'Cannibalism' between stars: New research shows the turbulent past of our sun

February 5, 2016
Simulation of a gravitationally unstable circumstellar disk by means of hydrodynamic calculations. Protoplanetary 'embryo' form in the disc thanks to gravitational fragmentation. The three small pictures show the successive 'disappearance' of the lump by the star. Credit: (c) Eduard Vorobyov, Universität Wien

Stars are born inside a rotating cloud of interstellar gas and dust, which contracts to stellar densities thanks to its own gravity. Before finding itself on the star, however, most of the cloud lands onto a circumstellar disk forming around the star owing to conservation of angular momentum.The manner in which the material is transported through the disk onto the star, causing the star to grow in mass, has recently become a major research topic in astrophysics.

It turned out that may not accumulate their final mass steadily, as was previously thought, but in a series of violent events manifesting themselves as sharp stellar brightening. The young FU Orionis star in the constellation of Orion is the prototype example, which showed an increase in brightness by a factor of 250 over a time period of just one year, staying in this high-luminosity state now for almost a century.

One possible mechanism that can explain these brightening events was put forward 10 years ago by Eduard Vorobyov, now working at the Astrophysical Department of the Vienna University, in collaboration with Shantanu Basu from the University of Western Ontario, Canada.

According to their theory, stellar brightening can be caused by fragmentation due to gravitational instabilities in massive gaseous disks surrounding young stars, followed by migration of dense gaseous clumps onto the star. Like the process of throwing logs into a fireplace, these episodes of clump consumption release excess energy which causes the young star to brighten by a factor of hundreds to thousands. During each episode, the star is consuming the equivalent of one Earth mass every ten days. After this, it may take another several thousand years before another event occurs.

Polarized intensities of four selected FU Orionis objects observed with the 8.2-meter Subaru Telescope. Significant asymmetries, such as elbows, arms and broad trends -- typical of gravitationally unstable disks -- are indicated by arrows. Credit: (c) Eduard Vorobyov, Universität Wien

Eduard Vorobyov describes the process of clump formation in circumstellar disks followed by their migration onto the star as "cannibalism on astronomical scales". These clumps could have matured into giant planets such as Jupiter, but instead they were swallowed by the parental star. This invokes an interesting analogy with the Greek mythology, wherein Cronus, the leader of the first generation of Titans, ate up his newborn children (though failing to gobble up Zeus, who finally brought death upon his father).

With the advent of advanced observational instruments, such as SUBARU 8.2 meter optical-infrared telescope installed in Mauna Kea (Hawaii), it has become possible for the first time to test the model predictions. Using high-resolution, adaptive optics observations in the polarized light, an international group of astronomers led by Hauyu Liu from European Space Observatory (Garching, Germany) has verified the presence of the key features associated with the disk fragmentation model—large-scale arms and arcs surrounding four undergoing luminous outbursts, including the prototype FU Orionis star itself. The results of this study were accepted for publication in Science Advances - a peer-review, open-access journal belonging to the Science publishing group.

"This is a major step towards our understanding of how stars and planets form and evolve", says Vorobyov, "If we can prove that most stars undergo such episodes of brightening caused by disk gravitational instability, this would mean that our own Sun might have experienced several such episodes, implying that the giant planets of the Solar system may in fact be lucky survivors of the Sun's tempestuous past".

Explore further: Modeling Jupiter and Saturn's possible origins

More information: Hauyu Baobab Liu, Michihiro Takami, Tomoyuki Kudo, Jun Hashimoto, Ruobing Dong, Eduard I. Vorobyov, Tae-Soo Pyo, Misato Fukagawa, Motohide Tamura, Thomas Henning, Michael M. Dunham, Jennifer Karr, Nobuhiko Kusakabe, Toru Tsuribe: "Circumstellar Disks of the Most Vigorously Accreting Young Stars", published online February 5, 2016. advances.sciencemag.org/content/2/2/e1500875

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cantdrive85
2.5 / 5 (16) Feb 05, 2016
Stars are born inside a rotating cloud of interstellar gas and dust, which contracts to stellar densities thanks to its own gravity.

Nothing but conjecture, without evidence to boot...
Maggnus
3.7 / 5 (18) Feb 05, 2016
Nothing but conjecture, without evidence to boot...
Well, other than those nice pictures from the Subaru observatory. And those observations over the last 2 centuries. And physics.

EU is pseudo-science based on the interpretation of pretty pictures on cave walls by a mentally unstable hermit. You are a laughably inept acolyte promoting his delusions. I think you are the worse of the two.
eachus
4.3 / 5 (7) Feb 05, 2016
Another interesting possibility has to do with the transition from Brown dwarf (burning only deuterium) to main sequence star. At some point during clump accretion, the protostar will cross the boundary, but it is possible that a clump either produces a shock that starts hydrogen burning, or stirs up the star's center delaying ignition.

Given the expected frequency of these events, it is a question worth asking. My suspicion is that the answer is both. The stirring effect of a clump can bring new deuterium to the core, while lowering core temperatures.
NiteSkyGerl
2.9 / 5 (17) Feb 05, 2016
cantthinkatall 1/5 (2,354,231)
Nothing but conjecture, without evidence to boot...


Yeah. That's why we'd like you to shove off.
Phys1
2.3 / 5 (7) Feb 05, 2016
The current definition of embryo is something like this:
"An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of fertilization through sexual reproduction until birth, hatching, or germination."
https://en.wikipe...i/Embryo
Please keep it that way.
Stars do not cannibalise stars anymore than raindrops cannibalise raindrops when they form a pool of water.
Please do not scare the children among us with this kind of language ;-) .

AGreatWhopper
2.8 / 5 (11) Feb 05, 2016
The compulsive anthropomorphizing in science writing in general, and astronomy in particular, is a discredit to science, an obstacle, not an aid, to comprehension...besides being a banal attempt to pimp out the content.

But it's what you'd expect from a page that uses Outbrain, Adblade and Taboola adverts and panders to conservative trolls.
Psilly_T
4.1 / 5 (9) Feb 05, 2016
The compulsive anthropomorphizing in science writing in general, and astronomy in particular, is a discredit to science, an obstacle, not an aid, to comprehension...besides being a banal attempt to pimp out the content.

I disagree and find it entertaining. some people have imaginations and like to use them. maybe this is a discredit in your eyes but does that make it so for all? no, you sir are just stating an opinion that does nothing but serve as negative criticism of the author. Unless you have science to back up your claim that being creative with our writing is harmful to science.
Protoplasmix
2.3 / 5 (3) Feb 05, 2016
I watched a very good lecture today, "Modeling the physics of galaxy formation in a expanding universe," and with the brilliant technique of "AMR" (explained in the lecture) the above work will make a good extension of the smaller scales to the state-of-the-art modelling efforts.

What the crowd of regulars here will appreciate, and should recognize straightaway, is the scale at which electromagnetism begins to play a part. It's a small part, on the scale of kiloparsecs, and is easily recognized in the mechanism known as AGN feedback.

But the kicker comes in the Q&A after the lecture when someone asks, "On what length scales do magnetic, or electromagnetic effects start to pay a role?" I won't spoil it, the lecture's too good.
SLOOHCox
1 / 5 (1) Feb 06, 2016
But it's what you'd expect from a page that uses Outbrain, Adblade and Taboola adverts and panders to conservative trolls.


It never ceases to amaze me how site operators think only of revenue and don't ever seem to consider how much those fraudulent adverts really degrade the site.
viko_mx
1 / 5 (4) Feb 06, 2016
Modern shamans can see in the past and predict the future. They did not need any evidence. They have super computers instead of crystal balls, that can be programmed as they wish. Their simulations are as real as the world of Quake.
Phys1
2.8 / 5 (6) Feb 06, 2016
The compulsive anthropomorphizing in science writing in general, and astronomy in particular, is a discredit to science, an obstacle, not an aid, to comprehension...besides being a banal attempt to pimp out the content.

I disagree and find it entertaining. some people have imaginations and like to use them. maybe this is a discredit in your eyes but does that make it so for all? no, you sir are just stating an opinion that does nothing but serve as negative criticism of the author. Unless you have science to back up your claim that being creative with our writing is harmful to science.

Science is not entertainment.
jonesdave
3.7 / 5 (6) Feb 06, 2016
But the kicker comes in the Q&A after the lecture when someone asks, "On what length scales do magnetic, or electromagnetic effects start to pay a role?" I won't spoil it, the lecture's too good.


Then they shouldn't have any trouble in finding evidence of it.
You do realise that the total lack of evidence predicted by Peratt for his model was why his hypothesis is as dead as a dodo, don't you?
You do realise that the Sun powering stream of electrons required by Scott is not only unseen, but impossible?
You do realise that after 18 months, 67P is proving to be remarkably unelectric?
And the calculations used to get to it plugged in numbers based purely on gravity?

EU: more invisible things than "mainstream", and not the tiniest bit of use in actually getting us around the solar system. What's the point of it?
Old_C_Code
4.7 / 5 (3) Feb 06, 2016
jonesdave FYI:

IEEE Plasma Cosmology never concludes stars are powered by interstellar currents, Alfvén either. That's EU stuff.
Zorcon
3 / 5 (2) Feb 06, 2016
Nothing but conjecture, without evidence to boot...
-cantdrive85
------------------------------------------------------------------------------
con·jec·ture

verb
1. to make a supposition without hard data from primitive religious texts to back it up.
"the infidel conjectured that 2+2=4"
Psilly_T
5 / 5 (4) Feb 06, 2016

Science is not entertainment.

That statement doesn't make science any less entertaining to those whom view it as such. That is like saying politics is not entertainment. When clearly it can serve that purpose as well. Have fun with your boring opinions, I know I and others will.
TechnoCreed
5 / 5 (5) Feb 06, 2016
The current definition of embryo is something like this:
"An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of fertilization through sexual reproduction until birth, hatching, or germination."
https://en.wikipe...i/Embryo
Please keep it that way.
Stars do not cannibalise stars anymore than raindrops cannibalise raindrops when they form a pool of water.
Please do not scare the children among us with this kind of language ;-) .


The human thoughts require that its means of communication be sufficiently flexible to allow all its nuances to be expressed. Should we cast words in definitive boundaries, we would need an infinite amount of them to convey our ideas with the desired acuteness.
viko_mx
2 / 5 (4) Feb 07, 2016
""Stars are born inside a rotating cloud of interstellar gas and dust, which contracts to stellar densities thanks to its own gravity."

According to modern shamans stars are born from rotating cloud of dust and gas, which big bang theorist claims that are expanding with the speed which are tens of percentage of the speed of light. Why this fictional clouds must rotate in different directions is another hard questions for this theorists. They believe in invisible and elusive for the scientific equipment fictional phenomena like dark matter and energy, black holes, neutron stars, additional dimensions, quantum fluctuations and abstract geometric space, on which can be applied arbitrary mathematical transformations without physical restrictions. But do not believe in the Creator of this universe, Who is hidden from the eyes of the people because of our wickedness, but whose presence can be seen in all aspects of human life.
Phys1
2.7 / 5 (3) Feb 07, 2016
The current definition of embryo is something like this:
"An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of fertilization through sexual reproduction until birth, hatching, or germination."
https://en.wikipe...i/Embryo
Please keep it that way.
Stars do not cannibalise stars anymore than raindrops cannibalise raindrops when they form a pool of water.
Please do not scare the children among us with this kind of language ;-) .


The human thoughts require that its means of communication be sufficiently flexible to allow all its nuances to be expressed. Should we cast words in definitive boundaries, we would need an infinite amount of them to convey our ideas with the desired acuteness.

I fully agree, but star embryo's cannibalising each other, while a black hole monster is lurking, that is over the top.
Protoplasmix
4.3 / 5 (6) Feb 07, 2016
@jonesdave – please look deeper, past the objectivity, at the science. Both the lecture and my comment slam the EU pretty good, I thought. For example, the AGN feedback mechanism is obviously dominated by the gravitational force. Did you watch the lecture? Most of the EU regulars here *hate* models and simulations. They also *hate* magnetohydrodynamics, which is what was used for incorporating the physics of AGN feedback into the simulation.
Phys1
1 / 5 (2) Feb 07, 2016
...That is like saying politics is not entertainment.

Politics is not entertainment.
Have fun with your boring opinions, I know I and others will.

A lot of fools out there.
Protoplasmix
3 / 5 (2) Feb 07, 2016
Politics is not entertainment.
It's serious business, no doubt. There's and underlying science to it, because physics. But you apparently didn't see the Gawker live stream/live blog simulcast of the GOP debate /Vets benefit when their top candidate sought to avoid being bullied by tough questions. I'll tell you what, if there was a GOP debate with the Gawker crew as moderators, all the candidates would drop out of the race, and likely keep from showing their mugs in public ever again.
cantdrive85
2.6 / 5 (5) Feb 07, 2016
They also *hate* magnetohydrodynamics


No, MHD is *great*, for when it is relevant. Too bad that astrophysicists apply it to *everything* and is applicable to *nothing* to which they study.
cantdrive85
2.3 / 5 (6) Feb 08, 2016
jonesdave FYI:

IEEE Plasma Cosmology never concludes stars are powered by interstellar currents, Alfvén either.

That is a false statement, Birkeland currents are a primary consideration is PC. Anthony Peratt, Alfven protege, said this about Don Scott's book 'The Electric Sky' which proposes that exact mechanism;

"It is gratifying to see the work of my mentor, Nobel Laureate Hannes Alfvén enumerated with such clarity. I am also pleased to see that Dr. Scott has given general readers such a lucid and understandable summary of my own work." --Anthony L. Peratt, PhD, USC, Fellow of the IEEE (1999), former scientific advisor to the U.S. Department of Energy and member of the Associate Laboratory Directorate of the Los Alamos National Laboratory. He is the author of Physics of the Plasma Universe

antialias_physorg
3 / 5 (4) Feb 08, 2016
I disagree and find it entertaining. some people have imaginations and like to use them.

The thing about using ones imagination is this: If you get stuck in misleading analogies then the resulting understanding will be flawed

E.g. like some posters here get caught up in trying to fit everything to a 'wave' model while failing to understand that what we see as waves are the results of deeper forces (EM, or in the larger cases gravity) - thus falling for an entirely circular
Best put by Feynman in this short video
https://www.youtu...Pe-DwULM
(if you're impatient just watch the last 2 minutes)

So you have to be very careful about the things you say around scientific subjects. This is why scientific language is very precise and as soon as anyone starts interpreting based on another definition of a word you can always immediately go "stop. you're wrong" because there is no way that they are on the right track.
Protoplasmix
3.7 / 5 (3) Feb 08, 2016
No, MHD is *great*, for when it is relevant. Too bad that astrophysicists apply it to *everything* and is applicable to *nothing* to which they study.
Understanding not just MHD, but all the physics of cosmology, which includes all viable hypotheses and how to test them, requires an intellectual ability not one iota shy of brilliance. If your physics is a valid model and in a simulation it produces results that match observations at the relevant scale, as does MHD, then your physics is equivalent to MHD. Show us that's the case, mister brilliant.

Hyzenbuhrg, zeez ahr MAY truhzeez!
cantdrive85
2.6 / 5 (5) Feb 08, 2016
Understanding not just MHD, but all the physics of cosmology, which includes all viable hypotheses and how to test them, requires an intellectual ability not one iota shy of brilliance.

So you agree astrophysicists for the most part are NOT brilliant, great!

If your physics is a valid model and in a simulation it produces results that match observations at the relevant scale, as does MHD, then your physics is equivalent to MHD.

But, MHD does NOT match observations. One need only refer to magnetic reconnection for proof there. It's still a mystery to astrophysicists due to misapplied physics.

Psilly_T
5 / 5 (1) Feb 08, 2016
...That is like saying politics is not entertainment.

Politics is not entertainment.
Have fun with your boring opinions, I know I and others will.

A lot of fools out there.

your just dodging my point which is that science can be used for entertainment and it doesn't hurt anyone but bitter old people. I'd rather be a fool than a grumpy complainer with nothing better to do than to post negative feedback like an EU poster.
Phys1
1 / 5 (1) Feb 08, 2016
@Psilly_T
Perhaps I could learn a few things from you on how to be totally superficial!
So tell me is the refugee crisis entertaining? The credit crunch ?
Reinstoring waterboarding but better ? Hahaha !
(How am I doing ?)

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