A search for radio emission from exoplanets around evolved stars
Artikel i vetenskaplig tidskrift, 2018

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.

planets and satellites: aurorae

radio continuum: planetary systems

surveys

planets and satellites: magnetic fields

stars: evolution

planets and satellites: detection

Författare

Eamon O Gorman

Dublin Institute for Advanced Studies

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

C. P. Coughlan

Dublin Institute for Advanced Studies

Wouter Vlemmings

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Galaktisk astrofysik

Eskil Varenius

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium, Onsala rymdobservatorium, Observationssupport

S. Sirothia

Square Kilometre Array

Rhodes University

Tata Institute of Fundamental Research

T. P. Ray

Dublin Institute for Advanced Studies

H. Olofsson

Unknown organization

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 612 A52

Magnetic fields and the outflows during the formation and evolution of stars (OUTFLOWMAGN)

Europeiska kommissionen (FP7), 2014-05-01 -- 2019-04-30.

Ämneskategorier

Astronomi, astrofysik och kosmologi

Fusion, plasma och rymdfysik

Den kondenserade materiens fysik

DOI

10.1051/0004-6361/201731965