Period-Luminosity Relations of SX Phoenicis Stars (original) (raw)

NASA/ADS

Abstract

We propose the following criteria to distinguish between fundamental (F) and first-overtone (H) pulsating SX Phoenicis variables: the (H) pulsators are SX Phe stars with nearly symmetrical light curves and light amplitudes (total range) <= 0.20^m^ in V; the (F) pulsating stars have light amplitudes >= 0.25^m^ in V and asymmetrical light curves. These criteria provide a separation of the stars into two groups that lead to two parallel P-L relations that are offset by 0.37^m^. This offset is in excellent agreement with the offset, 0.36^m^, predicted from the double- mode pulsating variable SX Phe. The (H) pulsating variables have shorter periods on average than the (F) pulsators as predicted by P_1_/P_0_ = Q_1_/Q_0_ ~ 0.778. The mean periods of the SX Phe stars in globular clusters are shown to be correlated with the metallicity [Fe/H] in the sense that the shortest period variables are found in the most metal-poor clusters. The fundamental-mode SX Phe stars in the Carina dwarf galaxy give a distance modulus of 20.0 and [Fe/H]= - 1.5.

Publication:

The Astronomical Journal

Pub Date:

April 1995

DOI:

10.1086/117405

Bibcode:

1995AJ....109.1751M

Keywords: