by Ann » Fri Jan 13, 2012 9:35 am
TNT wrote:With this type of supernova, shouldn't the companion erupt due to the mass it gained while it was being buffeted by the supernova? I think the star's gases and dust that was blown out could have collected on the companion, therefore it gaining a lot of mass. If this were to happen, would there be a breach in the nebula?
This supernova presumably resulted from two white dwarfs merging. Before the two white dwarfs merged, there is no reason to think that they received any mass to speak of before they merged, because the strong gravity of each white dwarf would have held on tightly to their highly compressed atmospheres. So they blew when they merged. Alternatively , one white dwarf might have blown first, and the gas and dust that was dumped on its white dwarf companion would have sent that one over the brink, too.
FloridaMike wrote:
Oops! guess I was inking without thinking on that one. But still, could the white dwarf star that is going supernova pull enough mass from its companion that it ceases to be a functioning star? I’d like to understand what happens to a star whose mass is artificially reduced this way. As its mass is reduced the gravitational pressure would start decreasing and the star would expand. With the decreasing pressure the ability to fuse atoms would reduce and the expansion would stop. As the companion struggles to find an equilibrium as it continues to loose mass, what is the end game? Does it just evaporate away?
I don't think that white dwarfs will usually be able to pull enough gas from a star to stop it from "functioning as a star" - that is, I don't think a white dwarf will usually be able to steal enough gas from a companion to make that star unable to keep its fusion processes going.
A few days ago Regulus and dwarf galaxy Leo 1 were the Astronomy Picture of the Day. Regulus, as it happens, has a close-in companion that might be an underweight white dwarf. This emaciated white dwarf was probably created when its progenitor evolved into a bloated red giant and started dumping gas on its smaller but more compact main sequence companion. Because the companion stayed compact and the red giant stayed bloated, more and more of the red giant's mass was transferred onto the companion. Or, to summarize - the red giant became sufficiently "diluted" that its gravity lost much of its grip on its outer layers. The diluted outer layers expanded until they were "caught" by the main sequence companion. This started "funneling" the red giant's outer atmosphere onto the companion until the companion had grown relatively massive. The red dwarf eventually shrunk into a "too light-weight" white dwarf.
But the companion didn't explode, and the red giant didn't "evaporate into nothing".
However...
There
is something called the Black Widow pulsar.
http://en.wikipedia.org/wiki/Black_Widow_Pulsar wrote:
The Black Widow Pulsar (B1957+20) is an eclipsing binary millisecond pulsar that orbits with a brown dwarf companion with a period of 9.2 hours with an eclipse duration of approximately 20 minutes. When it was discovered in 1988 it was the first eclipsing binary pulsar known.[1] The prevailing theoretical explanation for the system implied that the companion is being destroyed by the gravitational environment (Roche lobe overflow) caused by the neutron star, and so the sobriquet black widow was applied to the object. Subsequent to this, other objects with similar features have been discovered, and the name has been applied to the class of millisecond pulsars with an ablating companion.
In other words, the Black Widow pulsar appears to be a tight binary system where the extreme gravity of the pulsar is destroying the companion star. The companion is now a light-weight brown dwarf, but it was probably a normal star before its pulsar companion started "eating it".
What will happen to the brown dwarf companion? Will it just "evaporate away"? I doubt it. I guess that the brown dwarf will end its days as a small compact body similar to a planet, unless it will merge with the pulsar and be destroyed that way.
Ann
[quote="TNT"]With this type of supernova, shouldn't the companion erupt due to the mass it gained while it was being buffeted by the supernova? I think the star's gases and dust that was blown out could have collected on the companion, therefore it gaining a lot of mass. If this were to happen, would there be a breach in the nebula?[/quote]
This supernova presumably resulted from two white dwarfs merging. Before the two white dwarfs merged, there is no reason to think that they received any mass to speak of before they merged, because the strong gravity of each white dwarf would have held on tightly to their highly compressed atmospheres. So they blew when they merged. Alternatively , one white dwarf might have blown first, and the gas and dust that was dumped on its white dwarf companion would have sent that one over the brink, too.
[quote]FloridaMike wrote:
Oops! guess I was inking without thinking on that one. But still, could the white dwarf star that is going supernova pull enough mass from its companion that it ceases to be a functioning star? I’d like to understand what happens to a star whose mass is artificially reduced this way. As its mass is reduced the gravitational pressure would start decreasing and the star would expand. With the decreasing pressure the ability to fuse atoms would reduce and the expansion would stop. As the companion struggles to find an equilibrium as it continues to loose mass, what is the end game? Does it just evaporate away?[/quote]
I don't think that white dwarfs will usually be able to pull enough gas from a star to stop it from "functioning as a star" - that is, I don't think a white dwarf will usually be able to steal enough gas from a companion to make that star unable to keep its fusion processes going.
A few days ago Regulus and dwarf galaxy Leo 1 were the Astronomy Picture of the Day. Regulus, as it happens, has a close-in companion that might be an underweight white dwarf. This emaciated white dwarf was probably created when its progenitor evolved into a bloated red giant and started dumping gas on its smaller but more compact main sequence companion. Because the companion stayed compact and the red giant stayed bloated, more and more of the red giant's mass was transferred onto the companion. Or, to summarize - the red giant became sufficiently "diluted" that its gravity lost much of its grip on its outer layers. The diluted outer layers expanded until they were "caught" by the main sequence companion. This started "funneling" the red giant's outer atmosphere onto the companion until the companion had grown relatively massive. The red dwarf eventually shrunk into a "too light-weight" white dwarf.
But the companion didn't explode, and the red giant didn't "evaporate into nothing".
However...
There [i]is[/i] something called the Black Widow pulsar.
[quote]http://en.wikipedia.org/wiki/Black_Widow_Pulsar wrote:
The Black Widow Pulsar (B1957+20) is an eclipsing binary millisecond pulsar that orbits with a brown dwarf companion with a period of 9.2 hours with an eclipse duration of approximately 20 minutes. When it was discovered in 1988 it was the first eclipsing binary pulsar known.[1] The prevailing theoretical explanation for the system implied that the companion is being destroyed by the gravitational environment (Roche lobe overflow) caused by the neutron star, and so the sobriquet black widow was applied to the object. Subsequent to this, other objects with similar features have been discovered, and the name has been applied to the class of millisecond pulsars with an ablating companion.[/quote]
[float=right][img2]http://api.ning.com/files/l1QiPVN15x5G64IIVHjbkFDw7VJxA4OiLbZuUl926bH24zq6Bnhw6oEj8bMLkw7zsh9vZ0p8rXbGXxetyyf5*rH4QrrjLU21/black_widow_pulsar.png?width=737&height=552[/img2][/float]In other words, the Black Widow pulsar appears to be a tight binary system where the extreme gravity of the pulsar is destroying the companion star. The companion is now a light-weight brown dwarf, but it was probably a normal star before its pulsar companion started "eating it".
What will happen to the brown dwarf companion? Will it just "evaporate away"? I doubt it. I guess that the brown dwarf will end its days as a small compact body similar to a planet, unless it will merge with the pulsar and be destroyed that way.
Ann