Possibility of Detecting Moons of Pulsar Planets through Time-of-Arrival Analysis
Abstract
The perturbation caused by planet-moon binarity on the time-of-arrival signal of a pulsar with an orbiting planet is derived for the case in which the orbits of the moon and the planet-moon barycenter are both circular and coplanar. The signal consists of two sinusoids with frequency (2np - 3nb) and (2np - nb), where np and nb are the mean motions of the planet and moon around their barycenter, and the planet-moon system around the host, respectively. The amplitude of the signal is the fraction sin I [ 9(MpMm)/16(Mp + Mm)2][r/R]5 of the system crossing time R/c, where Mp and Mm are the masses of the planet and moon, r is their orbital separation, R is the distance between the host pulsar and planet-moon barycenter, I is the inclination of the orbital plane of the planet, and c is the speed of light. The analysis is applied to the case of PSR B1620-26b, a pulsar planet, to constrain the orbital separation and mass of any possible moons. We find that a stable moon orbiting this pulsar planet could be detected, if its mass were >5% of its planet's mass, and if the planet-moon distance were ~2% of the planet-pulsar separation.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 2008
- DOI:
- 10.1086/592743
- arXiv:
- arXiv:0805.4263
- Bibcode:
- 2008ApJ...685L.153L
- Keywords:
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- planetary systems;
- pulsars: general;
- pulsars: individual: PSR B1620–26;
- stars: oscillations;
- Astrophysics
- E-Print:
- 11 pages, 3 figures