Quasiperiodic pulsations in stellar flares observed with XMMNewton

Quasi-periodic pulsations in stellar flares observed with XMM-Newton Alexey Kuznetsov, Robert Sych Institute of Solar-Terrestrial Physics (Irkutsk, Russia)

Example of observations (AD Leo, started on 14 May 2001, 21: 04: 21 UT): XMM-Newton: imaging spectroscopic observations in the soft X-ray range (0. 1– 12 ke. V), FOV 30′× 30′. Image Spectrum XMM-Newton Serendipitous Source Catalogue (Rosen, Webb, Watson, et al. , 2016): http: //xmmssc. irap. omp. eu/ 3 XMM-DR 7 Interface – Observatory of Strasbourg: http: //xcatdb. unistra. fr/3 xmmdr 7/ Light curve

Pye, Rosen, Fyfe, & Schroder (2015): Ø correlation of the XMM-Newton Serendipitous Source Catalogue with the Hipparcos-Tycho catalogue; Ø 2000 -2007 years; Ø search for flares; Ø F-M stars selected. ~130 flares on ~70 stars were found. Our subset: single (or wide binaries) main-frequency stars only (no RS CVn, T Tau, etc. ) 45 light curves with flares on 40 stars were selected. Time resolution: ≥ 10 s. .

Analysis: Ø Fourier analysis (to obtain integral power spectra of oscillations); Ø wavelet analysis (to study the dynamics of oscillations). Aim: search for oscillations and analyze their parameters. Significance level: 90%.

Features found in the XMM light curves v “Slow flare” without pulsations GSC 09414 -00787 (G 5) 70 Oph (K 0+K 5)

Features found in the XMM light curves v “Fast flare” without pulsations NU UMa (G 5) HD 59581 (F 6)

Features found in the XMM light curves v “Slow flare” with QPPs chi 01 Ori (G 0? ) Periods: 0. 9, 5. 6, 15 min. EQ Peg (M 3. 5+M 4. 5) Periods: 10, 33, 61 min.

Features found in the XMM light curves v Drifting QPPs before/after flare HK Aqr (M 0) Periods: 61, 107, 307 min. 47 Cas B (G 0) Periods: 15, 34, 92 min.

Features found in the XMM light curves v QPPs with frequency jump CD-53 544 (K 6) Periods: 45, 64, 103 min.

Features found in the XMM light curves v QPPs with increasing/decreasing intensity HD 166191 (F 4) Periods: 16, 45, 205 min. HD 285845 (G 6) Periods: 116 min.

Features found in the XMM light curves v Quasi-periodic bursts (flares) DG CVn (M 4) Periods: 35, 50, 102 min. AD Leo (M 3. 5) Periods: 60, 118, 199 min.

Summary Among 45 light curves: Ø “slow flares” without QPPs: 6 (14. 3%); Ø “fast flares” without QPPs: 11 (26. 2%); Ø “slow flares” with QPPs: 6 (14. 3%); Ø flares with QPPs with drifting frequency: 6 (14. 3%); Ø damping QPPs at the decay phase of the flare: 2 (4. 5%); Ø growing QPPs at the pre-flare phase: 1 (2. 2%); Ø quasi-periodic flares: 10 (23. 8%). In some “slow flares”, high-frequency pulsations (with periods of ~5 min) were detected. Such pulsations may be caused by the processes similar to the solar P-mode oscillations. Impulsive flares make the high-frequency pulsations unobservable, and only the relatively slow pulsations were detected.