Pair instability supernova?

I've been reading theories about the earliest generations of
super-massive stars, and I've found the consensus seems to be the
following fates are likely:

8-30 solar masses: Supernova - neutron star
30-140 solar masses: Hypernova - black hole
140-260 solar masses: Pair instability supernova - complete
disruption, no remnant
260- solar masses: Hypernova - black hole

Can anyone explain what a pair instability supernova is? (Google shows
lots of scientific papers mentioning it, but they all seem to assume
the reader already knows about this stuff ) Is there a
layman-understandable explanation of how/why stars in that mass range
can be completely disrupted, and not above and below it?

Also, what's the expected quantity of material in the other mass
ranges that gets blown off rather than ending up in the black hole? (I
know for the lowest mass range, only 10-20% of the total mass ends up
in the neutron star, with much of the rest presumably contributing to
the metallicity of the interstellar medium.)

Thanks,

--
"Sore wa himitsu desu."
To reply by email, remove
the small snack from address.
http://www.esatclear.ie/~rwallace

Russell Wallace wrote:

I've been reading theories about the earliest generations of
super-massive stars, and I've found the consensus seems to be the
following fates are likely:

8-30 solar masses: Supernova - neutron star
30-140 solar masses: Hypernova - black hole
140-260 solar masses: Pair instability supernova - complete
disruption, no remnant
260- solar masses: Hypernova - black hole


Stars have a physical upper limit of about 120 solar masses as
increased radiation simple blows of the outer layers of mass.

On Fri, 19 Mar 2004 05:16:25 GMT, Sam Wormley
wrote:

Stars have a physical upper limit of about 120 solar masses as
increased radiation simple blows of the outer layers of mass.

I can't say of my own knowledge whether this is correct - I'm no
astronomer - but I've found a few dozen articles by people who are,
claiming that isn't the case, and suggesting several hundred solar
masses and upward as physical possibilities.

--
"Sore wa himitsu desu."
To reply by email, remove
the small snack from address.
http://www.esatclear.ie/~rwallace

Russell Wallace wrote:

On Fri, 19 Mar 2004 05:16:25 GMT, Sam Wormley
wrote:

Stars have a physical upper limit of about 120 solar masses as
increased radiation simple blows of the outer layers of mass.

I can't say of my own knowledge whether this is correct - I'm no
astronomer - but I've found a few dozen articles by people who are,
claiming that isn't the case, and suggesting several hundred solar
masses and upward as physical possibilities.

Cite References Please

Russell Wallace wrote:

On Fri, 19 Mar 2004 05:16:25 GMT, Sam Wormley
wrote:

Stars have a physical upper limit of about 120 solar masses as
increased radiation simple blows of the outer layers of mass.

I can't say of my own knowledge whether this is correct - I'm no
astronomer - but I've found a few dozen articles by people who are,
claiming that isn't the case, and suggesting several hundred solar
masses and upward as physical possibilities.

--
"Sore wa himitsu desu."
To reply by email, remove
the small snack from address.
http://www.esatclear.ie/~rwallace

See: http://scienceworld.wolfram.com/astronomy/Star.html

On Fri, 19 Mar 2004 06:29:15 GMT, Sam Wormley
wrote:

Cite References Please

Certainly, here's a bunch I found last night:

http://www.google.ie/search?q=%22pai...-8&hl=en&meta=

Most of these appear to be articles for scientific journals, written
by professional astronomers. I've seen some authors suggest the
possibility of stars forming with up to a million solar masses (and
collapsing fairly quickly into black holes), but I don't have
references for those.

--
"Sore wa himitsu desu."
To reply by email, remove
the small snack from address.
http://www.esatclear.ie/~rwallace

On Fri, 19 Mar 2004 06:48:38 GMT, Sam Wormley
wrote:

See: http://scienceworld.wolfram.com/astronomy/Star.html

You mean the bit where it quotes the most massive star known as being
80-100 solar masses? *nod* I understand Eta Carinae and the Pistol
Star are comparable to that; the context I've seen in which
substantially greater masses than this are discussed is that of
"Population III" stars, i.e. the first generation, formed with zero
metallicity.

--
"Sore wa himitsu desu."
To reply by email, remove
the small snack from address.
http://www.esatclear.ie/~rwallace

In sci.astro Russell Wallace wrote:
I've been reading theories about the earliest generations of
super-massive stars, and I've found the consensus seems to be the
following fates are likely:

8-30 solar masses: Supernova - neutron star
30-140 solar masses: Hypernova - black hole
140-260 solar masses: Pair instability supernova - complete
disruption, no remnant
260- solar masses: Hypernova - black hole

Can anyone explain what a pair instability supernova is? (Google shows
lots of scientific papers mentioning it, but they all seem to assume
the reader already knows about this stuff ) Is there a
layman-understandable explanation of how/why stars in that mass range
can be completely disrupted, and not above and below it?

Also, what's the expected quantity of material in the other mass
ranges that gets blown off rather than ending up in the black hole? (I
know for the lowest mass range, only 10-20% of the total mass ends up
in the neutron star, with much of the rest presumably contributing to
the metallicity of the interstellar medium.)

From some meeting notes, if I can decode them properly -
pair instability sets in when the core gets so hot that the energy
per nucleon allows production of electron-positron pairs
in the presence of additional particles to conserve momentum.
This is a dramatic cooling mechanism, which brings on core
collapse since the nucleons suddenly cool when the core temperature
first gets this hot. For primordial stars, this is calculated to
happen for 100 solar masses and up (noting a difference from your
table - different groups get different mass ranges...).

Above 260 solar masses or so, an additional mechanism sets in
that one could call reverse fusion. The temperature during collapse
can reach 10^9 K, at which point iron-peak nuclei are ripped
apart into neutrons and He nuclei. This can sap so much energy that
the star collapses without a supernova (hypernova) explosion.

A pair-instability SN ends up with most of the star's mass bound and
going into the remnant black hole. In the business, folks speak
of the mass cut being high (the mass cut being the point in
the star's mass where interior material doesn not escape the
explosion).

In principle, we should be able to see characteristic patterns of
chemical abundances at high redshift resulting from these various
ways to blow up stars. We may see some, others don't obviously
show up. One major project for the James Webb Space Telescope (assuming
it survives the next 6 years of NASA restructuring) is seeking the
supernova outbursts of these first-generation stars. We expect to see
one of these about every 8 seconds around the whole sky - the
problem is finding objects that are 26th magnitude in the infrared
bands and whose location we don't know. One advantage is that time
dilation at that redshift makes the peak brightness of a supernova
last a year or more.

Bill Keel

Russell Wallace wrote:

On Fri, 19 Mar 2004 06:29:15 GMT, Sam Wormley
wrote:

Cite References Please

Certainly, here's a bunch I found last night:

http://www.google.ie/search?q=%22pai...-8&hl=en&meta=

Most of these appear to be articles for scientific journals, written
by professional astronomers. I've seen some authors suggest the
possibility of stars forming with up to a million solar masses (and
collapsing fairly quickly into black holes), but I don't have
references for those.


Thank you! Reading....

"William C. Keel" wrote in message
...

From some meeting notes, if I can decode them properly -
pair instability sets in when the core gets so hot that the energy
per nucleon allows production of electron-positron pairs
in the presence of additional particles to conserve momentum.
This is a dramatic cooling mechanism, which brings on core
collapse since the nucleons suddenly cool when the core temperature
first gets this hot. For primordial stars, this is calculated to
happen for 100 solar masses and up (noting a difference from your
table - different groups get different mass ranges...).

Above 260 solar masses or so, an additional mechanism sets in
that one could call reverse fusion. The temperature during collapse
can reach 10^9 K, at which point iron-peak nuclei are ripped
apart into neutrons and He nuclei. This can sap so much energy that
the star collapses without a supernova (hypernova) explosion.

Thanks, that's very helpful (and I didn't even ask).

A pair-instability SN ends up with most of the star's mass bound and
going into the remnant black hole. In the business, folks speak
of the mass cut being high (the mass cut being the point in
the star's mass where interior material doesn not escape the
explosion).

http://arxiv.org/abs/astro-ph/0305333

seems to say 90% of the metals would be ejected.

"In particular, if the star has a mass in the narrow
interval 140 M_star 260M_sun , it will explode as
a pair-instability supernova (PISN), leading to the
complete disruption of the progenitor (Fryer, Woosley,
& Heger 2001; Heger et al. 2003). Pop III stars with
masses below or above the PISN range are predicted to
form black holes. This latter fate is not accompanied
by a significant dispersal of heavy elements into the
intergalactic medium (IGM), since most of the newly
synthesized metals will be locked up in the black hole.
The PISN, however, will contribute /all/ its heavy
element production to the surrounding gas."

In principle, we should be able to see characteristic patterns of
chemical abundances at high redshift resulting from these various
ways to blow up stars. We may see some, others don't obviously
show up. One major project for the James Webb Space Telescope (assuming
it survives the next 6 years of NASA restructuring) is seeking the
supernova outbursts of these first-generation stars. We expect to see
one of these about every 8 seconds around the whole sky - the
problem is finding objects that are 26th magnitude in the infrared
bands and whose location we don't know. One advantage is that time
dilation at that redshift makes the peak brightness of a supernova
last a year or more.

AIUI, the neutral gas of the 'dark ages' lie in between.
What parts of the spectrum could reach us?

George