Beta
×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Smallest Known Black Hole Found

timothy posted more than 2 years ago | from the minor-suckage dept.

NASA 69

smitty777 writes "Adding to the recent black hole discoveries of gas clouds and a quasar accretion disc, Forbes is reporting on a recent discovery by NASA's Rossi X-Ray Timing Explorer (RXTE) on the smallest known black hole. From the article: 'If the astronomers' calculations are correct, this black hole is located about 16,000 to 56,000 light years away from Earth (a more precise distance hasn't yet been determined). The black hole itself is only about three times the mass of the Sun, which means that the original star was just barely big enough to form a black hole.'"

Sorry! There are no comments related to the filter you selected.

That's odd... (1, Funny)

Anonymous Coward | more than 2 years ago | (#38408588)

How did my ex-wife end up way the hell out there?

Re:That's odd... (-1)

Anonymous Coward | more than 2 years ago | (#38408606)

How did my ex-wife end up way the hell out there?

black hole makes me think of knee-growz and the welfare system. or knee-growz and the prison system.

Re:That's odd... (-1)

Anonymous Coward | more than 2 years ago | (#38409164)

How did my ex-wife end up way the hell out there?

black hole makes me think of knee-growz and the welfare system. or knee-growz and the prison system.

NIGGER

Re:That's odd... (0)

Anonymous Coward | more than 2 years ago | (#38418948)

How did my ex-wife end up way the hell out there?

black hole makes me think of knee-growz and the welfare system. or knee-growz and the prison system.

NIGGER

Commenting just to comment on yourself doesn't really look that cool.

Re:That's odd... (1)

RockDoctor (15477) | more than 2 years ago | (#38415102)

... particularly when you knew you'd buried her out in the backwoods?

Well, it just proves you were right - vampire or zombie is undecided, but "Living Dead" for sure.

Smallest first post... (-1)

Anonymous Coward | more than 2 years ago | (#38408590)

Frst pst

Re:Smallest first post... (0)

Anonymous Coward | more than 2 years ago | (#38414036)

bzzzztthankyouforplaying....

Some day (0)

Anonymous Coward | more than 2 years ago | (#38408594)

we'll understand everything there is to know about the universe (provided we don't blow ourselves to kingdom come first) and things like black holes will seem unreasonably trivial...

Think about it.

WHAT THE FUCK IS THIS! (5, Funny)

Anonymous Coward | more than 2 years ago | (#38408602)

WHAT THE FUCK! Is this for real? Maybe I'm just imagining this, but this article looks like, dare I say it, it may just be "news for nerds!" After months of articles about various shitty Apple devices, copyright, American politics, and shitty Apple devices again, it's stunning to finally see an article about a scientific discovery again.

Re:WHAT THE FUCK IS THIS! (0)

Anonymous Coward | more than 2 years ago | (#38408632)

Have you tried science.slashdot.org?

Re:WHAT THE FUCK IS THIS! (1)

Intron (870560) | more than 2 years ago | (#38408812)

Have you tried science.slashdot.org?

NIH Restricts Use of Chimpanzees in Labs [slashdot.org] - and how is this a science article?

Re:WHAT THE FUCK IS THIS! (3, Informative)

khallow (566160) | more than 2 years ago | (#38409084)

NIH Restricts Use of Chimpanzees in Labs - and how is this a science article?

Is that supposed to be a trick question? If this goes through, it's a significant constraint on animal research (the science angle that you're looking for) that could expand in the future.

Re:WHAT THE FUCK IS THIS! (0)

Anonymous Coward | more than 2 years ago | (#38408834)

My reaction was, is Slashdot turning into Scientific American? Another story about that latest wrinkle from cosmology that only a few specialists care about.

Re:WHAT THE FUCK IS THIS! (0)

Anonymous Coward | more than 2 years ago | (#38409614)

Yeah, no kidding, Between clueless people drooling over 3D printers and even more delusional people earnestly proposing interstellar colonization, slashdot is more about the collective hallucinations of daydreaming adolescents.

Re:WHAT THE FUCK IS THIS! (1)

smitty777 (1612557) | more than 2 years ago | (#38411060)

What's worse, the daydreaming adolescents, or those that act like they have something better to do but keep droning on about how bad it is. If you don't like it so much, why don't you actually contribute something to the discussion?

May be small but still big enough (1)

glutenenvy (1248588) | more than 2 years ago | (#38408610)

to steal socks from the washer.

Tight (5, Funny)

oldhack (1037484) | more than 2 years ago | (#38408630)

That's a tight hole.

Re:Tight (0, Offtopic)

Gaygirlie (1657131) | more than 2 years ago | (#38408638)

That's what she said.

Re:Tight (3, Funny)

ArcherB (796902) | more than 2 years ago | (#38408690)

That's a tight hole.

That's what she said.

Shouldn't that be "That's what HE said"?

Never mind. I just read your username.

I was also thinking:
Answer: That's a tight hole.
Clue: Name something your mother will never hear.

Re:Tight (0, Troll)

melikamp (631205) | more than 2 years ago | (#38408776)

Natalie Portmans black hole is even tighter, closer, and has been rediscovered many times by independent researchers.

Re:Tight (4, Funny)

DoofusOfDeath (636671) | more than 2 years ago | (#38408804)

And it sucks hard.

Too bad it's in the red-shift district.

Re:Tight (1)

oodaloop (1229816) | more than 2 years ago | (#38409306)

But does it have hair?

Re:Tight (1)

Anonymous Coward | more than 2 years ago | (#38409792)

Not for external observers.

Re:Tight (1)

mattr (78516) | more than 2 years ago | (#38412836)

The researchers found that among all intelligent sexually reproducing species in the galaxy, every single one had a list of sexual innuendoes related to black holes.

interesting, but vaguely in line with estimates (4, Interesting)

Trepidity (597) | more than 2 years ago | (#38408634)

There have been a bunch of claims of black holes roughly in the range 3-4x solar masses, some subsequently revised upwards (this one [wikipedia.org] made some news in 2008, and there are some other candidates as well). The "normal" range for stellar black holes is roughly 3-30x solar masses, according to current understanding.

Anyone have a link to a good explanation of the current estimated values for a minimum? My understanding is that there isn't really a theoretical physical minimum (black holes can exist at any size), but that there's a mass level beneath which astrophysicists consider it very unlikely that conditions would have really existed to produce a black hole through stellar collapse of a star. But I can't seem to find a solid estimate of what that number is, just these sorts of indirect references to 3x being "close" to the minimum (looking at Google Books, I find an old textbook that also mentions 3.2x as "just above" the theoretical minimum, but doesn't elaborate).

Re:interesting, but vaguely in line with estimates (4, Informative)

Trepidity (597) | more than 2 years ago | (#38408646)

Replying to myself: it appears that the minimum is related to the Tolman–Oppenheimer–Volkoff limit [wikipedia.org] for the maximum mass of a neutron star, which isn't known to great accuracy. Wikipedia cites a 1996 journal article with an estimate of "approximately 1.5 to 3.0 solar masses".

Very close to the Chandrasekhar limit? (1)

grimJester (890090) | more than 2 years ago | (#38408774)

Here [wikipedia.org] it's claimed that the limit for a white dwarf collapsing to a neutron star is about 1.4 solar masses. Some statistics of how common black holes are relative to neutron stars could probably narrow down that 1.5 to 3.0 maximum for a neutron star quite a bit. At the lower end neutron stars should be fairly rare, shouldn't they?

Re:interesting, but vaguely in line with estimates (2)

arth1 (260657) | more than 2 years ago | (#38408782)

There is, I believe, another limiting factor in Hawking radiation. Because the area of the horizon relative to the mass of the hole is larger the smaller the mass, a too small hole will "evaporate" (for lack of a better term) in an accelerating process, before it winks out with a "tzing!"

There is no fixed "limit" for this, nor do I believe one would make much sense, as it would also depend on how well fed the black hole is. And unless in our back yard, or rather, on our doorstep, we can only observe the black holes that are close enough to mass to feed on it.

Hawking evaporation limit (5, Interesting)

TuringCheck (1989202) | more than 2 years ago | (#38409172)

A black hole that would grow by absorbing radiation instead of shrinking at the ~4K average temperature of the universe can be around the mass of the Moon. Such a small black hole cannot form just by gravitational collapse but can go on indefinitely unless the universe cools down.

The question here was about the minimum mass a star can have to become a black hole instead of remaining a neutron star - or maybe something more exotic but still fighting gravity. The Tolman–Oppenheimer–Volkoff equation gives an estimate but since noone managed to observe exactly what happens with matter at the densities found in a neutron star there are still a lot of assumptions.

Re:interesting, but vaguely in line with estimates (2, Interesting)

Anonymous Coward | more than 2 years ago | (#38409196)

Evaporation is an issue for very small black holes, and usually important to question of primordial black holes that have been around since when the early universe could have created them without requiring a star collapse. While a kilogram sized black hole would evaporate on the order of femtoseconds, and even a million kilogram one would be gone in a minute, the evaporation time goes with mass cubed. So by the time you get to a single solar mass, it is 10^67 years to evaporate, as it is radiating at about 10^-28 W. Even if you could squeeze the Earth into a sphere about a centimeter across to get a black hole, it would last for 10^50 years.

Re:interesting, but vaguely in line with estimates (1)

Ruie (30480) | more than 2 years ago | (#38411844)

Replying to myself: it appears that the minimum is related to the Tolman–Oppenheimer–Volkoff limit [wikipedia.org] for the maximum mass of a neutron star, which isn't known to great accuracy. Wikipedia cites a 1996 journal article with an estimate of "approximately 1.5 to 3.0 solar masses".

There is a recent observation of a neutron star with 2.0 solar mass (+/- a small uncertainty).

Re:interesting, but vaguely in line with estimates (2)

Tynin (634655) | more than 2 years ago | (#38408666)

Anyone have a link to a good explanation of the current estimated values for a minimum?

I know you asked for a good link, but here is a wiki article for what it is worth. This part specifically:

http://en.wikipedia.org/wiki/Black_hole#High-energy_collisions [wikipedia.org]

Re:interesting, but vaguely in line with estimates (1)

Hentes (2461350) | more than 2 years ago | (#38408762)

Here is a hard limit. [wikipedia.org]

Re:interesting, but vaguely in line with estimates (4, Informative)

Gaygirlie (1657131) | more than 2 years ago | (#38408866)

I may be wrong as I'm not a physicist, but as I understand it that chandrasekhar limit applies only if a black hole is formed through a star collapsing. If a black hole is formed by some other means then its mass could be something entirely different, including the minimum limit for forming one. As wikipedia so helpfully lists there are two known ways for a black hole to form: gravitational collapse and high-energy collisions. There could be some as-of-yet-unknown means, too.

The more precise answer to the OP's question thus would seem to be: the Planck mass [wikipedia.org]

Re:interesting, but vaguely in line with estimates (2)

Hentes (2461350) | more than 2 years ago | (#38409358)

As wikipedia so helpfully lists there are two known ways for a black hole to form: gravitational collapse and high-energy collisions. There could be some as-of-yet-unknown means, too.

Black hole forming from high-energy collisions is poorly understood, as on that scale both quantum and gravitational effects play a role, and there is no solid quantum gravitational theory. Theoretically, there could be other ways of black hole formation, such as ones that formed in the Big Bang, but those are also areas that we know little about. So yes, in some exotic theories small black holes could exist, but those theories are all unconfirmed.

Also, we are yet to observe a small black hole. Now small black holes are not easy to see, but if the Hawking radiation [wikipedia.org] exists, we should be able to detect the radiation of small black holes.

So I would say that other than some really weird theories there is no proof of black holes forming other means than by star collapses.

Re:interesting, but vaguely in line with estimates (3, Informative)

whoisisis (1225718) | more than 2 years ago | (#38411084)

I am a physicist, although not an astronomer. Indeed, microscopic black holes (less than the earth mass) are speculated to exist. They're called primordial black holes [wikipedia.org] and must be created in the early universe.

They're candidates for the sources of gamma ray bursts.

Re:interesting, but vaguely in line with estimates (0)

Anonymous Coward | more than 2 years ago | (#38413960)

"I may be wrong as I'm not a physicist" Uh, you could be a physicist and still be wrong.

Re:interesting, but vaguely in line with estimates (1)

VortexCortex (1117377) | more than 2 years ago | (#38415492)

"I may be wrong as I'm not a physicist" Uh, you could be a physicist and still be wrong.

Yeah, especially considering that we actually don't have correct laws of physics to work with. We have vague approximations that do us just fine at the macro level for some things, but when it comes to what's really happening, we're no better off than the blokes who coined the term "Atom" and then found it actually IS divisible after all.

TL;DR: If you're a physicist, you're certainly wrong; We just don't know exactly why yet.

Re:interesting, but vaguely in line with estimates (1)

Trepidity (597) | more than 2 years ago | (#38409624)

That's definitely one hard limit, but I believe the open question is whether there are other minimum bounds for a black hole formed through stellar collapse, which may be higher than the Chandrasekhar limit. The Chandrasekhar limit is the maximum size of a white dwarf, but there may be other ways of preventing collapse into a black hole at higher masses; for example, the TOV limit that governs neutron star formation.

Re:interesting, but vaguely in line with estimates (2)

mikael (484) | more than 2 years ago | (#38410560)

There is the Chandrasekhar limit [newworldencyclopedia.org] which defines the maximum size of a White dwarf star .

There is a theoretical maximum limit for a neutron star [nasa.gov] , which seems to be about 3 - 3.2. This also applies to pulsars, which are spinning neutron stars.

There is also an upper limit [sciencedaily.com] to the size that a black hole can become

There is the Schwarzfield radius [radiushttp] which defines the escape limit for the speed of light.

Maybe the maximum size of neutron star is the minimum size of a black hole? Or is there something inbetween?

Re:interesting, but vaguely in line with estimates (1)

retiarius (72746) | more than 2 years ago | (#38415846)

Link desired? I'm not a physicist, but I remember "Schwartzchild radius"
from high school, and, as per usual, Wikipedia fills in the blanks coming
up with closed-form solutions for stellar black holes near 3 solar masses,
to wit:

http://en.wikipedia.org/wiki/Schwarzschild_radius [wikipedia.org]

The biggest black hole (1, Funny)

Hoi Polloi (522990) | more than 2 years ago | (#38408652)

The biggest hole is here at work.

There is no "size" in this universe (0)

Anonymous Coward | more than 2 years ago | (#38408670)

But I am nitpicking...

Re:There is no "size" in this universe (1)

Ruie (30480) | more than 2 years ago | (#38411852)

Planck length.

Re:There is no "size" in this universe (0)

Anonymous Coward | more than 2 years ago | (#38412742)

:O

turns out i was wrong

thanks

Really? (0)

Anonymous Coward | more than 2 years ago | (#38408692)

I thought it was in my wallet.

Re:Really? (1)

TuringCheck (1989202) | more than 2 years ago | (#38412444)

More likely it was sucking money out of your wallet...

Forbes is reporting? (2, Insightful)

Anonymous Coward | more than 2 years ago | (#38408758)

Astronomical errata aren't exactly what people turn to Forbes for. I keep waiting for the punch line... Is it a bank? A country that threatens the stability of the Euro? A cell phone manufacturer that bet its future on WP7?

Re:Forbes is reporting? (2)

maxwell demon (590494) | more than 2 years ago | (#38409276)

Maybe the punch line is that it's too small to have been formed by stellar collapse, and therefore is evidence of a former intelligent alien species who have built an LHC and created a black hole that way, which then ate their star. :-)

Titel not answered (1)

zAPPzAPP (1207370) | more than 2 years ago | (#38408806)

So, how small is it?

Re:Titel not answered (1)

Anonymous Coward | more than 2 years ago | (#38408888)

black hole "radius", or the radius of its event horizon, is related to its mass.
for a non rotating black hole: R=2G*M/c^2
G being newton constant, M the black hole's mass, and c speed of light
if you take M to be three times the mass of the sun, you'll get R=8860 meters

Re:Titel not answered (2)

Surt (22457) | more than 2 years ago | (#38408934)

About 9 km.

Re:Titel not answered (1)

kestasjk (933987) | more than 2 years ago | (#38414814)

18km wide, I dont think GP was talking about the radius.

Re:Titel not answered (1)

Surt (22457) | more than 2 years ago | (#38416562)

Good point. He probably wasn't.

Some of the last science for RXTE (5, Interesting)

Anonymous Coward | more than 2 years ago | (#38408824)

This is the probably the last big science release for Rossi X-ray Timing Explorer (RXTE). RXTE will be turned off at the end of this year and disabled. This is mostly because of NASA budget reductions and reduced prioritization by peer review committees, but also because of its aging on-board systems. The systems were designed for a two year life-time but lasted for more than sixteen! The satellite will probably remain in orbit for quite a few more years - passive - before re-entering the atmosphere. The scientific community will lose the only working X-ray observatory that can measure the fast heartbeats of black holes and neutron star systems, and do complicated monitoring observations.

RXTE has done a lot of great science in the past 16 years, some of it featured [slashdot.org] here [slashdot.org] on Slashdot [slashdot.org] . The legacy will live on though, since the data archive will remain publicly available. Sometimes great science can come from the archive as well!

(speaking for myself only) CM

The proof is right in front of us (0)

Anonymous Coward | more than 2 years ago | (#38408826)

The Orion Group is behind every black hole.

The Orion Group is a Draconian controlled and manipulated regressive extraterrestrial political body that is specifically made up of eighteen different star systems within the Orion constellation.

Prominent members of this consortium are from Beta, Alpha and Gamma Orions -- as well as groups who are from Ursa Minor and Ursa Major, who are strongly associated with it. The races consist of a mixture of reptilians, humans, hybrids and other species.

The collective human minds are manipulated from the Moon, which is actually a spacecraft controlled by the reptilians.

Mandatory post about (-1, Offtopic)

Fuzzums (250400) | more than 2 years ago | (#38408894)

uranus.

Awwww (0)

Anonymous Coward | more than 2 years ago | (#38408930)

How cute! It's just a baby!

nonsense (0)

Anonymous Coward | more than 2 years ago | (#38409086)

That's ridiculous nonsense - I have in my possession the smallest black hole known to men. Possession is 9/10th of the law.

totally incorrect slashdot summary (5, Informative)

bcrowell (177657) | more than 2 years ago | (#38409214)

Here [arxiv.org] is the scientific paper. It makes no claim whatsoever about the mass of IGR J17091-3624. On p. 6, they say:

Figure 5 implies that if IGR J17091-3624 emits at Eddington, then either it harbors the lowest mass black hole known today (< 3Msolar for distances lower than 17 kpc), or, it is very distant. Such a large distance, together with its b ~2.2deg Galactic latitude, would imply a significant, but not necessarily implausible, altitude above the disk

Here [nasa.gov] is the NASA press release summarizing the paper for people who aren't scientists. It quotes the lead author as saying:

Just as the heart rate of a mouse is faster than an elephant's, the heartbeat signals from these black holes scale according to their masses

The Forbes article morphs this into "NASA Satellite May Have Found The Smallest Known Black Hole," and says, "An international team of astronomers utilizing NASA's Rossi X-Ray Timing Explorer (RXTE), believe that they've identified a candidate for the smallest known black hole[...]"

The slashdot summary says:

The black hole itself is only about three times the mass of the Sun[...]

This is completely incorrect. It's a candidate for a very low mass black hole. What that means is that they're suggesting that astronomers do follow-up observations on this object and actually determine its mass, which may be unusually low.

It is of very great interest to relativists and astronomers to find the smallest black holes. There is a limit called the Tolman-Oppenheimer-Volkoff limit on the largest mass that a neutron star can have. There are big theoretical uncertainties in this number, but it is probably around three solar masses. However, we don't know for sure whether anything too massive to be a stable neutron star necessarily becomes a black hole. There have been all kinds of goofy objects hypothesized by theorists that might be intermediate between neutron stars and black holes, including black stars, gravastars, fuzzballs, quark stars, boson stars, and electroweak stars. Observing a low-mass black hole narrows the gap in mass between the heaviest stable neutron star and the lightest black hole, leaving less wiggle room to believe in these exotic objects.

Even smaller black hole (2)

Wowsers (1151731) | more than 2 years ago | (#38409538)

I beg to differ with the scientists, I've found an even smaller black hole, my girlfriend's purse!

Re:Even smaller black hole (0)

Anonymous Coward | more than 2 years ago | (#38410382)

"Purse"? That's what you call it? Does she like that?

I thought black holes got smaller (0)

Anonymous Coward | more than 2 years ago | (#38410196)

I thought black holes got smaller as they gained more mass because all that gravity pulls everything ever closer together. Have I been wrong all this time?

Thats not a natural black hole... (0)

Anonymous Coward | more than 2 years ago | (#38411042)

It was made with red matter.

Stephen Hawking Says... (0)

Bob Gortician (246811) | more than 2 years ago | (#38411204)

In response to "What would happen if a small black hole struck the earth", Mr. Hawking says it would pass through it, bounce back and forth until it came to rest in the center of the planet, and would put out light and heat...

Neato.

Inverted sig alert
http://thepiratebay.org/torrent/6848623/Perfect_Me_By_Jason_Z._Christie [thepiratebay.org]

I put Kate Bush in space (1)

nessus42 (230320) | more than 2 years ago | (#38412094)

I know this is neither here nor there, but I was a software engineer for RXTE and I snuck Kate Bush lyrics into an unused part of one of the ROMs.

|>ouglas

P.S. Peek-a-boo, little Earth.

Wow... only 3 times the mass of the Sun.... (0)

Anonymous Coward | more than 2 years ago | (#38412350)

You mean they actually managed to find a black hole smaller than your mom?

Correction.. (1)

Kongzilla (892890) | more than 2 years ago | (#38423982)

It's just grit.
Check for New Comments
Slashdot Login

Need an Account?

Forgot your password?