Assigned ID: 141 ----- Attempting Submission 1 (Thu Feb 23 06:04:40 GMT 2012) ----- Hot Jupiters unleash photoevaporative winds that are powered by ionizing radiation from their parent stars. Spectral signatures of such winds have been observed with HST STIS and COS in various UV absorption lines from H I, O I, C II, Mg II, and Si III. Interpretation of these absorption signatures is still debated, and the metal line observations have seen little modeling. Absorption by H I Lyman-alpha occurs at velocities of +/- 100 km/s; such large velocities are difficult to explain because thermal outflows from hot Jupiters have speeds < 30 km/s. Holmstrom et al. (2009) proposed that the anomalously energetic H I arises from charge exchange between planetary H I and protons from the incident stellar wind. If true, then basic quantities--e.g., the planetary mass loss rate, which we hope to infer from the HST data--would need re-calculation to account for the influence of the stellar wind. Charge exchange has not yet been integrated into models of photoevaporative winds. We propose to carry out hydrodynamic simulations of colliding planetary and stellar winds, including charge exchange, that would explain the HST Ly-a observations, thereby clarifying how the inferred planetary mass loss rate depends on stellar wind parameters. We also propose to incorporate photoionization heating by metals, and radiative line cooling by metals, both of which have not been simultaneously treated. The goal will be to reproduce the many HST line spectra of neutral and ionized metals and determine their import for the metallicity and mass loss rate of the planetary wind. EXTRA-SOLAR PLANETS 12 Medium false 0.0 0.0 false false true false SUPPORTED