Photometric Observations of Flares on AD Leo from GWAC-F30 and TESS

Bai, Jianying; Ji, Wang; Li, H. L.; Xin, L. P.; Li, G. W.; Yang, Yuangen; Wei, J. Y.

doi:10.1088/1538-3873/acdea8

Cited by 4 publications

(1 citation statement)

References 57 publications

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“…These flares and properties of host stars are given in Table 1. Several of them have been carefully studied in Wang et al (2021), Xin et al (2021), Wang et al (2022), Li et al (2023b), andBai et al (2023). In Section 2 we will introduce the observations and data; in Section 3, we will present the properties of GWAC flares and their host stars; in Section 4, the rotation-ageactivity relationship will be studied; in Section 5 the lower limit of the maximum flare energy that a star can produce is presented; the star age and activity pattern are discussed in Section 6; and at last, the conclusion is given in Section 7.…”

Section: Introductionmentioning

confidence: 99%

The White-light Superflares from Cool Stars in GWAC Triggers

Li 李,

Wang 王,

Yuan 袁

et al. 2024

ApJ

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M-type stars are the ones that flare most frequently, but how big their maximum flare energy can reach is still unknown. We present 163 flares from 162 individual M2 through L1-type stars that triggered the GWAC, with flare energies ranging from 1032.2 to 1036.4 erg. The flare amplitudes range from △G = 0.84 to ∼10 mag. Flare energy increases with stellar surface temperature (T eff) but both △G and equivalent duration log 10 ( ED ) seem to be independent of T eff. Combining periods detected from light curves of TESS and K2, spectra from LAMOST, the Sloan Digital Sky Survey, the 2.16 m telescope, and the Gaia DR3 data, we found that these GWAC flare stars are young. For the stars that have spectra, we found that these stars are in or very near the saturation region, and log 10 ( L H α / L bol ) is lower for M7–L1 stars than for M2–M6 stars. We also studied the relation between GWAC flare bolometric energy E bol and stellar hemispherical area S, and found that log 10 E bol (in erg) increases with increasing S (in square centimeters), and the maximum flare energy log 10 E bol , max ≥ log 10 S + 14.25 . For M7–L1 stars, there seem to be other factors limiting their maximum flare energies in addition to the stellar hemispherical area.

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Section: Introductionmentioning

confidence: 99%

The White-light Superflares from Cool Stars in GWAC Triggers

Li 李,

Wang 王,

Yuan 袁

et al. 2024

ApJ

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Time-domain analysis of multiwaveband flares from AD Leonis

Zhang,

Li,

Gao

et al. 2024

Monthly Notices of the Royal Astronomical Society

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Radio bursts of magnetically active stars reveal the intensity and activity of the stellar magnetic field. They may also be related to the planets around the stars. We monitored a radio-active star, AD Leonis, 3000 seconds per day for 17 days in November 2020, and 5000 seconds per day for 5 days in July 2023 with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Based on the simultaneous flux increases in Stokes I and Stokes V, one left-hand circular polarized radio burst is identified. The $\sim 50~{{\%}}$ degree of circular polarization indicates the burst being originated from non-thermal radiation related to the stellar magnetic field. Combining the newly discovered burst with previous observations of radio and X-ray bursts from AD Leonis, we did a periodicity analysis for the 49 bursts in total. No periodicity with confidence level >3σ is found, while a candidate period of 3.04 days at ≈2σ confidence level is presented and discussed. Results of recent FAST observations and the periodicity analysis suggest a more compact campaign of observation toward this source, from which a more optimistic result of period search could be achieved.

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Potential Chromospheric Evaporation in the M Dwarf’s Flare Triggered by Einstein Probe Mission

Wang,

Mao,

Gao

et al. 2024

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Although flares from late-type main-sequence stars have been frequently detected in the multiwavelength, the associated dynamical process has been rarely reported so far. Here, we report follow-up observations of an X-ray transient triggered by Wide-field X-ray Telescope onboard the Einstein Probe at UT08:45:08 in 2024, May 7. The photometry in multibands and time-resolved spectroscopy started at 3 hr and 7.5 hr after the trigger, which enables us to identify the transient as a flare of the M-dwarf 2MASS J12184187−0609123. The bolometric energy released in the flare is estimated to be ∼1036 erg from its X-ray light curve. The Hα emission-line profile obtained at about 7 hr after the trigger shows an evident blue asymmetry with a maximum velocity of 200–250 km s−1. The blue wing can be likely explained by the chromospheric temperature (cool) upflow associated with chromospheric evaporation, in which the mass of the evaporating plasma is estimated to be 1.2 × 1018 g. In addition, a prominence eruption with an estimated mass of 7 × 1015 g < M p < 7 × 1018 g cannot be entirely excluded.

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Photometric Observations of Flares on AD Leo from GWAC-F30 and TESS

Cited by 4 publications

References 57 publications

The White-light Superflares from Cool Stars in GWAC Triggers

The White-light Superflares from Cool Stars in GWAC Triggers

Time-domain analysis of multiwaveband flares from AD Leonis

Potential Chromospheric Evaporation in the M Dwarf’s Flare Triggered by Einstein Probe Mission

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