I found this nice galaxy that only has stars in the center. the rest of it is only dense galaxy clouds containing green nebula balls. some of them has a white dwarf inside in the center with really strong forces (bends the light more than usual). I also found some oddly shaped nebulas that don't even look natural. they are shaped strange ways with geometry. Can show some pictures. There is one wierd thing about this. after updating the neutron stars in the center of some of these green sphere nebulas has disappeared. That was not cool because it looked awesome when they where inside. Why are they gone now?
These balls used to have white dwarfs in the middle but gone after update?
According to the screenshot in Zef's album, it's a planetary nebula. Harbinger has also already confirmed that the one you found was a fluke, a planetary nebula that just happened to land smack dab in the middle of a quasar galaxy (which is an awesomely rare find I would imagine).
Quasars are also a phenomenon of the early universe, so to visit one, you would have to travel back in time. I'm not sure that is how Space Engine works. Would be cool to see one in action though.
EDIT: Harbinger posted the same time as me which made my post redundant
Edited by Bells_Theorem - Tuesday, 28.07.2015, 22:25
I've seen a "dead" galaxy myself recently. I have yet to try visiting it in other versions of the game to see whether it's a bug or just an anomaly.
Regarding quasars, my understanding is that a quasar is simply any active galaxy (meaning the central black hole is currently in the process of accreting mass) which is tilted in a way that we on Earth can see down the radio jets into the center. So can't a quasar exist at any time, including the present?
(Also I've found several quasars in SE, suggesting that SpaceEngineer agrees)
Active galaxies that point their jets in our direction are blazars.
I don't know of any hard and fast rules on what constitutes a quasar and what constitutes an AGN, but from what I understand, quasars are extremely active galaxies releasing thousands of times more energy than the rest of the galaxy. AGNs (active galaxies) are on a scale orders of magnitude less energetic. So the two processes I believe are different.
Quasars, I believe, are super massive black holes that have not yet cleared out their galactic nuclei and are still feeding from the primordial gas on the order of tens to hundreds of solar masses each year, and AGNs are intermittent snacks that happen to wander close due to interacting galaxies, etc...
Since the primordial gas in the galactic nuclei is limited, over time quasars will run out of fuel and become dormant or occasionally AGNs but never quasars again (unless galactic collisions are capable of providing the required amount of gas). Which means they become exceedingly rare over time.
I don't know of any hard and fast rules on what constitutes a quasar and what constitutes an AGN
An AGN is a galaxy that it's galactic disk is in the way of seeing the core, but we know it has jets. A quasar is the same thing except that it's not pointed at us or has the galactic disk in the way. And as you said, a blazar is a quasar that has it's jets pointing nearly or completely straight at us.
Living among the stars, I find my way. I grow in strength through knowledge of the space I occupy, until I become the ruler of my own interstellar empire of sorts. Though The world was made for the day, I was made for the night, and thus, the universe itself is within my destiny.