Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published May 23, 2003 | Published + Submitted
Journal Article Open

Temperature and cooling age of the white dwarf companion of PSR J0218+4232

Abstract

We report on Keck optical BVRI images and spectroscopy of the companion of the binary millisecond pulsar PSR J0218+4232. A faint bluish (V = 24.2, B - V = 0.25) counterpart is observed at the pulsar location. Spectra of this counterpart reveal Balmer lines which confirm that the companion is a helium-core white dwarf. We find that the white dwarf has a temperature of T_(eff) = 8060 ± 150 K. Unfortunately, the spectra are of insufficient quality to put a strong constraint on the surface gravity, although the best fit is for low log g and hence low mass (~0.2 M_⊙), as expected. We compare predicted white dwarf cooling ages with the characteristic age of the pulsar and find similar values for white dwarf masses of 0.19 to 0.3 M_⊙. These masses would imply a distance of 2.5 to 4 kpc to the system. The spectroscopic observations also enable us to estimate the mass ratio between the white dwarf and the pulsar. We find q = 7.5 ± 2.4, which is consistent with the current knowledge of white dwarf companions to millisecond pulsars.

Additional Information

© 2003 ESO. Received: 7 February 2003. Accepted: 6 March 2003. C.G.B. is indebted to F. Hulleman for help with the photometry. We thank P. Bergeron, A. Serenelli and B. Stappers for very useful discussions about white dwarf atmospheres, white dwarf interiors and radio observations, respectively. The observations reported here were obtained at the W.M. Keck Observatory, which is operated by the California Association for Research in Astronomy. The reduction was done using the Munich Image Data Analysis System, which is developed and maintained by the European Southern Observatory. This research made use of the SIMBAD database. M.H.v.K. acknowledges support of a fellowship of the Royal Netherlands Academy of Arts and Sciences, and S.R.K. of grants from NSF and NASA.

Attached Files

Published - aah4293.pdf

Submitted - 0303439.pdf

Files

0303439.pdf
Files (607.9 kB)
Name Size Download all
md5:97ed5c49e282268e205c5591d710f430
287.2 kB Preview Download
md5:6c37afb6934157dcfafc02f84471e881
320.7 kB Preview Download

Additional details

Created:
August 22, 2023
Modified:
October 18, 2023