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Black Holes...Pink?
st. augustine writes "Australian astronomers have discovered that some black holes are actually pink. Here's a Wired article, and here's the Australians themselves. I was more excited before I found out they were already expecting the black holes to be blue. "
No, it's not Hawking radiation (as I tried to point out in the earlier "Clarifications" comment). Hawking radiation just wouldn't be intense enough, it gets weaker for larger bodies (like huge quasars). It wouldn't be pink either, but some pure blackbody temperature.
I dread the posting of items astronomical on Slashdot. The (*attempting to be judicious*) ignorance and jeering, peasant-like-tone, calls to question and account the elder statement that hackers match in their interests the pursuit of *science fiction*, an integral aspect of which is astronomy or at the least, astrophysics. But the queries here encoded? Abominable! I hail my fellow Anonymous Cowards (Scores 5 and 4) who anticipated the spate of questions and answered them.
All here, 't'would seem, hail Star Trek and Star Wars... but sit in discussing actual phenomena and knowledge of even our own mere star system like ignorant old European men discussing some 19th century war!
To answer a pair of (almost unasked) queries -
The speed of light is c. 299,792.4562 km/s. Rounding to 3EX is useful for rough estimates, but when one wishes to assess the highly dependent values such as the distance to a given Cepheid variable, such rounding *would not* occur!
How long, then, is a light year? This, too, may depend on the astronomer's hewing to his or her art. The civil year is measured as being 365.0 days of 24 hours - but the sidereal year (the actual momentum of the planet) measures as 365.26 rotations, each 23 hours, 56 minutes, 4 seconds in length. Multiply the value of C by the sidereal to determine a light year, if you wish.
A parsec is 3.2616 light years in length... it derives from the measure of parallax on the dome of the sky, helping to measure proper motion and the like. Barnard's Star, a dim red dwarf, was discovered and made known as remarkable for it's proper motion, greatest of any star! It is only 5.2 light years distant. Doubtless many such red dwarfs arc nearby in this our section of the galactic disk, hidden by their radiative obscurity.
I despair for our culture. We seem to be regressing toward the primitive expansion of old human memes within a terrestrially advanced framework rather than rising to the sublime. But, what may I expect? Observe those men who walked on Luna and saw the glories of our world in the 1960s - they could hardly be named pioneers or visionaries, or revolutionaries! Only one of them was a scientist (the geologist of Apollo 17). John Glenn, *snort* - a politician, and most actually believe that he walked the Lunar regolith. We are surrounded by our wondrous networking technology (and yet arguing over ludicrous obvious issues such as whether our operating systems should be open engineering works), but how many of you feel that the future the old stories promised has come? Belter cultures, Lunar cities, Martian wars of independence? How prefer you instead, "Congress would like to pass the US Space Shuttle to business and fly it until the 2020s"?
As I posted this, I was notified that the International Space Station was passing overhead. Due to my presence in the city and it's low altitude, I was unable to see it on this pass. But I observe it when I may! A strange sight, to see that star-like object moving through the sky so quickly, still stranger to *know what it is*... but how many of you look up even to the few works our hands have acheived?
Posted by AnnoyingMouseCoward:
Essentially, I have to agree with the general point of your posting. People these days spend too much time reading Sci-Fi and not enough time actually reading about science.
Sci-Fi is not about science, it's about our own terrestrial obsessions projected onto a bunch of aliens.
As a point in case, just consider the amount of Sci-Fi which is set here in the solar-system versus the amount which is set on *habitable* planets around other stars.
Having discovered that there are no easy frontiers here in our own backyard, we ignore the possibilities and look elsewhere, in spite of the enourmous resources in terms of material and energy that we could tap.
In short, most Sci-Fi looks at the past. It's an attempt to re-enact the process of European colonialism on a larger scale. Because of that, few people are interested in anything that isn't a habitable planet.
Still, things are gradually changing. The terra-forming of Mars is gradually coming into the conceptual realm of the general public and it may simply be a matter of time before we re-adjust our perspective away from terrestrial obsessions. Unfortunatly for me, it's not likely to be during my lifetime though.
It's not offensive or anything, it's just humour
Maybe I don't get it....
---
"Hasta la victoria siempre!" El Comandante
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"Hasta la victoria siempre!" El Comandante
To my knowledge, relativity and qm have not been merged, that is the whole point of all the work that has been done on grand unified theories (guts).
You wouldn't happen to be from Fresno would you? People from Fresno might be able to confirm your theory. (Now that's an obscure reference, anyone get it? ;)
Shop Smart, Shop S-mart!
The same precise conversion is done in measuring all their distances.
-- perl -e'print pack"H*","6e656d6f406d38792e6f7267"'
Then I wanted to sneak those two zeros in there.
oops.
thanks.
-- perl -e'print pack"H*","6e656d6f406d38792e6f7267"'
I thought at first, oh, they're just using a British billion (a million million) but that would have put them off by a factor of 10.
Good question, and even more interesting that the same calculation is repeated in all their distance measurements.
-- perl -e'print pack"H*","6e656d6f406d38792e6f7267"'
Hmm, yes, it's only a theory, probably the best but have they had any major breakthroughs with the observational data in the last few years?
I'm just interested to know.
I'm out of my tree just now but please feel free to leave a banana.
Why do they assume that quasars and black holes are one and the same thing? I know there are theories about the "power source" of quasars being not larger than a certain size because their luminosity varies with a certain period, so the speed of light limits the size etc.
In the last few years, what new findings have their been?
I'm out of my tree just now but please feel free to leave a banana.
Yes, and in Disney, mice can talk.
;-)
I'm out of my tree just now but please feel free to leave a banana.
When I said about and approximate, I mean +/- a much smaller delta than a factor of three. eg. The speed of light in a vacuum is 3e8 m/s +/- 1e7 m/s (a far cry from saying its between 1e8 and 1e9). Same for the 9.5e15 (+/- 1e14). It's called significant figures.
The issue is that they used the exact same (incorrect) conversion for each place that they mentioned a light-year to kilometer conversion.
Now, on the other hand, if I were approximating with logarithms, and took an exponent (either that, or I looked at a slide rule with a severe astigmatism), I could expect a factor of 3 error very easily, because that's a linear error of only 0.5 in the log10 domain.
--Joe--
Program Intellivision!
When I took all of my science courses, I was taught that 1 light-year == the distance light travels in one year in a vacuum. In the article, they mention the following:
In other words, one billion light-years is 3e25 meters. Interpreting one billion as 1e9, this implies that one light year is 3e16 meters.
Now, if I recall correctly, the speed of light in a vacuum is approximately 3e8 meters/second. There are approximately 3.16e7 seconds in a year (365.24 * 24 * 60 * 60). Multiplying these together gives me a light-year of about 9.5e15.
So, is it just me, or are their light-years off by about a factor of 3?
--Joe--
Program Intellivision!
This was my thought.
If the black hole is sucking in gas towards the viewer, it will appear to be blue (shorter wave length)
If the direction of suck is away from the viewer, it ought to appear red (longer wave length).
And if the acretion disk were viewed edge-on, one would see both red- and blue- shifted light.
I'm no high-energy astrophysicist, but doesn't this explanation make sense?
Glad to be of service! Share and enjoy!
-- Some things are to be believed, though not susceptible to rational proof.
So is the "pinkness" the result of Hawking Radiation from the black holes? Steven Hawking (did I spell his name right?) predicted many years ago that black holes emmitted radiation - kind of combining gravatation theory with the Heisenberg Uncertainty Principle.
I recall seeing a TV program in England about 1982/3 where Hawking said that if they ever actually found his radiation, he would get a Nobel Prize.
Well, I am sure that these Australians would have thought of this (since Hawking Radiation is rather well known) and maybe it just isn't in the right frequency range.
(P.S. that TV show had a 1 second shot of me crossing the street - I just happened to be in front of the camera when they were filming Trinity Street in Cambridge.)
Denser clouds would heat more by friction, pushing it from red-hot to yellow-hot to blue-hot. . .or would it ???
As far as a doppler effect due to rotation, no. The effects of a receding edge would effectively be countered by the approaching edge. . .
I agree, but wouldn't much of the material being drawn toward the observer be located on the oposite side of the event horizon so as to be out of sight. It seams the net affect would be more of the visable acretion disk would be red shifted. Another question: Is the relative velocity of the acreting material with respect to the object great enough to be significant when compared to the expansion of the universe?
Sorry, I should do some research, I'm not much of an astronomer yet...
oh sh-- just wait untill the rev jerry falwell hears about this...
Point and Grunt
Could the light be redshifted? Perhaps one side is orbiting away from us so fast it is redshifted to pink? But then you'd expect the opposite side to be blueshifted...is the telescope resolution high enough to see that?
I still say we go with the Red Dwarf idea.
Find 100 perfect suns in the right combination, make them all go nova, so all around the universe everybody can read....
Enjoy Coke.
And now after that happens the big novad stars will be a cute pink. What a beautiful universe.
It's turtles all the way down.
For someone who acts so holier-than-thou, you should at least get your facts right.
The year that we measure on the planet is 365.24 days (hence the leap year every 4 years). A sidreal year is actually 366.24 years . . .
Just thought you might want to know. . .
I couldn't tell if you were experimenting with poor-man's cryogenics or looking for the orange sherbet.
How is it possible that the velocity of the jets exceeds c? It should never exceed c from _any_ reference frame.
I couldn't tell if you were experimenting with poor-man's cryogenics or looking for the orange sherbet.
It's not the velocity of the jet that exceeds c. It's the velocity of the spot illuminated by the jet. Things like that are called superluminal sources because they _appear_ to go faster than light. Imagine you shining a flashlight on a wall. If you turn the flashlight fast enough, the spot on the wall will move faster than the speed of light even though the flashlight isn't. There are superluminal sources in the earth's atmosphere during thunderstorms (caused by an em pulse from lightning propagating upward from the cloud).
Pink holes
When seeking information on the Internet about important new developments in astrophysics, using the search term "pink holes" will probably not give you completely satisfactory results with most search engines, even though the hit count may be large.
These objects are distant quasars. The quasar population was largest when the universe was around a third of its present size (a redshift of 2) and about a fifth (specifically, one 3*sqrt(3)th) of its current age. At this distance, which is around ten billion light years, the resolution of ground-based telescopes is around five thousand light years (this is a limit set by the Earth's atmosphere). So we know that the whole galactic nucleus of the host galaxy, as viewed by us, is "pink". A quasar should dominate the light output from this region- and the light is emitted from a region a few light-days across. This is known because quasars vary in brightness on timescales of weeks.
When astronomers refer to colors, typically "red" or in this case "pink" refers to emission of larger amounts of light at long wavelengths at short ones. Given the telescopes used, I would guess that they were observing in the "optical" band, which is from around 350 nm (near UV) to around 800 nm (infrared). These would be emitted by the quasar as UV and would lengthen into this band in the observer frame. At redshift 2, these would be emitted at 117 to 267 nm. So, a better headline would be "black holes found to emit more near-UV than far-UV". Of course, this wouldn't be very striking.
The accepted mechanism for quasar action is that matter falls toward a black hole, collides with other matter, and emits radiation. In fact, there is an equilibrium where the matter falling in produces enough radiation that radiation pressure keeps more matter from falling in. This process should be very hot and so should produce light that is "blue" even in the far UV region.
There are, however, some additional details of the procedure. Some quasars have what are called "jets" of ejected material. We know these are extremely fast because the apparent velocity across the line of sight exceeds the speed of light in many cases. This is allowed by relativity if the jet moves at a speed near the speed of light pointing directly at us. The jet phenomenon is believed to be connected with a preferred axis of rotation for the material falling into the black hole, and with "synchrotron radiation" emitted by charged particles accelerated by the black hole's gravity. The report seems to suggest that the "pink" light is connected with the jet phenomenon, perhaps in cases where the jet is pointed directly at us.