期刊
ASTRONOMY & ASTROPHYSICS
卷 648, 期 -, 页码 -出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361/202039144
关键词
stars: low-mass; radio continuum: stars; stars: individual: CR Draconis
资金
- Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)
- SURF Co-operative [e-infra 160022, e-infra 160152]
- European Research Council Advanced Grant [NEWCLUSTERS-321271]
- UK Science and Technology Funding Council [ST/P000096/1]
- NASA Explorer Program
- Jet Propulsion Laboratory (JPL) - NASA through the Sagan Fellowship Program
- National Science Foundation Graduate Research Fellowship Program [DGE-1746045]
- CNRS/INSU programme of plantelogy
- UK STFC [ST/R000972/1]
- ERC Starting Grant ClusterWeb [804208]
- European Research Council [743029]
Recently detected low-frequency radio emission from M dwarf systems shows similarities with emission from gas giant planets in our Solar System, possibly driven by interactions between a rotating plasma disk and a stellar magnetosphere. A study on the M dwarf binary CR Draconis reveals a high detection rate of bright radio bursts with distinctive features, providing insights into the nature of the emission.
Recently detected coherent low-frequency radio emission from M dwarf systems shares phenomenological similarities with emission produced by magnetospheric processes from the gas giant planets of our Solar System. Such beamed electron-cyclotron maser emission can be driven by a star-planet interaction or a breakdown in co-rotation between a rotating plasma disk and a stellar magnetosphere. Both models suggest that the radio emission could be periodic. Here we present the longest low-frequency interferometric monitoring campaign of an M dwarf system, composed of twenty-one approximate to 8 h epochs taken in two series of observing blocks separated by a year. We achieved a total on-source time of 6.5 days. We show that the M dwarf binary CR Draconis has a low-frequency 3 sigma detection rate of 90(-8)(+5)% when a noise floor of approximate to 0.1 mJy is reached, with a median flux density of 0.92 mJy, consistent circularly polarised handedness, and a median circularly polarised fraction of 66%. We resolve three bright radio bursts in dynamic spectra, revealing the brightest is elliptically polarised, confined to 4 MHz of bandwidth centred on 170 MHz, and reaches a flux density of 205 mJy. The burst structure is mottled, indicating it consists of unresolved sub-bursts. Such a structure shares a striking resemblance with the low-frequency emission from Jupiter. We suggest the near-constant detection of high brightness temperature, highly-circularly-polarised radiation that has a consistent circular polarisation handedness implies the emission is produced via the electron-cyclotron maser instability. Optical photometric data reveal the system has a rotation period of 1.984 +/- 0.003 days. We observe no periodicity in the radio data, but the sampling of our radio observations produces a window function that would hide the near two-day signal.
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