Absolute parameters of young stars: QZ Carinae


Walker W. S. G. , Blackford M., Butland R., Budding E.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, vol.470, no.2, pp.2007-2017, 2017 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 470 Issue: 2
  • Publication Date: 2017
  • Doi Number: 10.1093/mnras/stx1153
  • Title of Journal : MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
  • Page Numbers: pp.2007-2017

Abstract

New high-resolution spectroscopy and BVR photometry together with literature data on the complex massive quaternary star QZ Car are collected and analysed. Absolute parameters are found as follows. System A: M-1 = 43 (+/- 3), M-2 = 19 (+3 -7), R-1 = 28 (+/- 2), R-2 = 6 (+/- 2), (circle dot); T-1 similar to 28 000, T-2 similar to 33 000 K; System B: M-1 = 30 (+/- 3), M-2 = 20 (+/- 3), R-1 = 10 (+/- 0.5), R-2 = 20 (+/- 1), (circle dot); T-1 similar to 36 000, T-2 similar to 30 000 K (model dependent temperatures). The wide system AB: Period = 49.5 (+/- 1) yr, Epochs, conjunction = 1984.8 (+/- 1), periastron = 2005.3 (+/- 3) yr, mean separation = 65 (+/- 3), (au); orbital inclination = 85 (+5 - 15) deg, photometric distance similar to 2700 (+/- 300) pc, age = 4 (+/- 1) Myr. Other new contributions concern: (a) analysis of the timing of minima differences (O - C) s for the eclipsing binary (System B); (b) the width of the eclipses, pointing to relatively large effects of radiation pressure; (c) inferences from the rotational widths of lines for both Systems A and B; and (d) implications for theoretical models of early-type stars. While feeling greater confidence on the quaternary's general parametrization, observational complications arising from strong wind interactions or other, unclear, causes still inhibit precision and call for continued multiwavelength observations. Our high-inclination value for the AB system helps to explain failures to resolve the wide binary in the previous years. The derived young age independently confirms membership of QZ Car to the open cluster Collinder 228.