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Probable optical counterpart of the eclipsing millisecond pulsar system, 1957 + 20

Kulkarni, S. R. and Djorgovski, S. and Fruchter, A. S. (1988) Probable optical counterpart of the eclipsing millisecond pulsar system, 1957 + 20. Nature, 334 (6182). pp. 504-506. ISSN 0028-0836. doi:10.1038/334504a0.

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Following the discovery of an eclipsing, millisecond pulsar 1957+20 (ref. 1) we conducted a series of optical observations to identify the optical counterpart of the system. We report the detection of a probably variable object (hereafter star X) with a mean apparent V magnitude of ∼20 within the astrometric error circle of the equatorial radio position of the pulsar. Star X appears fainter at orbital phase 0.21, the onset of the pulsar eclipse, compared with the quadrature position, suggesting that it is probably the optical counterpart. We argue that the secondary heated by the pulsar wind and not the pulsar itself makes the dominant contribution to the visible radiation from this system. The absolute magnitude of star X is M_v ≈ 10.5, assuming a distance of ∼ 0.8 kpc derived from the dispersion measure. The optical luminosity of the counterpart directly measures the fraction of the pulsar wind power responsible for heating the secondary. Future optical observations may be able to constrain the nature of the pulsar wind.

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Kulkarni, S. R.0000-0001-5390-8563
Djorgovski, S.0000-0002-0603-3087
Additional Information:© 1988 Nature Publishing Group. Received 23 May; accepted 8 July 1988. We thank M. Shara and the other members of the Hubble Space Telescope Guide Star Project for permission to use the Guide Star Catalog, R. Lucas and D. Rehner for help in extracting the astrometric data of the secondary stars, J. Schombert for help in digitizing at the Jet Propulsion Laboratory, J. Cohen for obtaining the earlier CCD images, and R. J. Rand, J. M. Hester and the staff at Palomar Observatory for assistance with the observations. The Palomar 60-in telescope is operated jointly by the California Institute of Technology and the Carnegie Institution of Washington. This work was supported in part by the California Institute of Technology.
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Issue or Number:6182
Record Number:CaltechAUTHORS:20190724-160106243
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ID Code:97396
Deposited By: Tony Diaz
Deposited On:24 Jul 2019 23:10
Last Modified:16 Nov 2021 17:31

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