EPIC 216747137: a new HW Vir eclipsing binary with a massive sdOB primary and a low-mass M-dwarf companion

Abstract

EPIC 216747137 is a new HW~Virginis system discovered by the Kepler spacecraft during its K2 "second life". Like the other HW Vir systems, EPIC 216747137 is a post-common-envelope eclipsing binary consisting of a hot subluminous star and a cool low-mass companion. The short orbital period of 3.87 hours produces a strong reflection effect from the secondary (~9% in the R band). Together with AA Dor and V1828 Aql, EPIC 216747137 belongs to a small subgroup of HW Vir systems with a hot evolved sdOB primary. We find the following atmospheric parameters for the hot component: Teff=40400$\pm$1000 K, logg=5.56$\pm$0.06, log(N(He)/N(H))=$-$2.59$\pm$0.05. The sdOB rotational velocity vsini=51$\pm$10 km/s implies that the stellar rotation is slower than the orbital revolution and the system is not synchronized. When we combine photometric and spectroscopic results with the Gaia parallax, the best solution for the system corresponds to a primary with a mass of about 0.62 Msun close to, and likely beyond, the central helium exhaustion, while the cool M-dwarf companion has a mass of about 0.11 Msun.

arXiv comment16 pages, 16 figures, MNRAS, accepted for publication

References in corpus (55)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III
• Gaia Data Release 2: The astrometric solution
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• Evolutionary models for cool brown dwarfs and extrasolar giant planets. The case of HD 20945
• Achieving better than 1 minute accuracy in the Heliocentric and Barycentric Julian Dates
• The Origin of Subdwarf B Star (I): the Formation Channels
• Gaia Data Release 2: Photometric content and validation
• The origin of sdB stars (II)
• Optimal Techniques in Two-dimensional Spectroscopy: Background Subtraction for the 21st Century
• SkyMapper Southern Survey: First Data Release (DR1)
• The unWISE Catalog: Two Billion Infrared Sources from Five Years of WISE Imaging
• Hot subluminous stars
• Spectroscopic Analysis of DA White Dwarfs: Stark Broadening of Hydrogen Lines Including Non-Ideal Effects
• The binary fraction of extreme horizontal branch stars
• An Analysis of the Shapes of Interstellar Extinction Curves. VII. Milky Way Spectrophotometric Optical-through-Ultraviolet Extinction and Its R-Dependence
• Gravity darkening in rotating stars
• SkyMapper Southern Survey: Second Data Release (DR2)
• CERES: A Set of Automated Routines for Echelle Spectra
• The Evolution of Early-Type Galaxies in Distant Clusters II: Internal Kinematics of 55 Galaxies in the z=0.33 Cluster CL1358+62
• Milky Way Mass Models for Orbit Calculations
• Can Planets Influence the Horizontal Branch Morphology?
• Close binary EHB stars from SPY
• A reanalysis of the Gaia Data Release 2 photometric sensitivity curves using HST/STIS spectrophotometry
• Precise mass and radius values for the white dwarf and low mass M dwarf in the pre-cataclysmic binary NN Serpentis
• Physical properties of IP Pegasi: an eclipsing dwarf nova with an unusually cool white dwarf
• 3D kinematics of white dwarfs from the SPY project II
• A Comparative Study of the Mass Distribution of Extreme Ultraviolet-Selected White Dwarfs
• Spectral analysis of sdB stars from the Hamburg Quasar Survey
• The scatter of the M dwarf mass-radius relationship
• Hot subdwarf binaries from the MUCHFUSS project - Analysis of 12 new systems and a study of the short-period binary population
• HS 0705+6700: a new eclipsing sdB binary
• The first ultracompact Roche lobe-filling hot subdwarf binary
• Single and Composite Hot Subdwarf Stars in the Light of 2MASS Photometry
• Alone but not lonely: Observational evidence that binary interaction is always required to form hot subdwarf stars
• Binaries discovered by the MUCHFUSS project SDSS J08205+0008 - An eclipsing subdwarf B binary with brown dwarf companion
• Binaries discovered by the MUCHFUSS project: SDSS J162256.66$+$473051.1 - An eclipsing subdwarf B binary with a brown dwarf companion
• Gravity and limb-darkening coefficients for compact stars: DA, DB, and DBA eclipsing white dwarfs
• The EREBOS project -- Investigating the effect of substellar and low-mass stellar companions on late stellar evolution
• Formation of sdB-stars via common envelope ejection by substellar companions
• Kepler detection of a new extreme planetary system orbiting the subdwarf-B pulsator KIC10001893
• How to Make a Singleton sdB Star via Accelerated Stellar Evolution
• A photometric and spectroscopic study of NSVS 14256825: the second sdOB+dM eclipsing binary
• Population Synthesis of Hot Subdwarfs: A Parameter Study
• An eclipsing post common-envelope system consisting of a pulsating hot subdwarf B star and a brown dwarf companion
• A quantitative spectral analysis of 14 hypervelocity stars from the MMT survey
• On the sdOB primary of the post common-envelope binary AA Doradus (LB 3459)
• Tidal Interactions in Post Common-Envelope sdB Binaries
• Hot Subdwarf Stars Identified in Gaia DR2 with Spectra of LAMOST DR6 and DR7. II. Kinematics
• Kinematics of Subluminous O and B Stars by Surface Helium Abundance
• Hot Subdwarf All Southern Sky Fast Transit Survey with the Evryscope
• No close companions to a sample of bright sdB stars

Cited by in corpus (7)

• The population of hot subdwarf stars studied with Gaia -- IV. Catalogues of hot subluminous stars based on Gaia EDR3
• A hot subdwarf-white dwarf super-Chandrasekhar candidate supernova Ia progenitor
• A Catalogue of Potential Post Common Envelope Binaries
• Filling the gap between synchronized and non-synchronized sdBs in short-period sdBV+dM binaries with TESS: TIC 137608661, a new system with a well defined rotational splitting
• K2 photometry on oscillation mode variability: the new pulsating hot B subdwarf star EPIC 220422705
• Space observations of AA Doradus provide consistent mass determinations. New HW-Vir systems observed with TESS
• Anomalous Orbital Characteristics of the AQ Col (EC 05217-3914) System