Orbital effects of non-isotropic mass depletion of the atmospheres of evaporating hot Jupiters in extrasolar systems

We analytically and numerically investigate the long-term, i.e. averaged over one full revolution, orbital effects of the non-isotropic percent mass loss \dot m/m experienced by several transiting hot Jupiters whose atmospheres are hit by severe radiations flows coming from their close parent stars. The semi-major axis a, the argument of pericenter \omega and the mean anomaly M experience net variations, while the eccentricity e, the inclination I and the longitude of the ascending node remain unchanged, on average. In particular, a increases independently of e and of the speed Vesc of the ejected mass. By assuming |\dot m| <= 10^17 kg yr-1, corresponding to |\dot m/m| <= 10^-10 yr-1 for a Jupiter-like planet, it turns out \dot a = 2.5 m yr^-1 for orbits with a = 0.05 au. Such an effect may play a role in the dynamical history of the hot Jupiters, especially in connection with the still unresolved issue of the arrest of the planetary inward migrations after a distance a >= 0.01 au is reached. The retrograde pericenter variation depends, instead, on e and V_esc. It may, in principle, act as a source of systematic uncertainty in some proposed measurements of the general relativistic pericenter precession; however, it turns out to be smaller than it by several orders of magnitude.Comment: LaTex2e, 16 pages, no tables, 6 figures. To appear in New Astronomy (NA

The Great Escape: How Exoplanets and Smaller Bodies Desert Dying Stars

Mounting discoveries of extrasolar planets orbiting post-main sequence stars motivate studies aimed at understanding the fate of these planets. In the traditional "adiabatic" approximation, a secondary's eccentricity remains constant during stellar mass loss. Here, we remove this approximation, investigate the full two-body point-mass problem with isotropic mass loss, and illustrate the resulting dynamical evolution. The magnitude and duration of a star's mass loss combined with a secondary's initial orbital characteristics might provoke ejection, modest eccentricity pumping, or even circularisation of the orbit. We conclude that Oort clouds and wide-separation planets may be dynamically ejected from 1-7 Solar-mass parent stars during AGB evolution. The vast majority of planetary material which survives a supernova from a 7-20 Solar-mass progenitor will be dynamically ejected from the system, placing limits on the existence of first-generation pulsar planets. Planets around >20 Solar-mass black hole progenitors may easily survive or readily be ejected depending on the core collapse and superwind models applied. Material ejected during stellar evolution might contribute significantly to the free-floating planetary population.Comment: 23 pages, 16 figures, accepted for publication in MNRA