Supernova minimum mass

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?

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.

Bs 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.

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?

coxellis2 wrote:

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.

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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. There's a Universe Today article that 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... *

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What is the maximum age of a type II supernova?

about 100 million years.... and as short as a few million years.

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....

astrolover wrote:

Bs 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.

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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?

Well how about a bosenova? does that count? Certainly very minimal mass.

Clive_D wrote:

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.

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?

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.

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?

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