How many known stars has disappeared from sight for no known natural reasons, if any?

[JEL]

Hey guys,

How many observed/confirmed stars has disappeared from sight for no known natural reason, if any?

Stars which, based on the current mainstream understanding of how they should evolve, should still be there, but aren't.

My question relates to the theory of black-hole's, and I was wondering if there have ever been any observations that directly (or at-least more or less directly) suggests a star having been 'eaten' by a black-hole (I've never heard of such observation myself, but maybe someone else has?)

All stars I can see and recognize with my naked eye are still there, so if going only by that the answer is zero.

 

[Pyromaniac605]

There could just be a small cloud or something in the way, are you sure they are just gone?

Darren

 

[garyw]

I don't fully understand the question. As far as I know the total number of stars to vanish within the past generation is zero.

The total number of stars to vanish in the past 1000 years is one which went supernova around 1054 AD but that's a natural event.

Surely, a star dissappearing for no known natural reason could be a sign of a dyson shell? Certainly, the change in luminosity of a star is a key search criteria for SETA (Search for Extra-Terrestrial Artiefacts).

 

[jinglesassy]

The odds are it has happened before but the odds are about 99.99% chance it hasn't happened in at least a few million years in our galaxy.

 

[T.Neo]

Surely, a star dissappearing for no known natural reason could be a sign of a dyson shell?

A Dyson shell is a massive, implausible, unstable structure...

Dyson swarms or Dyson "bubbles" make far more sense...

 

[donatelo200]

Stars can't be eaten by a black hole in the amount of time sessisary for them to dissapear suddenly. Also black holes will emit light as they pull material away from stars. There was one star that didn't become a red giant and went supernova. SN 1987A is what i think you are looking for. Though natural it was unexpected that it was a blue supergiant when it died.

 

[Izack]

The total number of stars to vanish in the past 1000 years is one which went supernova around 1054 AD but that's a natural event.

As far as I know there were at least two others, in 1572 and 1604 (two in less than a generation.) The 1604 event was the last supernova observed to date.

But who knows? At least several stars have likely gone nova in the intervening years, but we won't find out for many years to come.

EDIT: Sorry, it was the last supernova observed in the Milky Way to date.

 

[Fizyk]

My question relates to the theory of black-hole's, and I was wondering if there have ever been any observations that directly (or at-least more or less directly) suggests a star having been 'eaten' by a black-hole

Star having been 'eaten' by a black hole wouldn't look like "star, pop, no star" As the star would approach the black hole, its light would become more and more red-shifted. Also, it would appear to us as if it was approaching the black hole slower and slower due to gravitational time dilation. Actually, it would take infinite time (as perceived on Earth) for the star to fall into a black hole completely.

I'm pretty sure such an event would be recognized (mostly the red shift would be quite characteristic) and widely announced

 

[JEL]

Thanks a lot for your thoughts and answers so far

I get from this that there are no actual known observations suggesting towards a star having ever met a theoretical black-hole, and that there are zero known missing stars which current mainstream theories would expect to still be there in stable condition (which in this case excludes "SN1987A", although interesting ). That fits what I've been able to dig out via google myself

 

[garyw]

What about Cygnus X-1? http://en.wikipedia.org/wiki/Cygnus_X-1

 

[donatelo200]

It's not going to dissapear any time soon. It's actually hevier than the black hole witch orbits it.

 

[Urwumpe]

It's not going to dissapear any time soon. It's actually hevier than the black hole witch orbits it.

That has nothing to say, since the black hole has the higher density. It just means that the black hole has more food.

 

[T.Neo]

I have a feeling a star going into a black hole would be pretty bright, too.

And I have a feeling it wouldn't occur instantly either.

 

[jedidia]

I get from this that there are no actual known observations suggesting towards a star having ever met a theoretical black-hole,

I think you're looking for the wrong indications. You don't know that there probably is a black hole by having a star there and then suddenly not having it there anymore. That's not the way it works. If anything, a black hole would tear a star apart, but that would only be in the last stadium of the process, and should be fairly rare on a galactic scale.

A star too close to a black hole makes itself noticed by irregularities in its trajectory, not by vanishing from one moment to the next.

There are some stars that show irregularities that are easiest explained by a nearby black hole, so if you are looking for observable indications for black holes, that would be them.

 

[statickid]

Remember two things about a black hole:

1. they are collapsed stars
2. as a body in space they follow the same physics and rules of gravitation as anything else (in most respects)


"1" is important because you will find that a black hole would tend to be the same distance from other stars the majority of stars are, and we don't typically see any stars just running into each other as they are pretty far apart (with some exceptions such as binary systems)

"2" is important because black holes don't "suck" or "eat" up anything. their gravitational influence is not so different than it was before it turned into a black hole, for example, if the sun were a black hole we could orbit it in much the same way as we do now (regardless of whether we were dead or not). So also you don't typically see stars capturing other stars into their gravitational feilds and having them collide, or even if they did, they'd probably orbit each other for a while.

The last thing is that you can look up suspected black hole objects in a star catalouge. they are actually some of the brightest objects in the sky and emit huge amounts of radiation if they are "eating" something

 

[RisingFury]

In a Milky Way sized galaxy, a star goes supernova once every roughly 50 years. Only a few of those will be visible with the naked eye from Earth.

Stars live for a minimum of a few millions to a maximum of a few billion years before they die, so I hope you're not actually watching to see one evolve in front of your eyes.

 

[JEL]

There are some stars that show irregularities that are easiest explained by a nearby black hole, so if you are looking for observable indications for black holes, that would be them.

Yes, thanks
Do you know where I may be able to find further info on those stars/irregularities you mention?

Actually, it's not so much indications of black-holes I'm looking for, but rather indications of encounters between stable stars and black-holes (either by collisions or close-proximity passes)

Stars live for a minimum of a few millions to a maximum of a few billion years before they die, so I hope you're not actually watching to see one evolve in front of your eyes.

I was looking at the night-sky a few days ago when I came to think about this. All the known star-signs are still there (that covers at-least a few thousand years of human history), all the stars used for navigation throughout relatively modern times are still there (that's at-least 500 years of human history), and that just made me wonder if there are any examples at all of known stars that were once observed but can't be today (and in extension of that I came to think of black-holes)

My own personal quick first-hand evaluation of this was to simply count how many stars I have seen myself through time that I can't locate anymore, which is zero. All stars I can recognize are still there, thus zero is missing. Rough and basic, certainly, but the most direct observation of the night-sky none-the-less

 

[jedidia]

In a Milky Way sized galaxy, a star goes supernova once every roughly 50 years.

I thought that a SUPERnova is a rather rare event, while simple novae are pretty common?

 

[statickid]

I haven't brushed up on any facts about this, but just garnering from what is posted here a 1 supernova in a galaxy every 50 years sounds pretty rare to me considering all the stars...although maybe it isn't very rare considering how short 50 years is cosmically. I don't think I ever realized how many stars there REALLY are until i downloaded celestia along with one of those 2 million star catalogues, then turned the brightness up and zoomed out. Just our local visible/telescopable starfield is rather impressive!

 

[Unstung]

I haven't brushed up on any facts about this, but just garnering from what is posted here a 1 supernova in a galaxy every 50 years sounds pretty rare to me considering all the stars...although maybe it isn't very rare considering how short 50 years is cosmically. I don't think I ever realized how many stars there REALLY are until i downloaded celestia along with one of those 2 million star catalogues, then turned the brightness up and zoomed out. Just our local visible/telescopable starfield is rather impressive!

These stars live millions or billions of years, so 50 years is a pretty often occurrence, especially compared to the age of things in space. You just said that last part yourself.
There are about 100 billion stars in this galaxy, and not all of them are able to turn into supernovae.