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Fraser
2006-Apr-14, 05:22 AM
SUMMARY: Astronomers recently noticed that the normally dim star RS Ophiuchi had brightened enough to be visible without a telescope. This white dwarf star has brightened like this 5 times in the last 100 years, and astronomers believe it's about to collapse into a neutron star. RS Ophiuchi is in a binary system with a much larger red giant star. The two stars are so close that the white dwarf is actually inside the envelope of the red giant, and explodes from within it every 20 years or so.

View full article (http://www.universetoday.com/am/publish/star_into_star.html)
What do you think about this story? post your comments below.

antoniseb
2006-Apr-14, 12:21 PM
Who would have guessed with today's Eta Carinae story that there would be an even better supernova type story. RSOph sounds like it is worthy of some big budget study. Here we have something that might become a type 1a SN, 5000 light years away. It is evolving before our eyes.

We could really benefit from getting a high precision measure of the masses of these two stars. Modeling the total infall on the white dwarf would be useful too. How will the outburst around 2027 be different from this one?

cfosterstars
2006-Apr-14, 05:22 PM
I thought that when white dwarf in a close binary reaches the chandrashakar mass of 1.4 solar masses by acretion of gas from the companion star that it results in a type 1a supernova that completely consumes the white dwarf in run away nuclear fusion. There is no colapsed remanent neutron star when this happens. The article said that the star was going to colapse into a neutron star. I think that this is wrong.

antoniseb
2006-Apr-14, 06:09 PM
I thought that when white dwarf in a close binary reaches the chandrashakar mass of 1.4 solar masses by acretion of gas from the companion star that it results in a type 1a supernova that completely consumes the white dwarf in run away nuclear fusion. There is no colapsed remanent neutron star when this happens. The article said that the star was going to colapse into a neutron star. I think that this is wrong.

The article also mentioned something about at Type II supernova having previously happened in that system. There was a lot there that seemed not fully explained. A pointer to the actual work, and not the press release would be useful. The implication is that this is no normal white dwarf, but I agree with you. This looks like a Type 1a supernova waiting to happen as far as what I've been told in the article (aside from the things in the article that contradict the idea).

Gerald Lukaniuk
2006-Apr-14, 11:09 PM
Are these burps a neutron matter-producing phase that self-aborts? At neutron, star that builds up in layers with possibly a super nova for dessert. The stability of neutron matter and its interactions with baryonic matter and plasma is an important thing to know lest we produce some in a collider. Sites of Intermittent high magnitude energy production would be a logical place to look for effect or lack of effects attributed to dark matter, energy, gravitons, or maybe even neutrinos on external bodies.
There should be serious money and attention to this type of crucible. Iím happy to donate ĺ of my salary which unfortunately on 2 bits after taxes.

antoniseb
2006-Apr-15, 12:37 PM
Are these burps a neutron matter-producing phase that self-aborts?

more likely there is a buildup of material on the surface of the white dwarf, and after twenty years it is dense enough to cause a fusion event, in which most of the new material is blown out.

I agree with you r sentiment that this system needs more study. I'm not sure I followed what you were saying about why.

neilzero
2006-Apr-16, 12:12 PM
A white dwarf at 1.4 solar mass: My guess is it does not make the transition to neutron star until lots more mass is added suddenly in a big chunk. A large pressure pulse is needed, I think. Some of the hydrogen falling from the red giant may not become white star stuff, because the pressure pulse is not strong enough, but some of the infalling may fuse to helium = the process in the H bomb and main sequence stars. My guess is this is the source of the brightening. Still more likely the process is more complex than we have imagined, so research is a good idea. Neil

Kootenaistar
2006-Apr-16, 06:20 PM
Not being into deep science, I still love the observations and reports and discussions. All may learn from such events and I am thrilled by the availabiltiy of open computer discussions so that all (such as me) may learn and share. The thoughts of one may add to the work of another and this is one of those events that all available can share for best learning of the whole. Congrat's on the observations and studies. Keep it up! We're with you on the sidelines too.

Gerald Lukaniuk
2006-Apr-16, 07:22 PM
more likely there is a buildup of material on the surface of the white dwarf, and after twenty years it is dense enough to cause a fusion event, in which most of the new material is blown out.

I agree with you r sentiment that this system needs more study. I'm not sure I followed what you were saying about why.
Dense material would sink as in any other fluidic stellar body. A surface explosion would certainly compress inward as it blasts outward. The compressed matter would either absorb energy to re expand cooling the mass or form a stable substance which certainly would be denser(perhaps non luminous like a dark matter). Electrons and protons would be forced together at least temporarily at velocities that could exceede supercolliders. Loss of mass one would think would put an end to this type of reaction if there was not an inflow of material not effected by the explosion. Perhaps there is something directional about the outflow and inflow streams. A core buildup would certainly increase the frequency of this event if material inflow was constant and while twenty years is too long to wait subtle differences in luminousity and spectrum I sure will be compared to any previous records. There is likely more happening here than just a pressure release reaction as there is no confinement. Hydrogen fusion be able to be actualized in a piston engine type technigue if we understood the substrate on the surface after the explosion reveals it.

ToSeek
2006-Jul-19, 04:22 PM
Nuclear explosion on a dead star -- astronomers probe aftermath (http://www.physorg.com/news72523674.html)


A team of astronomers from the UK and Germany have found that a nuclear explosion on the surface of a star 5,000 light years from Earth resulted in a blast wave moving at over 1,700 km per second (one thousand miles per second or almost four million miles per hour!). The discovery, reported in the 20th July issue of Nature, was made by bringing together many of the world's radio telescopes into arrays capable of seeing the aftermath of the explosion in incredible detail.

antoniseb
2006-Jul-19, 04:38 PM
Nice find, and well done conecting it back to this three month old thread.

ToSeek
2006-Jul-19, 05:49 PM
I'm tired of getting ToSeeked by Blob, so I'm trying to be more careful.

antoniseb
2006-Jul-19, 05:57 PM
Blob is being pretty quick. On UT, I used to report lot of these things first, but after the merge, some other guy kept getting the stories up before I did. After an adjustment period, I was willing to let it just happen. Maybe he's in line to take our jobs.

On another front (closer to the OP), there was a cool paper a few days ago about a category of WR stars (WR8) that might have comapanion neutron stars orbiting inside them. This from careful examination of one in this galaxy.

Jerry
2006-Jul-20, 01:23 PM
Still more likely the process is more complex than we have imagined, so research is a good idea. Neil

Since it has become obvious that supernova explosions involve binary systems, the hard fast rules about what isolate a type Ia from other supernova subclasses becomes blurred by the possibility of multiple explosions and sympathetic detonations. Although this still allows white dwarfs to be used as standard candles, we need to find a way to discriminate between different types of binary systems, and the effect that they have on supernova magnitudes. spectra and light curve lengths.

(It is naive to assume we have a good enough handle on white dwarf systems to use white dwarf magnitudes to predict cosmological parameters.)

Fraser
2006-Jul-21, 03:38 AM
I just did an interview with the primary investigator on this story. I should have the podcast posted in a day or so.

BigDon
2006-Jul-21, 07:44 AM
What will happen when the white dwarf collects enough material to collapse into a neutron star? With the outer shell already gone what is going to constitute the material of its "outburst"? (I have a layman's familiarity with type II SN) I can imagine that this is going to be a truly energetic event. And a very visible one at that range.

antoniseb
2006-Jul-21, 09:47 AM
The thought is that this is a type Ia progenitor, and that the event will be very bright, but not leave a neutron star behind.

Blob
2006-Jul-21, 01:44 PM
Hum,
some more info Here (http://www.bautforum.com/showthread.php?t=38075&highlight=Ophiuchi)

BigDon
2006-Jul-22, 06:51 PM
I thought the first article insinuated that the white dwarf was already at its Chandrasekhar limit. Even if the hydrogen flashes like it does isn't it still adding mass to the WD? I thought it was possible for it to eventually collaspe further, considering the steady source of infalling material.

(Oh BTW Blob, you might want to have your isolation mounts looked at, I keep picking up this hum whenever you post. :shifty: )

BD

publiusr
2006-Aug-25, 06:52 PM
Interesting.