imsahoamtiskaw t1_iu9zk1r wrote
>Astronomers estimate that 100 million black holes roam among the stars in our Milky Way galaxy, but they have never conclusively identified an isolated black hole.
That's an insane number. Also glad none if them is close to us lol.
Imagine being worried about the SMBH at the center and some other one creeps up towards you (or a 3+ stellar mass one collapses in on itself and forms beside you as a neighbor).
f_d t1_iuaaw8w wrote
>Also glad none if them is close to us lol.
How would we know until it was almost on top of us?
LaunchTransient t1_iubbhwh wrote
It would be visible, or rather, its effects would be.
It might not be as noticeable as, say, a comet in the night sky, but an approaching black hole would resemble a moving distortion in the background behind it due to gravitational lensing.
And the moment it moves through anything with signifcant mass (e.g. a gas cloud), it'd show up as that gas gets pulled into an accretion disk and starts emitting light when the gravitational shear forces superheat it.
astro_osrs t1_iub7bif wrote
I think gravitational effects would be noticed, an incoming black hole with, let's just say 12x the mass of the sun, would definitely shift some orbits (marginally), but enough for us to detect them. Since we aren't detecting anything (except for like, planet x, which could be a black hole?) Safe to assume there isn't one "near" but honestly I could be completely wrong lol
f_d t1_iubfdac wrote
By the time it was shifting planetary orbits, it would be on top of us compared to anything else in the galaxy. So if it was speeding toward us from an empty area of the sky, while not getting close enough to other stars to give away its presence easily, we might not realize it until very late.
Wombat_Racer t1_iubx4ci wrote
What would we do anyway? Take photos I guess.
astro_osrs t1_iug987i wrote
It's hard to think that from a far enough distance, it would give us more than a few centuries notice atleast?
I feel like if there was, even a sun mass object, within the oort cloud, we would 1000000% know it. So if a 12x mass black hole was moving towards us, surely we'd be able to detect it. When I say shifting orbits, I'm saying very marginally, not enough of a difference, but enough to be detected to where we know something big is headed toward us.
Jupiter has a very noticeable effect on the sun, and the sun is like, 99.8% of the solar systems mass. Surely a 12x black hole would affect something enough for us to detect. Our planets/sun would surely feel it from very far away, and Im sure we would be able to detect the increasing shift due to the black hole heading towards us
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