Three Galaxies in Draco (2009 July 1)

[Vivian]

As time goes by, will these three galaxies get closer because of gravity?

http://apod.nasa.gov/apod/ap090701.html

[Mike]

What are the estimated distances separating the three galaxies?

[bystander]

Are they gravitationally bound? If so, then they will probably merge eventually.

[Chris Peterson]

As time goes by, will these three galaxies get closer because of gravity?

It isn't known for certain if these three galaxies form a group, or if they are possibly part of a larger group of galaxies. That would determine the degree to which they might be gravitationally bound.

In any case, however, gravity doesn't generally make things get closer. If the bodies are gravitationally bound, it means they are in some kind of orbital pattern around each other, so they will spend about as much time moving apart as coming together. Eventual mergers can occur, but not really because gravity pulls galaxies together. Rather, the chaotic orbits produced by a multiple body system eventually result in a collision.

[emc]

Speaking of galactic collisions... that became even more intriguing for me when I realized that the odds of actual body to body contact is very small (considering the typical enormous expanse between objects). And the “expanse” is even more intriguing when I consider a typical Earth spaceship’s relative range. Sure we can see a long way, but getting there.... well.... Kind of makes me feel small… “it happens to us all”

[emc]

As time goes by, will these three galaxies get closer because of gravity?

http://apod.nasa.gov/apod/ap090701.html

Hi Vivian,

I’ve been thinking about your question and want you to know that I think your query is an intelligent one. One would surmise that close proximity dictates attraction… gravitationally speaking. After all, (and correct me if I am wrong you smart space intelligent guys out there) our space craft are able to return to earth due to that attraction…. They just have to slow down enough to allow earth's gravity to work. Therein lays the rub for the galaxy attractor factor… Galaxies have their own momentum, therefore are affected by a neighboring galaxy only when relative speed and proximity induce an effect.

Hope this helps... it was fun writing!

I am particularly fond of today’s APOD since it stems from the Dragon.

[harry]

G'day from the land of ozzzzzzzzz

Three Galaxies in Draco APOD: 2009 July 1
http://apod.nasa.gov/apod/ap090701.html

This intriguing trio of galaxies is sometimes called the Draco Group, located in the northern constellation of (you guessed it) Draco. From left to right are edge-on spiral NGC 5981, elliptical galaxy NGC 5982, and face-on spiral NGC 5985 -- all within this single telescopic field of view spanning a little more than half the width of the full moon. While the group is far too small to be a galaxy cluster and has not been cataloged compact group, these galaxies all do lie roughly 100 million light-years from planet Earth. On close examination with spectrographs, the bright core of the striking face-on spiral NGC 5985 shows prominent emission in specific wavelengths of light, prompting astronomers to classify it as a Seyfert, a type of active galaxy. Not as well known as other tight groupings of galaxies, the contrast in visual appearance makes this triplet an attractive subject for astrophotographers. This impressively deep exposure of the region also reveals faint and even more distant background galaxies.

It's just amazing

I keep observing the night sky and yet never get tired of watching.

[harry]

G'day

oooops the same topic was already open.

Thank you for correcting me.

Please do not whip me.