The bright southern Cepheid l Carinae - The radial velocity curve, distance and size

• Published in: Monthly notices of the Royal Astronomical Society Vol. 292; no. 3; pp. 662 - 672
• Main Authors: Taylor, Melinda M, Booth, Andrew J, Albrow, Michael D, Cottrell, P L
• Format: Journal Article
• Language: English
• Published: 11.12.1997
• DOI: 10.1093/mnras/292.3.662
• ISSN: 0035-8711

Using 137 high-resolution optical spectra from Mount John University Observatory and Mount Stromlo Observatory, a new, high-accuracy, radial velocity curve for the bright southern Cepheid l Carinae (HR 3884) is presented. We investigate recent period variations in l Carinae, cycle-to-cycle and long-term variations in the velocity curve, and the reliability of the combination of velocity data from different observatories. Such information should help to secure Cepheid distance scale calibrations, such as long-baseline interferometry and the Baade-Wesselink method, which depend on the accuracy of radial velocity data. A Barnes-Evans analysis is used to determine the radius of and distance to this Cepheid. The radius is found to be R = 179.2 +/- 2.7 +/- 10 solar radii, and the distance d = 571.1 + /- 8.5 +/- 21 pc. We highlight some of the problems involved with such distance techniques when applied to long-period Cepheids. (Author)