09:23 〜 09:45
[PEM14-02] Detecting stellar CMEs through post-flare coronal dimmings
★Invited Papers
キーワード：Sun, Stars, Coronal mass ejections
Coronal dimmings are sudden decreases of the solar EUV and X-ray emission caused by coronal mass ejection (CMEs). From the solar observations, we know that dimming regions map to the bipolar ends of closed magnetic field lines that become stretched or temporarily opened during an eruption, and are a result of the depletion of coronal plasma caused by the expansion and mass loss due to the CME. Recent statistical studies showed distinct correlations between CME mass and speed with key parameters of the associated coronal dimmings such as their spatial extent and intensity drop.
While CMEs from our Sun are regularly imaged by white-light coronagraphs, and their speeds and masses are derived from these observations, for stars such direct imaging is not possible. Here, we present a new approach to detect stellar mass ejections through post-flare coronal dimmings. To this aim, we study Sun-as-a-star broad-band EUV light curves derived from SDO’s Extreme ultraviolet Variability Experiment (EVE) as a testbed to investigate whether coronal dimmings can be also observed on stars and used for stellar CME detection. We demonstrate that large eruptive solar flares are with a high probability associated with a post-flare coronal dimming, with intensity drops in the 15-25 nm full-Sun light curves up to 5%. Searching for similar patterns of post-flare dimmings in the X-ray and EUV light curves of solar-like and late-type stars, we identify 21 stellar CME candidates. The derived intensity drops are an order of magnitude larger than for the Sun, suggesting that in the detected events a substantial part of the stellar corona gets ejected by the CME.
This study is published in: A.M. Veronig, P. Odert, M. Leitzinger, K. Dissauer, N. Fleck, H.S. Hudson, Indications of stellar coronal mass ejections through coronal dimmings, Nature Astronomy 5, 697-706 (2021). https://www.nature.com/articles/s41550-021-01345-9
While CMEs from our Sun are regularly imaged by white-light coronagraphs, and their speeds and masses are derived from these observations, for stars such direct imaging is not possible. Here, we present a new approach to detect stellar mass ejections through post-flare coronal dimmings. To this aim, we study Sun-as-a-star broad-band EUV light curves derived from SDO’s Extreme ultraviolet Variability Experiment (EVE) as a testbed to investigate whether coronal dimmings can be also observed on stars and used for stellar CME detection. We demonstrate that large eruptive solar flares are with a high probability associated with a post-flare coronal dimming, with intensity drops in the 15-25 nm full-Sun light curves up to 5%. Searching for similar patterns of post-flare dimmings in the X-ray and EUV light curves of solar-like and late-type stars, we identify 21 stellar CME candidates. The derived intensity drops are an order of magnitude larger than for the Sun, suggesting that in the detected events a substantial part of the stellar corona gets ejected by the CME.
This study is published in: A.M. Veronig, P. Odert, M. Leitzinger, K. Dissauer, N. Fleck, H.S. Hudson, Indications of stellar coronal mass ejections through coronal dimmings, Nature Astronomy 5, 697-706 (2021). https://www.nature.com/articles/s41550-021-01345-9