A stellar flare-coronal mass ejection event revealed by X-ray plasma motions
Journal
Date Issued
2019
Author(s)
•
•
Drake, J. J.
•
•
Testa, P.
•
•
•
•
Abstract
Coronal mass ejections (CMEs), often associated with flares1-3, are the most powerful magnetic phenomena occurring on the Sun. Stars show magnetic activity levels up to ten thousand times higher4, and CME effects on stellar physics and circumstellar environments are predicted to be substantial5-9. However, stellar CMEs remain observationally unexplored. Using time-resolved high-resolution X-ray spectroscopy of a stellar flare on the active star HR 9024 observed with the High Energy Transmission Grating Spectrometer onboard the Chandra X-ray Observatory space telescope, we distinctly detected Doppler shifts in S xvi, Si xiv and Mg xii lines that indicate upward and downward motions of hot plasmas (around 10-25 MK) within the flaring loop, with velocities of 100-400 km s-1, in agreement with a model of a flaring magnetic tube. Most notably, we also detected a later blueshift in the O viii line that reveals an upward motion, with velocity 90 ± 30 km s-1, of cool plasma (about 4 MK), that we ascribe to a CME coupled to the flare. From this evidence we were able to derive a CME mass of 1 .2-0.8+2.6×1 021 g and a CME kinetic energy of 5 .2-3.6+27.7×1 034 erg. These values provide clues in the extrapolation of the solar case to higher activity levels in other stars, suggesting that CMEs could indeed be a major cause of mass and angular momentum loss.
Volume
3
Start page
742
Issn Identifier
2397-3366
Ads BibCode
2019NatAs...3..742A
Rights
open.access
File(s)![Thumbnail Image]()
![Thumbnail Image]()
Loading...
Name
argiroffi21019_pdfeditoriale.pdf
Description
[Administrators only]
Size
3.34 MB
Format
Adobe PDF
Checksum (MD5)
33a38b33fd123c21472e16d0f5e25dea
Loading...
Name
argiroffi2019_postprint.pdf
Description
postprint
Size
2.83 MB
Format
Adobe PDF
Checksum (MD5)
0d48b2261b82e03a7665e28e0d66f8b3