Rotationally modulated highly circularly polarised radio pulses from the rapidly rotating M dwarf ASKAP J181335-604720

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Hauptverfasser: Wang, Shouzhi, Jiang, Biwei, Huang, Qichen, Huang, Shaoteng, Nie, Jundan
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Veröffentlicht: 2026
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author Wang, Shouzhi
Jiang, Biwei
Huang, Qichen
Huang, Shaoteng
Nie, Jundan
author_facet Wang, Shouzhi
Jiang, Biwei
Huang, Qichen
Huang, Shaoteng
Nie, Jundan
contents We report the detection of strong, highly circularly polarised, and rotationally modulated radio pulses from the early-mid M dwarf ASKAP J181335-604720, based on strictly simultaneous radio and optical observations with the Australian Square Kilometre Array Pathfinder (ASKAP) and the Transiting Exoplanet Survey Satellite (TESS). The ASKAP data reveal recurrent broadband radio pulses across 800-1088 MHz, with peak circular polarisation fractions approaching 100%. A dominant period of P = 5.607 +- 0.003 h is derived from the TESS light curve using a Lomb-Scargle analysis, which we interpret as the stellar rotation period. When phase-folded on this period, the radio emission is confined to narrow phase intervals and recurs at fixed rotational phases, consisting of a dominant pulse and a weaker secondary component. No contemporaneous optical flares are detected at the epochs of the radio pulses in the simultaneous TESS data. Even under conservative assumptions, the inferred brightness temperature exceeds Tb > 1.8 * 10^12 K, ruling out incoherent emission mechanisms. Combining the observed characteristics, we interpret the emission as coherent electron cyclotron maser (ECM) radiation arising from the stellar magnetosphere, with the observed frequencies implying local magnetic field strengths of at least several hundred Gauss in the radio-emitting region. This work provides a clean, well-constrained, and strictly simultaneous radio-optical case, demonstrating that coordinated radio and optical observations offer a powerful means of distinguishing magnetospheric coherent radio emission from flare-associated coronal activity in M dwarfs.
format Preprint
id arxiv_https___arxiv_org_abs_2605_15587
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Rotationally modulated highly circularly polarised radio pulses from the rapidly rotating M dwarf ASKAP J181335-604720
Wang, Shouzhi
Jiang, Biwei
Huang, Qichen
Huang, Shaoteng
Nie, Jundan
Solar and Stellar Astrophysics
We report the detection of strong, highly circularly polarised, and rotationally modulated radio pulses from the early-mid M dwarf ASKAP J181335-604720, based on strictly simultaneous radio and optical observations with the Australian Square Kilometre Array Pathfinder (ASKAP) and the Transiting Exoplanet Survey Satellite (TESS). The ASKAP data reveal recurrent broadband radio pulses across 800-1088 MHz, with peak circular polarisation fractions approaching 100%. A dominant period of P = 5.607 +- 0.003 h is derived from the TESS light curve using a Lomb-Scargle analysis, which we interpret as the stellar rotation period. When phase-folded on this period, the radio emission is confined to narrow phase intervals and recurs at fixed rotational phases, consisting of a dominant pulse and a weaker secondary component. No contemporaneous optical flares are detected at the epochs of the radio pulses in the simultaneous TESS data. Even under conservative assumptions, the inferred brightness temperature exceeds Tb > 1.8 * 10^12 K, ruling out incoherent emission mechanisms. Combining the observed characteristics, we interpret the emission as coherent electron cyclotron maser (ECM) radiation arising from the stellar magnetosphere, with the observed frequencies implying local magnetic field strengths of at least several hundred Gauss in the radio-emitting region. This work provides a clean, well-constrained, and strictly simultaneous radio-optical case, demonstrating that coordinated radio and optical observations offer a powerful means of distinguishing magnetospheric coherent radio emission from flare-associated coronal activity in M dwarfs.
title Rotationally modulated highly circularly polarised radio pulses from the rapidly rotating M dwarf ASKAP J181335-604720
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2605.15587