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UVIT open cluster study. I. Detection of a white dwarf companion to a blue straggler in M67: Evidence of formation through mass transfer

UVIT open cluster study. I. Detection of a white dwarf companion to a blue straggler in M67: Evidence of formation through mass transfer
UVIT open cluster study. I. Detection of a white dwarf companion to a blue straggler in M67: Evidence of formation through mass transfer
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 UVIT on ASTROSAT. Near-simultaneous observations in three far-UV bands combined with GALEX, IUE, ground and space based photometric data covering 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 Teff ~ 13250-13750K and a radius of 0.09±0.01 R. A comparison with WD models suggests it to be a low mass WD (~ 0.18 M), in agreement with the kinematic mass from the literature. As a low mass WD (< 0.4 M) necessitates formation through mass transfer (MT) 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.
astro-ph.SR
0004-637X
Sindhu, N
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Subramaniam, Annapurni
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Jadhav, Vikrant V
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Chatterjee, Sourav
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Geller, Aaron M
358fcd0f-def3-47e2-8595-ab16cdb12f3a
Knigge, Christian
ac320eec-631a-426e-b2db-717c8bf7857e
Leigh, Nathan
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Puzia, Thomas H
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Shara, Michael
bac39df6-4548-4335-a751-9be1122e8c33
Simunovic, Mirko
ce9a236f-751d-49c4-90e9-b53fa8a6a028
Sindhu, N
317ad9d0-998f-416a-9033-c57572df15c4
Subramaniam, Annapurni
6a91cb92-e7e8-40cb-b457-cc5abac5e924
Jadhav, Vikrant V
7a9cc29e-74ab-4d79-8c16-3ac2b057feb1
Chatterjee, Sourav
c00d4b13-14fc-41e7-8a96-6dfa189ba8a6
Geller, Aaron M
358fcd0f-def3-47e2-8595-ab16cdb12f3a
Knigge, Christian
ac320eec-631a-426e-b2db-717c8bf7857e
Leigh, Nathan
90069e68-a317-4cce-92e3-2401e3518751
Puzia, Thomas H
b625d688-ed67-462d-9691-6e7f9b69807b
Shara, Michael
bac39df6-4548-4335-a751-9be1122e8c33
Simunovic, Mirko
ce9a236f-751d-49c4-90e9-b53fa8a6a028

Sindhu, N, Subramaniam, Annapurni, Jadhav, Vikrant V, Chatterjee, Sourav, Geller, Aaron M, Knigge, Christian, Leigh, Nathan, Puzia, Thomas H, Shara, Michael and Simunovic, Mirko (2019) UVIT open cluster study. I. Detection of a white dwarf companion to a blue straggler in M67: Evidence of formation through mass transfer. The Astrophysical Journal, 882 (1), [43]. (doi:10.3847/1538-4357/ab31a8).

Record type: Article

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 UVIT on ASTROSAT. Near-simultaneous observations in three far-UV bands combined with GALEX, IUE, ground and space based photometric data covering 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 Teff ~ 13250-13750K and a radius of 0.09±0.01 R. A comparison with WD models suggests it to be a low mass WD (~ 0.18 M), in agreement with the kinematic mass from the literature. As a low mass WD (< 0.4 M) necessitates formation through mass transfer (MT) 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.

Text
1907.05556v1 - Accepted Manuscript
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Accepted/In Press date: 9 July 2019
e-pub ahead of print date: 30 August 2019
Keywords: astro-ph.SR

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Local EPrints ID: 432734
URI: http://eprints.soton.ac.uk/id/eprint/432734
ISSN: 0004-637X
PURE UUID: d5d8b1d4-98af-40ef-9afe-d66f3e51b9fa

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Date deposited: 25 Jul 2019 16:30
Last modified: 06 Oct 2020 22:48

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Contributors

Author: N Sindhu
Author: Annapurni Subramaniam
Author: Vikrant V Jadhav
Author: Sourav Chatterjee
Author: Aaron M Geller
Author: Nathan Leigh
Author: Thomas H Puzia
Author: Michael Shara
Author: Mirko Simunovic

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