Multicolor photometry of the Vela pulsar

Abstract

Multicolor photometry of the Vela pulsar (PSR B0833-45), updated by recent HST/WFPC2 observations obtained in the 555W, 675W and 814W filters, is presented. The available data provide the best characterization so far of the pulsar spectral shape, which is dominated by a flat power law continuum with spectral index alpha = -0.2 +/- 0.2, consistent with the extrapolation in the optical domain of the power law component of the X-ray spectrum detected by CHANDRA. In addition, a marginally significant dip (~3sigma ) seems to be present at about 6500 Å. Spectroscopic observations with the VLT, now in progress, will undoubtly provide a much better assessment of the reality and characteristics of this feature. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc. under contract No. NAS 5-26555.}\fnmsep\thanks{Based on observations collected at the European Southern Observatory, La Silla, Chile.