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The majority of searches for radio emission from exoplanets have to date focused on short period planets, i.e., the so-called hot Jupiter type planets. However, these planets are likely to be tidally locked to their host stars and may not generate sufficiently strong magnetic fields to emit electron cyclotron maser emission at the low frequencies used in observations (typically >150 MHz). In comparison, the large mass-loss rates of evolved stars could enable exoplanets at larger orbital distances to emit detectable radio emission. Here, we first show that the large ionized mass-loss rates of certain evolved stars relative to the solar value could make them detectable with the Low Frequency Array (LOFAR) at 150 MHz ($lambda$ = 2 m), provided they have surface magnetic field strengths >50 G. We then report radio observations of three long period (>1 au) planets that orbit the evolved stars $beta$ Gem, $iota$ Dra, and $beta$ UMi using LOFAR at 150 MHz. We do not detect radio emission from any system but place tight 3$sigma$ upper limits of 0.98, 0.87, and 0.57 mJy on the flux density at 150 MHz for $beta$ Gem, $iota$ Dra, and $beta$ UMi, respectively. Despite our non-detections these stringent upper limits highlight the potential of LOFAR as a tool to search for exoplanetary radio emission at meter wavelengths.
In this paper, we investigate the detectability of radio emission from exoplanets, especially hot Jupiters, which are magnified by gravitational microlensing. Because hot Jupiters have orbital periods much shorter than the characteristic timescale of
The CARMENES exoplanet survey of M dwarfs has obtained more than 18 000 spectra of 329 nearby M dwarfs over the past five years as part of its guaranteed time observations (GTO) program. We determine planet occurrence rates with the 71 stars from the
Like the magnetised planets in our Solar System, magnetised exoplanets should emit strongly at radio wavelengths. Radio emission directly traces the planetary magnetic fields and radio detections can place constraints on the physical parameters of th
We present a sensitive search for methanol line emission in evolved stars at 1 cm, aiming to detect, for the first time, methanol masers in this type of objects. Our sample comprised post-AGB stars and young planetary nebulae (PNe), whose mass-loss p
We report the results of a 154 MHz survey to search for emission from exoplanets located in the Upper Scorpius subgroup of the Sco Cen OB2 Association, the closest substantial region of recent star formation. This survey is different from previous ef