APOD: Black Hole Safety Video (2019 Oct 01)

[APOD Robot]

[img]https://apod.nasa.gov/apod/calendar/S_191001.jpg[/img] Black Hole Safety Video

Explanation: If you were a small one-eyed monster, would you want to visit a black hole? Well the one in this video does -- but should it? No, actually, but since our little friend is insistent on going, the video informs it what black holes really are, and how to be as safe as possible when visiting. Black holes are clumps of matter so dense that light cannot escape. Pairs of black holes, each several times the mass of our Sun, have recently been found to merge by detection of unusual gravitational radiation. The regions surrounding supermassive black holes in the centers of galaxies can light up as stars that near them get shredded. The closest known black hole to the Earth is V616 Mon, which is about 3,300 light years away. The best way for our monster friend to stay safe, the video informs, is to not go too close.

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[De58te]

Hmm if NASA has to put out a safety video for tourists in rocket ships visiting a black hole I was thinking shouldn't the tourist visit Tabby's star instead? Tabby's star would be a lot easier to get to since at 1,500 ly away it is half the distance of the nearest black hole and there is a big mystery with the star. It could possibly have a Dyson Sphere around it and I would presume a Dyson Sphere would be a lot safer visiting than a black hole. (Note however I just recently seen a documentary that since the star deflects ultraviolet light the mystery could really be just dust in front of the star.)

[bgdavenport@bellsouth.net]

How does one acquire a facsimile of the flight safety brochure out little alien was carrying? it would be great for school children who are learning about such things.

[orin stepanek]

No; No; I don't want to go! I'll stay right here! Interesting little video clip though!

[BDanielMayfield]

An under appreciated role that black holes can play is that they can help disperse stars out from the stellar nurseries they form in. Their strong gravity doesn't just pull things in; it can also pull things apart. For example, when a binary star system approaches a BH the pair can be split via gravitational exchanges of momentum. One of the pair will be pulled closer while the other is flung out of the cluster altogether.

The existence of BHs also must help limit the amount of destruction that would otherwise be caused by supernova explosions. Some SN detonations are choked off by direct core collapse into BHs. Some stars that where massive enough at first to eventually explode as SN never will if they are in a system containing a BH, because as the star swells much of its mass will get drained away into the BH.

Yes kids, black holes really are our friends. They help make the universe safer

Bruce

[Chris Peterson]

An under appreciated role that black holes can play is that they can help disperse stars out from the stellar nurseries they form in. Their strong gravity doesn't just pull things in; it can also pull things apart. For example, when a binary star system approaches a BH the pair can be split via gravitational exchanges of momentum. One of the pair will be pulled closer while the other is flung out of the cluster altogether.

The existence of BHs also must help limit the amount of destruction that would otherwise be caused by supernova explosions. Some SN detonations are choked off by direct core collapse into BHs. Stars massive enough to eventually explode as SN never will if they are in a system containing a BH, because as the star swells much of its mass will get drained away into the BH.

Yes kids, black holes really are our friends. They help make the universe safer :!:

Supernovas are our friends. We certainly don't want to prevent them. Black holes are doing us no favors there!

[BDanielMayfield]

An under appreciated role that black holes can play is that they can help disperse stars out from the stellar nurseries they form in. Their strong gravity doesn't just pull things in; it can also pull things apart. For example, when a binary star system approaches a BH the pair can be split via gravitational exchanges of momentum. One of the pair will be pulled closer while the other is flung out of the cluster altogether.

The existence of BHs also must help limit the amount of destruction that would otherwise be caused by supernova explosions. Some SN detonations are choked off by direct core collapse into BHs. Stars massive enough to eventually explode as SN never will if they are in a system containing a BH, because as the star swells much of its mass will get drained away into the BH.

Yes kids, black holes really are our friends. They help make the universe safer

Supernovas are our friends. We certainly don't want to prevent them. Black holes are doing us no favors there!

Both are needed, certainly. But too many SN can't be a good thing for habitability.

[Chris Peterson]

An under appreciated role that black holes can play is that they can help disperse stars out from the stellar nurseries they form in. Their strong gravity doesn't just pull things in; it can also pull things apart. For example, when a binary star system approaches a BH the pair can be split via gravitational exchanges of momentum. One of the pair will be pulled closer while the other is flung out of the cluster altogether.

The existence of BHs also must help limit the amount of destruction that would otherwise be caused by supernova explosions. Some SN detonations are choked off by direct core collapse into BHs. Stars massive enough to eventually explode as SN never will if they are in a system containing a BH, because as the star swells much of its mass will get drained away into the BH.

Yes kids, black holes really are our friends. They help make the universe safer :!:

Supernovas are our friends. We certainly don't want to prevent them. Black holes are doing us no favors there!

Both are needed, certainly. But too many SN can't be a good thing for habitability.

It can be bad luck if you're too close to one. But most likely, places where SNs generally happen are unlikely to have any complex life, so habitability probably isn't much of a factor. (And remember, a system where a black hole bleeds off matter from a companion has already experienced a recent SN anyway.)

[BDanielMayfield]

If black holes didn't exist in this universe, would it be more, or less hospitable for life

[Chris Peterson]

If black holes didn't exist in this universe, would it be more, or less hospitable for life :?:

I suspect it wouldn't make any difference, unless black holes played some important cosmological role very early in the Universe. Black holes, after all, are dynamically almost identical to stars. Same gravity, same impact on surrounding bodies.

[Ann]

Many years ago, perhaps in the 1990s, I read a funny little text in Sky & Telescope about the care and feeding of a pet black hole. The author explained to us how to capture the black hole (with magnetism, I think) and how to feed it, carefully, so that it didn't grow too big. It was a fun and whimsical little editorial (or something), and I started searching the web to see if I could find it.

But lo and behold, now the quirky little text has transformed into a kiddie story. I won't post a link to it here.

Ann

[neufer]

How does one acquire a facsimile of the flight safety brochure out little alien was carrying?
it would be great for school children who are learning about such things.

Safety Brochure

Also found in your spacesuit pocket, this helpful brochure will give you all the tips, tricks, and facts you'll need for your next (inadvisable) black hole vacation! Download the brochure using the links below.

Download a printable version here:
https://svs.gsfc.nasa.gov/vis/a010000/a ... _final.pdf

Download a web version here:
https://svs.gsfc.nasa.gov/vis/a010000/a ... _final.pdf

[neufer]

Click to play embedded YouTube video.

If black holes didn't exist in this universe, would it be more, or less hospitable for life

I suspect it wouldn't make any difference, unless black holes played some important cosmological role very early in the Universe.

Black holes, after all, are dynamically almost identical to stars. Same gravity, same impact on surrounding bodies.

• Assuming they aren't currently in the process of noshing.

[Nosh: To eat or nibble, as in
“I’d like something to nosh on before dinner.”]

Image of entire sky in 100 MeV or greater gamma rays as seen by the EGRET instrument aboard the CGRO spacecraft. Bright spots within the galactic plane are pulsars while those above and below the plane are thought to be quasars.

---

<<More powerful gamma rays from very distant quasars and closer active galaxies are thought to have a gamma ray production source similar to a particle accelerator. High energy electrons produced by the quasar, and subjected to inverse Compton scattering, synchrotron radiation, or bremsstrahlung, are the likely source of the gamma rays from those objects. It is thought that a supermassive black hole at the center of such galaxies provides the power source that intermittently destroys stars and focuses the resulting charged particles into beams that emerge from their rotational poles. When those beams interact with gas, dust, and lower energy photons they produce X-rays and gamma rays. These sources are known to fluctuate with durations of a few weeks, suggesting their relatively small size (less than a few light-weeks across). Such sources of gamma and X-rays are the most commonly visible high intensity sources outside our galaxy. They shine not in bursts, but relatively continuously when viewed with gamma ray telescopes. The power of a typical quasar is about 10⁴⁰ watts, a small fraction of which is gamma radiation.>>

[BDanielMayfield]

Supernovas are our friends. We certainly don't want to prevent them. Black holes are doing us no favors there!

Both are needed, certainly. But too many SN can't be a good thing for habitability.

It can be bad luck if you're too close to one.

That was my main point.

But most likely, places where SNs generally happen are unlikely to have any complex life, so habitability probably isn't much of a factor.

While its true that most SN will be happening in un-inhabitable galactic locations, part of the reason for the danger to life there is proximity to SN, again, making my point. But also, SN can and do occur anywhere stars are inside (and even outside) a galaxy. Once enough metals have been produced and spread to foster life lowering the SN rate lessens the odds of a SN caused extinction event.

(And remember, a system where a black hole bleeds off matter from a companion has already experienced a recent SN anyway.)

That is a good point. But where ALL such BHs themselves made via SN? (But that's just a minor quibble. Your point is still valid.)

Bruce

[BDanielMayfield]

If black holes didn't exist in this universe, would it be more, or less hospitable for life

I suspect it wouldn't make any difference, unless black holes played some important cosmological role very early in the Universe. Black holes, after all, are dynamically almost identical to stars. Same gravity, same impact on surrounding bodies.

I hope people ponder this question thoughtfully. I've come to suspect that black holes play a vital role in making the universe more clement for life. Chris gave a caveat that they might have been important early in the universe. If primordial BHs formed that would very likely be so I would think.

Another key question involves galactic dynamics. It has been observed that the proportional mass of Supermassive BHs at the cores of all large galaxies tracks closely with the mass of the whole galaxy. This is puzzling due to the vast spatial differences between the two objects. Does this have anything to do with habitability on galactic scales? I suspect that it does, but I don't know enough to prove it.

Consider the Milky Way's 4.1 million solar mass SBH, located safely about 26,500 light years away at the galactic core. Just think how many more SN would surely have occurred inside our galaxy if black holes couldn't form Our SBH may have snuffed out tens of thousands of SN that would otherwise have gone off if BHs didn't form.

Now consider how many of the rare elements are toxic to life as we know it. But if SN where much more numerous than they've been, then these toxic heavy metals wouldn't be rare at all. So it's not just proximity that makes SNs potentially dangerous. Too many of them could render space too toxic for livable planets to form.

Therefore I think BHs are an important piece of the puzzle as to why life is possible in this universe.

Bruce

[Chris Peterson]

Both are needed, certainly. But too many SN can't be a good thing for habitability.

It can be bad luck if you're too close to one.

That was my main point.

But most likely, places where SNs generally happen are unlikely to have any complex life, so habitability probably isn't much of a factor.

While its true that most SN will be happening in un-inhabitable galactic locations, part of the reason for the danger to life there is proximity to SN, again, making my point. But also, SN can and do occur anywhere stars are inside (and even outside) a galaxy. Once enough metals have been produced and spread to foster life lowering the SN rate lessens the odds of a SN caused extinction event.

(And remember, a system where a black hole bleeds off matter from a companion has already experienced a recent SN anyway.)

That is a good point. But where ALL such BHs themselves made via SN? (But that's just a minor quibble. Your point is still valid.)

I think the overwhelming majority of stellar mass black holes are the endpoint of supernovas.

[pferkul]

Black Hole Lives Matter!