APOD: HD 163296: Jet from a Star in Formation (2021 Jun 22)

[APOD Robot]

HD 163296: Jet from a Star in Formation

Explanation: How are jets created during star formation? No one is sure, although recent images of the young star system HD 163296 are quite illuminating. The central star in the featured image is still forming but seen already surrounded by a rotating disk and an outward moving jet. The disk is shown in radio waves taken by the Atacama Large Millimeter Array (ALMA) in Chile, and show gaps likely created by the gravity of very-young planets. The jet, shown in visible light taken by the Very Large Telescope (VLT, also in Chile), expels fast-moving gas -- mostly hydrogen -- from the disk center. The system spans hundreds of times the Earth-Sun distance (au). Details of these new observations are being interpreted to bolster conjectures that the jets are generated and shaped, at least in part, by magnetic fields in the rotating disk. Future observations of HD 163296 and other similar star-forming systems may help fill in details.

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[TerribleTadpole]

Does this picture in any way support my view that solar systems in their early stages consist of multiple competing protoplanetary bodies interacting until eventually one body reaches sufficient mass to dominate the system? In my model direct collisions would be rare as the early bodies would be relatively diffuse, so interactions would be likely to result in the transfer of material from smaller to larger bodies and the possible disruption of smaller bodies if the interaction is sufficiently intense. The dominant body would heat under gravitational compression and radioactive decay until the rotating molten core would start to produce a magnetic field. Then, much later, when the dominant body reaches critical mass and hydrogen fusion begins the resulting explosion would expel much of the remaining unaggregated material from the inner system and would also strip away the loosely bound outer parts of the inner bodies to leave only relatively rocky cores.

This seems much more realistic than the more common view I see described in general documentaries; where the star forms first followed by the planets. That model seems to have great difficulty describing a credible process by which the inner planets in particular end up consisting primarily of mantle or core material (e.g. Mercury), or how there could possibly be sufficient material remaining to form the planets.

I ask this because the picture appears to show a stellar system in its very earliest stages of formation, before the dominant body has even begun hydrogen fusion, and yet there are orbital zones that may have already been cleared by planetary bodies.

Comments, corrections, and directions to resources would be most welcome!

[shaileshs]

3 questions top of my head -

1) Why multiple disks ? Can there be 1, 2, many ? How many and depends on what ?
2) Why opposite side of jet is disjoint (floating) as if it has no connection with source (jet coming towards us seems more uniform comparitively)
3) Any idea if plane of disks is deterministic (say compared to plane of solar system or plane of galaxy etc) ? Or is completely random (un-deterministic, unpredictable) ?

Thanks in advance for all comments/thoughts/answers.

[JohnD]

Tadpole,
The gas giants of the Solar System may have developed much closer to the Sun than they are now, and we have evidence of extra solar gas giants that orbit as close, or closer, to their suns than the Earth. Some event caused the rearrangement of Solar orbits that we see today, so there is no need for an explosive explanation for 'rocky planets in, gas giants out' arrangement.

That re-arrangment involved changing the orbits of planets, in a way similar to your "multiple competing protoplanetary bodies" theory, but with an already active Sun that has a mass a thousand times more than its largest planet. So I fear it isn't evidence for your theory.

shaileshs,
There's one disc there. It has gaps, that like Saturn's rings which are associated with moons, may be associated with planets. "Deterministic" implies a conscious choice of the disc plane, which I would dispute, and instead say that physics and conservation of momentum force a spinning ball of dust and gas to flatten into a disc, that is perpendicular to its axis.
JOhn

[De58te]

3 questions top of my head -

1) Why multiple disks ? Can there be 1, 2, many ? How many and depends on what ?
2) Why opposite side of jet is disjoint (floating) as if it has no connection with source (jet coming towards us seems more uniform comparitively)
3) Any idea if plane of disks is deterministic (say compared to plane of solar system or plane of galaxy etc) ? Or is completely random (un-deterministic, unpredictable) ?

Thanks in advance for all comments/thoughts/answers.

Number 2) This may be my unscientific theory, but the disc is taken by radio waves by ALMA, and the jet by visible light from VLT. That means that some technician had to combine the two images in some photo lab. Perhaps the disc should be placed further back. In addition since that is a star forming region how do we know there is behind there in the gap some dense dark cloud that hasn't begun to form yet and isn't emitting any radio waves, yet is dark enough to block the visible light heading in our direction?

[orin stepanek]

The jets are so confusing; that even kitty cant figure them out!

The empty spots in the discs are very tell tail as to where planets
may be forming! interesting to catch this in process!

[Dee Phlat]

Is this jet the same as a Herbig-Haro object?

[Chris Peterson]

3 questions top of my head -

1) Why multiple disks ? Can there be 1, 2, many ? How many and depends on what ?
2) Why opposite side of jet is disjoint (floating) as if it has no connection with source (jet coming towards us seems more uniform comparitively)
3) Any idea if plane of disks is deterministic (say compared to plane of solar system or plane of galaxy etc) ? Or is completely random (un-deterministic, unpredictable) ?

Thanks in advance for all comments/thoughts/answers.

Number 2) This may be my unscientific theory, but the disc is taken by radio waves by ALMA, and the jet by visible light from VLT. That means that some technician had to combine the two images in some photo lab. Perhaps the disc should be placed further back. In addition since that is a star forming region how do we know there is behind there in the gap some dense dark cloud that hasn't begun to form yet and isn't emitting any radio waves, yet is dark enough to block the visible light heading in our direction?

Astrometric techniques for both optical and radio data are good enough to know the position of data at subarcsecond scales, which is much, much smaller than the size of the objects here. There is no possibility of their being out of alignment.

[JohnD]

Further, in answer to Shaleshs, stellar jets may be intermittent, and/or assymmetric.
See the Wiki entry: https://en.wikipedia.org/wiki/Astrophys ... 87_jet.jpg
And this Hubble pic: http://www.eg.bucknell.edu/~mead/HomePa ... Disk3.html

John

[bystander]

Is this jet the same as a Herbig-Haro object?

Herbig-Haro objects are shock waves formed when the high energy jets collide with the interstellar medium.

[neufer]

Is this jet the same as a Herbig-Haro object?

Herbig-Haro objects are shock waves formed when the high energy jets collide with the interstellar medium.

Herbig–Haro (HH) objects are bright patches of nebulosity associated with shock waves formed when protostar high energy polar jets collide with the very cloud of gas and dust from which protostars form. Sometimes the HHs are hidden from view at optical wavelengths by that same cloud of gas & dust.

HH objects are formed when accreted material is ejected by a protostar as ionized gas along the star's axis of rotation

---

<<Herbig–Haro (HH) objects are bright patches of nebulosity associated with newborn stars. They are formed when narrow jets of partially ionised gas ejected by stars collide with nearby clouds of gas and dust at several hundred kilometres per second.

HH objects associated with very young stars or very massive protostars are often hidden from view at optical wavelengths by the cloud of gas and dust from which they form. The intervening material can diminish the visual magnitude by factors of tens or even hundreds at optical wavelengths. Such deeply embedded objects can only be observed at infrared or radio wavelengths, usually in the frequencies of hot molecular hydrogen or warm carbon monoxide emission. In recent years, infrared images have revealed dozens of examples of "infrared HH objects". Most look like bow waves (similar to the waves at the head of a ship), and so are usually referred to as molecular "bow shocks". The physics of infrared bow shocks can be understood in much the same way as that of HH objects, since these objects are essentially the same – supersonic shocks driven by collimated jets from the opposite poles of a protostar. It is only the conditions in the jet and surrounding cloud that are different, causing infrared emission from molecules rather than optical emission from atoms and ions. In 2009 the acronym "MHO", for Molecular Hydrogen emission-line Object, was approved for such objects, detected in near infrared, by the International Astronomical Union Working Group on Designations, and has been entered into their on-line Reference Dictionary of Nomenclature of Celestial Objects. The MHO catalog contains over 2000 objects.>>

[VictorBorun]

Sagittarius, right?
I took coordinates 17 56 21.26 -21 57 21.6 from here
and entered them here

[VictorBorun]

The jets are magnetic pigtails, right?
Starting as many centrifugal-forced jets from the hotter inner part of accretion disk where magnetic lines (forming a thorus around circular electric current) are at 30° to the axis.
And then the matter of many little jets stretch the magnetic lines until they wind into a pigtail, a hollow cylinder around the axis.

And we are closing on that pair of pigtails, both observingly and model-tuningly

[johnnydeep]

Sagittarius, right?
I took coordinates 17 56 21.26 -21 57 21.6 from here
and entered them here

Apparently. Those coordinates match the ones in Simbad: http://simbad.u-strasbg.fr/simbad/sim-i ... #lab_basic

Using the Aladin Lite viewer, and zooming, out you might be able to identify nearby stars. I myself cannot.

HD 163296 And Vicinity

[neufer]

---

The jets are magnetic pigtails, right? Starting as many centrifugal-forced jets from the hotter inner part of accretion disk where magnetic lines (forming a thorus around circular electric current) are at 30° to the axis. And then the matter of many little jets stretch the magnetic lines until they wind into a pigtail, a hollow cylinder around the axis. And we are closing on that pair of pigtails, both observingly and model-tuningly.

Swedish Alfvén waves may be involved.

[Sa Ji Tario]

Terrible, do not forget that when bodies with gravity appear, so do the Lagrange points and the planets can be prior to the primaries

[neufer]

Terrible, do not forget that when bodies with gravity appear, so do the Lagrange points
and the planets can be prior to the primaries

• Trojan minor planets & moons... but few actual stable co-orbital exoplanets:

<<Trojan objects orbit 60° ahead of (L4) or behind (L5) a more massive object, both in orbit around an even more massive central object. The best known example are the asteroids that orbit ahead of or behind Jupiter around the Sun. Trojan objects do not orbit exactly at one of either Lagrangian points, but do remain relatively close to it, appearing to slowly orbit it. In technical terms, they librate around ( Δ λ , Δ ϖ ) = (±60°, ±60°). The point around which they librate is the same, irrespective of their mass or orbital eccentricity.
...................................................
Trojan minor planets: There are several thousand known trojan minor planets orbiting the Sun. Most of these orbit near Jupiter's Lagrangian points, the traditional Jupiter trojans. As of 2015 there are also 13 Neptune trojans, 7 Mars trojans, 2 Uranus trojans (2011 QF99 and 2014 YX49) and 1 Earth trojan (2010 TK7) known to exist.
...................................................
Trojan moons: The Saturnian system contains two sets of trojan moons. Both Tethys and Dione have two trojan moons each, Telesto and Calypso in Tethys's L4 and L5 respectively, and Helene and Polydeuces in Dione's L4 and L5 respectively.

Polydeuces is noticeable for its wide libration: it wanders as far as ±30° from its Lagrangian point and ±2% from its mean orbital radius, along a tadpole orbit in 790 days (288 times its orbital period around Saturn, the same as Dione's).
...................................................
Trojan planets: A pair of co-orbital exoplanets was proposed to be orbiting the star Kepler-223, but this was later retracted. The possibility of a trojan planet to Kepler-91b was studied but the conclusion was that the transit-signal was a false-positive. One possibility for the habitable zone is a trojan planet of a giant planet close to its star.
...................................................
Formation of the Earth–Moon system: According to the giant impact hypothesis, the Moon formed after a collision between two co-orbital objects: Theia, thought to have had about 10% of the mass of Earth (about as massive as Mars), and the proto-Earth—whose orbits were perturbed by other planets, bringing Theia out of its trojan position and causing the collision.>>