GMRT search for 150 MHz radio emission from the transiting extrasolar planets HD189733b and HD209458b

TL;DR

This study used the GMRT to search for 150 MHz radio emissions from two transiting exoplanets, setting upper limits on their emissions and discussing implications of the non-detections.

Contribution

It provides the first sensitive upper limits on meter-wavelength emissions from HD189733b and HD209458b using GMRT observations.

Findings

No emission detected from HD209458b with an upper limit of 3.6 mJy.

A marginal detection near HD189733b with about 1.9 mJy, but unconfirmed.

Established tight upper limits for radio emissions from these exoplanets.

Abstract

We report a sensitive search for meter-wavelength emission at 150 MHz from two prominent transiting extrasolar planets, HD189733b and HD209458b. To distinguish any planetary emission from possible stellar or background contributions, we monitored these systems just prior to, during, and after the planet's eclipse behind the host star. No emission was detected from HD209458b with a 3-sigma upper limit of 3.6 mJy. For HD189733b we obtain a 3-sigma upper limit of 2.1 mJy and a marginal 2.7-sigma detection of about 1.9+/-0.7 mJy from a direction just 13" from the star's coordinates (i.e., within the beam), but its association with the planet remains unconfirmed. Thus, the present GMRT observations provide unprecedentedly tight upper limits for meter wavelengths emissions from these nearest two transiting type exoplanets. We point out possible explanations of the non-detections and briefly discuss the resulting constraints on these systems.