The Progenitor of the Vela Pulsar

With Gaia parallaxes it is possible to study the stellar populations associated with individual Galactic supernova remnants (SNR) to estimate the mass of the exploding star. Here we analyze the luminous stars near the Vela pulsar and SNR to find that its progenitor was probably (>90%) low mass (8.1-10.3Msun). The presence of the O star gamma2 Vel a little over 100 pc from Vela is the primary ambiguity, as including it in the analysis volume significantly increases the probability (to 5%) of higher mass (>20Msun) progenitors. However, to be a high mass star associated with gamma2 Vel's star cluster at birth, the progenitor would have to a runaway star from an unbound binary with an unusually high velocity. The primary impediment to analyzing large numbers of Galactic SNRs in this manner is the lack of accurate distances. This can likely be solved by searching for absorption lines from the SNR in stars as a function of distance, a method which yielded a distance to Vela in agreement with the direct pulsar parallax. If Vela was a 10Msun supernova in an external galaxy, the 50 pc search region used in extragalactic studies would contain only ~10% of the stars formed in a 50~pc region around the progenitor at birth and ~90% of the stars in the search region would have been elsewhere.