There's a black hole lurking within 1,000 light years of Earth – and you can see stars circling it with the naked eye Astronomers have stumbled across the nearest black hole to us yet. The void lies at the heart of a stellar system just 1,000 light years away, and indications to its location are visible to the naked eye. A team of researchers were observing HR 6819 with the European Southern Observatory's (ESO) 2.2m MPG/ESO telescope in Chile …
It is in Telescopium about 57 degrees South, so in theory visible from anywhere south of about 33 degrees North, which now puts me in the southern hemisphere. I'll have to check which way the water circulates down my toilet's black hole and see if it has changed.
Lucky you if you're in south !
Geez, sometimes I wish I had taken this doctoral thesis in stellar dynamics, several decades ago ...
Back then, black holes were purely hypothetical. And today, not only do we know there's one more or less in the center of every galaxy, but also one we can observe (not directly of course) without any tooling ! Which is right next door !
As for observation, you could probably pin point the movement of the 2 stars day after day during one month, by taking a pic with a telescope each day and see the rotation around "it".
But you would need to correct it by the rotation of the 2 stars set caused by their elevation vs. the solar plane and the trajectory of earth. Looks like Euler trigonometry is in order :)
I am assuming that there couldn't be nearly enough of these black holes (by a very large factor) to account for dark matter. But it does remind me of the incident in the Cyberiad when Trurl creates the machine that Klapaucius tells to do Nothing, and it does Nothing, which explains why space is so empty these days.
There can't be, as you say. Black holes are 'visible' by gravitational microlensing: if you look through an area where there are BHs, even ones which are not accreting material, then they will gravitationally lens objects behind them. If you work out how many BHs (or other compact massive object: splendidly called 'MACHOs': massive compact halo objects) you would need to account for the missing mass, then you can work out about how many microlensing events you should see, and you can then look to see how many you do see, and it's not enough.
I don't think a black hole would entering our solar system would end particularly well.......
Whilst it might rid us of Musk's roadster it would probably take a fair bit of the solar system with it as well.
It is difficult to know how something like this will react it it comes into proximity of another star. It may be fairly passive now but that simply could be because it has not come close enough to anything of note to create the accretion disk.
I would have thought that the smaller rocky bits on the edges were all nicely digestible sized blobs to be ingested with some gas as icing on the top. Maybe even the larger inner planets it you look at the scale of the weights.
Even if it did not ingest planets the gravity changes would make enough of a mess to more than likely render Earth uninhabitable. Either way it would clean up the mess that mankind has made although we would not survive the encounter.
Imagine light's motion is across some [unspecified] field. I compress the field by a factor of 2 and now it takes twice as long [unspecified units] to cross that field. It has twice as much of [unspecified] field to cross.
Now also suppose that light's motion and matters motion is the same, also across the field. Matter too, takes twice as long to move across that compressed field, and its dimensional size is also compressed by 2x. So when I measure the speed of light, if I'm in the same compressed field, I get the same speed of light.
Regardless of the compression factor, as long as we're in the same field as the light we're measuring, we'll get the same result for the speed of light.
OK, so now lets suppose that I'm outside the field looking into this compressed field. Now to me (at 1x compressed field), light has slowed by a factor of 2, relative to me.
i.e. compressed field = stretched space.
It might sound like I'm playing semantics here. That I'm just swapping "stretched space" for compressed field over fixed space. But space is just an arbitrary coordinate system chosen by us, if our definition of space was actually bending then it just means we screwed up our models defined in that coordinate system. If we'd defined the coordinates a different way, then space would have to bend in a different way to fixup our model. So space doesn't bend.
On the other hand, the actual field that light moves over is an actual thing. Independent of any coordinate system we choose.
To my point:
There really is no difference between the vacuum between atoms and the vacuum between planets. The speed of light through glass or through space, its the same. It ~1 local resonant wavelength per resonant oscillation, and how we measure it and perceive it changes depending on the field we're in vs the field the light is in.
So inside that black hole, is a compressed field. If it was perfect 2x compression (with no inner spinning black holes) viewed relative to our local universe, it would be perfectly dark, nothing in, nothing out and no outer spin or wobble. If you were inside it, space would appear to be normal, the speed of light would be the same, any experiment you perform outside on outside-matter would get the same result inside on inside-matter. If there are blackholes inside that blackhole, then field is even more compressed than 2x and the universe (the 'space') inside is far more stretched. The deeper the compression the larger the apparent universe to the people inside and the colder the universe appears to them.
You see how its a lot easier to think in terms of compressed resonant field wavelength than in terms of stretched space. It's a lot easier to model too if you lock your coordinate system down too.
A pic would be nice. Bouman?
And the practical implication is......
If this thing has escaped detection up to now, and its practically parked on the bloody driveway next to the Green Waste Bin, and theres probably millions of them, then zipping across interstellar space at breakneck pace might turn out to be a bit more dangerous than we imagine.....
If this thing has escaped detection up to now, and its practically parked on the bloody driveway next to the Green Waste Bin, and theres probably millions of them, then zipping across interstellar space at breakneck pace might turn out to be a bit more dangerous than we imagine.....
As Douglas Adams said:
“Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space."
Even if there were 1000 black holes in a 1000 light-year radius of us, that volume of space is so big and stellar-mass black holes are so small (if there were supermassive blackholes that near they would have been seen by gravitational lensing by now even if they are quiet), that you'd have more chance of finding a specific grain of sand (3-dimensional volume of beach, not just 2-d surface) on a beach than of randomly smacking into a black hole.
Well, I guess we are now starting to understand where all the so called "Dark Matter" is then, since Singularities seem to be more common than previously thought. And don't worry about them "zipping around space". Anything with that mass is going to get noticed if it gets anywhere near us. 1000ly is a LONG way away!! Travelling at C it would still take it 1000 years to get here!
Harder to rule out stellar mass black holes, especially out in galaxy halo where there isn't much stuff to form x-ray emitting accretion disks.
One of the ideas of LIGO is that if there are so many smallish black holes out there then they are going to collide and create gravity waves
See my other comment: Richard Boyce is right, black holes and other compact, massive objects have been essentially ruled out as accounting for the missing mass because there are not enough gravitational lensing events.
@Richard: yes I remember a report ona MACHOs search concluding there are not enough massive Compact Halo Objects to be Dark Matter. Published about a decade ago. That left light stuff like neutrinos, aka WIMPS. Even they were ruled out. Where, cant recall. So we have the kludge of Dark matter and Energy to make the sums work right. I cant help feeling something is wrong with the models but no idea what . MOND does not feel right as it involves "special" conditions of a sort. But what would I know ?
No, this doesn't account for Dark Energy.
Perhaps I should have said "EVEN travelling at C", not that anything substantial can travel at C in our universe.
We only ever see objects by their effects. Some emit radiation, some reflect radiation, some distort space-time, some occlude radiation emitters/reflectors, etc.
The idea that Singularities have been "ruled out" as a contributory factor is against ALL scientific principles. A real scientist rules out nothing, just observes and theorises. When the observed data changes, so does the theory.
But the observed data is not changing. If dark matter is BHs we know about how much gravitational lensing we would see, and we don't see anything like enough. So unless there is something hugely wrong with the experiments we've done, BHs are indeed ruled out as a significant contribution to the missing mass.
In fact the situation is really the reverse: models of star formation predict a lot more black holes than we have so far seen (but hugely fewer than would be needed to explain the missing mass): the paper the article refers to says that we expect somewhere around 100 million to a billion stellar mass black holes in the galaxy, but we only see a few hundred x-ray binaries, of which most contain neutron stars, not BHs. So there must be a lot more which are not actively accreting mass which we don't see, and people are busily looking for them.
Well the thing about a black hole, its main distinguishing feature is its black. And the thing about space, the colour of space, your basic space colour.... is its black.
So how are you supposed to see them?
Lets hope this one doesn't turn out to be grit!
Pint to the boffins for finding it before Holly.
Now I am no astronomer, but I do know that if one object has 6 solar masses and another has 4, then the heavier is certainly not orbiting the lighter. Throw in a second 6-solar-mass object and the 4-baby is just a bit of fluff. So how one of the bigger ones "orbited an invisible [smaller] companion" needs some explaining, as does the apparently total rubbish artist's impression.
In fact, as an example of the three-body problem, either this system is highly unstable or the mass estimates are way off.
The article doesn't make it clear but if you look at the PDF you'll see that the system is hierarchical - there's an inner binary consisting of one star and the BH, both being orbited by the 2nd star which is much further out.
Additionally, the 4 solar masses quoted is just a minimum size for the black hole. They don't have an estimate for its upper size (that I could see on a quick skim through) but - to address your point - the 6 solar masses star is orbiting a 4 + 5 = 9 solar masses binary.
I think you need to go do some more studying on orbital mechanics. To be precise they will all be orbiting a common point in space, but since the larger masses are farther away, then the common point will probably end up in or near the Singularity, which we then define as the object being orbited. In this case the common point will be moving around considerably but should be in or near the Singularity most of the time.
They think the BH is significantly lighter than the stars: the system is really two nested binaries, with the BH and one of the stars in orbit around each other, and the other star orbiting the inner pair. The Barycentre of the system as a whole will be outside any of the objects in it, I think, although it could possibly pass through one or both of the inner objects (but I think it probably doesn't).
Nothing is ever observed to cross the event horizon by distant observers. But things which approach it rapidly become undetectable by distant observers as no more photons reach them. So there is no possible observational difference between not having crossed the horizon and having crossed it. It's safe to say that whatever crud surrounded the BH has indeed fallen into it in any sense that matters (if it has got close enough).
Having grown up in a world where people were just beginning to realise that black holes were not just mathematical curiosities, to be alive in one where we not only know that they're just everywhere, but we have heard them colliding, we have pictures of the immediate surroundings of one, and now we can see, without a telescope, stars which are in a system including a black hole is just astonishing. We live in a golden age for astronomy and astrophysics.
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