EDP Sciences
Free access
Volume 479, Number 3, March I 2008
Page(s) 793 - 803
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20077728

A&A 479, 793-803 (2008)
DOI: 10.1051/0004-6361:20077728

Possible optical detection of a fast, nearby radio pulsar PSR B1133+16

S. V. Zharikov1, Yu. A. Shibanov2, R. E. Mennickent3, and V. N. Komarova4, 5

1  Observatorio Astronómico Nacional SPM, Instituto de Astronomía, Universidad Nacional Autónomia de México, Ensenada, BC, México
    e-mail: zhar@astrosen.unam.mx
2  Ioffe Physical Technical Institute, Politekhnicheskaya 26, St. Petersburg 194021, Russia
    e-mail: shib@astro.ioffe.ru
3  Departamento de Fisica, Universidad de Concepcion, Casilla 160-C, Concepcion, Chile
    e-mail: rmennick@stars.cfm.udec.cl
4  Special Astrophysical Observatory, Russian Academy of Science, Nizhnii Arkhyz, Russia, 369167
    e-mail: vkom@sao.ru
5  Isaac Newton Institute of Chile, SAO Branch, Russia

(Received 26 April 2007 / Accepted 1 November 2007)

Aims.We performed deep optical observations of the field of an old, fast-moving radio pulsar PSR B1133+16 in an attempt to detect its optical counterpart and a bow shock nebula.
Methods.The observations were carried out using the direct imaging mode of FORS1 at the ESO VLT/UT1 telescope in the B, R, and H$_\alpha$ bands. We also used archival images of the same field obtained with the VLT in the B band and with the Chandra/ACIS in X-rays.
Results. In the B band we detected a faint (B = 28 $.\!\!^{\rm m}$1 $\pm$ 0 $.\!\!^{\rm m}$3) source that may be the optical counterpart of PSR B1133+16, as it is positionally consistent with the radio pulsar and with the X-ray counterpart candidate published earlier. Its upper limit in the R band implies a color index B-R $\la$ 0 $.\!\!^{\rm m}$5, which is compatible with the index values for most pulsars identified in the optical range. The derived optical luminosity and its ratio to the X-ray luminosity of the candidate are consistent with expected values derived from a sample of pulsars detected in both spectral domains. No Balmer bow shock was detected, implying a low density of ambient matter around the pulsar. However, in the X-ray and H$_\alpha$ images we found the signature of a trail extending ~ $ 4^{\prime\prime}{-}5^{\prime\prime}$ behind the pulsar and coinciding with the direction of its proper motion. If confirmed by deeper studies, this is the first time such a trail has been seen in the optical and X-ray wavelengths.
Conclusions.Further observations at later epochs are necessary to confirm the identification of the pulsar by the candidate's proper motion measurements.

Key words: pulsars: general -- pulsars: individual: PSR B1133+16 -- stars: neutron

© ESO 2008