Coordinated X-ray, optical, and radio observations of YZ Canis Minoris

Karpen, J. T.; Crannell, C. J.; Hobbs, R. W.; Maran, S. P.; Moffett, T. J.; Bardas, D.; Clark, G. W.; Hearn, D. R.; Li, F. K.; Markert, T. H.; McClintock, J. E.; Primini, F. A.; Richardson, J. A.; Cristaldi, S.; Rodono, M.; Galasso, D. A.; Magun, A.; Nelson, Gareth; Slee, O. B.; Chugajnov, P. F.; Chugainov, P. F.; Efimov, Yu. S.; Shakhovskoj, N. M.; Shakhovskoy, N. M.; Viner, M. R.; Venugopal, V. R.; Spangler, S. R.; Kundu, M. R.; Evans, David S.

doi:10.1086/155489

Cited by 34 publications

(4 citation statements)

References 23 publications

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“…The synchrotron mechanism for optical flaring emission from red dwarfs had been initially proposed by Gordon (1954), who noted that the detection of polarized flares might be the proof for it. However, the sparse and irregular (see Section 1) polarimetric observations of UV Ceti-type stars have been fruitless until now (Karpen et al 1977; Eritsian 1978; Tuominen et al 1989; Alekseev et al 1994). It seems that the majority of flares, especially the longer ones studied in these works, are dominated by thermal emission.…”

Section: Discussionmentioning

confidence: 99%

“…Numerous attempts to detect the polarization in flares of YZ CMi, AD Leo, EV Lac and YY Gem, observed with various telescopes (Karpen et al 1977; Eritsian 1978; Tuominen et al 1989), were also unsuccessful. Most reliable data have been acquired during EV Lac study using 1.25-m telescope of the Crimean Astrophysical Observatory (Alekseev et al 1994).…”

Section: Introductionmentioning

confidence: 99%

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Discovery of the Sub-second Linearly Polarized Spikes of Synchrotron Origin in the UV Ceti Giant Optical Flare

Beskin

Карпов

Plokhotnichenko

et al. 2017

Publ. Astron. Soc. Aust.

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During our optical monitoring of UV Ceti, iconic late-type flaring star, with high temporal resolution using the Russian 6-m telescope in 2008 we detected a giant flare with the amplitude of about 3 magnitudes in U -band. Near flare maximum more than a dozen of spike bursts have been discovered with triangular shapes and durations from 0.6 to 1.2 s and maximal luminosities in the range (1.5 − 8) × 10 27 erg s −1 . For the half of these events the linear polarization exceeds 35% with significance better than 5σ. We argue that these events are synchrotron emission of electron streams with the energies of several hundred MeV moving in the magnetic field of about 1.4 kG. Emission from such ultrarelativistic (with energies far exceeding 10 MeV) particles is being routinely observed in solar flares, but has never been detected from UV Ceti type stars. This is the first ever detection of linearly polarized optical light from the UV Ceti-type stars which indicates that at least some fraction of the flaring events on these stars are powered by a non-thermal synchrotron emission mechanism.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Discovery of the Sub-second Linearly Polarized Spikes of Synchrotron Origin in the UV Ceti Giant Optical Flare

Beskin

Карпов

Plokhotnichenko

et al. 2017

Publ. Astron. Soc. Aust.

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“…Many flaring stars are known to exhibit activity in both radio and X-ray wavelengths such as the giant outburst from a young stellar object reported by Bower et al (2003), but the detection of radio flares having no apparent associated X-ray emission is not uncommon. For example, radio flares from UV Ceti stars with seconds to minutes time-scale were detected at low frequencies by Spangler, Shawhan & Rankin (1974) and Karpen et al (1977) with YZ Canis Minoris where no corresponding X-ray emission was found. At higher frequencies (4.9 and 8.4 GHz), Osten et al (2005) reported short duration radio flares from the dMe flare star EV Lacertae which was not clearly related to the star's X-ray flares.…”

Section: Discussionmentioning

confidence: 99%

Transient nature of J195754+353513

Pal,

Patra,

Hollick

et al. 2017

Preprint

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We have searched for transient and/or variable radio sources in the field of Galactic micro-quasar Cygnus X-1 in 1.4 GHz (L band) using data from the Karl G. Jansky Very Large Array (JVLA). We used twenty years of data between 1983 and 2003. We found a source J195754+353513 showing transient behavior. The source was also mentioned earlier in NVSS and WENSS catalog but its transient nature was not reported earlier. The source is located 23.8 arcminutes far from Cygnus X-1. It is detected many times during the span of our study and it varied between less than 0.3 mJy to 201 mJy. J195754+353513 also showed high intra-day variability. In one occasion, the source rose from ∼ 20 mJy to ∼ 180 mJy 700 second. For limited number of cases circularly polarized emission could be detected from the source with V /I vary between 0.15 to 0.25. 2MASS J19575420+3535152 may be the near-infrared counterpart of the source. We compared the properties of the source with other Galactic transient sources having similar properties. The nature of the source is still unknown. We speculate on its possible nature.

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“…Multiwavelength flare observations of dMe stars have frequently resulted in the disappointing statement that there was no radio enhancement during a n optical or X-ray flare, or that no optical or X-ray counterpart was observed during a radio flare (e.g. Karpen et al 1977, Kahler et al 1982. There is a strong suspicion that in all such cases the radio telescope was not sufficiently sensitive to detect the weakly polarized synchrotron emission or, respectively, the radio emission was strongly polarized, indicating highly efficient coherent emission by a possibly minor flare.…”

Section: Radio/x-ray Ratio Of G-star Flaresmentioning

confidence: 99%

Radio Emission from Flares in Single Late-type Stars

Benz

1995

International Astronomical Union Colloquium

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Radio observations provide the most direct information on nonthermal electrons in stellar flares and in the coronae of late-type stars. Radio emissions of single main-sequence F, G, and of many K stars have recently been discovered, in addition to the well-known dwarf M stars. Their long-duration radio flares with low circular polarization, slow variations and broad bandwidth can be attributed to gyrosynchrotron emission of mildly relativistic electrons. The same holds for the low-level ('quiescent') radio emission. On the other hand, highly polarized radio flares of M stars have been interpreted by coherent emissions from loss-cone instabilities of magnetically trapped electrons. These conjectures are consistent with recent VLBI observations. The identification of the radio emission process allows to estimate the high-energy component of the flare and compare it to the total flare energy. The weakly polarized radio emission may serve as a proxy for hard X-ray signatures of relativistic electrons. The fraction of primary energy released into energetic electrons then appears to be large and similar to solar flares.

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Coordinated X-ray, optical, and radio observations of YZ Canis Minoris

Cited by 34 publications

References 23 publications

Discovery of the Sub-second Linearly Polarized Spikes of Synchrotron Origin in the UV Ceti Giant Optical Flare

Discovery of the Sub-second Linearly Polarized Spikes of Synchrotron Origin in the UV Ceti Giant Optical Flare

Transient nature of J195754+353513

Radio Emission from Flares in Single Late-type Stars

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