Timeline for If a black hole was headed for our solar system and would arrive within a year, would we necessarily know of it?
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15 events
| when toggle format | what | by | license | comment | |
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| Jul 27, 2021 at 7:47 | comment | added | fraxinus | @A.Kvåle in these terms, smaller black holes release more Hawking radiation because of stronger tidal effect near the event horizon. | |
| Jul 26, 2021 at 22:50 | comment | added | A. Kvåle | Do smaller black holes release more Hawking radiation because they have less gravity? | |
| Jul 26, 2021 at 6:59 | comment | added | fraxinus | @PM2Ring ...only to see how much unimportant is the Hawking radiation in the context of the question. | |
| Jul 26, 2021 at 6:56 | comment | added | PM 2Ring | @A.Kvåle Take a look at the Hawking radiation calculator. | |
| Jul 21, 2021 at 19:15 | comment | added | fraxinus | The smaller the black hole, the brighter is the black hole itself (Hawking radiation). But we are not aware of any black hole that has even theoretically detectable Hawking radiation. The properties of the accretion disk depend on a lot of factors that I am not competent to comment, but the main factor in their brightness/luminosity is the matter available for accretion. Bigger (heavier) black holes are brighter as a matter of scale (they attract matter from bigger volume of space). | |
| Jul 21, 2021 at 15:03 | comment | added | A. Kvåle | Not sure where I got this idea (I thought someone commented it on this post), but is it true that the smaller the black hole, the brighter the accretion disk? According to Wikipedia, the higher the mass of the central body, the higher the frequency of the EM radiation. Now, is the luminosity similarly correlated? The higher the mass, the higher the luminosity? If so, it would probably make my first idea incorrect. | |
| Jul 21, 2021 at 13:19 | comment | added | fraxinus | Yes, it will look like a star. Brighter and brighter. No, I think we will never be able to resolve the accretion disk with naked eye - the Earth will be blown into pieces before that (tidal forces) and the atmosphere will be long gone even before that (x-rays). And I think there is no safe distance for a human to see the stellar black hole accretion disk. | |
| Jul 21, 2021 at 11:36 | comment | added | A. Kvåle | Would it look like another star on the sky, or would it look more unique? At what point would we be able to actually see the accretion disk? | |
| Jul 21, 2021 at 11:24 | comment | added | fraxinus | Pretty much yes. | |
| Jul 21, 2021 at 10:37 | comment | added | A. Kvåle | By my calculations; if using the smallest estimate for the Oort cloud's outer bound (0.08 light years), and using the highest estimate for the black hole's velocity (1000km/s), then it would enter the Oort cloud when it is about 30 years away from us. So, then the question is, if it's 0.08 ly away from us, to what degree would we see its accretion disk? Could we see it with the naked eye? | |
| Jul 20, 2021 at 18:32 | comment | added | fraxinus | The famous Cygnus X-1 is estimated at four orders of magnitude higher luminosity in x-ray than our Sun in its whole spectrum. Its accretion disk is powered by its companion's stellar wind. Well, our environment is rather weaker in stellar winds, but goog luck missing a black hole near the Oort cloud. | |
| Jul 20, 2021 at 17:58 | comment | added | ProfRob | Can you establish that it would be a bright X-ray source? I think this is the key point. | |
| Jul 20, 2021 at 15:23 | comment | added | fraxinus | The event horizon emits Hawking radiation, for a stellar mass black hole (or bigger) it is WAY colder than the cosmic microwave background. X-rays, gamma-rays (and everything softer as well) come from the accretion disk and from the polar jets. And yes, it will be probably visible in UV-Vis as well. | |
| Jul 20, 2021 at 12:41 | comment | added | jwenting | and not just an X-ray source. The event horizon emits all over the spectrum, wouldn't be surprised if all the space dust and other objects being sucked towards it will cause it to emit light in the visual spectrum as well. | |
| Jul 20, 2021 at 9:45 | history | answered | fraxinus | CC BY-SA 4.0 |