The Hot Companion and Circumbinary Disk of the Be Star HR 2142

Abstract

We present a spectroscopic investigation of the Be+sdO binary system HR 2142 that is based upon large sets of ultraviolet observations from the International Ultraviolet Explorer and ground-based H-alpha observations. We measured radial velocities for the Be star component from these spectra, and computed a revised orbit. In order to search for the spectral signature of the hot subdwarf, we cross-correlated the short wavelength end of each IUE spectrum with a model hot star spectrum, and then we used the predicted Doppler shifts of the subdwarf to shift-and-add all the cross-correlation functions to the frame of the subdwarf. This merged function shows the weak signal from the spectral lines of the hot star, and a best fit is obtained with a mass ratio M_2/M_1 = 0.07 +/- 0.02, companion temperature T_{eff} > 43 +/- 5 kK, projected rotational velocity V sin i < 30 km/s, and a monochromatic flux ratio near 1170 Angstroms of f_2/f_1 > 0.009 +/- 0.001. This hot subdwarf creates a one-armed spiral, tidal wake in the disk of the Be star, and we present a circumbinary disk model that can explain the occurrence of shell absorption lines by gas enhancements that occur where gas crossing the gap created by the subdwarf strikes the disk boundaries. The faint companion of HR 2142 may be representative of a significant fraction of Be stars with undetected former mass donor companion stars.

arXiv commentaccepted by ApJ, 49 pages

References in corpus (16)

• Stellar Multiplicity
• A Grid of NLTE Line-Blanketed Model Atmospheres of O-type Stars
• Classical Be Stars: Rapidly Rotating B Stars with Viscous Keplerian Decretion Disks
• The incidence of stellar mergers and mass gainers among massive stars
• Three-dimensional Calculations of High and Low-mass Planets Embedded in Protoplanetary Discs
• Effects of gravitational darkening on the determination of fundamental parameters in fast rotating B-type stars
• Formation of contact in massive close binaries
• Viscous Effects on the Interaction between the Coplanar Decretion Disc and the Neutron Star in Be/X-Ray Binaries
• On the wake generated by a planet in a disc
• On the formation of Be stars through binary interaction
• Estimating Be Star Disk Radii using H-alpha Emission Equivalent Widths
• FUV Detection of the Suspected Subdwarf Companion to the Be Star 59 Cygni
• Spectral and spatial imaging of the Be+sdO binary phi Persei
• Detection of a Hot Subdwarf Companion to the Be Star FY Canis Majoris
• Be discs in binary systems I. Coplanar orbits
• The binary fraction and mass-ratio of Be and B stars: a comparative VLT/NACO study

Cited by in corpus (36)

• Detection of additional Be+sdO systems from IUE spectroscopy
• The Detection and Characterization of Be+sdO Binaries from HST/STIS FUV Spectroscopy
• Investigating the lack of main-sequence companions to massive Be stars
• Electromagnetic signals following stellar-mass black hole mergers
• Prevalence of SED turndown among classical Be stars: Are all Be stars close binaries?
• A stripped-companion origin for Be stars: clues from the putative black holes HR 6819 and LB-1
• Clues about the scarcity of stripped-envelope stars from the evolutionary state of the sdO+Be binary system phi Persei
• Revealing the structure of the outer disks of Be stars
• Detection of the Ultraviolet Spectrum of the Hot Subdwarf Companion of 60 Cygni (B1 Ve) from a Survey of IUE Spectra of Be Stars
• On the kinematics of a runaway Be star population
• gamma Cas stars: Normal Be stars with disks impacted by the wind of a helium-star companion?
• Velocity monitoring of gamma-Cas stars reveals their binarity status
• Be discs in coplanar circular binaries: Phase-locked variations of emission lines
• The Remarkable Be+sdOB Binary HD 55606 I: Orbital and Stellar Parameters
• Population Synthesis of Galactic Be-star Binaries with A Helium-star Companion
• The orbital and physical properties of five southern Be+sdO binary systems
• TESS observations of Be stars: a new interpretation
• Interferometric detections of sdO companions orbiting three classical Be stars
• Evidence for Different Disk Mass Distributions Between Early and Late-Type Be Stars in the BeSOS Survey
• The X-ray emission of Be+stripped star binaries
• Short-term variability and mass loss in Be stars IV. Two groups of closely spaced, approximately equidistant frequencies in three decades of space photometry of $\nu$ Puppis (B7-8 IIIe)
• Extreme isolation of WN3/O3 stars and implications for their evolutionary origin as the elusive stripped binaries
• Spectro-interferometric observations of a sample of Be stars. Setting limits to the geometry and kinematics of stable Be disks
• Identification of new classical Be stars from the LAMOST MRS survey
• Chemical abundances of fast-rotating massive stars. II. Interpretation and comparison with evolutionary models
• Ultraviolet Spectropolarimetry: on the origin of rapidly rotating B stars
• Formation and Destiny of White Dwarf and Be Star Binaries
• The spins of stripped B stars support magnetic internal angular momentum transport
• The H-alpha Emission Line Variations of HR 6819
• A Spectroscopic Orbit for the late-type Be star $\beta$ CMi
• Populations of evolved massive binary stars in the Small Magellanic Cloud I: Predictions from detailed evolution models
• High-spatial-resolution simulations of Be star disks in binary systems: I. Structure and kinematics of coplanar disks
• Classical Nova Carinae 2018: Discovery of circumbinary iron and oxygen
• A peculiar interacting Be star binary in the Small Magellanic Cloud
• AstroSat/UVIT Study of NGC 663: First detection of Be+sdOB systems in a young star cluster
• Ultraviolet spectroscopy reveals a hot and luminous companion to the Be star+black hole candidate MWC 656