UVIT Open Cluster Study. I. Detection of a White Dwarf Companion to a Blue Straggler in M67: Evidence of Formation through Mass Transfer

N. Sindhu, Annapurni Subramaniam, Vikrant V. Jadhav, Sourav Chatterjee, Aaron M. Geller, Christian Knigge, Nathan Leigh, Thomas H. Puzia, Michael Shara, Mirko Simunovic

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

The old open cluster M67, populated with blue straggler stars (BSSs), is a well-known test bed to study the BSS formation pathways. Here, we report the first direct detection of a white dwarf (WD) companion to a BSS in M67, using far-UV images from the Ultra-Violet Imaging telescope on ASTROSAT. Near-simultaneous observations in three far-UV bands combined with Galaxy Evolution Explorer, International Ultraviolet Explorer, and ground- and space-based photometric data covering a 0.14-11.5 μm range for WOCS1007 were found to require a binary fit to its spectral energy distribution (SED), consisting of a BSS and a hot companion. On the other hand, a single spectral fit was found to be satisfactory for the SEDs of two other BSSs, WOCS1006 and WOCS2011, with the latter showing a deficient far-UV flux. The hot companion of WOCS1007 is found to have a ∼ 13,250-13,750 K and a radius of 0.09 0.01 . A comparison with WD models suggests it to be a low-mass WD (∼), in agreement with the kinematic mass from the literature. As a low-mass WD (<) necessitates formation through mass transfer in close binaries, WOCS1007 with a known period of 4.2 days along with its fast rotation, is likely to be formed by a case A or case B binary evolution.

Original languageEnglish (US)
Article number43
JournalAstrophysical Journal
Volume882
Issue number1
DOIs
StatePublished - Sep 1 2019

Keywords

  • open clusters and associations: individual (M67)
  • stars: individual (blue stragglers, white dwarfs)
  • ultraviolet: stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'UVIT Open Cluster Study. I. Detection of a White Dwarf Companion to a Blue Straggler in M67: Evidence of Formation through Mass Transfer'. Together they form a unique fingerprint.

  • Cite this

    Sindhu, N., Subramaniam, A., Jadhav, V. V., Chatterjee, S., Geller, A. M., Knigge, C., Leigh, N., Puzia, T. H., Shara, M., & Simunovic, M. (2019). UVIT Open Cluster Study. I. Detection of a White Dwarf Companion to a Blue Straggler in M67: Evidence of Formation through Mass Transfer. Astrophysical Journal, 882(1), [43]. https://doi.org/10.3847/1538-4357/ab31a8