2. On the website, there is much clear evidence of a black hole in the central region of the Virgo cluster galaxy M 87.Thefirst picture shows a spiral shaped hot gas at the core of our active galaxy.The gas is rotating so rapidly that there must be a black hole at the center.The region M 87 fits the description of a black hole.It weights as much as three billion suns, but is concentrated into a space no larger than our solar system.This strong gravitational pull towards the center is clear evidence of a black hole.Also…