EDP Sciences
Free Access
Volume 440, Number 2, September III 2005
Page(s) 693 - 700
Section Stellar structure and evolution
DOI https://doi.org/10.1051/0004-6361:20052987

A&A 440, 693-700 (2005)
DOI: 10.1051/0004-6361:20052987

The near-UV pulse profile and spectrum of the pulsar PSR B0656+14

Yu. A. Shibanov1, J. Sollerman2, P. Lundqvist2, T. Gull3 and D. Lindler3, 4

1  Ioffe Physico-Technical Institute, Politekhnicheskaya 26, 194021 St. Petersburg, Russia
    e-mail: shib@astro.ioffe.ru
2  Stockholm Observatory, AlbaNova Science Center, Department of Astronomy, 106 91 Stockholm, Sweden
3  Goddard Space Flight Center, Exploration of the Universe Division, Code 667, USA
4  Advanced Computer Concepts, Inc. Potomac, MD, USA

(Received 4 March 2005 / Accepted 1 June 2005 )

We have observed the middle-aged pulsar PSR B0656+14 with the prism and the NUV MAMA detector of the Space Telescope Imaging Spectrograph (STIS) to measure the pulsar spectrum and periodic pulsations in the near-ultraviolet (NUV). The pulsations are clearly detected, double-peaked and very similar to the optical pulse profile. The NUV pulsed fraction is $70\pm12$%. The spectral slope of the dereddened phase-integrated spectrum in the ~ 1800-3200 Å range is ~ $\alpha_{\nu}=0.35\pm0.5$ which together with the high pulse fraction indicates a non-thermal origin for the NUV emission. The total flux in the range ~ 1700-3400 Å is estimated to be $3.4\pm0.3\times10^{-15}$ erg s-1 cm-2 when corrected for E(B-V)=0.03 mag. At a distance of 288 pc this corresponds to a luminosity $L_{\rm NUV}=3.4\times10^{28}$ erg s-1 assuming isotropy of the emission. We compare the NUV pulse profile with observations from radio to gamma-rays. The first NUV sub-pulse is in phase with the gamma-ray pulse marginally detected with EGRET, while the second NUV sub-pulse is similar both in shape and in phase with the non-thermal pulse in hard X-rays. This indicates a single origin of the non-thermal emission in the optical-NUV and in the X-rays. This is also supported by the observed NUV spectral slope, which is compatible with a blackbody plus power-law fit extended from the X-ray range, but dominated by the power-law component in most of the NUV range.

Key words: stars: pulsars: individual: PSR B0656+14 -- stars: pulsars: individual: PSR J0659+1414

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© ESO 2005