The ultra-cool white dwarf companion of PSR J0751+1807

Abstract

We present optical and near-infrared observations with Keck of the binary millisecond pulsar PSR J0751+1807. We detect a faint, red object - with R=25.08+-0.07, B-R=2.5+-0.3, and R-I=0.90+-0.10 - at the celestial position of the pulsar and argue that it is the white dwarf companion of the pulsar. The colours are the reddest among all known white dwarfs, and indicate a very low temperature, Teff~4000 K. This implies that the white dwarf cannot have the relatively thick hydrogen envelope that is expected on evolutionary grounds. Our observations pose two puzzles. First, while the atmosphere was expected to be pure hydrogen, the colours are inconsistent with this composition. Second, given the low temperature, irradiation by the pulsar should be important, but we see no evidence for it. We discuss possible solutions to these puzzles.

9 pages, 3 figures, accepted for publication in A&A

References in corpus (4)

• The ATNF Pulsar Catalogue
• The ATNF Pulsar Catalogue
• A 2.1 Solar Mass Pulsar Measured by Relativistic Orbital Decay
• The Mass of a Millisecond Pulsar

Cited by in corpus (20)

• The Second Fermi Large Area Telescope Catalog of Gamma-ray Pulsars
• The NANOGrav Nine-year Data Set: Mass and Geometric Measurements of Binary Millisecond Pulsars
• The formation of low-mass helium white dwarfs orbiting pulsars: Evolution of low-mass X-ray binaries below the bifurcation period
• On type Ia supernovae and the formation of single low-mass white dwarfs
• Multi-periodic pulsations of a stripped red giant star in an eclipsing binary
• The timescale of low-mass proto-helium white dwarf evolution
• Discovery of the Eclipsing Detached Double White Dwarf Binary NLTT 11748
• The spectrum of the recycled PSR J0437-4715 and its white dwarf companion
• A Catalogue of Potential Post Common Envelope Binaries
• Additional Ultracool White Dwarfs Found in the Sloan Digital Sky Survey
• Inferring the composition of super-Jupiter mass companions of pulsars with radio line spectroscopy
• Cool white dwarf companions to four millisecond pulsars
• Long-term timing of four millisecond pulsars
• Evolution of Low-Mass X-ray Binaries: the Effect of Donor Evaporation
• The ultracool helium-atmosphere white dwarf companion of PSR J0740+6620?
• Progenitor neutron stars of the lightest and heaviest millisecond pulsars
• Searching for optical companions to four binary millisecond pulsars with the Gran Telescopio Canarias
• Diagnosing pulsar winds in black-widow, redback, and other binary millisecond pulsar systems
• On the effect of pulsar evaporation on the cooling of white dwarfs
• Possible tidal dissipation in millisecond pulsar binaries