Letter to the Editor
Radius and distance estimates of the isolated neutron stars Geminga and PSR B0656+14 using optical photometry
Received 2 October 1998 / Accepted 10 December 1998
Integrated ground-based and HST optical studies of isolated neutron stars have provided important independent datasets in the determination of emission activity, particularly in the fitting of anticipated Rayleigh-Jeans extrapolations from EUV/soft X-ray datasets, despite their intrinsic faintness. Differentiation of the pulsed and unpulsed fluxes and consequently of the nonthermal and thermal modes of emission could provide definitive data with which to constrain this blackbody continuum. Based upon high speed photometric observations of Geminga and PSR B0656+14 in the B band, we have combined upper limits of unpulsed emission with recently published model-fits with a view to assessing possible implications for the parameter. For Geminga, with a known distance of 160 pc, we find that 9.5 km for a blackbody source, and 10.0 km with the presence of a magnetized H atmosphere. In addition, we suggest that PSR B0656+14 is some 4-5 times closer than the 760 pc estimated from DM measurements alone.
Key words: stars: pulsars: individual: Geminga, PSR B0656+14
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© European Southern Observatory (ESO) 1999
Online publication: December 22, 1998