Cho, I. H., Cho, K. S., Nakariakov, V. M. (Valery M.), Kim, S. and Kumar, P. (2016) Comparison of damped oscillations in solar and stellar X-ray flares. Astrophysical Journal, 830 (2). 110. doi:10.3847/0004-637X/830/2/110

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Abstract

We explore the similarity and difference of the quasi-periodic pulsations (QPPs) observed in the decay phase of solar and stellar flares at X-rays. We identified 42 solar flares with pronounced QPPs, observed with the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and 36 stellar flares with QPPs, observed with X-ray Multi Mirror Newton observatory (XMM-Newton). The Empirical Mode Decomposition (EMD) method and least-square fit by a damped sine function were applied to obtain the periods (P) and damping times (τ ) of the QPPs. We found that (1) the periods and damping times of the stellar QPPs are 16.21±15.86 min and 27.21±28.73 min, while those of the solar QPPs are 0.90±0.56 and 1.53±1.10 min, respectively. (2) The ratio of the damping times to the periods (τ/P) observed in the stellar QPPs (1.69±0.56) are statistically identical to those of solar QPPs (1.74±0.77). (3) The scalings of the QPP damping time with the period are well described by the power law in both solar and stellar cases. The power indices of the solar and stellar QPPs are 0.96±0.10 and 0.98±0.05, respectively. This scaling is consistent with the scalings found for standing slow magnetoacoustic and kink modes in solar coronal loops. Thus, we propose that the underlying mechanism responsible for the stellar QPPs is the natural magnetohydrodynamic oscillations in the flaring or adjacent coronal loops, as in the case of solar flares.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Solar flares , Magnetohydrodynamics
Journal or Publication Title:	Astrophysical Journal
Publisher:	IOP Publishing
ISSN:	0004-637X
Official Date:	20 October 2016
Dates:	Date Event 20 October 2016 Published 17 October 2016 Available 2 August 2016 Accepted 9 May 2016 Submitted
Volume:	830
Number:	2
Article Number:	110
DOI:	10.3847/0004-637X/830/2/110
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	European Research Council (ERC), Han'guk Ch'ŏnmun Yŏn'guwŏn [Korea Astronomy and Space Science Institute] (KASI), Korea (South). Kyoyuk Kwahak Kisulbu [Ministry of Education, Science and Technology] (MEST)
Grant number:	Grant no. 321141 SeismoSun (ERC), BK21 plus (MEST)

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