A blue straggler binary with three progenitors in the core of a globular cluster?

C. Knigge, R. L. Gilliland, A. Dieball, D. R. Zurek, M. M. Shara, K. S. Long

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We show that the X-ray source W31 in the core of the globular cluster 47 Tucanae is physically associated with the bright blue straggler BSS 7. The two sources are astrometrically matched to 07061, with a chance coincidence probability of less than 1%. We then analyze optical time-series photometry obtained with the Hubble Space Telescope (HST) and find that BSS 7 displays a 1.56 day periodic signal in the I band. We also construct a broadband (far-ultraviolet through far-red) spectral energy distribution for BSS 7 and fit this with single and binary models. The binary model is a better fit to the data, and we derive the corresponding stellar parameters. All of our findings are consistent with BSS 7 being a detached binary consisting of a blue straggler primary with an X-ray-active, upper-main-sequence companion. The formation of such a system would necessarily involve at least three stars, which is consistent with recent JV-body models in which blue stragglers often form via multiple encounters that can involve both single and binary stars. However, we cannot yet entirely rule out the possibility that BSS 7 descended directly from a binary system via mass transfer. The system parameters needed to distinguish definitively between these scenarios may be obtainable from time-resolved spectroscopy.

Original languageEnglish (US)
Pages (from-to)281-287
Number of pages7
JournalAstrophysical Journal
Volume641
Issue number1 I
DOIs
StatePublished - Apr 10 2006

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globular clusters
stars
binary stars
spectral energy distribution
Hubble Space Telescope
encounters
mass transfer
photometry
x rays
spectroscopy
time series
broadband
energy
parameter

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Knigge, C., Gilliland, R. L., Dieball, A., Zurek, D. R., Shara, M. M., & Long, K. S. (2006). A blue straggler binary with three progenitors in the core of a globular cluster? Astrophysical Journal, 641(1 I), 281-287. https://doi.org/10.1086/500311
Knigge, C. ; Gilliland, R. L. ; Dieball, A. ; Zurek, D. R. ; Shara, M. M. ; Long, K. S. / A blue straggler binary with three progenitors in the core of a globular cluster?. In: Astrophysical Journal. 2006 ; Vol. 641, No. 1 I. pp. 281-287.
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Knigge, C, Gilliland, RL, Dieball, A, Zurek, DR, Shara, MM & Long, KS 2006, 'A blue straggler binary with three progenitors in the core of a globular cluster?', Astrophysical Journal, vol. 641, no. 1 I, pp. 281-287. https://doi.org/10.1086/500311

A blue straggler binary with three progenitors in the core of a globular cluster? / Knigge, C.; Gilliland, R. L.; Dieball, A.; Zurek, D. R.; Shara, M. M.; Long, K. S.

In: Astrophysical Journal, Vol. 641, No. 1 I, 10.04.2006, p. 281-287.

Research output: Contribution to journalArticle

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Knigge C, Gilliland RL, Dieball A, Zurek DR, Shara MM, Long KS. A blue straggler binary with three progenitors in the core of a globular cluster? Astrophysical Journal. 2006 Apr 10;641(1 I):281-287. https://doi.org/10.1086/500311