A Spectroscopic Orbit for the Late-type Be Star β CMi

A Spectroscopic Orbit for the Late-type Be Star β CMi

The late-type Be star β CMi is remarkably stable compared to other Be stars that have been studied. This has led to a realistic model of the outflowing Be disk by Klement et al. These results showed that the disk is likely truncated at a finite radius from the star, which Klement et al. suggest is e...

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Bibliographic Details
Published in:The Astrophysical journal Vol. 836; no. 1; pp. 112 - 116
Main Authors: Dulaney, Nicholas A., Richardson, Noel D., Gerhartz, Cody J., Bjorkman, J. E., Bjorkman, K. S., Carciofi, Alex C., Klement, Robert, Wang, Luqian, Morrison, Nancy D., Bratcher, Allison D., Greco, Jennifer J., Hardegree-Ullman, Kevin K., Lembryk, Ludwik, Oswald, Wayne L., Trucks, Jesica L.
Format: Journal Article
Language:English
Published: Philadelphia The American Astronomical Society 10-02-2017
IOP Publishing
Subjects:
AMPLITUDES
Archives & records
Astrophysics
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
BALMER LINES
binaries: spectroscopic
Binary stars
CMi
Companion stars
COMPARATIVE EVALUATIONS
DOPPLER EFFECT
EVOLUTION
H alpha line
MASS
ORBITS
Overflow
PERIODICITY
ROCHE EQUIPOTENTIALS
SPECTRA
Stars & galaxies
stars: emission-line, Be
stars: individual
Stellar evolution
Subdwarf stars
ULTRAVIOLET RADIATION
Ultraviolet spectra
WHITE DWARF STARS
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Summary:The late-type Be star β CMi is remarkably stable compared to other Be stars that have been studied. This has led to a realistic model of the outflowing Be disk by Klement et al. These results showed that the disk is likely truncated at a finite radius from the star, which Klement et al. suggest is evidence for an unseen binary companion in orbit. Here we report on an analysis of the Ritter Observatory spectroscopic archive of β CMi to search for evidence of the elusive companion. We detect periodic Doppler shifts in the wings of the H line with a period of 170 days and an amplitude of 2.25 km s−1, consistent with a low-mass binary companion (M 0.42 M ). We then compared small changes in the violet-to-red peak height changes (V/R) with the orbital motion. We find weak evidence that it does follow the orbital motion, as suggested by recent Be binary models by Panoglou et al. Our results, which are similar to those for several other Be stars, suggest that β CMi may be a product of binary evolution where Roche lobe overflow has spun up the current Be star, likely leaving a hot subdwarf or white dwarf in orbit around the star. Unfortunately, no direct sign of this companion star is found in the very limited archive of International Ultraviolet Explorer spectra.
Bibliography:AAS03912
Stars and Stellar Physics
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/836/1/112