Neutron stars mass limits

The question of upper mass limits to stars which explode as SN II and leave neutron-star remnants is discussed by Maeder (1992,1993) and by Brown, Bruenn and Wheeler (1992) it is highly controversial. (Note that Koppen and Arimoto (1991) when referring to the Scalo IMF use the version with b T) = 1, as I have done, whereas Maeder (1993) uses the version with b (T) = 0.48, corresponding to yields that are 3 times higher )... 

The mass function, which is a pure combination of observables, is a lower limit to the possible mass of star 2 if the orbit is other than edge-on (that is, if % < 90°) or the observed star has mi > 0, then m2 > / Thus, observation of one star constrains the mass of the other star. Note, incidentally, that in a neutron star binary system with a high-mass companion (mi m2), / is low... 

The possibility to have metastable hadronic stars, together with the feasible existence of two distinct families of compact stars, demands an extension of the concept of maximum mass of a neutron star with respect to the classical one introduced by Oppenheimer Volkoff (1939). Since metastable HS with a short mean-life time are very unlikely to be observed, the extended concept of maximum mass must be introduced in view of the comparison with the values of the mass of compact stars deduced from direct astrophysical observation. Having in mind this operational definition, we call limiting mass of a compact star, and denote it as Mum, the physical quantity defined in the following way ... 

Perhaps the most novel aspect of SNl987a is the detection [6,7] of neutrinos from the production and cooling of a compact remnant. One hopes this is only the beginning of a new field of astronomy. The analysis I present here [5], parallel to the analysis of many other authors [23-28], finds remnant binding energy 2.0 0.5 X 1053 ergs and remnant mass 1.2 to 1.7 Mq consistent with what one expects for neutron star generation. An upper limit of 10-15 eV may also be inferred for the electron neutrino mass. 

There are a number of other interesting limits to be drawn on neutrino properties by somewhat more sophisticated use of the supernova dynamics. Putting another neutrino-antineutrino pair [30], i.e., another two species, into any calculation of the neutron star cooling would probably accelerate this process unacceptably. Further, one can place an upper limit [5] of 45 eV on the mass of any species mixing with the electron neutrino, else no supernova mechanism would succeed, delayed or prompt. 

Oppenheimer-Volkoff limit The maximum mass a neutron star can have before it undergoes gravitational collapse to a black... 

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