Physical Sciences and Mathematics Commons^™

Low-Mass Spectroscopic Binaries In The Hyades: A Candidate Brown Dwarf Companion, I. Neill Reid, S. Mahoney

Dartmouth Scholarship

We have used the HIRES echelle spectrograph on the Keck I telescope to obtain high-resolution spectroscopy of 51 late-type M dwarfs in the Hyades cluster. Cross-correlating the calibrated data against spectra of white dwarfs allows us to determine heliocentric velocities with an accuracy of ±0.3 km s⁻¹. 27 stars were observed at two epochs in 1997; two stars, RHy 42 and RHy 403, are confirmed spectroscopic binaries. RHy 42 is a double-lined, equal-mass system; RHy 403 is a single-lined, short-period binary, P∼1.275 d. RHy 403A has an absolute magnitude of M_I=10.85, consistent with a mass …

Spectroscopy And Orbital Periods Of The Old Novae V533 Herculis, V446 Herculis And X Serpentis, J. R. Thorstensen, C. J. Taylor

Dartmouth Scholarship

We report spectroscopic orbital periods of 0.147 d (= 3.53 h) for V533 Her, 0.207 d (= 4.97 h) for V446 Her and 1.478 d for X Ser. V533 Her (Nova Herculis 1963) shows absorption features in its He i and Balmer lines which appear only in a limited range of orbital phase, suggesting that it is a low-inclination SW Sextantis star. V446 Her is unusual in that it has started normal dwarf nova eruptions after a nova outburst, but we find nothing else unusual about it — in particular, a distance estimate based on its dwarf nova outbursts agrees …

A Newly-Discovered Cataclysmic Binary Near The Rosat Galactic Plane Source Rx J1910.8+2856, J R. Thorstensen, F Haberl

Dartmouth Scholarship

We report the discovery of a new cataclysmic binary star from the ROSAT Galactic Plane Survey. The star has V >∼ 18.5atminimumlightandwehavemeasureditasbrightasV = 15.7. Spectroscopy shows broad hydrogen and helium emission lines; HeII λ4686 is not detected. Hα radial velocities yield an orbital period of 0.1429 ± 0.0004 d (3.430 ± 0.010 h). Time- series photometry covering one orbital cycle near maximum light shows irregular variability, but no evidence of an eclipse. ThesystemappearstobeanewdwarfnovaoftheUGemorZ Cam type, and is unlikely to be a magnetic system. Its period is unusually short for a U Gem star.

Curiously, the new cataclysmic binary is 83′′ …