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Open Astronomy

formerly Baltic Astronomy

Editor-in-Chief: Barbuy, Beatriz


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2543-6376
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Volume 26, Issue 1

Issues

Are sdAs helium core stars?

Ingrid Pelisoli
  • Corresponding author
  • Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, 91501-900, Brazil
  • Email
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ S. O. Kepler
  • Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, 91501-900, Brazil
  • Email
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Detlev Koester
Published Online: 2017-12-29 | DOI: https://doi.org/10.1515/astro-2017-0433

Abstract

Evolved stars with a helium core can be formed by non-conservative mass exchange interaction with a companion or by strong mass loss. Their masses are smaller than 0.5 M⊙. In the database of the Sloan Digital Sky Survey (SDSS), there are several thousand stars which were classified by the pipeline as dwarf O, B and A stars. Considering the lifetimes of these classes on the main sequence, and their distance modulus at the SDSS bright saturation, if these were common main sequence stars, there would be a considerable population of young stars very far from the galactic disk. Their spectra are dominated by Balmer lines which suggest effective temperatures around 8 000-10 000 K. Several thousand have significant proper motions, indicative of distances smaller than 1 kpc. Many show surface gravity in intermediate values between main sequence and white dwarf, 4.75 < log g < 6.5, hence they have been called sdA stars. Their physical nature and evolutionary history remains a puzzle. We propose they are not H-core main sequence stars, but helium core stars and the outcomes of binary evolution. We report the discovery of two new extremely-low mass white dwarfs among the sdAs to support this statement.

Keywords: white dwarfs; subdwarfs; binaries

References

  • Althaus, L. G., Miller Bertolami, M. M., Córsico, A. H. 2013, A&A, 557, A19.Google Scholar

  • Althaus, L. G., Serenelli, A. M., Córsico, A. H., Montgomery, M. H. 2003, A&A, 404, 593-609.Google Scholar

  • Badenes, C., Maoz, D. 2012, ApJ, 749, L11.Google Scholar

  • Bland-Hawthorn, J., Gerhard, O. 2016, Annual Review of Astronomy and Astrophysics, 54, 529-596.Google Scholar

  • Brown, W. R., Beers, T. C., Wilhelm, R., Allende-Prieto, C., Geller, M. J., Kenyon, S. J., et al. 2008, ApJ, 135, 564-574.Google Scholar

  • Brown, W. R., Gianninas, A., Kilic, M., Kenyon, S. J., Allende Prieto, C. 2016, ApJ, 818, 155.Google Scholar

  • Brown, W. R., Kilic, M., Allende Prieto, C., Gianninas, A., Kenyon, S. J. 2013, ApJ, 769, 66.Google Scholar

  • Brown, W. R., Kilic, M., Allende Prieto, C., Kenyon, S. J. 2010, ApJ, 723, 1072-1081.Google Scholar

  • Brown, W. R., Kilic, M., Allende Prieto, C., Kenyon, Scott J. 2012, ApJ, 744, 142.Google Scholar

  • Brown, W. R., Kilic, M., Gianninas, A. 2017, ApJ, 839, 23.Google Scholar

  • Clewley, L., Warren, S. J., Hewett, P. C., Norris, J. E., Evans, N. W. 2004, MNRAS, 352, 285-298.Google Scholar

  • De Rosa, R. J., Patience, J., Wilson, P. A., Schneider, A., Wiktorowicz, S. J., Vigan, A. 2014, MNRAS, 437, 1216-1240.Google Scholar

  • Duchêne G., Kraus A. 2013, ARA&A, 51, 269-310.Google Scholar

  • Gentile-Fusillo, N. P., Gaensicke, B. T., Greiss, S. 2015, MNRAS, 448, 2260-2274.Google Scholar

  • Gianninas, A., Kilic, M., Brown, W. R., Canton, P., Kenyon, S. J. 2015, ApJ, 812, 167.Google Scholar

  • Hermes, J. J., G´’ansicke, B. T., Breedt, E. 2017, In: P.-E. Tremblay, B. Gaensicke, T. Marsh (Ed.), Proceedings of 20th European White Dwarf Workshop (25-29 July 2016, Coventry, UK), ASP Conference Series, 509, 453-459.Google Scholar

  • Istrate, A. G., Marchant, P., Tauris, T. M., Langer, N., Stancliffe, R. J., Grassitelli, L. 2016, A&A, 595, A35.Google Scholar

  • Johnson, D. R. H. and Soderblom, D. R. 1987, AJ, 93, 864-867.Google Scholar

  • Kepler, S. O., Pelisoli, I., Koester, D., Ourique, G., Romero, A. D., Reindl, N. et al. 2016, MNRAS, 455, 3413-3423.Google Scholar

  • Kilic, M., Brown, W. R., Allende Prieto, C., Ag´’ueros, M. A., Heinke, C., Kenyon, S. J. 2011, ApJ, 727, 3.Google Scholar

  • Kilic, M., Brown, W. R., Allende Prieto, C., Kenyon, S. J., Heinke, C. O., Ag´’ueros, M. A., et al. 2012, ApJ, 751, 141.Google Scholar

  • Kilic, M., Stanek, K. Z., Pinsonneault, M. H. 2007, ApJ, 671, 761-766.Google Scholar

  • Kinman, T. D., Suntzeff, N. B., Kraft, R. P. 1994, AJ, 108, 1722-1772.Google Scholar

  • Koester, D. 2010, MmSAI, 81, 921-931.Google Scholar

  • Kordopatis, G., Recio-Blanco, A., de Laverny, P., Gilmore, G., Hill, V., Wyse, R. F. G. 2011, A&A, 535, A107.Google Scholar

  • Lance, C. M. 1988, AJ, 334, 927-946.Google Scholar

  • Lenz, P., Breger, M. 2005, Communications in Asteroseismology, 46, 53-136.Google Scholar

  • Maxted, P. F. L., Bloemen, S., Heber, U., Geier, S., Wheatley, P. J., Marsh, T. R. et al. 2014, MNRAS, 437, 1681-1697.Google Scholar

  • Munn, J. A., Monet, D. G., Levine, S. E., Canzian, B., Pier, J. R., Harris, H. C. et al. 2004, AJ, 127, 3034-3042.Google Scholar

  • Munn, J. A., Harris, H. C., von Hippel, T., Kilic, M., Liebert, J. W., Williams, K. A. et al. 2014, AJ, 148, 132.Google Scholar

  • Norris, J.E. & Hawkins, M.R.S. 1991, 380, 104-115.Google Scholar

  • Pelisoli, I., Kepler, S. O., Koester, D., Romero, A. D. 2017, In: P.-E.Google Scholar

  • Tremblay, B. Gaensicke, T. Marsh (Ed.), Proceedings of 20th European White Dwarf Workshop (25-29 July 2016, Coventry, UK), ASP Conference Series, 509, 447-452.Google Scholar

  • Preston, G. W., Beers, T. C., Shectman, S. A. 1994, AJ, 108, 538-554.Google Scholar

  • Rodgers, A. W., Harding, P., Sadler, E. 1981, AJ, 244, 912-918.Google Scholar

  • Romero, A. D., Campos, F., Kepler, S. O. 2015, MNRAS, 450, 3708-3723.Google Scholar

  • Schneider, F. R. N., Izzard, R. G., Langer, N., de Mink, S. E. 2015, ApJ, 805, 20.Google Scholar

  • Tokovinin A. 2014, AJ, 147, 87.Google Scholar

  • Xue, X. X., Rix, H. W., Zhao, G., Re Fiorentin, P., Naab, T., Steinmetz, M. et al. 2008, ApJ, 684, 1143-1158.Google Scholar

  • Yuan, H. B., Liu, X. W., Xiang, M. S. 2013, MNRAS, 430, 2188-2199.Google Scholar

About the article

Received: 2017-09-30

Accepted: 2017-10-23

Published Online: 2017-12-29

Published in Print: 2017-12-20


Citation Information: Open Astronomy, Volume 26, Issue 1, Pages 169–178, ISSN (Online) 2543-6376, DOI: https://doi.org/10.1515/astro-2017-0433.

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

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