Letter to the Editor

Assisted stellar suicide in V617 Sagittarii

¹ Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, 05508-900 São Paulo, SP, Brasil e-mail: [steiner;tiago]@astro.iag.usp.br
² SOAR Telescope, Casilla 603, La Serena, Chile e-mail: aoliveira@ctio.noao.edu
³ Laboratório Nacional de Astrofísica / MCT, CP21, Itajubá, MG, Brasil
⁴ Divisão de Astrofísica, Instituto Nacional de Pesquisas Espaciais, CP 515, S. J. dos Campos, Brasil e-mail: deo@das.inpe.br

Received: 7 December 2005
Accepted: 18 December 2005

Abstract

Context.V617 Sgr is a V Sagittae star – a group of binaries thought to be the galactic counterparts of the Compact Binary Supersoft X-ray Sources – CBSS. Aims.To check this hypothesis, we measured the time derivative of its orbital period. Methods.Observed timings of eclipse minima spanning over 30 000 orbital cycles are presented. Results.We found that the orbital period evolves quite rapidly: years. This is consistent with the idea that V617 Sgr is a wind driven accretion supersoft source. As the binary system evolves with a time-scale of about one million years, which is extremely short for a low mass evolved binary, it is likely that the system will soon end either by having its secondary completely evaporated or by the primary exploding as a supernova of type Ia. Conclusions.