APOD: Heavy Black Hole Jets in 4U1630 47 (2013 Nov 20)

[APOD Robot]

Heavy Black Hole Jets in 4U1630 47

Explanation: What are black hole jets made of? Many black holes in stellar systems are surely surrounded by disks of gas and plasma gravitationally pulled from a close binary star companion. Some of this material, after approaching the black hole, ends up being expelled from the star system in powerful jets emanating from the poles of the spinning black hole. Recent evidence indicates that these jets are composed not only electrons and protons, but also the nuclei of heavy elements such as iron and nickel. The discovery was made in system 4U1630-47 using CSIRO's Compact Array of radio telescopes in eastern Australia, and the European Space Agency's Earth-orbiting XMM-Newton satellite. The 4U1630-47 star system is depicted above in an artist's illustration, with a large blue star on the right and jets emanating from a black hole in the center of the accretion disc on the left. Although the 4U1630-47 star system is thought to contain only a small black hole -- a few times the mass of our Sun -- the implications of the results may be larger: that black holes of larger sizes might also be emitting jets of massive nuclei into the cosmos.

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[Wes D]

Let me get this strait, the gravity of a black hole is so strong that nothing can escape it, not even light, so how is material getting expelled from around there?

[Nitpicker]

Obtaining first evidence of the emission of massive atomic nuclei from "X-ray binary black hole jets" is impressive.

I found reference to the 4U1630-47 star system in the SIMBAD database, as being in Norma, near Ara, very close to the Galactic Plane. Any idea on its distance from us?

More importantly, what might be the significance of the possibility "that black holes of larger sizes might also be emitting jets of massive nuclei into the cosmos"?

[Nitpicker]

Let me get this strait, the gravity of a black hole is so strong that nothing can escape it, not even light, so how is material getting expelled from around there?

Pretty sure the jet material never makes it past the event horizon of the black hole. It must be ejected beforehand.

[Ann]

Chris Peterson wrote, in another thread:

The history of any given particle around a black hole depends on how it interacts with other particles. Material will either be in an open or closed orbit until it becomes dense enough to lose energy through momentum transfer processes (such as collisions). Material that loses enough energy will fall into the black hole. Material that gains energy (as jet material does) will be ejected from the system before reaching the event horizon.

See http://asterisk.apod.com/viewtopic.php?p=214132#p214132.

Ann

[owlice]

The resident 20-year-old would like to know the following: why is material ejected along the polar axes rather than in any direction, for example, in the (basic) plane of the accretion disk, and is the accretion disk always perpendicular to axis of rotation of the black hole?

[Markus Schwarz]

They take in 3d material, and convert it to dark energy and dark matter, that is the reason for universe expansion.

If initial condition are right, matter can fall into the black hole. But then it will never come out of it. Or matter can circulate around the black hole, just as the Earth orbits the Sun. In case of accretion discs and jets, matter can be expelled from the accretion disc (not the black hole!). This has nothing to do with dark matter or energy. While dark energy is associated with the expansion of the universe, it has nothing to with black holes, nor is it created by them.

[Boomer12k]

Nature's way of spreading Star Seeds??? As well as the Impending Type 1A Supernova??? Assuming there is a companion dwarf drawing that off....

The Universe never stops amazing me....

:---[===]*

[BDanielMayfield]

I’m happy to see that this important finding has been selected as today’s APOD. I first became aware of it after reading an article about this story on Sky and Telescope’s site. See: http://www.skyandtelescope.com/news/Bla ... 48421.html

It is IMO an amazing and important discovery that the jets of ordinary, stellar massed black holes can contain heavy nuclei like iron and nickel. Since the jet is observed to contain these elements wouldn’t it follow that all lighter elements should be there too?

Fe and Ni are normally produced deep inside massive stars just before and as they go supernova. Where were these observed metals produced? Most were probably created by the massive star who’s core became this black hole as the star exploded. It’s close binary companion would then have had taken a close range blast and received a heavy metal injection. Now, some of these metals in the outer surface of the companion star are spilling out of the star’s Roche lobe and are falling back toward the BH.

Or, is it possible that fusion reactions even up to Fe and Ni could be happening in the accretion disk too? Do conditions in BH accretion disks get extreme enough for fusion to be taking place there too? What temperature extremes can be reached by accretion disk matter?

[neufer]

The resident 20-year-old would like to know the following: why is material ejected along the polar axes rather than in any direction, for example, in the (basic) plane of the accretion disk, and is the accretion disk always perpendicular to axis of rotation of the black hole?

It's all extremely hot ionized plasma just outside the event horizon.

The conducting plasma is confined by a tight spiral of strong magnetic field around the equator.

However the plasma is corkscrewed out the poles by rapidly rotating magnetic helices.

[neufer]

Nature's way of spreading Star Seeds??? As well as the Impending Type 1A Supernova???
Assuming there is a companion dwarf drawing that off....

:---[===]*

<<A frugivore is any type of herbivore or omnivore where fruit is a preferred food type. Because approximately 20% of all mammalian herbivores also eat fruit, frugivory is considered to be common among mammals. Since frugivores eat large volumes of fruit they are highly dependent on the abundance and nutritional composition of fruits. Frugivores can either benefit fruit-producing plants by dispersing seeds, or they can negatively affect plants by digesting seeds along with the fruits. When both the fruit-producing plant and the frugivore species benefit by fruit-eating behavior their interaction is called a mutualism.

Seed dispersal is important for plants because it allows their progeny to move away from their parents in space and time. The advantages of seed dispersal may have led to the evolution of fleshy fruits, which entice animals to eat the fruits and move the plants seeds from place to place. While many fruit producing plant species would not disperse far without frugivores, they can usually germinate even if they fall to the ground directly below the parent plant.

Many types of animals are seed dispersers. Mammal and bird species represent the majority of seed dispersing species. However, frugivorous tortoises, lizards, amphibians and even fish also disperse seeds. While frugivores and fruit-producing plant species are worldwide, there is some evidence that tropical forests have more frugivore seed dispersers than the temperate zone.

There are a number of fruit characteristics that seem to be adaptive characteristics to attract frugivores. Many animal-dispersed fruits advertise their palatability to animals with bright colors and attractive smells (mimetic fruits). Fruit pulp is generally rich in water and carbohydrates and low in protein and lipids. However, the exact nutritional composition of fruits varies widely. The seeds of animal-dispersed fruits are often adapted to survive digestion by frugivores. For example, seeds can become more permeable to water after passage through an animal’s gut. This leads to higher germination rates. Some mistletoe seeds even germinate inside the disperser’s intestine.

In order for frugivores to be good seed dispersers they must digest fruits without consuming a high proportion of the seeds. Many seed-dispersing animals have specialized digestive systems to process fruits which leave seeds intact. Some bird species have shorter intestines to rapidly pass seeds from fruits, while some frugivorous bat species have longer intestines. Some seed-dispersing frugivores have short gut-retention times and others can alter intestinal enzyme composition when eating different types of fruits.>>

[Tara_Li]

Unless this star is very unusual, it is going to contain heavy metals, up to and including iron - and probably even a bit beyond. Iron contained in the star material gets drawn off into the accretion disk, spirals in and gets ejected in the disk...

Who honestly *DIDN'T* expect to see iron & nickel in the jets? I have no clue of the densities and energies at the inner edge of the accretion disk, so I don't have any way of knowing if iron & such might be forged there, but seriously - the star has it, the jet is made from material drawn from the star, so of course the jet is going to have it!

Detection is neat, but really not unexpected.

[geckzilla]

I was under the impression that the reason it's unexpected is because the jets move at such speeds that the heavier stuff wouldn't be in them since it takes that much more energy to accelerate a heavier object.

[Chris Peterson]

Unless this star is very unusual, it is going to contain heavy metals, up to and including iron - and probably even a bit beyond. Iron contained in the star material gets drawn off into the accretion disk, spirals in and gets ejected in the disk...

Who honestly *DIDN'T* expect to see iron & nickel in the jets?

Well, given what was known about jets, there was no particular reason to expect this. All that was known about the jet mechanism is that it produced a stream of electrons, positrons, and possibly low mass nuclei. With the detection of more massive nuclei, our understanding of the physical processes underlying jet formation is expanded.

Depending on the models used to describe jets, they may or may not eject all types of material found in the accretion disc (which does, of course, include heavy elements). That's why this observation is important, and if not terribly surprising, neither at all certain.

[neufer]

[b][color=#0000FF]The onion-like layers of a massive, evolved star just before core collapse.[/color][/b]

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Unless this star is very unusual, it is going to contain heavy metals, up to and including iron - and probably even a bit beyond. Iron contained in the star material gets drawn off into the accretion disk, spirals in and gets ejected in the disk... Who honestly *DIDN'T* expect to see iron & nickel in the jets?

I was under the impression that the reason it's unexpected is because the jets move at such speeds that the heavier stuff wouldn't be in them since it takes that much more energy to accelerate a heavier object.

Being heavy, the iron would mostly reside deep within the scavenged star and, hence, not be readily available in the material drawn off into the black hole accretion disk.

[JohnD]

Pretty unlikely, I know, but what if the axis of rotation of the star and the BH were at right angles, with one BH pole pointing INTO the star?
What if the iron originates in the BH's accretion disc, from lighter elements extracted from the star's outer layers? Then the jet would recirculate the iron back into the star, increasing the amount of iron in the core and accelerating the star's degenaration towards nova. Early novas.

What if.....

John

[BDanielMayfield]

Being heavy, the iron would mostly reside deep within the scavenged star and, hence, not be readily available in the material drawn off into the black hole accretion disk.

True, but if your next door neighbor has recently (astronomically speaking) went SN there could still be all kinds of metals mixed throughout the companion star.

But neufer's point does bring into play the idea that some fusion is taking place in the disk.

Bruce

[Case]

... what if the axis of rotation of the star and the BH were at right angles, with one BH pole pointing INTO the star

Interesting thought. Most artist impressions of a black hole in a binary system show the accretion disc in the same orientation with regard to the companion star. I can't think of a good reason why it always has to be like that, unless the orbits somehow align the rotation of the individual bodies over time. If the rotation axis can be different, then I suppose it wouldn't be impossible for the jet to point to the companion. And such might be cause for some weird fireworks!

[Chris Peterson]

Interesting thought. Most artist impressions of a black hole in a binary system show the accretion disc in the same orientation with regard to the companion star. I can't think of a good reason why it always has to be like that, unless the orbits somehow align the rotation of the individual bodies over time. If the rotation axis can be different, then I suppose it wouldn't be impossible for the jet to point to the companion. And such might be cause for some weird fireworks!

I'm not sure it's possible to have a close binary star system where the stars have significantly different rotation axes. But in a system where one star is losing material to the other, they would be so close that tidal forces would rapidly orient their spin axes.

[JohnD]

Thanks, Chris!
Real life, real physics and real astronomy tend to quench the wilder ideas!
John

[Cousin Ricky]

I’m going to play Ann today. I have a few color questions.

I haven’t seen very many detailed paintings of blue stars, but on those that I have seen, the stellar prominences (and chromospheres, for that matter) are depicted in blue. Don’t prominences get their color from H-alpha emissions? Wouldn’t they be red regardless of the star’s temperature? (I would also imagine that the photosphere is so bright that the prominences would hardly be visible by comparison, but I’m more than willing to grant artistic license on that.)

Do blue giants show limb-darkening?

How hot is an accretion disc, and how fast does the temperature go up the nearer to the event horizon? The one depicted here goes from red hot to white hot, but if these things emit x-rays, I would think that they would appear blue towards the center. Would the red shift caused by the gravity well sufficiently counteract the wavelengths of the thermal emissions to keep them from appearing blue?

What color would the gas outside the photosphere be? Would it cool off as it approaches the accretion disc? Does it reflect the light from the star and the accretion disc? Would it be the same pearly white color as the Sun’s corona? (And why does the Sun’s corona glow white when it is x-ray hot?)

[Just_Jackson]

In the artist's depiction, what is the bright spot where the streamer from the star joins the accretion disc?

[MarkBour]

Pretty unlikely, I know, but what if the axis of rotation of the star and the BH were at right angles, with one BH pole pointing INTO the star?
What if the iron originates in the BH's accretion disc, from lighter elements extracted from the star's outer layers? Then the jet would recirculate the iron back into the star, increasing the amount of iron in the core and accelerating the star's degenaration towards nova. Early novas.

What if.....

John

I'm a newb, so correct me if I'm wrong. The mechanism I'm thinking created this scenario is that the BH is pulling in material from the companion star. This material would define and dominate the angular momentum with respect to the BH, and so the BH would definitely rotate around an axis perpendicular to the line between the companion star and the BH.

Actually, here's a question related to JohnD's that I cannot answer. When looking at jets from BH's we are really talking about material that never entered the BH. So, the jets are really pointed in a direction dependent on the angular momentum of the matter that swirls around but never enters a BH. But does this also determine or influence the angular momentum of material inside the BH as well? Or can it possibly occur that the angular momentum of the BH is independent of and quite different from the angular momentum in the accretion disk?

[Chris Peterson]

I haven’t seen very many detailed paintings of blue stars, but on those that I have seen, the stellar prominences (and chromospheres, for that matter) are depicted in blue. Don’t prominences get their color from H-alpha emissions? Wouldn’t they be red regardless of the star’s temperature?

The color of a prominence depends on the atoms that are ionized. Prominences aren't really red... reddish would be a better description, since Ha is only one of the emission lines. Still, a several solar mass blue star has a hydrogen envelope, so it's prominences should be substantially similar in color to what we see on the Sun.

Do blue giants show limb-darkening?

I can't think of any reason they wouldn't. But keep in mind that limb darkening is essentially a continuum phenomenon. In narrow spectral bands, it may not be present, or you can even get limb brightening. And this artistic representation pretty clearly shows the blue star as it would appear in some narrow band, not white light.

How hot is an accretion disc, and how fast does the temperature go up the nearer to the event horizon? The one depicted here goes from red hot to white hot, but if these things emit x-rays, I would think that they would appear blue towards the center.

The maximum temperature for an accretion disc around a small black hole is around 10⁷ K. This occurs near the inside, but not completely so. That will appear bluish-white to the eye, although the peak output will be well into the gamma rays. The temperature is approximately proportional to r^-3/4 over most of the radius, so the temperature rise from outside to inside will be gradual. But it will rapidly appear white. I'd expect the disk to have a very narrow outer band going from red to orange to yellow, then the rest essentially white or blue-white.

Would the red shift caused by the gravity well sufficiently counteract the wavelengths of the thermal emissions to keep them from appearing blue?

I don't think it would have any visible impact.

What color would the gas outside the photosphere be? Would it cool off as it approaches the accretion disc? Does it reflect the light from the star and the accretion disc? Would it be the same pearly white color as the Sun’s corona? (And why does the Sun’s corona glow white when it is x-ray hot?)

Good question. I'd guess it might be similar to the corona- very hot but very tenuous, so not very bright.

[ta152h0]

boy, this APOD is just begging for the inevitable question about gold atoms or wait for the W26 APOD.