X Cygni - Duplicity, period stability, and atmospheric velocity structure

Abstract

view Abstract Citations (17) References (42) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X Cygni : duplicity, period stability and atmospheric velocity structure. Evans, N. R. Abstract Observations of X Cygni which can be used as tests of duplicity are discussed, including light variations, ultraviolet spectra, radial velocities, and period variations. IUE observations show no sign of a blue companion in the 2500-3000 A region, ruling out a single companion more massive than about 2.5 solar masses. The high luminosity of X Cygni does not invalidate most photometric tests for duplicity. The limit of + or - 3 km/s on the orbital radial velocity variations is confirmed and makes orbital light time effects an unlikely explanation for the apparent period variations. The period change in the last 20 years is confirmed; it is several standard deviations in magnitude and is not consistent with either orbital light-time variations or a continuous evolutionary change. Radial velocities from 16 lines formed high in the solar atmosphere are shown to have small velocity differences with respect to the velocities of the neutral metal lines. Publication: The Astrophysical Journal Pub Date: June 1984 DOI: 10.1086/162154 Bibcode: 1984ApJ...281..760E Keywords: Cepheid Variables; Companion Stars; Stellar Atmospheres; Ultraviolet Astronomy; Cygnus Constellation; Iue; Radial Velocity; Astrophysics full text sources ADS | data products SIMBAD (1) MAST (1) INES (1)