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Open Astronomy

formerly Baltic Astronomy

Editor-in-Chief: Barbuy, Beatriz


IMPACT FACTOR 2018: 0.350

CiteScore 2018: 0.24

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ICV 2018: 120.66

Open Access
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ISSN
2543-6376
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Volume 27, Issue 1

Issues

Chemical fingerprints of He-sdO stars

Markus Schindewolf / Peter Németh / Ulrich Heber / Tiara Battich
  • Instituto de Astrofísica de La Plata, CONICET-UNLP, Argentina; Facultad de Ciencias Astronómicas y Geofísicas, UNLP, La Plata, Argentina
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Marcelo M. Miller Bertolami / Marilyn Latour
Published Online: 2018-02-28 | DOI: https://doi.org/10.1515/astro-2018-0010

Abstract

The chemical composition of helium-rich hot subluminous O stars plays an important role to understand and model their formation history. We present a spectroscopic analysis of four He-sdO stars,CD-31° 4800, [CW83] 0904- 02, LSS 1274 and LS IV +10° 9. The analysis is based on archival optical and UV high-resolution spectra. We used Tlusty200/Synspec48 to compute line blanketed non-LTE model atmospheres and their corresponding synthetic spectra and derive the atmospheric parameters as well as the abundances of the most prominent elements. All stars have helium-dominated atmospheres with hardly any hydrogen and temperatures between 42000 K and 47000 K while their surface gravity spans between log g = 5.4 and 5.7. CD-31° 4800 shows an enrichment of nitrogen and the characteristic pattern of hydrogen burning via the CNO-cycle, while the rest of the elements have about the solar abundance. This points to the slow merger of two helium white dwarfs as the most likely origin for this system. The other three stars are enriched in carbon, nitrogen and neon while their intermediate mass element’s abundance scatters around the solar value. They were possibly formed in the deep mixing late hot flasher scenario.

Keywords: subdwarfs; abundances; He-sdO; hot flasher; slow merger; atmospheric parameters; stellar atmospheres

References

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About the article

Received: 2017-09-29

Accepted: 2017-12-07

Published Online: 2018-02-28


Citation Information: Open Astronomy, Volume 27, Issue 1, Pages 27–34, ISSN (Online) 2543-6376, DOI: https://doi.org/10.1515/astro-2018-0010.

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© 2018, published by De Gruyter. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License. BY-NC-ND 4.0

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