On the numbers, birthrates, and final states of moderate- and high-mass stars

Using counts of stars in the solar neighborhood and conventional stellar-lifetime calculations, we find death rates of stars in the mass ranges (4 < M/M0 < 8) and (8 < M/M0) to be 3.6 X 1(h1I and 1.1 X t(hli pc-2, respectively. If the moderate-mass stars each ejected 1.4 M0 of iron peak elements at death and if the heavy stars each produced a neutron-star pulsar, then the calculated pulsar birthrate would be a factor 5 smaller than the "observed" rate S X t(h11 pc-2 . Also, the local iron abundance would be larger by a factor 6(B /B(T) than the observed value 1.4 X 1O Since the ratio of the average to the present bfrthrate of moderate-mass stars, (B /B(T), is of order 10', the discrepancy is a factor of 60 and probably so large as to preclude the possibility that 8 M0 stars eject iron cores. The statistical arguments are quite consistent with the suggestion by Arnett and Schramm that, while the iron cores of high-mass stars implode, the outer portions explode, providing the principal means of nuclear processing in the Galaxy. Subject headings: stellar evolution - stellar statistics - supernovae