HD314884: A Slowly Pulsating B star in a Close Binary

Abstract

We present the results of a spectroscopic and photometric analysis of HD314884, a slowly pulsating B star (SPB) in a binary system with detected soft X-ray emission. We spectrally classify the B star as a B5V-B6V star with T${}_{eff}$ = 15,490 $\pm$ 310 K, log $g$ = 3.75 $\pm$ 0.25 dex, and a photometric period of P${}_0$ = 0.889521(12) days. A spectroscopic period search reveals an orbital period for the system of P${}_{orb}$ = 1.3654(11) days. The discrepancy in the two periods and the identification of a second and third distinct frequency in the photometric fourier transform at P${}_1$ = 3.1347(56) and P${}_2$ = 1.517(28) days provides evidence that HD314884 is a slowly pulsating B star (SPB) with at least three oscillation frequencies. These frequencies appear to originate from higher-order, non-linear tidal pulsations. Using the dynamical parameters obtained from the radial velocity curve, we find the most probable companion mass to be M${}_1$ = $\sim$0.8 M${}_{\odot }$ assuming a typical mass for the B star and most probable inclination. We conclude that the X-ray source companion to HD314884 is most likely a coronally active G-type star or a white dwarf (WD), with no apparent emission lines in the optical spectrum. The mass probability distribution of the companion star mass spans 0.6-2.3 M${}_{\odot }$ at 99$\%$ confidence which allows the possibility of a neutron star companion. The X-ray source is unlikely to be a black hole unless it is of a very low mass or low binary inclination.

Accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS)- July 29, 2014. 7 pages, 8 figures, 1 table

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Cited by in corpus (2)

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