2026ApJ...998..287W

Query : 2026ApJ...998..287W

2026ApJ...998..287W - Astrophys. J., 998, 287 (2026/February-3)

Multiwavelength Study of a Superflare on RS CVn-Type Star HD 22468 Triggered at Hard X-Ray by SVOM.

WANG J., XIE W.J., CANGEMI F., COLEIRO A., LI H.L., XU Y., HAN X.H., YANG H., XIN L.P., MAO X., ZHENG J., JIN J.J., LI G.W., RODRIGUEZ J., TAO L., CORDIER B., WEI J.Y., BACON P., BELLEMONT N., BOUCHET L., CAI H.B., CAVET C., DAI Z.G., GODET O., GOLDWURM A., GUILLOT S., HUANG L., HUANG M.H., JIANG N., LIANG E.W., LU X.M., SCHANNE S., LE STUM S., QIU Y.L., WANG X.G., WANG X.Y., WU C., ZHANG L., ZHANG S.N. and ZHENG S.J.

Abstract (from CDS):

Detection of stellar flares at hard X-ray is still rare at the current stage. A transient was recently detected by the hard X-ray camera ECLAIRs on board the SVOM mission at 11:39:01.2 UT on 2025 January 09. Simultaneous monitoring in the optical band on the ground by SVOM/GWAC and follow-up spectroscopy enabled us to confirm that the transient is caused by a superflare on HD 22468, an RS CVn-type star. The bolometric energy released in the flare is estimated to be ∼7.2 × 1037-1.7 × 1038 erg. The hard X-ray spectra of the event at the peak can be reproduced by the “apec” model of a hot plasma with a temperature of $10{6}_{-22}^{+27}$ MK. In the optical range, the Hα emission-line profile obtained at ∼1.7 hr after the trigger shows a bulk blueshift of -96 ± 20 km s–1, which can be explained by either a chromospheric evaporation or a prominence eruption. The ejected mass is estimated to be 3.9 × 1020 g for the evaporating plasma and to be 3.2 × 1021 g < Mp < 8.8 × 1021 g for the erupted prominence.

Abstract Copyright: © 2026. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): Gamma-ray sources - Stellar flares - Stellar x-ray flares - RS Canum Venaticorum variable stars - Stellar chromospheres - Spectroscopy

Simbad objects: 7

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Number of rows : 7
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 SVOM J00365+0033 ev 03 36 39.0 +00 33 25           ~ 1 0
2 HD 22468 RS* 03 36 47.2904292073 +00 35 15.943692002 7.09 6.79 5.90     K2:Vnk 1206 0
3 M 1 SNR 05 34 31.8 +22 01 03           ~ 6516 1
4 HD 251108 Ro* 06 04 14.9929371672 +12 45 51.088959756   11.25 9.899   8.520 K2 20 0
5 V* EV Lac PM* 22 46 49.7312610268 +44 20 02.374381562   11.85 10.26 9.89   M4.0Ve 993 2
6 UCAC4 745-080649 Er* 23 01 00.0714601703 +58 57 31.187532171   15.105 14.623 15.560   ~ 2 0
7 HD 224085 RS* 23 55 04.0520383542 +28 38 01.245426862 8.88 8.20   6.9   K2+IVeFe-1 756 0

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