From: buell@phyast.nhn.uoknor.edu (Jim Buell)
Subject: Re: Supermassive stars and HD limit (was Big Bang...)
Organization: Engineering Computer Network, University of Oklahoma, Norman, OK, USA
Distribution: sci
Date: Wed, 22 Jul 1992 18:07:06 GMT

njzy@vax5.cit.cornell.edu (T. Joseph Lazio, Cornell University) writes:

>In article <BroBAA.Bp7@well.sf.ca.us>,
>metares@well.sf.ca.us (Tom Van Flandern) writes: 
>> 
>> yaron@astro.as.utexas.edu (Yaron Sheffer) writes (referring to the Crab
>> Nebula pulsar and its radio jets):
>> 
>>> after the pulsar flies away and the nebula disperses, NOTHING IS LEFT
>>> BEHIND! Does Tom see ANY similarity between this scenario and galaxy cores
>>> that "eject quasars"? As far as I know, the mammoth core is still there
>>> intact after such imaginary ejection! Or should we wait to see a galactic
>>> core exploding as a supernova and vanishing?!
>> 
>>      I was using the Crab Nebula pulsar as a possible example of a transition
>> case.  If the source body is small enough, after collapse we get a neutron
>> star / pulsar with radio jets.  It is flying away, and will eventually leave
>> the galaxy.  Now scale this up several orders of magnitude to the case for a
>> supermassive star.  Is it in any way strange that, when supermassive stars
>> collapse, they are ejected from the galaxy with high speed, and develop radio
>> jets of their own?  The cases look parallel to me.

[stuff deleted]

> Secondly, in reading your paragraph above, I see it making two, testable 
> predictions. 
> I)  When "normal" stars collapse, the result is a supernova.  When these 
> putative supermassive stars collapse, they should produce 
> super-supernovae.  Presumably these super-supernovae could be distinguished
> in some fashion from the "run-of-the-mill" supernovae.  What would the 
> distinguishing characteristics be and have any super-supernovae ever 
> been observed?  I can think of one characteristic:  The absolute 
> magnitude.  Surely these super-supernovae would be much brighter than 
> regular supernovae; have there been unusually bright supernovae reported?
> (By unusually bright, I would suspect a few to several magnitudes, not 
> merely 0.1 magnitude or so [remember this is in the absolute magnitude].)

Actually you have to be careful with trying to make a connection between
the optical luminosity and the mass of the progenitor star. The type II
supernovae, which are associated with core collapse of massive stars, 
release most of their energy as neutrinos. The neutrinos from SN1987A
carried away approximately 99% of the energy.     

The brightest known supernovae are the type Ia supernovae. This type of
supernovae is believed to be associated with white dwarfs in binaries. 
These supernovae are approximately 2 magnitudes brighter than the type
IIa SN. The type II SN have a large dispersion in magnitude, while the
type Ia may have no dispersion in magnitude (AJ 100, pg 530).  

> II) Some QSOs are seen well removed from galaxies.  Has there ever been 
> a case in which a supernova was observed being well removed from the 
> outer extent of a galaxy?  (I mean by, say, a few arcminutes, not merely
> on the outer edge of the optical emission of a galaxy.)

The type IIa SN are strongly associated with HII regions. There is
evidence for this in measurements of the positions of SNs and HII
regions in external galaxies (I have no reference handy at the moment).
The type IIa SN seem to occur very close to HII regions and these are
the massive ones. I don't believe that any type IIa SN (at least good
ones, I mean ones that are definitely type IIs). have been observed 
[stuff deleted]

> T. Joseph Lazio                | Why relativity? and Why  
> 514 Space Sciences             | turbulence?  I really believe   
> Ithaca, NY  14853              | [God] will have an answer for the
> (607) 255-6420                 | first [question].
> lazio@astrosun.tn.cornell.edu  |   -- W. Heisenberg, on his death bed
>ICBM:                           |
> 42 deg. 20' 08" N              |              STOP RAPE
> 76 deg. 28' 48" W              |

Jim Buell

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