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chornedsnorkack
2010-May-22, 10:06 AM
What is the minimum zero age main sequence mass above which a star shall explode as Type II supernova? Also in view of mass loss from main sequence and giant evolution, what is the mass remaining at the time of explosion (core and envelope)?

What is the maximum age of a type II supernova?

harkeppler
2010-May-22, 10:44 AM
That cannot be said, because the mass loss of a Red Giant depends on its chemical composition. Stars with more metal varys a lot in their evolution, because the different composition allows other absorption effects of the emitted radiation coming from the core (an effect of the atoms of different elements). Dependig on the composition, the star forms larger or smaller convection zones and the energy distribution is changed. It can become larger or smaller, so stellar winds are more or less effective in removing mass.

Nereid
2010-May-22, 02:15 PM
One further complication: mass transfer in close binaries (which are not at all uncommon).

Somewhat less directly related: stellar collisions are expected to occur in the cores of globular clusters. So any such collisions (immediately) result in Type II supernovae?

Cougar
2010-May-22, 04:37 PM
What is the minimum zero age main sequence mass above which a star shall explode as Type II supernova?

If I understand your question correctly, the 'generic' answer is about 8 to 9 solar masses.


Also in view of mass loss from main sequence and giant evolution, what is the mass remaining at the time of explosion (core and envelope)?

You mean just before it goes supernova? There is apparently a broadly diverse family of solutions to this question. The more massive the progenitor star, the more furiously it will blow off mass as it nears the end of its life cycle. This Universe Today article (http://www.universetoday.com/2009/11/30/slow-motion-supernova/) talks about a (possible) Luminous Blue Variable that could have been ~100 solar masses that apparently blew off enough mass that it still ended up going supernova rather than collapsing directly to a black hole.... which is a bit odd, because...






With the current accuracy of the models, progenitors more massive than 40 M_solar form black holes directly with no supernova explosion... *


What is the maximum age of a type II supernova?

caltech.edu (http://nedwww.ipac.caltech.edu/level5/March01/Panagia/Panagia2.html) says about 100 million years.... and as short as a few million years.

_____________________________
* Mass Limits For Black Hole Formation, Fryer, Chris L., The Astrophysical Journal, Volume 522, Issue 1, pp. 413-418.

chornedsnorkack
2010-May-22, 07:06 PM
Is Alcyone too light, and Pleiades too old, to explode as Type II supernova?

Are there any white dwarfs in Pleiades? And are there any neutron stars in Pleiades? (Nebulae would be likely to have dissipated - one would be expected to form per 10 millions of years, and dissipate in ten thousand years.)

Roughly what B class dwarfs are heavy enough to become supernovae?

And what can evolved stars look like before explosion? Sanduleak proved that blue giants are eligible, not just red giants....

Shaula
2010-May-22, 08:42 PM
** range from 2 to 16 times the mass of the Sun so you are looking at the top end of the B class stars before you see supernovae. B5 is canonically 6-7 solar masses so you are looking at B4/B3 before you see a bang. A quick check shows that all of the bright stars in the Pleiades are B6-B8, so no bangs are likely barring something odd. Which leads on to... Sanduleak was a unusual type of blue giant IIRC - it was classed B3 but there were theories that it had been larger and lost mass to a close encounter or that it was the result of a merger between smaller stars. Certainly wasn't a typical type IIa.

Further note - with a mass of 6 solar masses you'd expect a lifetime of around 1.1x10^8, and the cluster is thought to be about 1x10^8 years old. So even the largest stars there should only just be getting to the end of their lives. Guess that limits the number of white dwarfs you'd expect. Haven't seen any references to any - but there are a load of brown dwarves there that are quite well studied because they are young and comparatively bright.

chornedsnorkack
2010-May-22, 08:55 PM
** range from 2 to 16 times the mass of the Sun so you are looking at the top end of the B class stars before you see supernovae. B5 is canonically 6-7 solar masses so you are looking at B4/B3 before you see a bang. A quick check shows that all of the bright stars in the Pleiades are B6-B8, so no bangs are likely barring something odd.
Yes, but they are giants, not dwarfs. Taygeta is either B6V or B6IV, Electra is B6III, Alcyone is B7III. They might have been earlier B classes when they were dwarfs.

Which leads on to... Sanduleak was a unusual type of blue giant IIRC - it was classed B3 but there were theories that it had been larger and lost mass to a close encounter or that it was the result of a merger between smaller stars. Certainly wasn't a typical type IIa.

Further note - with a mass of 6 solar masses you'd expect a lifetime of around 1.1x10^8, and the cluster is thought to be about 1x10^8 years old. So even the largest stars there should only just be getting to the end of their lives.
Yes, but did Pleiades once contain larger and more massive stars that have by now completed fusion?

Guess that limits the number of white dwarfs you'd expect. Haven't seen any references to any - but there are a load of brown dwarves there that are quite well studied because they are young and comparatively bright.

Shaula
2010-May-22, 10:59 PM
OK some digging reveals:
Site with some decent background on (http://seds.org/messier/m/m045.html)
There are some white dwarves in there.

Think you might back your classes back to front? Or I am misunderstanding your use of the word earlier. Earlier ** (closer to B0) are more massive - B3 and above are giants. But the later ** like the Pleiades don't evolve into them AIUI. They go to red giant. The terminology is confusing because a blue giant is usually a transitory phase and is not equivalent to a red giant in evolutionary terms (or at least not as I understand it). Blue giants become bright giants which go red unless they lose mass.

Sorry if I am wrong on this - my astro is getting very rusty.

tommac
2010-May-22, 11:56 PM
Well how about a bosenova? does that count? Certainly very minimal mass.

Shaula
2010-May-23, 05:12 AM
Well how about a bosenova? does that count? Certainly very minimal mass.
And how many stars do you think end up as a BEC made of one type of atom, sat in a magnetic trap with a field that changes value? The question was about stars and supernovae, not vaguely supernova-like laboratory events! Bosenova != supernova. It just bears a slight visual resemblance to it. The physics driving the events are quite different.

chornedsnorkack
2010-May-23, 06:43 AM
OK some digging reveals:
Site with some decent background on (http://seds.org/messier/m/m045.html)
There are some white dwarves in there.

Think you might back your classes back to front? Or I am misunderstanding your use of the word earlier. Earlier ** (closer to B0) are more massive - B3 and above are giants.
Mass or letter number have nothing to do with being giant. A 120 solar mass O3V main sequence star is still a dwarf.

But the later ** like the Pleiades don't evolve into them AIUI.
What I meant is that early type dwarves, like B3V, might have evolved into late B type white giants like B7III.

They go to red giant. The terminology is confusing because a blue giant is usually a transitory phase and is not equivalent to a red giant in evolutionary terms (or at least not as I understand it). Blue giants become bright giants which go red unless they lose mass.

The brightest stars of Hyades are four red clump yellow giants, types G8III to K0III. By contrast, red and yellow giants are absent in Pleiades - the brightest Pleiades are several white giants. The total absence of red giants in Pleiades and large number of blue giants shows that blue giant could not be a transitory phase.

Shaula
2010-May-23, 07:58 AM
Take your point on the giant comment - I had started to confuse myself.

tommac
2010-May-25, 08:57 PM
And how many stars do you think end up as a BEC made of one type of atom, sat in a magnetic trap with a field that changes value? The question was about stars and supernovae, not vaguely supernova-like laboratory events! Bosenova != supernova. It just bears a slight visual resemblance to it. The physics driving the events are quite different.

Forget about what is causing it ... but wouldnt that show that any mass can potentially supernova? But I guess he is talking about stars in particular ... what is the smallest possible star?

Shaula
2010-May-25, 09:27 PM
Forget about what is causing it ... but wouldnt that show that any mass can potentially supernova?
No because a bosenova is not a supernova. It just has some characteristics in common. The underlying physics is different, it is just the larger pictures that can be described in similar (ish) terms.

neilzero
2010-May-26, 01:51 AM
Perhaps the answer is 8 solar mass at birth typically becomes a supernova II at death. Just before supernova, 6 solar mass is minimum. Less than 6 we get a white dwarf without a supernova II. More than 30? solar mass becomes a black hole without a supernova II ?

Not very intuitive, all main sequence bodies are dwarves. No other bodies are properly called stars or dwarves with one exception = white dwarf which is a compact body that was a red giant before it ran out of fusonable material in it's core.
The supernova II produces enough energy to fuse even elements heavier than iron. How come you experts prefer generalities to numbers? Neil

Hornblower
2010-May-26, 03:28 AM
Perhaps the answer is 8 solar mass at birth typically becomes a supernova II at death. Just before supernova, 6 solar mass is minimum. Less than 6 we get a white dwarf without a supernova II. More than 30? solar mass becomes a black hole without a supernova II ?

Not very intuitive, all main sequence bodies are dwarves. No other bodies are properly called stars or dwarves with one exception = white dwarf which is a compact body that was a red giant before it ran out of fusonable material in it's core.
The supernova II produces enough energy to fuse even elements heavier than iron. How come you experts prefer generalities to numbers? NeilAre you asserting that a red giant is not properly called a star?

If it were my call, I would not call any main-sequence star a dwarf if it is larger than the Sun.