# BINARY CEPHEIDS: SEPARATIONS AND MASS RATIOS IN 5 M ☉ BINARIES*

@article{Evans2013BINARYCS,
title={BINARY CEPHEIDS: SEPARATIONS AND MASS RATIOS IN 5 M ☉ BINARIES*},
author={Nancy Remage Evans and Howard E. Bond and Gail H. Schaefer and Brian D. Mason and Margarita Karovska and Evan Tingle},
journal={The Astronomical Journal},
year={2013},
volume={146},
pages={93}
}
Deriving the distribution of binary parameters for a particular class of stars over the full range of orbital separations usually requires the combination of results from many different observing techniques (radial velocities, interferometry, astrometry, photometry, direct imaging), each with selection biases. However, Cepheids—cool, evolved stars of ~5 M ☉—are a special case because ultraviolet (UV) spectra will immediately reveal any companion star hotter than early type A, regardless of the…

## Figures and Tables from this paper

Hubble Space Telescope Snapshot Survey for Resolved Companions of Galactic Cepheids: Final Results.
Cepheids in multiple systems provide information on the outcome of the formation of massive stars. They can also lead to exotic end-stage objects. This study concludes our survey of 70 galactic
Hubble Space Telescope: Snapshot Survey for Resolved Companions of Galactic Cepheids
We have conducted an imaging survey with the Hubble Space Telescope Wide Field Camera~3 (WFC3) of 70 Galactic Cepheids, typically within 1~kpc, with the aim of finding resolved physical companions.
Mind your Ps and Qs: the Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars
• Physics
• 2016
We compile observations of early-type binaries identified via spectroscopy, eclipses, long-baseline interferometry, adaptive optics, common proper motion, etc. Each observational technique is
Multiplicity of Galactic Cepheids from long-baseline interferometry
Aims. We aim at detecting and characterizing the main-sequence companions of a sample of known and suspected Galactic binary Cepheids. The long-term objective is to accurately and independently
Multiplicity of Galactic Cepheids and RR Lyrae stars from Gaia DR2
Context. Classical Cepheids (CCs) and RR Lyrae stars (RRLs) are important classes of variable stars used as standard candles to estimate galactic and extragalactic distances. Their multiplicity is
Binary Properties from Cepheid Radial Velocities (CRaV)
We have examined high accuracy radial velocities of Cepheids to determine the binary frequency. The data are largely from the CORAVEL spectrophotometer and the Moscow version, with a typical
A Search for Mass Loss on the Cepheid Instability Strip using HI 21-cm Line Observations
• Physics
• 2016
We present the results of a search for HI 21-cm line emission from the circumstellar environments of four Galactic Cepheids (RS Pup, X Cyg, $\zeta$ Gem, and T Mon) based on observations with the Karl
The Orbit of the Close Companion of Polaris: Hubble Space Telescope Imaging, 2007 to 2014
As part of a program to determine dynamical masses of Cepheids, we have imaged the nearest and brightest Cepheid, Polaris, with the Hubble Space Telescope Wide Field Planetary Camera 2 and Wide Field
Multiplicity of Galactic Cepheids and RR Lyrae stars from Gaia DR2
Context. The multiplicity of classical Cepheids (CCs) and RR Lyrae stars (RRLs) is still imperfectly known, particularly for RRLs. Aims. In order to complement the close-in short orbital period
Revealing δ Cephei's Secret Companion and Intriguing Past
Classical Cepheid variable stars are crucial calibrators of the cosmic distance scale thanks to a relation between their pulsation periods and luminosities. Their archetype, {\delta} Cephei, is an

## References

SHOWING 1-10 OF 35 REFERENCES
The orbits of southern binary Cepheids
• Physics
• 2004
High-resolution spectroscopic observations have been made of a number of southern Cepheids. The stars studied were part of a long-term programme to observe southern variable stars and to complete a
A magnitude-limited survey of Cepheid companions in the ultraviolet
Results of a magnitude-limited survey of classic Cepheids brighter than 8th mag carried out to search for hot main-sequence companions are presented. Spectra of 76 stars obtained with the IUE
MASSIVE STAR MULTIPLICITY: THE CEPHEID W Sgr*
• Physics
• 2009
We have obtained spectra of the W Sgr system with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope (HST). The spectra resolve the system into a distant companion B which is the
A New Look at the Binary Characteristics of Massive Stars
• Physics
• 2006
We constrain the properties of massive binaries by comparing radial velocity data on early-type stars in Cygnus OB2 with the expectations of Monte Carlo models. Our comparisons test several popular
Classical Cepheid luminosities from binary companions
Luminosities for the classical Cepheids Eta Aql, W Sgr, and SU Cas are determined from IUE spectra of their binary companions. Spectral types of the companions are determined from the spectra by
Toward an Orbit for the High-Luminosity Cepheid T Monocerotis*
We have obtained new velocities of the long-period Cepheid T Mon from the ground and velocities of its hot companion with the Hubble Space Telescope (HST) and the International Ultraviolet Explorer
A photometric and spectroscopic study of the brightest northern Cepheids — III. A high-resolution view of Cepheid atmospheres
• Physics
• 2000
We present new high-resolution spectroscopic observations (λ/Δλ≈40 000) of 18 bright northern Cepheids carried out at the David Dunlap Observatory in 1997. The measurements mainly extend those
Cepheid Masses: FUSE Observations of S Muscae
• Physics
• 2006
S Mus is the Cepheid with the hottest known companion. The large ultraviolet flux means that it is the only Cepheid companion for which the velocity amplitude could be measured with the echelle mode
THE SEARCH FOR LOW-MASS COMPANIONS OF B STARS IN THE CARINA NEBULA CLUSTER TRUMPLER 16*
We have developed lists of likely B3-A0 stars (called "late B" stars) in the young cluster Trumpler 16. The following criteria were used: location within 3' of η Car, an appropriate V and B - V
The primordial binary population. II.. Recovering the binary population for intermediate mass stars in Scorpius OB2
• Physics, Computer Science
• 2007
The fact that practically all stars in Sco OB2 are part of a binary (or multiple) system demonstrates that multiplicity is a fundamental factor in the star formation process, at least for intermediate mass stars.