Survivor of stellar collision is new type of pulsating star

Jun 28, 2013
Artist's impression of the eclipsing, pulsating binary star J0247-25. Credit: Keele University

A team of astronomers from the UK, Germany and Spain have observed the remnant of a stellar collision and discovered that its brightness varies in a way not seen before on this rare type of star. By analysing the patterns in these brightness variations, astronomers will learn what really happens when stars collide. This discovery will be published in the 27 June 2013 issue of the journal Nature.

Stars like our Sun expand and cool to become red giant stars when the hydrogen that fuels the in their cores starts to run out. Many stars are born in so an expanding red giant star will sometimes collide with an orbiting . As much as 90% of the red 's mass can be stripped off in a stellar collision, but the details of this process are not well understood. Only a few stars that have recently emerged from a stellar collision are known, so it has been difficult to study the connection between stellar collisions and the various exotic stellar systems they produce. When an containing one such star turned up as a by-product of a search for , Dr Pierre Maxted and his colleagues decided to use the high-speed camera ULTRACAM to study the eclipses of the star in detail. These new high-speed brightness measurements show that the remnant of the stripped red giant is a new type of pulsating star.

Many stars, including our own Sun, vary in brightness because of pulsations caused by sound waves bouncing around inside the star. For both the Sun and the new variable star, each pulsation cycle takes about 5 minutes. These pulsations can be used to study the properties of a star below its visible surface. Computer models produced by the discovery team show that the sound waves probe all the way to the centre of the new pulsating star. Further observations of this star are now planned to work out how long it will be before the star starts to cool and fade to produce a stellar corpse ("white dwarf'") of abnormally low mass.

Dr Pierre Maxted from Keele University, who led the study, said "We have been able to find out a lot about these stars, such as how much they weigh, because they are in a binary system. This will really help us to interpret the pulsation signal and so figure out how these stars survived the collision and what will become of them over the next few billion years."

Explore further: Millisecond pulsars clearly demonstrate that pulsars are neutron stars

More information: www.vikdhillon.staff.shef.ac.uk/ultracam
Paper: www.nature.com/nature/journal/… ull/nature12192.html

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cantdrive85
1.5 / 5 (17) Jun 28, 2013
Many stars, including our own Sun, vary in brightness because of pulsations caused by sound waves bouncing around inside the star.


Utter nonsense. Stars are roiling balls of plasma driven by EM forces, pulsations are certainly not caused by sound waves.
no fate
1.4 / 5 (11) Jun 28, 2013
I have to agree. An internally generated solar wide phenomena based on sound and a five minute cycle doesn't add up. Although I didn't check out the whole paper to see if this is explained better as acoustics do play a role in EM interactions, the effect would have to be generated outside the sun or in a layer at or very near the surface... it would be a process shared by two totally different stars.
Protoplasmix
2.5 / 5 (8) Jun 28, 2013
Many stars, including our own Sun, vary in brightness because of pulsations caused by sound waves bouncing around inside the star.


Utter nonsense. Stars are roiling balls of plasma driven by EM forces, pulsations are certainly not caused by sound waves.

I think the driving force is gravity, and you may want to check the field of "helioseismology"...
GSwift7
3.9 / 5 (7) Jun 28, 2013
Utter nonsense. Stars are roiling balls of plasma driven by EM forces, pulsations are certainly not caused by sound waves


Just when I think you couldn't possibly get any funnier, you totally surprise me and come up with something new.

I have to agree


Yeah, you would. Good grief.
cantdrive85
1.3 / 5 (16) Jun 28, 2013
I think the driving force is gravity, and you may want to check the field of "helioseismology"...

I'm aware of that pseudo-science, an entire field based upon false presumptions.
Protoplasmix
3.5 / 5 (11) Jun 28, 2013
@cantdrive85: It's really a shame if you believe that, as observations and analysis of the p-modes, g-modes and f-modes facilitates viewing internal structures and dynamics, and even sunspots on the far side of the sun can likewise be viewed. Why miss out on that? Fascinating work!
Fleetfoot
5 / 5 (3) Jun 29, 2013
Many stars, including our own Sun, vary in brightness because of pulsations caused by sound waves bouncing around inside the star.


Utter nonsense. Stars are roiling balls of plasma driven by EM forces, pulsations are certainly not caused by sound waves.


Simple fact: a ball of plasma primarily has the properties of a fluid and must support all the same oscillation modes of any fluid. Features moving at the speed of sound are observed and are a powerful tool for studying the interior.
cantdrive85
1.3 / 5 (12) Jun 29, 2013
Simple fact: a ball of plasma primarily has the properties of a fluid and must support all the same oscillation modes of any fluid.


Your simple fact is simply wrong, a ball of plasma primarily has the properties of a PLASMA, and must support all the modes of that plasma and that is primarily driven by EM forces. Fluid models, ideal gas models, and the homogeneous plasma models (w/o DL's) used by astrophysicists are far too simplistic and fail miserably in explaining reality. Although it is without question that much info can be discerned by the methods employed by these "scientists", the basis of their theories are terribly flawed, and therefore any conclusions reached will be equally flawed.
cantdrive85
1.3 / 5 (12) Jun 29, 2013
"As neither double layer nor circuit can be derived from magnetofluid models of a plasma, such models are useless for treating energy transfer by means of double layers. They must be replaced by particle models and circuit theory… Application to the heliospheric current systems leads to the prediction of two double layers on the sun's axis which may give radiations detectable from Earth. Double layers in space should be classified as a new type of celestial object."
— H. Alfvén, Double Layers and Circuits in Astrophysics, IEEE Transactions On Plasma Science, Vol. PS-14, No. 6, December 1986.
Protoplasmix
2.1 / 5 (7) Jun 29, 2013
Although it is without question that much info can be discerned by the methods employed by these "scientists", ...

Yes, and it's probably safe to say they detest flaws every bit as much as any other truth-seeker.

Would sound waves propagate across a DL? For the star in the article they can probe all the way to the center. I think sound waves would increase the ion pressure gradient and hence prevent double layers from forming in the first place, wouldn't they? And what about the effect of gravitational confinement of the plasma regarding DL formation or, more to the point, satisfying the conditions of the Bohm criterion?
Requiem
2.3 / 5 (6) Jun 30, 2013
Why do you do this, cantdrive85?
GSwift7
2.3 / 5 (3) Jul 02, 2013
Why do you do this, cantdrive85?


Acting out on dissocial disorder impulses. He probably doesn't have enough human interaction, and therefore doesn't have any checks and balances on his thought processes. You see this a lot in people who are isolated too often. They tend to do a lot of self-talk out loud, which validates any whacky ideas that pop into their head. His blind fixation is a tell-tale symptom.

See the following wiki page, in the section on "Dissocial personality disorder". Under the list of symptoms, I think we see symptoms number 2,4,5 and 6 clearly. 2)disregard of norms, 4)frustration, 5)no learning from experience, and 6)no rationalization.

If he is using multiple online identities, I might go as far as full fledged sociopath, but that is a more serious diagnosis.

I'm glad I don't know him in real life, but that's just my personal opinion.
no fate
3 / 5 (2) Jul 09, 2013
Gravitational confinement of plasma is an interesting notion, if someone has done it experimentally I would love to see the link.

Yes GSwift7 I did agree, and can tell you specifically why so my answer is much better than "CD85 said it so it must be wrong".

How do you believe the P-waves are generated so that the cycles match?
Be careful with this one, unlike the experts here have posted it can't have anything to do with gravity or fusion and must be a process that is not effected by density.
barakn
5 / 5 (1) Jul 10, 2013
Gravitational confinement of plasma is an interesting notion, if someone has done it experimentally I would love to see the link.

Go outside. Look at the sun. Behold, a ball of gravitationally confined plasma. Now go see a doctor about those damaged retinas.
no fate
3 / 5 (2) Jul 10, 2013
Gravitational confinement of plasma is an interesting notion, if someone has done it experimentally I would love to see the link.

Go outside. Look at the sun. Behold, a ball of gravitationally confined plasma. Now go see a doctor about those damaged retinas.


Plasma reacts to magnetic fields, period. In every vacuum chamber experiment done (which have all been conducted in earths gravity) with plasma, in not one did it collect at the bottom of the chamber. Gravity isn't what keeps the solar plasma confined, we actually have pictures that show the true nature of the granularity on the surface of the sun.
Research before you post.