M87 – A Weird Galaxy

M87 is a galaxy very much different from our own Milky Way Galaxy. Founded in 1781 by astronomer Charles Messier, this galaxy is an elliptical galaxy. The Milky Way Galaxy is a spiral galaxy. Other differences include the fact that it is much bigger than an average galaxy, it is found in the core of a cluster of galaxies called the Virgo Cluster, and the fact that it shows a high number of globular clusters. These globular clusters surround the bright center of M87 as visible faint spots. This elliptical galaxy contains a similar number of stars as other spiral galaxies, but unlike spiral galaxies which are flat, is ellipsoidal in shape. It has little dust and gas and absolutely no spiral structure.

M87 seems to be quite different from other elliptical galaxies because of an apparent black hole within its center. The center of the giant galaxy is very hot and dense. A disk of scorching gas has been found orbiting it. The discovery of the black hole is based on the velocity measurements on a spinning cycle of this hot gas. Scientists began by measuring the speeds of the orbiting gas on either side of the disk. This was done by studying how light from the disk was blue shifted and red shifted. Calculations were made and scientists determined that the disk was rotating quite rapidly around a quite massive, yet rather compact central item. The measurement of the speeds was used to find the mass of the central object. This mass lead scientists to predict that indeed a black hole was located at the center of the M87. The disk allows one to make an appropriate measurement of the mass of the object at the center of it. The only hypothesized object that could live with a central density as high as it is is a black hole.

The black hole appears to be the cause of violent energetic activity producing radio signals observed from the galaxy. Hot gas in the form of huge bubbles currently exists, and are still being created at the core of the M87. The source creating these bubbles appear to be jets, pointing back to the center where the black hole is believed to dwell. The black hole is thought to be the power behind the massive energy activating the jets. Energy flow from the black hole is formed when extremely hot material falls onto it. This causes the emission of beams of electrons, the jets. These are thought to be the reason behind the radio waves. They are released by something in the center, assumingly a black hole. The entire radio source is about two hundred fifty light years across. This is bigger then the entire visible M87 galaxy. The small core appears to be energizing its entire galactic neighborhood.

At the current point in time, scientist still do not know whether or not the object at the center of the M87 galaxy is indeed a black hole. It is possible that it is something that astronomers have yet to dream of. At this time, scientists are attempting to get a closer look at the center of the galaxy to obtain at more detailed analysis of the processes actually occurring there. They will be able to obtain a more accurate judgement of the speeds at which the disk is orbiting. This will then permit an even better measurement of how large the supposed black hole is. We can count on the Hubble telescope images to do this job.

My References…

http://antwrp.gsfc.nasa.gov/apod/ap950913.html

http://antwrp.gsfc.nasa.gov/apod/ap990216.html

http://antwrp.gsfc.nasa.gov/apod/ap960305.html

http://www.enn.com/enn-news-archive/1998/01/010798/galaxy.asp