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:

The optical counterpart of the isolated neutron star RX J185635−3754

Nature volume 389, pages 358–360 (1997)Cite this article

An Erratum to this article was published on 20 November 1997

Abstract

The extreme densities1 of neutron stars make them an ideal system in which to investigate the equation of state of nuclear matter; accurate determinations of neutron star masses and radii are crucial for this. Current observations of neutron stars in binary systems yield masses that are generally consistent with theory2. But measurements of radii are more difficult as they require the detection of thermal radiation from the surface, which in general is masked by emission from non-thermal processes in radio pulsars3 and X-ray binary systems4. Isolated radio-quiet neutron stars5 offer the best opportunity to observe the surface thermal emission. Here we report the detection of the optical counterpart of a candidate isolated neutron star, RX J185635−3754 (ref. 6). Our optical flux data, combined with existing extreme ultraviolet7 and X-ray6 observations, show the spectrum to be approximately thermal. By adopting the upper bound to the distance of the source, and assuming a plausible model for the spectral energy distribution, we find that the radius of the object cannot exceed 14 km. This result is inconsistent with a number of recent equations of state8 proposed for neutron stars.

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 central 400 × 400 pixels (17.5 × 17.5 arcsec) of the planetary camera images.
Figure 2: The spectral energy distribution of RX J185635−3754.

Similar content being viewed by others

References

  1. Baym, G. & Pethick, C. Physics of neutron stars. Annu. Rev. Astron. Astrophys. 17, 415–443 (1979).

    Article  ADS  CAS  Google Scholar 

  2. van Paradijs, J. & McClintock, J. E. in X-Ray Binaries (eds Lewin, W. H. G., van Paradijs, J. & van den Heuvel, E. P. J.) 58–125 (Cambridge Univ. Press, (1995)).

    Google Scholar 

  3. Phinney, E. S. & Kulkarni, S. R. Binary and millisecond pulsars. Annu. Rev. Astron. Astrophys. 32, 591–639 (1994).

    Article  ADS  Google Scholar 

  4. White, N. E., Nagase, F. & Parmar, A. N. in X-Ray Binaries (eds Lewin, W. H. G., van Paradijs, J. & van den Heuvel, E. P. J.) 1–57 (Cambridge Univ. Press, (1995)).

    Google Scholar 

  5. Carraveo, P. A., Bignami, G. F. & Trümper, J. Radio-silent isolated neutron stars as a new astronomical reality. Astron. Astrophys. Rev. 7, 209–216 (1996).

    Article  ADS  Google Scholar 

  6. Walter, F. M., Wolk, S. J. & Neuhäuser, R. Discovery of a nearby isolated neutron star. Nature 379, 233–235 (1996).

    Article  ADS  CAS  Google Scholar 

  7. Lampton, M. et al. An all-sky catalog of faint Extreme Ultraviolet sources. Astrophys. J. Suppl. 108, 545–557 (1997).

    Article  ADS  Google Scholar 

  8. Prakash, M. & Lattimer, J. M. The radius of the neutron star RX J185635-3754 and implications for the equation of state. Astrophys. J. Lett.(submitted).

  9. Marraco, H. G. & Rydgren, A. E. On the distance and membership of the R CrA T association. Astron. J. 86, 62–68 (1981).

    Article  ADS  CAS  Google Scholar 

  10. Wang, Q. D. in The Soft X-Ray Cosmos (AIP Conference Proceedings 313) (eds Schlegel, E. M. & Petre, R.) 301–305 (AIP, New York, (1994)).

    Google Scholar 

  11. Neuhäuser, R., Thomas, H.-C., Danner, R., Peschke, S. & Walter, F. M. On the X-ray position and deep optical imaging of the neutron star candidate RXJ1856.5-3754. Astron. Astrophys. 318, L43–L46 (1996).

    ADS  Google Scholar 

  12. Campana, S., Mereghetti, S. & Sidoli, L. Is RXJ1856.5-3754 an old neutron star? Astron. Astrophys. 320, 783–786 (1997).

    ADS  Google Scholar 

  13. Leitherer, C. (ed.) HST Data Handbook (Space Telescope Science Inst., Baltimore, (1995)).

    Google Scholar 

  14. Seaton, M. Interstellar extinction in the UV. Mon. Not. R. Astron. Soc. 187, 73P–76P (1979).

    Article  ADS  Google Scholar 

  15. Bignami, G. F., Caraveo, P. A., Mignani, R., Edelstein, J. & Bowyer, S. Multiwavelength data suggest cyclotron feature on the hot thermal continuum of Geminga. Astrophys. J. Lett. 456, L111–L114 (1996).

    Article  ADS  Google Scholar 

  16. Pavlov, G. G., Stringfellow, G. S. & Córdova, F. A. Hubble Space Telescope observations of pulsars. Astrophys. J. 467, 370–384 (1996).

    Article  ADS  Google Scholar 

  17. Blaes, O., Warren, O. & Madau, P. Accreting, isolated neutron stars: III. Preheating of infalling gas and cometary H II regions. Astrophys. J. 454, 370–381 (1995).

    Article  ADS  CAS  Google Scholar 

  18. Greenstein, G. & Hartke, G. J. Pulselike character of blackbody radiation from neutron stars. Astrophys. J. 271, 283–293 (1983).

    Article  ADS  CAS  Google Scholar 

  19. Pavlov, G. G., Zavlin, V., Trümper, J. & Neuhäuser, R. Multiwavelength observations of isolated neutron stars as a tool to prove the properties of their surfaces. Astrophys. J. Lett. 472, L33–L36 (1996).

    Article  ADS  CAS  Google Scholar 

  20. Holtzman, J. A. et al. The photometric performance and calibration of WFPC2. Pub. Astron. Soc. Pacif. 107, 1065–1093 (1995).

    Article  ADS  Google Scholar 

  21. Fruchter, A. S. & Hook, R. N. in The Hubble Space Telescope and the High Redshift Universe (eds Tanvir, N. R., Salamanca, A. & Wall, J. V.) (World Scientific, Singapore, (1997)).

    Google Scholar 

Download references

Acknowledgements

We thank A. M. Watson for performing the bulk of the image reduction, and J. Holtzman for peparing and providing the delta dark and superdark frames necessary for our data; we also thank them both for their time and patience in the discussion of data reduction issues. We acknowledge useful discussions with P. An, J. Lattimer and R. Neuhäuser.

Author information

Authors and Affiliations

  1. Department of Physics and Astronomy, Z = 3800, State University of New York, Stony Brook, 11794-3800, New York, USA

    Frederick M. Walter & Lynn D. Matthews

Authors
  1. Frederick M. Walter
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Lynn D. Matthews
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Frederick M. Walter.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Walter, F., Matthews, L. The optical counterpart of the isolated neutron star RX J185635−3754. Nature 389, 358–360 (1997). https://doi.org/10.1038/38682

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/38682

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