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Anyone here who's familiar with black hole formation and who could elaborate on why the BH is so special?
Earlier quoted context omitted.
On the other hand, if it had chosen our planet as its destination 1559 years ago, then we would have no way of being aware of this fact until next year
But then we wouldn't be seeing it at a distance of 1560 ly right now.
The same, of course, could be said for any other celestial body, currently observed or otherwise.
Earlier quoted context omitted.
But then we wouldn't be seeing it at a distance of 1560 ly right now.
In principle it could be approaching us at near the speed of light (for example, if it was hit by something big going near the speed of light from the other direction a few days after the presently observed light was emitted) and we would never know it until it's just about too late. The same, of course, could be said for any other celestial body, currently observed or otherwise.
Right, good point! I shouldn't have skipped my morning coffee.
> if it was hit by something big
For the record, I assume you mean not a literal "hit" but some sort of binary interaction with another very massive object that ends up transferring (a lot of) momentum to the black hole.
Exactly how terrified should I be at this news? Really super terrified, right?
Your reaction should be "astronomy fun fact, that will have no direct effects on anyone's life." This black hole is so dim and distant that it required a super powerful telescope to even notice it exists. It will have no effect on life on earth, except by adding to scientific understanding of the cosmos. Moreover, black holes aren't death machines or anything. This black hole puts out much less light and energy than…
Famous last words...
> The black hole is actually quite special. It is different from all other known black holes, and its existence is difficult to explain with standard binary evolution models. Anyone here who's familiar with black hole formation and who could elaborate on why the BH is so special?
Formation of a black hole is a pretty violent event - a supernova. Which sometimes ejects a companion star, and would certainly strip it of mass and change its chemical composition.
(edit) One other thing that makes a black hole 'special' is if they're really light (possibly formed via two neutron stars colliding).
> The fact that the star is very similar to the Sun is also quite special. It is different from the companions of most other known black holes (see the location of the newly found Gaia-BH1 with respect to the other known black holes as highlighted in Figure 1). If this system also contains planets, like a large fraction of solar-type stars do, it would be an even more interesting object for further studies!
https://en.wikipedia.org/wiki/Black_hole#Formation_and_evolu...
> The black hole is actually quite special. It is different from all other known black holes, and its existence is difficult to explain with standard binary evolution models. Given this and the difficulty in spotting dormant black holes, it will be interesting to see if these black holes are suprisingly common. Similar to the way gravitational microlensing led astronomers to find far more low-mass planets than they e…
We know BHs should be pretty common. Earlier generations of stars were composed of larger and more short lived stars (due to their low metallicity) that should mostly end up as black holes.
As to detecting gravitational microlensing it is not as easy as it sounds. A black hole remnant of a star will be microlensing the light just like a star -- only without very visible reason for the microlensing to be happening.
In practice what you would see is when a black hole moves in front of a star that star's light is suddenly magnified without any good reason. It is one time event, it is rare and afterwards there is nothing else to study. These types of events tend to be very hard to capture because they require you to look at entire sky all the time.
Exactly how terrified should I be at this news? Really super terrified, right?
If you should be terrified, you'd see it show up everywhere. At least as much news coverage as COVID got. If something happened that was likely to end the whole world, and it was detectable by many people, then you wouldn't only hear about it on one random internet forum. This is pure clickbait.