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Survival of a brown dwarf after engulfment by a red giant star


Many sub-stellar companions (usually planets but also some brown dwarfs) orbit solar-type stars. These stars can engulf their sub-stellar companions when they become red giants. This interaction may explain several outstanding problems in astrophysics1,2,3,4,5 but it is unclear under what conditions a low mass companion will evaporate, survive the interaction unchanged or gain mass1,4,5. Observational tests of models for this interaction have been hampered by a lack of positively identified remnants—that is, white dwarf stars with close, sub-stellar companions. The companion to the pre-white dwarf AA Doradus may be a brown dwarf, but the uncertain history of this star and the extreme luminosity difference between the components make it difficult to interpret the observations or to put strong constraints on the models6,7. The magnetic white dwarf SDSS J121209.31 + 013627.7 may have a close brown dwarf companion8 but little is known about this binary at present. Here we report the discovery of a brown dwarf in a short period orbit around a white dwarf. The properties of both stars in this binary can be directly observed and show that the brown dwarf was engulfed by a red giant but that this had little effect on it.

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Figure 1: Trailed spectrograms of WD 0137–349.
Figure 2: Infrared flux distribution of WD 0137–349.


  1. Nelemans, G. & Tauris, T. M. Formation of undermassive single white dwarfs and the influence of planets on late stellar evolution. Astron. Astrophys. 335, L85–L88 (1998)

    ADS  Google Scholar 

  2. Soker, N. & Harpaz, A. Rotation, planets, and the ‘second parameter’ of the horizontal branch. Mon. Not. R. Astron. Soc. 317, 861–866 (2000)

    Article  ADS  Google Scholar 

  3. Harpaz, A. & Soker, N. Evaporation of brown dwarfs in AGB envelopes. Mon. Not. R. Astron. Soc. 270, 734–742 (1994)

    Article  ADS  Google Scholar 

  4. Livio, M. & Soker, N. Star-planet systems as progenitors of cataclysmic binaries: tidal effects. Astron. Astrophys. 125, L12–L15 (1983)

    ADS  Google Scholar 

  5. Siess, L. & Livio, M. The accretion of brown dwarfs and planets by giant stars–II. Solar-mass stars on the red giant branch. Mon. Not. R. Astron. Soc. 308, 1133–1149 (1999)

    Article  ADS  CAS  Google Scholar 

  6. Rauch, T. AA Dor—an eclipsing subdwarf - brown dwarf binary. Rev. Mex. Astron. Astrophys. Ser. Conf. 20, 246 (2004)

    ADS  Google Scholar 

  7. Hilditch, R. W., Kilkenny, D., Lynas-Gray, A. E. & Hill, G. New VIC photometry of the sdOB binary AA Dor and an improved photometric model. Mon. Not. R. Astron. Soc. 344, 644–650 (2003)

    Article  ADS  Google Scholar 

  8. Schmidt, G. D. et al. Discovery of a magnetic white dwarf/probable brown dwarf short-period binary. Astrophys. J. 630, L173–L176 (2005)

    Article  ADS  CAS  Google Scholar 

  9. Preston, G. W., Shectman, S. A. & Beers, T. C. Photoelectric UBV photometry of stars selected in the HK objective-prism survey. Astrophys. J. Suppl. 76, 1001–1031 (1991)

    Article  ADS  Google Scholar 

  10. Beers, T. C., Doinidis, S. P., Griffin, K. E., Preston, G. W. & Shectman, S. A. Spectroscopy of hot stars in the Galactic halo. Astron. J. 103, 267–296 (1992)

    Article  ADS  CAS  Google Scholar 

  11. Napiwotzki, et al. Search for progenitors of supernovae type Ia with SPY. Astron. Nachr. 322, 411–418 (2001)

    Article  ADS  CAS  Google Scholar 

  12. Liebert, J. W. Extrasolar planetary companions and brown dwarfs. In Encyclopedia of Astronomy and Astrophysics (ed. Murdin, P.) (2002); (Institute of Physics Publishing, Bristol, 2002)

    Google Scholar 

  13. Farihi, J., Becklin, E. E. & Zuckerman, B. Low-luminosity companions to white dwarfs. Astrophys. J. Suppl. 161, 394–428 (2005)

    Article  ADS  CAS  Google Scholar 

  14. Littlefair, S. P., Dhillon, V. S. & Martín, E. L. On the evidence for brown dwarf secondary stars in cataclysmic variables. Mon. Not. R. Astron. Soc. 340, 264–268 (2003)

    Article  ADS  CAS  Google Scholar 

  15. Littlefair, S. P., Dhillon, V. S. & Martín, E. L. The K-band spectrum of the cataclysmic variable RXJ 0502.8 + 1624 (Tau 4). Astron. Astrophys. 437, 637–639 (2005)

    Article  ADS  CAS  Google Scholar 

  16. Schreiber, M. R. & Gänsicke, B. T. The age, life expectancy, and space density of Post Common Envelope Binaries. Astron. Astrophys. 406, 305–321 (2003)

    Article  ADS  Google Scholar 

  17. Politano, M. The formation of cataclysmic variable stars with brown dwarf secondaries. Astrophys. J. 604, 817–826 (2004)

    Article  ADS  Google Scholar 

  18. Endl, M. et al. HD 137510: An oasis in the brown dwarf desert. Astrophys. J. 611, 1121–1124 (2004)

    Article  ADS  Google Scholar 

  19. Grether, D. & Lineweaver, C. H. How dry is the brown dwarf desert? Quantifying the relative number of planets, brown dwarfs, and stellar companions around nearby Sun-like stars. Astrophys. J. 640, 1051–1062 (2006)

    Article  ADS  CAS  Google Scholar 

  20. Nelemans, G. & Tout, C. A. Reconstructing the evolution of white dwarf binaries: further evidence for an alternative algorithm for the outcome of the common-envelope phase in close binaries. Mon. Not. R. Astron. Soc. 356, 753–764 (2005)

    Article  ADS  CAS  Google Scholar 

  21. Marsh, T. R., Dhillon, V. S. & Duck, S. R. Low-mass white dwarfs need friends–Five new double-degenerate close binary stars. Mon. Not. R. Astron. Soc. 275, 828–840 (1995)

    Article  ADS  Google Scholar 

  22. Maxted, P. F. L., Marsh, T. R., Moran, C., Dhillon, V. S. & Hilditch, R. W. The mass and radius of the M dwarf companion to GD448. Mon. Not. R. Astron. Soc. 300, 1225–1232 (1998)

    Article  ADS  CAS  Google Scholar 

  23. Koester, D. et al. High-resolution UVES/VLT spectra of white dwarfs observed for the ESO SN Ia progenitor survey (SPY). Astron. Astrophys. 378, 556–568 (2001)

    Article  ADS  CAS  Google Scholar 

  24. Benvenuto, O. G. & Althaus, L. G. Grids of white dwarf evolutionary models with masses from M = 0.1 to 1.2 M . Mon. Not. R. Astron. Soc. 303, 30–38 (1999)

    Article  ADS  CAS  Google Scholar 

  25. Driebe, T., Schönberner, D., Blöcker, T. & Herwig, F. The evolution of helium white dwarfs. I. The companion of the millisecond pulsar PSR J1012 + 5307. Astron. Astrophys. 339, 123–133 (1998)

    ADS  CAS  Google Scholar 

  26. Bergeron, P., Wesemael, F. & Beauchamp, A. Photometric calibration of hydrogen- and helium-rich white dwarf models. Publ. Astron. Soc. Pacif. 107, 1047–1054 (1995)

    Article  ADS  Google Scholar 

  27. Vauclair, G., Schmidt, H., Koester, D. & Allard, N. White dwarfs observed by the HIPPARCOS satellite. Astron. Astrophys. 325, 1055–1062 (1997)

    ADS  Google Scholar 

  28. Dobbie, P. D. et al. A near-infrared spectroscopic search for very-low-mass cool companions to notable DA white dwarfs. Mon. Not. R. Astron. Soc. 357, 1049–1058 (2005)

    Article  ADS  CAS  Google Scholar 

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This Letter is based on observations collected at the European Southern Observatory, Chile, and makes use of data products from the Two Micron All Sky Survey (2MASS). P.D.D. is supported by PPARC. R.N. and M.R.B. acknowledge the support of PPARC Advanced Fellowships. Author Contributions P.F.L.M. analysed and interpreted the data from which the orbital period and other properties of the system were measured. R.N. identified WD 0137–349 as a strong candidate for a brown dwarf companion to a white dwarf from observations obtained as part of the SPY programme, of which he is the principal investigator. M.R.B. and P.D.D. analysed the 2MASS data for this object. All authors discussed and interpreted the results and commented on the manuscript.

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Correspondence to P. F. L. Maxted.

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Maxted, P., Napiwotzki, R., Dobbie, P. et al. Survival of a brown dwarf after engulfment by a red giant star. Nature 442, 543–545 (2006).

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