Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

An irradiated brown-dwarf companion to an accreting white dwarf

Nature volume 533, pages 366–368 (2016)Cite this article

Subjects

Abstract

Interacting compact binary systems provide a natural laboratory in which to study irradiated substellar objects. As the mass-losing secondary (donor) in these systems makes a transition from the stellar to the substellar regime, it is also irradiated by the primary (compact accretor)1,2. The internal and external energy fluxes are both expected to be comparable in these objects, providing access to an unexplored irradiation regime. The atmospheric properties of donors are largely unknown3, but could be modified by the irradiation. To constrain models of donor atmospheres, it is necessary to obtain accurate observational estimates of their physical properties (masses, radii, temperatures and albedos). Here we report the spectroscopic detection and characterization of an irradiated substellar donor in an accreting white-dwarf binary system. Our near-infrared observations allow us to determine a model-independent mass estimate for the donor of 0.055 ± 0.008 solar masses and an average spectral type of L1 ± 1, supporting both theoretical predictions and model-dependent observational constraints that suggest that the donor is a brown dwarf. Our time-resolved data also allow us to estimate the average irradiation-induced temperature difference between the dayside and nightside of the substellar donor (57 kelvin) and the maximum difference between the hottest and coolest parts of its surface (200 kelvin). The observations are well described by a simple geometric reprocessing model with a bolometric (Bond) albedo of less than 0.54 at the 2σ confidence level, consistent with high reprocessing efficiency, but poor lateral heat redistribution in the atmosphere of the brown-dwarf donor4,5. These results add to our knowledge of binary evolution, in that the donor has survived the transition from the stellar to the substellar regime, and of substellar atmospheres, in that we have been able to test a regime in which the irradiation and the internal energy of a brown dwarf are comparable.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: The average optical and near-infrared spectral energy distribution of SDSS J143317.78+101123.3.
Figure 2: Ellipsoidal and irradiation effects associated with the substellar donor in SDSS J143317.78+101123.3.

Similar content being viewed by others

References

  1. Knigge, C. The donor stars of cataclysmic variables. Mon. Not. R. Astron. Soc. 373, 484–502 (2006)

    Article  ADS  Google Scholar 

  2. Knigge, C., Baraffe, I. & Patterson, J. The evolution of cataclysmic variables as revealed by their donor stars. Astrophys. J. Suppl. 194, 28 (2011)

    Article  ADS  Google Scholar 

  3. Littlefair, S. P. et al. A J-band detection of the sub-stellar mass donor in SDSS J1433+1011. Mon. Not. R. Astron. Soc. 431, 2820–2825 (2013)

    Article  ADS  Google Scholar 

  4. Barman, T. S., Hauschildt, P. H. & Allard, F. Model atmospheres for irradiated stars in precataclysmic variables. Astrophys. J. 614, 338–348 (2004)

    Article  CAS  ADS  Google Scholar 

  5. Perez-Becker, D. & Showman, A. P. Atmospheric heat redistribution on hot Jupiters. Astrophys. J. 776, 134 (2013)

    Article  ADS  Google Scholar 

  6. Vernet, J. et al. X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope. Astron. Astrophys. 536, A105 (2011)

    Article  Google Scholar 

  7. Szkody, P. et al. Cataclysmic variables from Sloan Digital Sky Survey. VI. The sixth year (2005). Astron. J. 134, 185–194 (2007)

    Article  CAS  ADS  Google Scholar 

  8. Littlefair, S. P. et al. A brown dwarf mass donor in an accreting binary. Science 314, 1578–1580 (2006)

    Article  CAS  ADS  Google Scholar 

  9. Savoury, C. D. J. et al. Cataclysmic variables below the period gap: mass determinations of 14 eclipsing systems. Mon. Not. R. Astron. Soc. 415, 2025–2041 (2011)

    Article  ADS  Google Scholar 

  10. Hubeny, I. & Lanz, T. Non-LTE line-blanketed model atmospheres of hot stars. 1: hybrid complete linearization/accelerated lambda iteration method. Astrophys. J. 439, 875–904 (1995)

    Article  CAS  ADS  Google Scholar 

  11. Cushing, M. C., Rayner, J. T. & Vacca, W. D. An infrared spectroscopic sequence of M, L, and T dwarfs. Astrophys. J. 623, 1115–1140 (2005)

    Article  CAS  ADS  Google Scholar 

  12. Burgasser, A. J. et al. Not alone: tracing the origins of very-low-mass stars and brown dwarfs through multiplicity studies. In Protostars and Planets V (eds Reipurth, B. et al.) 427–441 (Univ. Arizona Press, 2007)

  13. Zorotovic, M., Schreiber, M. R. & Gänsicke, B. T. Post common envelope binaries from SDSS. XI. The white dwarf mass distributions of CVs and pre-CVs. Astron. Astrophys. 536, A42 (2011)

    Article  ADS  Google Scholar 

  14. Nordhaus, J. & Spiegel, D. S. On the orbits of low-mass companions to white dwarfs and the fates of the known exoplanets. Mon. Not. R. Astron. Soc. 432, 500–505 (2013)

    Article  ADS  Google Scholar 

  15. Gänsicke, B. T. et al. SDSS unveils a population of intrinsically faint cataclysmic variables at the minimum orbital period. Mon. Not. R. Astron. Soc. 397, 2170–2188 (2009)

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  17. Uthas, H., Knigge, C., Long, K. S., Patterson, J. & Thorstensen, J. The cataclysmic variable SDSS J1507+52: an eclipsing period bouncer in the Galactic halo. Mon. Not. R. Astron. Soc. 414, L85–L89 (2011)

    Article  ADS  Google Scholar 

  18. Arras, P. & Bildsten, L. Thermal structure and radius evolution of irradiated gas giant planets. Astrophys. J. 650, 394–407 (2006)

    Article  ADS  Google Scholar 

  19. Littlefair, S. P. et al. On the evolutionary status of short-period cataclysmic variables. Mon. Not. R. Astron. Soc. 388, 1582–1594 (2008)

    Article  CAS  ADS  Google Scholar 

  20. Ritter, H., Zhang, Z.-Y. & Kolb, U. Irradiation and mass transfer in low-mass compact binaries. Astron. Astrophys. 360, 969–990 (2000)

    ADS  Google Scholar 

  21. Ruciński, S. M. The proximity effects in close binary systems. II. The bolometric reflection effect for stars with deep convective envelopes. Acta Astron. 19, 245–255 (1969)

    ADS  Google Scholar 

  22. Stevenson, K. B. et al. Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy. Science 346, 838–841 (2014)

    Article  CAS  ADS  Google Scholar 

  23. Breton, R. P., Rappaport, S. A., van Kerkwijk, M. H. & Carter, J. A. KOI 1224: a fourth bloated hot white dwarf companion found with Kepler. Astrophys. J. 748, 115 (2012)

    Article  ADS  Google Scholar 

  24. Showman, A. P. & Kaspi, Y. Atmospheric dynamics of brown dwarfs and directly imaged giant planets. Astrophys. J. 776, 85 (2013)

    Article  ADS  Google Scholar 

  25. Tulloch, S. M., Rodríguez-Gil, P. & Dhillon, V. S. Radial velocity study of the post-period minimum cataclysmic variable SDSS J143317.78+101123.3 with an electron-multiplying CCD. Mon. Not. R. Astron. Soc. 397, L82–L86 (2009)

    Article  ADS  Google Scholar 

  26. Chanan, G. A., Middleditch, J. & Nelson, J. E. The geometry of the eclipse of a pointlike star by a Roche-lobe-filling companion. Astrophys. J. 208, 512–517 (1976)

    Article  ADS  Google Scholar 

  27. Lucy, L. B. Gravity-darkening for stars with convective envelopes. Z. Astrophys. 65, 89–92 (1967)

    ADS  Google Scholar 

  28. Cowan, N. B. & Agol, E. The statistics of albedo and heat recirculation on hot exoplanets. Astrophys. J. 729, 54 (2011)

    Article  ADS  Google Scholar 

Download references

Acknowledgements

This work is based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 085.D-0489. J.V.H.S. acknowledges support via studentships from CONACyT (Mexico) and the University of Southampton, as well as research support by the Royal Astronomical Society. R.P.B. has received funding from the European Union Eleventh Framework Programme under grant agreement PIIF-GA-2012-332393. B.T.G. was supported by ERC grant agreement number 320964. P.H.H. acknowledges computing time allocations at the Höchstleistungs Rechenzentrum Nord (HLRN), at the Regionales Rechenzentrum of the University of Hamburg and at the National Energy Research Supercomputer Center (NERSC), which is supported by the Office of Science of the US Department of Energy under contract number DE-AC03-76SF00098.

Author information

Authors and Affiliations

  1. Department of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK

    Juan V. Hernández Santisteban, Christian Knigge & Rene P. Breton

  2. Department of Physics and Astronomy, University of Sheffield, Sheffield, S3 7RH, UK

    Stuart P. Littlefair & Vikram S. Dhillon

  3. Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester, M13 9PL, UK

    Rene P. Breton

  4. Instituto de Astrofísica de Canarias, E-38205 La Laguna, Santa Cruz de Tenerife, Spain

    Vikram S. Dhillon

  5. Department of Physics, University of Warwick, Coventry, CV4 7AL, UK

    Boris T. Gänsicke & Thomas R. Marsh

  6. Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, UK

    Magaretha L. Pretorius

  7. Astrophysics Group, Keele University, Newcastle, ST5 5BG, UK

    John Southworth

  8. Hamburger Sternwarte, Gojenbergsweg 112, Hamburg, 21029, Germany

    Peter H. Hauschildt

Authors
  1. Juan V. Hernández Santisteban
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Christian Knigge
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Stuart P. Littlefair
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Rene P. Breton
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Vikram S. Dhillon
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Boris T. Gänsicke
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Thomas R. Marsh
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Magaretha L. Pretorius
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. John Southworth
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Peter H. Hauschildt
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

C.K., S.P.L., V.S.D., B.T.G., T.R.M., M.L.P. and J.S. proposed and planned the observations. All data analysis was done by J.V.H.S. with substantial feedback from C.K., R.P.B. and S.P.L. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Juan V. Hernández Santisteban.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 Posterior probability distributions for the irradiation model parameters.

Colour scale contours show the joint probability for every combination of parameters. Contours represent the 1σ, 2σ and 3σ levels. Marginal posterior distributions are shown as histograms with the median and 1σ marked as dashed lines. The AB distribution is quoted as a truncated distribution with a 2σ upper limit.

Extended Data Figure 2 Redistribution efficiency limits for the irradiated substellar donor.

Allowed family solutions of redistribution efficiencies ε as a function of Bond albedo AB are shown. The black and grey contours represent the 1σ and 2σ confidence levels, respectively.

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Santisteban, J., Knigge, C., Littlefair, S. et al. An irradiated brown-dwarf companion to an accreting white dwarf. Nature 533, 366–368 (2016). https://doi.org/10.1038/nature17952

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature17952

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing