A star with spiral arms

Nov 01, 2011 By Dr. Tony Phillips
Two spiral arms emerge from the gas-rich disk around SAO 206462, a young star in the constellation Lupus. This image, acquired by the Subaru Telescope and its HiCIAO instrument, is the first to show spiral arms in a circumstellar disk. The disk itself is some 14 billion miles across, or about twice the size of Pluto's orbit in our own solar system. Credit: NAOJ/Subaru

For more than four hundred years, astronomers have used telescopes to study the great variety of stars in our galaxy. Millions of distant suns have been catalogued. There are dwarf stars, giant stars, dead stars, exploding stars, binary stars; by now, you might suppose that every kind of star in the Milky Way had been seen.

That's why a recent discovery is so surprising.  Researchers using the Subaru in Hawaii have found a star with .

The name of the star is SAO 206462.  It's a young star more than four hundred light years from Earth in the constellation Lupus, the wolf.  SAO 206462 attracted attention because it has a circumstellar disk--that is, a broad disk of dust and gas surrounding the star. Researchers strongly suspected that new planets might be coalescing inside the disk, which is about twice as wide as the orbit of Pluto.

When they took a closer look at SAO 206462 they found not planets, but arms.  Astronomers have seen spiral arms before: they’re commonly found in pinwheel where hundreds of millions of stars spiral together around a common core.  Finding a clear case of spiral arms around an individual star, however, is unprecedented.

The arms might be a sign that planets are forming within the disk.

"Detailed computer simulations have shown us that the gravitational pull of a planet inside a circumstellar disk can perturb gas and dust, creating spiral arms,” says Carol Grady, an astronomer with Eureka Scientific, Inc., who is based at NASA's Goddard Space Flight Center. “Now, for the first time, we're seeing these dynamical features."

Grady revealed the image to colleagues on Oct. 19th at a meeting at Goddard entitled Signposts of Planets.

Theoretical models show that a single embedded planet may produce a spiral arm on each side of a disk. The structures around SAO 206462, however, do not form a matched pair, suggesting the presence of two unseen worlds, one for each arm.

Grady's research is part of a five-year international study of newborn stars and planets using the giant 8.2 meter Subaru Telescope. Operated by the National Astronomical Observatory of Japan, Subaru scans the heavens from a perch almost 14,000 feet above sea level at the summit of the Hawaiian volcano Mauna Kea. From there it has a crystal-clear view of innumerable young stars and their planet-forming disks throughout the .

"What we're finding is that once these systems reach ages of a few million years—that’s young for a star--their disks begin to show all kinds of interesting shapes,” says John Wisniewski, a collaborator at the University of Washington in Seattle. "We’ve seen rings, divots, gaps--and now spiral features. Many of these structures could be caused by planets moving within the disks."

However, it is not an open and shut case. The research team cautions that processes unrelated to planets might give rise to these structures. Until more evidence is collected--or until the planets themselves are detected--they can’t be certain.

Whatever the cause of the arms, their reality is undeniable and the great catalogue of has one more type.  Stay tuned to science@nasa for future entries.

Explore further: Gas cloud in the galactic centre is part of a larger gas streamer

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User comments : 17

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kevinrtrs
1.3 / 5 (31) Nov 01, 2011
People sure are desperate to see the accretion theory vindicated. Problem here is if there are no planets to be found, who's going to hang around for the next few million years to check if they eventually appear? No use making a record of it [and leaving it for posterity to confirm] without being able to have confirmation in one's own lifetime - that would simply reinforce the fact that one has to take the accretion theory by faith. REALLY, really, really strong faith.
Shelgeyr
1 / 5 (5) Nov 01, 2011
(ahem) EU! (cough cough)
Eikka
5 / 5 (15) Nov 01, 2011
Problem here is if there are no planets to be found, who's going to hang around for the next few million years to check if they eventually appear?


Just find older stars with similiar discs, and build up a series until you get the whole thing. If it works for one planetary system, it should work for the next one as well, so we should be able to find many different planetary systems in different stages of accretion, provided that we can observe them in enough detail.

Sound familiar?
TMEubanks
5 / 5 (2) Nov 01, 2011
Pluto's orbit isn't nearly that elliptical. They must be showing it nearly edge on to save space...
DaitoTsu
5 / 5 (10) Nov 01, 2011
No use making a record of it *** without being able to have confirmation in one's own lifetime - that would simply reinforce the fact that one has to take the accretion theory by faith. REALLY(x3) strong faith.


A very strange thing to say since the efforts of science & the discovery of knowledge have been past down from generations that came before us, when something hasn't been understood its observation has been noted and left for another generation to pick up.

Science adjusts its beliefs based on whats observed
Faith is the denial of observation so that Belief can be preserved.

Faith has nothing to do with it, hundreds upon hundreds of simulations using formulas & equations that doubtfully you can read let alone understand, written by people who have spent years refining them, have been run. They may not be perfect but we have a good working idea of how a solar system is formed.

This 'observation' will help refine the model & life cycle of a solar system.
antialias_physorg
4.7 / 5 (13) Nov 01, 2011
Problem here is if there are no planets to be found, who's going to hang around for the next few million years to check if they eventually appear?

And here I thought you were the one who was all about "believe what you can't see". My bad. Why don't you take that type of scepticism and apply it to your own beliefs? You didn't witness Jesus. Therefore - by your very own logic - he isn't real.

But seriously, like Eikka seid: We have billions of potential forming solar systems to look at. It seems we stand a pretty good chance of catching systems in various stages of formation.
Objectivist
5 / 5 (4) Nov 01, 2011
People sure are desperate to see the accretion theory vindicated. Problem here is if there are no planets to be found, who's going to hang around for the next few million years to check if they eventually appear?

You will Kevin, in your eternal afterlife. We're all counting on that.
omatwankr
4.6 / 5 (9) Nov 01, 2011
Looks like a fight between Dark matter, Repulsive Neutrons, Plasma Nonsense and Aether whatever theory.
I have seen fireworks with a similar shapes so maybe its just an alien pinwheel?
Ramael
3 / 5 (6) Nov 01, 2011
...that would simply reinforce the fact that one has to take the accretion theory by faith. REALLY, really, really strong faith.


As opposed to believing in god? Which there is no evidence for...
StarGazer2011
1.7 / 5 (6) Nov 01, 2011
EU ... much better theory than accretion i reckon. Pity it takes physics centuries to shake off dogma.
Deesky
5 / 5 (3) Nov 02, 2011
@kev

People sure are desperate to see religion vindicated. Problem here is if there are no gods to be found, who's going to hang around for the next coming to check if He eventually appears? No use making a record of it [and leaving it for posterity to confirm] without being able to have confirmation in one's own lifetime - that would simply reinforce the fact that one has to take the god theory by dumb faith. REALLY, really, really dumb faith.
Vendicar_Decarian
4.9 / 5 (7) Nov 02, 2011
If it doesn't have arms then how else will it hold on to it's proto-planetary children?

Huh? Ever ask yourself that? Ay?
rawa1
1 / 5 (1) Nov 02, 2011
IMO the spiral arms are the result of emergent gravitational interactions BETWEEN many particles in longitudinal waves, i.e. with tidal forces and pressure of radiation instead of interaction with light in transverse waves. We can say, when the number of objects inside of solar system increases and their density becomes sufficiently pronounced, then we could describe such solar system from intrinsic perspective of epicycles better, than from extrinsic perspective of Copernican system.

http://www.astro....ycle.pdf

It means, the epicycle model of solar system was not completely wrong, it just applies to different ratio of mutual interactions between objects and interactions between objects and their common center of mass. This insight can be extrapolated to many other systems, which are driven both with central laws, both with individual interactions of their peers, like the biological and social systems.
rawa1
1.3 / 5 (3) Nov 02, 2011
The reason why the spiral arms are rare around stars is, the density of matter inside of their protoplanetary disks is low in comparison to density of matter inside of star. At the case of galaxies this ratio is reversed: the mass of central black hole is usually low with compare to matter of stars around galaxy. But at the case of very young galaxies this ratio is reversed as such galaxies have no arms, but they're globular. So we can assume the existence of very large black holes inside of them, which violates the existing cosmological model.

In general, at the human scale the effects of both mutual, both central forces are balanced, at the atomic and planetary scale the central forces are most pronounced and with increasing distance from human observer scale (both toward quantum, both cosmological scales) the influence of mutual forces increases again. At the most distant scale the influence of both types of forces is balanced in the same way, like at the human scale.
Graeme
3 / 5 (2) Nov 02, 2011
It would be good to repeat the imaging over several years to see the motion of the arms. The results from that should make it clear if these are jets, waves or perturbations from one or two planets.
vidyunmaya
1 / 5 (1) Dec 31, 2011
Sub: Welcome image-SAO 206462-400 lY- Search UPE Model
Universal Plasma Energy Model- UPE- 1991-IEEE-ICOPS- by author clearly indicates -Source as drive to Spherical Disk and spiral in sequence.A DMVT process distribute Energy to Planets.
Between the hype created through images, let us apply our minds to the functional process that help Science to advance and catch-up with nature and Philosophy. Cosmology Vedas interlinks provides further inputs. Vidyardhi nanduri
Shelgeyr
1 / 5 (1) Dec 31, 2011
@omatwankr said:
Looks like a fight between Dark matter, Repulsive Neutrons, Plasma Nonsense and Aether whatever theory.


Plasma Nonsense?

For your reading pleasure, here's a little ditty from NASA's archives for you to enjoy:

http://ntrs.nasa....3880.pdf

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