A new age determination Gamma^2 Velorum from binary stellar evolution models

TL;DR

This paper revises the age of Gamma^2 Velorum to approximately 5.5 million years using binary stellar evolution models, indicating past interaction and mass transfer events that affect age estimates and binary characteristics.

Contribution

It introduces a new age estimate for Gamma^2 Velorum based on binary models, challenging previous single-star age estimates and highlighting the importance of binary interactions.

Findings

Older age of 5.5±1 Myrs for Gamma^2 Velorum.

Binary components interacted via Case B mass transfer.

Binary remains eccentric due to radiative envelopes during mass transfer.

Abstract

We derive a new age for the Gamma^2 Velorum binary by comparing recent observations to our set of binary models. We find that it is very unlikely the stars have not interacted, which implies that previous estimates of the age from single-star models of 3.5+/-0.4 Myrs are incorrect. We prefer an older age of 5.5+/-1 Myrs that agrees with the age of other lower mass stars in the Vela OB association. We also find that our favoured binary model shows the components of the binary have interacted in a Case B, post main-sequence, mass-transfer event. During the mass-transfer event, the envelopes of both components where radiative and therefore the damping of tidal forces are relatively weak. This explains why the binary is still eccentric after mass-transfer.