Coherent radio emission from a quiescent red dwarf indicative of star–planet interaction

Vedantham, H. K.; Callingham, J. R.; Shimwell, T. W.; Tasse, C.; Pope, Benjamin; Bedell, Megan; Snellen, I. A. G.; Best, P. N.; Hardcastle, M. J.; Haverkorn, M.; Mechev, A. P.; O’Sullivan, Shane; Röttgering, H. J. A.; White, G. J.

doi:10.1038/s41550-020-1011-9

Cited by 133 publications

(124 citation statements)

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“…These signatures include induced chromospheric activity (e.g., Cauley et al., 2019;Shkolnik et al., 2008) or modulation of coronal radio emissions (Cohen et al., 2018). The direct detection of exoplanets magnetic fields (via radio observations of auroral emissions Zarka, 2007) has recently been reported (Vedantham et al., 2020). This has only confirmed the existence of the magnetosphere: More work is needed to be able to estimate, for example, the magnetic moment from these observations.…”

Section: Developments Needed In Measurements and Modeling Of Atmosphementioning

confidence: 99%

Atmospheric Escape Processes and Planetary Atmospheric Evolution

et al. 2020

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The habitability of the surface of any planet is determined by a complex evolution of its interior, surface, and atmosphere. The electromagnetic and particle radiation of stars drive thermal, chemical, and physical alteration of planetary atmospheres, including escape. Many known extrasolar planets experience vastly different stellar environments than those in our solar system: It is crucial to understand the broad range of processes that lead to atmospheric escape and evolution under a wide range of conditions if we are to assess the habitability of worlds around other stars. One problem encountered between the planetary and the astrophysics communities is a lack of common language for describing escape processes. Each community has customary approximations that may be questioned by the other, such as the hypothesis of H‐dominated thermosphere for astrophysicists or the Sun‐like nature of the stars for planetary scientists. Since exoplanets are becoming one of the main targets for the detection of life, a common set of definitions and hypotheses are required. We review the different escape mechanisms proposed for the evolution of planetary and exoplanetary atmospheres. We propose a common definition for the different escape mechanisms, and we show the important parameters to take into account when evaluating the escape at a planet in time. We show that the paradigm of the magnetic field as an atmospheric shield should be changed and that recent work on the history of Xenon in Earth's atmosphere gives an elegant explanation to its enrichment in heavier isotopes: the so‐called Xenon paradox.

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Section: Developments Needed In Measurements and Modeling Of Atmosphementioning

confidence: 99%

Atmospheric Escape Processes and Planetary Atmospheric Evolution

et al. 2020

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“…We used the standard LoTSS pipeline for primary data reduction (Shimwell et al 2017(Shimwell et al , 2019). An additional selfcalibration step was applied in the direction of the target with a pipeline that is described in Vedantham et al (2020). All images were made with wsclean with Brigg's weighting.…”

Section: A1 Data Reductionmentioning

confidence: 99%

“…We used the Background And Noise Estimator (BANE) and source finder AEGEAN (v 2.1.1; Hancock et al 2012Hancock et al , 2018 to measure the flux density and location of BDR J1750+3809. Originally, we discovered BDR J1750+3809through a blind search for sources that were >4σ in Stokes-V emission, where σ is the local rms noise (Callingham et al 2019;Vedantham et al 2020). Once the position of the source was known, we applied the prioritized fitting option of AEGEAN for the other epochs, which fits for both the point-spread function shape and flux density of BDR J1750+3809.…”

Section: A1 Data Reductionmentioning

confidence: 99%

“…Searching for circularly polarized radio sources has proved to be a powerful technique to identify coherent stellar radio emission (Lynch et al 2017a;Callingham et al 2020;Vedantham et al 2020). There are three known types of radio emitters with a high circularly polarized (CP) fraction: (a) stars, (b) brown dwarfs and planets, and (c) pulsars.…”

Section: Introductionmentioning

confidence: 99%

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Direct Radio Discovery of a Cold Brown Dwarf

Vedantham

Callingham

Shimwell

et al. 2020

ApJL

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Magnetospheric processes seen in gas giants such as aurorae and circularly polarized cyclotron maser radio emission have been detected from some brown dwarfs. However, previous radio observations targeted known brown dwarfs discovered via their infrared emission. Here we report the discovery of BDR J1750+3809, a circularly polarized radio source detected around 144 MHz with the Low-Frequency Array (LOFAR) telescope. Follow-up near-infrared photometry and spectroscopy show that BDR J1750+3809 is a cold methane dwarf of spectral type T6.5±1 at a distance of-+ 65 pc 8 9. The quasi-quiescent radio spectral luminosity of BDR J1750 +3809 is ≈5×10 15 erg s −1 Hz −1 , which is over two orders of magnitude larger than that of the known population of comparable spectral type. This could be due to a preferential geometric alignment or an electrodynamic interaction with a close companion. In addition, as the emission is expected to occur close to the electron gyrofrequency, the magnetic field strength at the emitter site in BDR J1750+3809 is B25 G, which is comparable to planetary-scale magnetic fields. Our discovery suggests that low-frequency radio surveys can be employed to discover substellar objects that are too cold to be detected in infrared surveys.

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“…Hence, at sufficiently high efficiencies, even a sub-Earth-mass planet is plausible.While the data presented in this Letter conclusively rule out stellar and gas-giant companions, there is a substantial region of parameter space for terrestrial planetary companions that cannot be excluded and the star-planet interaction hypothesis remains reasonable. Furthermore, from the radio observations ofVedantham et al (2020) alone, it is possible that the emission from the GJ 1151 system could originate 1 Assuming a Parker-spiral configuration for the stellar magnetic field.…”

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No Massive Companion to the Coherent Radio-emitting M Dwarf GJ 1151

Pope

Bedell

Callingham

et al. 2020

ApJL

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The recent detection of circularly polarized, long-duration (> 8 hr) low-frequency (∼150 MHz) radio emission from the M4.5 dwarf GJ 1151 has been interpreted as arising from a star-planet interaction via the electron cyclotron maser instability. The existence or parameters of the proposed planets have not been determined. Using 20 new HARPS-N observations, we put 99 th -percentile upper limits on the mass of any close companion to GJ 1151 at M sin i < 5.6 M ⊕ . With no stellar, brown dwarf, or giant planet companion likely in a close orbit, our data are consistent with detected radio emission emerging from a magnetic interaction between a short-period terrestrial-mass planet and GJ 1151.

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Coherent radio emission from a quiescent red dwarf indicative of star–planet interaction

Cited by 133 publications

References 41 publications

Atmospheric Escape Processes and Planetary Atmospheric Evolution

Atmospheric Escape Processes and Planetary Atmospheric Evolution

Direct Radio Discovery of a Cold Brown Dwarf

No Massive Companion to the Coherent Radio-emitting M Dwarf GJ 1151

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