Starship Asterisk*

Hi All!

WRT today's (30th April 2008.. Arp272) pic, I wanted to ask this question:

What is at the center of the galaxy? Why is the center so bright?
Specially in the case of NGC6050

The center of the galaxy is more brighter and more distinct in case of image of "spiral galaxies in collision"
http://apod.nasa.gov/apod/ap080420.html

Is the density of stars their greater?

BTW, is this a valid question: Is the chances of life greater in the center of the galaxy or at the periphery of the galaxy?

indiaaditya wrote:What is at the center of the galaxy?

At the very center of our galaxy is a radio source called Sagittarius A*. It is thought to be a massive black hole of 3.7 million solar masses. The majority of spiral galaxies is thought to have a massive black hole at its center. But the black hole is not the observed brightness: what you see is many stars close together.

indiaaditya wrote:Why is the center so bright?

A dense population of stars (mostly very old stars). The central parsec around Sagittarius A* contains thousands of stars. (For comparison: the central parsec around the Sun contains one star: the Sun itself.)

indiaaditya wrote:Is the chances of life greater in the center of the galaxy or at the periphery of the galaxy?

Unknown; we haven't found any yet, beyond our own planet...
When looking for life elsewhere, the main focus tends to be looking for a planet in the habitable zone around a star (not to close, not to far). The star's life span may also be important, as some massive stars burn their fuel way to fast for life to develop.

Case wrote:When looking for life elsewhere, the main focus tends to be looking for a planet in the habitable zone around a star (not to close, not to far). The star's life span may also be important, as some massive stars burn their fuel way to fast for life to develop.

when looking for life elsewhere, we also focus on earth-like life. I dont know, but it always seemed to me that if we could expand the meaning of word "life" a little, we could have found something much sooner (already ?).

When looking for life elsewhere, the main focus tends to be looking for a planet in the habitable zone around a star (not to close, not to far). The star's life span may also be important, as some massive stars burn their fuel way to fast for life to develop.

Near the center of galaxies where stars are in closer proximity, traveling at a higher rates of speed and most everything is more "energetic" (the reason the galactic centers are brighter), decreases the likely hood of (Earth-like) life in these zones also. One of Earth's mass extinctions (2 million years ago?) is thought to be caused by a super nova event 150 light years away. So when looking for life in this galaxy or others, there maybe a type of "habitable zone" dependent on galactic energies, not exclusively on a star's habitable zone.

Following the thought chain of Makc, why does life have to meet our definition of life supporting physics and chemistry? I've often thought that just because we need this air mixture, gravity and certain density to live in, what makes us think that ALL life forms (if there are any) have to live in the same conditions as us? Some life may not need to breath as we know, may live on hotter or colder planets...With the current study of finding life forms, are we looking for life in general, or are we looking for similar life forms to what we already know and expect?