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There wouldn't be any observed lensing because you have to be the right distance between the lens and the source for that to be observed. (For objects of compa
by antognini 10y ago
There wouldn't be any observed lensing because you have to be the right distance between the lens and the source for that to be observed. (For objects of comparable mass, the lens has to be roughly halfway in between the source and the observer) But if there were a black hole accreting matter from the host star, there would be an accretion disk which would be visible in X-ray.
A black hole is also too small to explain the drop in brightness. That would require something planet-sized, but a black hole is only about the size of a city.
- tazjin 10y agoBlack holes are uniformly sized?
- XorNot 10y agoSchwarzchild radius means black holes are small. To dim the light from a star you need something very high in surface area whereas black holes by definition are the most compact objects in the universe
- m_mueller 10y agoStellar ones have a soft upper boundary. If they are so old and massive that they become planetary or even stellar sized - well the'd start drawing stealing a good chunk of the host galaxy and form their own one - with blackjack and hookers. I.e. a flickering star would be the least of your worries ;-).
- ethanbond 10y agoWhat causes the soft upper boundary?
- wbl 10y agoThe mass of the star before it went and formed a black hole. The bigger a star, the hotter it is, and the more evaporates from the surface, and the shorter it lives. Large blackholes grow through things falling into them.
- ethanbond 10y agoOh I read the parent comment as black holes having a soft upper boundary. Is that the case? Or if more stuff falls in they just get bigger (minus Hawking radiation)?
- wbl 10y agoSo there is a complication, which is space is filled with vast amounts of nothingness. For a black hole to get bigger objects need to be on a collision course with it, which is somewhat unusual. A black hole doesn't behave any differently from the same mass as something not a black hole. So once a star turns into a black hole, the accretion disk is usually remnants/maybe more if it is in a nebula. Once that's gone, that's it for growth.
- b34r 10y agoBased on current science, there are many geometries of black holes. We can't speak in such absolutes.