Angular Sizes and Effective Temperatures of O-type Stars from Optical Interferometry with the CHARA Array

Abstract

We present interferometric observations of six O-type stars that were made with the Precision Astronomical Visible Observations (PAVO) beam combiner at the Center for High Angular Resolution Astronomy (CHARA) Array. The observations include multiple brackets for three targets, $\lambda$~Ori~A, $\zeta$~Oph, and 10~Lac, but there are only preliminary, single observations of the other three stars, $\xi$~Per, $\alpha$~Cam, and $\zeta$~Ori~A. The stellar angular diameters range from 0.55 milliarcsec for $\zeta$~Ori~A down to 0.11 mas for 10~Lac, the smallest star yet resolved with the CHARA Array. The rotational oblateness of the rapidly rotating star $\zeta$ Oph is directly measured for the first time. We assembled ultraviolet to infrared flux measurements for these stars, and then derived angular diameters and reddening estimates using model atmospheres and an effective temperature set by published results from analysis of the line spectrum. The model-based angular diameters are in good agreement with observed angular diameters. We also present estimates for the effective temperatures of these stars derived by setting the interferometric angular size and fitting the spectrophotometry.

13 pages, 6 figures, Table 5 - MRT

References in corpus (9)

• A Grid of NLTE Line-Blanketed Model Atmospheres of Early B-type Stars
• UBVJHK synthetic photometry of Galactic O stars
• Bright OB stars in the Galaxy - III. Constraints on the radial stratification of the clumping factor in hot star winds from a combined Halpha, IR and radio analysis
• The VLT-FLAMES Tarantula Survey XVI. The optical+NIR extinction laws in 30 Doradus and the photometric determination of the effective temperatures of OB stars
• The MiMeS Survey of Magnetism in Massive Stars: CNO surface abundances of Galactic O stars
• Adaptive Optics Photometry and Astrometry of Binary Stars. III. A Faint Companion Search of O-Star Systems
• The weak magnetic field of the O9.7 supergiant zeta Orionis A
• The IACOB project: II. On the scatter of O-dwarf spectral type -- effective temperature calibrations
• A study of the effect of rotational mixing on massive stars evolution: surface abundances of Galactic O7-8 giant stars

Cited by in corpus (3)

• Angular Diameters and Fundamental Parameters of Forty-Four Stars from the Navy Precision Optical Interferometer
• Coordinated UV and X-ray spectroscopic observations of the O-type giant xi Per: the connection between X-rays and large-scale wind structure
• Spectroscopic Line Modeling of the Fastest Rotating O-type Stars