# Talk:NGC 1275

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## Collision question

If the Universe is expanding and each star moves away from each other, then how come that two galaxy collide? --195.228.39.215 14:06, 28 June 2007 (UTC)

Gravitationally bound systems will not move away from each other as the universe expands. Hence, galaxies that are close enough to each other will stop moving away from each other with the expansion of th universe and will collide. Dr. Submillimeter 14:28, 28 June 2007 (UTC)

Thank you very much, Dr. Submillimeter! I forgot about the gravity... :-) --195.228.39.215 14:52, 28 June 2007 (UTC)

Other Questions: What is the luminosity of Perseus A? How hot (estimated) is it? Is blue the only color that is emitted from it? How large is the galaxy? Including the HVS? What does the galaxy tell us? What is its importance?

Creinke (talk) 01:29, 20 April 2011 (UTC)creinke

I can't answer all of those questions, but I could point you in the right direction.
If you have the apparent brightness, you can calculate luminosity.
Objects produce light at all wavelengths, so not only does it produce colors other than blue, it produces UV, X-rays, Gamma rays, Infrared, microwaves, and radio waves.
Knowing its temperature tells you which wavelength is produced the most, which is called the "peak wavelength".
It's size can be calculated as well, using angular size (in radians) and its distance from Earth.
As for importance or what we could learn from it, I can't help. My apologies. --Bsltiger (talk) 17:08, 3 December 2012 (UTC)

## NEWS: X-ray signal

Perseus A: Mysterious X-ray Signal Intrigues Astronomers Release Date June 24, 2014