GALEX J184559.8-413827: a new extreme helium star identified using SALT
arXiv:1706.03377 · doi:10.1093/mnras/stx1442
Abstract
A high-resolution spectrum of the helium-rich `hot subdwarf' GALEX J184559.8-413827 (J1845-4138) obtained with SALT HRS demonstrates it to be the first extreme helium (EHe) star to be discovered in nearly 40 years. A quantitative analysis demonstrates it to have an atmosphere described by Teff = 26 170 +/- 750 K, log g /(cm s^-2) = 4.22 +/- 0.10, and a surface chemistry characterised by CNO-processed helium, a 1% contamination of hydrogen (by number), and a metallicity 0.4 dex subsolar. Its distance and position are consistent with membership of the Galactic bulge. Its sharp absorption lines place strong constraints on both the rotation and microturbulent velocities. Spectroscopically, J1845-4138 closely resembles the pulsating EHe star V652 Her, generally considered to be the product of a double helium white dwarf merger evolving to become a helium-rich sdO star.
arXiv commentMNRAS, in press, 10 pages, 6 figures
References in corpus (24)
- The Sloan Digital Sky Survey: Technical Summary
- The chemical composition of the Sun
- Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
- Flash Mixing on the White Dwarf Cooling Curve: Understanding Hot Horizontal Branch Anomalies in NGC 2808
- A selection of hot subluminous stars in the GALEX survey II. Subdwarf atmospheric parameters
- Hot subdwarfs from the ESO Supernova Ia Progenitor Survey: II. Atmospheric parameters of subdwarf O stars
- Modeling He-rich subdwarfs through the hot-flasher Scenario
- The Ultraviolet Sky: An Overview from the GALEX Surveys
- Double white dwarf mergers and elemental surface abundances in extreme helium and R Coronae Borealis stars
- An extremely peculiar hot subdwarf with a ten-thousand-fold excess of zirconium, yttrium, and strontium
- New binaries among UV-selected, hot subdwarf stars and population properties
- On the formation of single and binary helium-rich sdO stars
- Discovery of extremely lead-rich subdwarfs: does heavy metal signal the formation of subdwarf B stars?
- On helium-dominated stellar evolution: the mysterious role of the O(He)-type stars
- Discovery of a variable lead-rich hot subdwarf: UVO 0825+15
- A selection of hot subluminous stars in the GALEX survey I. Correlation with the Guide Star Catalog
- Abundance analyses of helium-rich subluminous B stars
- The helium-rich subdwarf CPD-20 1123: a post-common envelope binary evolving onto the extended horizontal branch
- Hydrogen in hot subdwarfs formed by double helium white dwarf mergers
- Neon and CNO Abundances for Extreme Helium Stars -- A Non-LTE Analysis
- Extreme helium stars: non-LTE matters Helium and hydrogen spectra of the unique objects V652 Her and HD144941
- Spectroscopic Orbital Elements for the Helium-Rich Subdwarf Binary PG1544+488
- A search for new hot subdwarf stars by means of Virtual Observatory tools II
- Subaru and Swift observations of V652 Herculis: resolving the photospheric pulsation
Cited by in corpus (14)
- Evolutionary models for R Coronae Borealis stars
- Further insight on the hypervelocity white dwarf, LP 40-365 (GD 492): a nearby emissary from a single-degenerate Type Ia supernova
- The SALT survey of helium-rich hot subdwarfs: methods, classification, and coarse analysis
- Evolving R Coronae Borealis Stars with MESA
- Modeling R Coronae Borealis Stars: Effects of He-Burning Shell Temperature and Metallicity
- A search for heavy-metal stars: abundance analyses of hot subdwarfs with Subaru
- Non-Local Thermodynamic Equilibrium abundance analyses of the extreme helium stars: V652 Her and HD 144941
- Detection of fluorine in hot Extreme Helium Stars
- Revised surface abundances of R Coronae Borealis stars
- Spectroscopic analysis of BPS CS 22940-0009: connecting evolved helium stars
- The distribution, kinematics and luminosities of extreme helium stars as probes of their origin and evolution
- Abundance analysis of a nitrogen-rich extreme-helium hot subdwarf from the SALT survey
- Detection of Enhanced Germanium in a New Cool Extreme Helium Star A 980: Insights and Implications
- Merged white dwarfs and nucleosynthesis