Radio Observations of HD 80606 Near Planetary Periastron
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This paper reports Very Large Array observations at 325 and 1425 MHz lambda 90 cm and lambda 20 cm during and near the periastron passage of HD 80606b on HJD 2454424.86 2007 November 20. We obtain flux density limits 3 sigma of 1.7mJy and micro-Jy at 325 and 1425 MHz, respectively, equivalent to planetary luminosity limits of 2.3 x 10exp 24 ergs and 2.7 x 10exp 23 ergs. Unfortunately, these are several orders of magnitude above the nominal Jovian value at 40 MHz of 2 x 10exp 18 ergs. The motivation for these observations was that the planetary magnetospheric emission is driven by a stellar-wind-planetary-magnetosphere interaction so that the planetary luminosity would be elevated near periastron. We estimate that, near periastron, HD80606b might be as much as 3000 times more luminous than Jupiter. Recent transit observations of HD 80606b provide reasonably stringent constraints on the planetary mass and radius, and, because of the planets highly eccentric orbit, its rotation period is likely to be pseudo-synchronized to its orbital period, allowing a robust estimate of the former. Consequently,we are able to make relatively robust estimates of the emission frequency of the planetary magnetospheric emission and find it to be around 60-90 MHz. While this is too low for our reported observations, we compare HD 80606b to other high-eccentricity systems and assess the detection possibilities for both near-term and more distant future systems.