Optical Observations of Binary Millisecond Pulsar Companions

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Session 47 -- Binary Stars
Display presentation, Thursday, June 15, 1995, 9:20am - 4:00pm

[47.03] Optical Observations of Binary Millisecond Pulsar Companions

S.C.Lundgren (NRL/NRC), J.M.Cordes (Cornell), R.S.Foster (NRL), A. Wolszczan (PSU), F.Camilo (Princeton)

Understanding the age and evolutionary history of millisecond pulsars (MSP) can be greatly enhanced by careful multi-color photometry of the white dwarf (WD) companions to binary MSPs. In observations at the Palomar 5-meter telescope, we have discovered two candidate companions of binary MSPs (m$_r$=24-25) in observations of 4 sources. We report the measured colors for sources observed at the positions of PSR J2145-0750 and PSR J1640+2224. For PSR J2229+2643 and PSR J0751+1807 we present upper limits. The luminosity and colors of the WD companions place constraints on the companion mass and age of the system, based on WD cooling models. With characteristic ages $>$13 billion years, PSR J1640+22 and PSR J2145-0750 could have been among the first pulsars formed in the galaxy. The estimated companion masses combined with the mass functions from timing the pulsars places upper bounds on the neutron star masses, potentially revealing clues about both the supernova explosions which created the neutron stars, and the later accretion which spun them up to millisecond periods.

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