Radial velocity variable, hot post-AGB stars from the MUCHFUSS project - Classification, atmospheric parameters, formation scenarios
Abstract
In the course of the MUCHFUSS project we recently discovered four radial velocity (RV) variable, hot (T_(eff)≈ 80 000−110 000 K) post-asymptotic giant branch (AGB) stars. Among them, we found the first known RV variable O(He) star, the only second known RV variable PG 1159 close binary candidate, as well as the first two naked (i.e., without planetary nebula (PN)) H-rich post-AGB stars of spectral type O(H) that show significant RV variations. We present a non-LTE spectral analysis of these stars along with one further O(H)-type star whose RV variations were found to be not significant. We also report the discovery of a far-infrared excess in the case of the PG 1159 star. None of the stars in our sample displays nebular emission lines, which can be explained well in terms of a very late thermal pulse evolution in the case of the PG 1159 star. The "missing" PNe around the O(H)-type stars seems strange, since we find that several central stars of PNe have much longer post-AGB times. Besides the non-ejection of a PN, the occurrence of a late thermal pulse, or the re-accretion of the PN in the previous post-AGB evolution offer possible explanations for those stars not harbouring a PN (anymore). In the case of the O(He) star J0757, we speculate that it might have been previously part of a compact He transferring binary system. In this scenario, the mass transfer must have stopped after a certain time, leaving behind a low-mass close companion that may be responsible for the extreme RV shift of 107.0 ± 22.0 km s^(-1) that was measured within only 31 min.
Additional Information
© 2016 ESO. Received 24 October 2015; Accepted 5 January 2016; Published online 25 February 2016. N.R. was supported by DFG (grant WE 1312/41-1) and DLR (grant 50OR 1507). We thank Marcelo Miguel Miller Bertolami for providing us with the post-AGB tracks before they were published. We thank Thomas Rauch and Peter van Hoof for helpful discussions and comments. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). Based on observations with the William Herschel and Isaac Newton Telescopes operated by the Isaac Newton Group at the Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias on the island of La Palma, Spain. Funding for SDSSIII has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the US Department of Energy Office of Science. The SDSS-III web site is http://www.sdss3.org/. SDSSIII is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University. This research made use of the VizieR catalogue access tool, CDS, Strasbourg, France.Attached Files
Published - aa27637-15.pdf
Submitted - 1601.00874v1.pdf
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Additional details
- Alternative title
- RV variable, hot post-AGB stars from the MUCHFUSS project - Classification, atmospheric parameters, formation scenarios
- Eprint ID
- 66615
- Resolver ID
- CaltechAUTHORS:20160503-101820755
- WE 1312/41-1
- Deutsche Forschungsgemeinschaft (DFG)
- 50OR 1507
- Deutschen Zentrums für Luft- und Raumfahrt (DLR)
- Alfred P. Sloan Foundation
- Participating Institutions
- NSF
- Department of Energy (DOE)
- Created
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2016-05-03Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field