A search for auroral radio emission from β Pictoris b

Shiohira, Yuta; Fujii, Yuka; Kita, Hajime; Kimura, Tomoki; Terada, Yuka; Takahashi, Keitaro

doi:10.1093/mnras/stad3990

Cited by 4 publications

(1 citation statement)

References 117 publications

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“…Observations have also not provided strong magnetic field constraints. Extensive efforts have been made to connect planetary magnetic field strength to, e.g., the circulation of neutral gas (Perna et al 2010;Menou 2012;Rauscher & Menou 2012;Batygin et al 2013;Rauscher & Menou 2013;Rogers & Komacek 2014;Rogers & Showman 2014;Rogers & McElwaine 2017;Beltz et al 2021;Knierim et al 2022) and their velocities measured with high-resolution spectroscopy (Kempton & Rauscher 2012;Beltz et al 2022Beltz et al , 2023, UV transit timing asymmetries from bow shocks (e.g., Vidotto et al 2011;Kislyakova et al 2014), radio auroral emission from the planet (e.g., Zarka 2007;Narang et al 2024;Shiohira et al 2024) and star (e.g., Pineda & Villadsen 2023), and helium line velocity measurements (Schreyer et al 2024) and spectropolarimetry (Oklopčić et al 2020). Despite these efforts, success has been isolated (Ben-Jaffel et al 2022), indirect (Cauley et al 2019), or difficult to reconcile across repeated observations (e.g., Lally & Vanderburg 2022;Turner et al 2023).…”

Section: Introductionmentioning

confidence: 99%

A New Lever on Exoplanetary B Fields: Measuring Heavy Ion Velocities

Savel,

Beltz,

Komacek

et al. 2024

ApJL

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Magnetic fields connect an array of planetary processes, from atmospheric escape to interior convection. Despite their importance, exoplanet magnetic fields are largely unconstrained by both theory and observation. In this Letter, we propose a novel method for constraining the B field strength of hot gas giants: comparing the velocities of heavy ions and neutral gas with high-resolution spectroscopy. The core concept of this method is that ions are directly deflected by magnetic fields. While neutrals are also affected by B fields via friction with field-accelerated ions, ionic gas should be more strongly coupled to the underlying magnetic field than bulk neutral flow. Hence, measuring the difference between the two velocities yields rough constraints on the B field, provided an estimate of the stellar UV flux is known. We demonstrate that heavy ions are particularly well suited for this technique because they are less likely to be entrained in complex hydrodynamic outflows than their lighter counterparts. We perform a proof-of-concept calculation with Ba ii, an ion whose velocity has been repeatedly measured at high confidence with high-resolution spectroscopy. Our work shows that a 10 G magnetic field would produce ∼1 km s−1 ion–neutral velocity differences at a microbar, whereas a 50 G magnetic field would produce ∼20 km s−1 velocity difference. With new leverage on magnetic fields, we will be able to investigate magnetic field generation in the extreme edge cases of hot gas giants, with wide-ranging consequences for planetary interior structure, dynamo theory, and habitability.

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Section: Introductionmentioning

confidence: 99%

A New Lever on Exoplanetary B Fields: Measuring Heavy Ion Velocities

Savel,

Beltz,

Komacek

et al. 2024

ApJL

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The Sydney Radio Star Catalogue: Properties of radio stars at megahertz to gigahertz frequencies

Driessen,

Pritchard,

Murphy

et al. 2024

Publ. Astron. Soc. Aust.

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We present the Sydney Radio Star Catalogue, a new catalogue of stars detected at megahertz to gigahertz radio frequencies. It consists of 839 unique stars with 3 405 radio detections, more than doubling the previously known number of radio stars. We have included stars from large area searches for radio stars found using circular polarisation searches, cross-matching, variability searches, and proper motion searches as well as presenting hundreds of newly detected stars from our search of Australian SKA Pathfinder observations. The focus of this first version of the catalogue is on objects detected in surveys using SKA precursor and pathfinder instruments; however, we will expand this scope in future versions. The 839 objects in the Sydney Radio Star Catalogue are distributed across the whole sky and range from ultracool dwarfs to Wolf-Rayet stars. We demonstrate that the radio luminosities of cool dwarfs are lower than the radio luminosities of more evolved sub-giant and giant stars. We use X-ray detections of 530 radio stars by the eROSITA soft X-ray instrument onboard the Spectrum Roentgen Gamma spacecraft to show that almost all of the radio stars in the catalogue are over-luminous in the radio, indicating that the majority of stars at these radio frequencies are coherent radio emitters. The Sydney Radio Star Catalogue can be found in Vizier or at https://radiostars.org.

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Follow-up LOFAR observations of the τ Boötis exoplanetary system

Turner,

Grießmeier,

Zarka

et al. 2024

A&A

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o tis (tau Boo) exoplanetary system was tentatively detected using LOFAR (LOW-Frequency ARray) beamformed observations. If confirmed, this detection will be a major contribution to exoplanet science. However, follow-up observations are required to confirm this detection. Here, we present such follow-up observations of the tau Boo system using LOFAR. These observations cover 70$<!PCT!>$ of the orbital period of tau Boo b including the orbital phases of the previous tentative detections. We used the BOREALIS pipeline to mitigate radio frequency interference and to search for bursty and slowly varying radio signals. BOREALIS was previously used to find the tentative radio signals from tau Boo. o tis exoplanetary system. o tis exoplanetary system.

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A search for auroral radio emission from β Pictoris b

Cited by 4 publications

References 117 publications

A New Lever on Exoplanetary B Fields: Measuring Heavy Ion Velocities

A New Lever on Exoplanetary B Fields: Measuring Heavy Ion Velocities

The Sydney Radio Star Catalogue: Properties of radio stars at megahertz to gigahertz frequencies

Follow-up LOFAR observations of the τ Boötis exoplanetary system

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