Murchison Widefield Array upper limits on radio emission from the Proxima Centauri exoplanetary system at 154 MHz
ATel #9465; M. E. Bell (CSIRO / CAASTRO), C. Lynch (U. Sydney / CAASTRO), D. L. Kaplan (U. Wisconsin-Milwaukee), T. Murphy (U. Sydney / CAASTRO), B. Gaensler (U. Toronto / CAASTRO), N. Hurley-Walker (ICRAR / Curtin), P. Hancock (ICRAR / Curtin / CAASTRO), E. Lenc (U. Sydney / CAASTRO), J. Callingham (U. Sydney / CAASTRO), K. S. Dwarakanath (RRI), Bi-Qing For (ICRAR / UWA), T. Franzen (ICRAR / Curtin), L. Hindson (Victoria University of Wellington), C. Jackson (ICRAR / Curtin/ CAASTRO), M. Johnston-Hollitt (Victoria University of Wellington), A. D. Kapinska (ICRAR / UWA / CAASTRO), B. McKinley (U. Melbourne/CAASTRO), J. Morgan (ICRAR / Curtin), A. Offringa (ASTRON), P. Procopio (U. Melbourne / CAASTRO), L. Staveley-Smith (ICRAR / Curtin / CAASTRO), R. Wayth (ICRAR / Curtin / CAASTRO), C. Wu (ICRAR / UWA), Q. Zheng (Victoria University of Wellington)
on 6 Sep 2016; 23:06 UT
Credential Certification: Martin Bell (martinbell81@googlemail.com)
Subjects: Star, Transient
Anglada-Escude et al. (2016) recently reported the detection of an exoplanet orbiting our closest stellar neighbour, the red dwarf star Proxima Centauri. This system is known to produce transient radio emission at GHz frequencies (Lim et al 1996; Slee et al. 2003). Two factors that may affect the habitability of this exoplanet are the frequency and nature of flares from the host star, and whether the planet has a magnetosphere that can protect its atmosphere and surface from these stellar flares. In principle both of these can be investigated via low-frequency radio observations.
We observed Proxima Centauri repeatedly with the Murchison Widefield Array (Tingay et al. 2013) as part of the MWA Transients Survey (MWATS) at 154 MHz. Data were taken as 165 x 112-second observations (total 5.1 hours) spread out over 12 epochs in 2014-2016. The dates of the epochs and the number of observations obtained on those dates are given below. We see no flares in total intensity or circular polarization.
In Stokes I we measure 3-sigma upper limits at the location of the Proxima Centauri system (corrected for proper motion) of 120.3 to 1050.0 mJy/beam in individual exposures, with a median upper limit of 367.0 mJy/beam and a standard deviation of 184.8 mJy/beam (at 154 MHz). In Stokes V we measure 3-sigma upper limits of 129.2 to 1350.0 mJy/beam with a median upper limit of 345.0 mJy/beam and a standard deviation of 185.0 mJy/beam (at 154 MHz).
We find no radio emission at the position of Proxima Centauri in a deep image obtained from the Murchison Widefield Array Galactic and Extragalactic Survey (GLEAM; Wayth et al. 2015). We therefore place deeper upper limits on any steady-state radio emission from this system in Stokes I of 42.3 mJy/beam (3-sigma) at 200 MHz.
Date (N obs):
2014-02-10 (1),
2014-03-31 (18),
2014-04-28 (19),
2014-06-30 (19),
2014-07-15 (15),
2015-02-24 (17),
2015-04-14 (4),
2015-05-26 (8),
2015-06-07 (19),
2016-02-01 (7),
2016-03-01 (19),
2016-04-30 (19),
This scientific work makes use of the Murchison Radio-astronomy Observatory, operated by CSIRO. We acknowledge the Wajarri Yamatji people as the traditional owners of the Observatory site. Support for the operation of the MWA is provided by the Australian Government (NCRIS), under a contract to Curtin University administered by Astronomy Australia Limited. We acknowledge the Pawsey Supercomputing Centre which is supported by the Western Australian and Australian Governments.
References:
Tingay et al. (2013), PASA, 30, e007
Wayth et al. (2015), PASA, 32, e025
