The Stellar CME–Flare Relation: What Do Historic Observations Reveal?

Moschou, S. P.; Drake, J. J.; Cohen, Ofer; Alvarado‐Gómez, Julián D.; Garraffo, Cecilia; Fraschetti, Federico

doi:10.3847/1538-4357/ab1b37

Cited by 111 publications

(117 citation statements)

References 155 publications

(337 reference statements)

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“…The recent observation of a CME around another star (Argiroffi et al., 2019) shows the possibilities of such measurements. However, they should be improved to have a better idea of the fluxes of particles at other stars and to validate the semiempirical laws linking flares and CME (Moschou et al., 2019). See also section 3.4.1.…”

Section: Developments Needed In Measurements and Modeling Of Atmosphementioning

confidence: 99%

Atmospheric Escape Processes and Planetary Atmospheric Evolution

et al. 2020

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The habitability of the surface of any planet is determined by a complex evolution of its interior, surface, and atmosphere. The electromagnetic and particle radiation of stars drive thermal, chemical, and physical alteration of planetary atmospheres, including escape. Many known extrasolar planets experience vastly different stellar environments than those in our solar system: It is crucial to understand the broad range of processes that lead to atmospheric escape and evolution under a wide range of conditions if we are to assess the habitability of worlds around other stars. One problem encountered between the planetary and the astrophysics communities is a lack of common language for describing escape processes. Each community has customary approximations that may be questioned by the other, such as the hypothesis of H‐dominated thermosphere for astrophysicists or the Sun‐like nature of the stars for planetary scientists. Since exoplanets are becoming one of the main targets for the detection of life, a common set of definitions and hypotheses are required. We review the different escape mechanisms proposed for the evolution of planetary and exoplanetary atmospheres. We propose a common definition for the different escape mechanisms, and we show the important parameters to take into account when evaluating the escape at a planet in time. We show that the paradigm of the magnetic field as an atmospheric shield should be changed and that recent work on the history of Xenon in Earth's atmosphere gives an elegant explanation to its enrichment in heavier isotopes: the so‐called Xenon paradox.

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Section: Developments Needed In Measurements and Modeling Of Atmosphementioning

confidence: 99%

Atmospheric Escape Processes and Planetary Atmospheric Evolution

et al. 2020

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“…Every so far detected stellar CME in optical spectra had a width in wavelength of >5Å (cf. Moschou et al 2019, and references therein), which can be explained by the expansion of a CME when it is ejected (see e.g. Howard 2015; Vida et al 2019, and references therein).…”

Section: Data Preparationmentioning

confidence: 99%

“…Using the method of Xray absorptions stellar CME masses up to 10 23 g are reported (cf. Moschou et al 2019, and references therein), but the majority of those stars are no late-type main-sequence stars. The deduced minimum detectable CME masses from the S/N values are in the ranges of the stellar CMEs detected by the method of Doppler shifted emission/absorption.…”

Section: Cmesmentioning

confidence: 99%

A census of coronal mass ejections on solar-like stars

Leitzinger

Odert

Greimel

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Coronal Mass Ejections (CMEs) may have major importance for planetary and stellar evolution. Stellar CME parameters, such as mass and velocity, have yet not been determined statistically. So far only a handful of stellar CMEs has been detected mainly on dMe stars using spectroscopic observations. We therefore aim for a statistical determination of CMEs of solar-like stars by using spectroscopic data from the ESO phase 3 and Polarbase archives. To identify stellar CMEs we use the Doppler signal in optical spectral lines being a signature of erupting filaments which are closely correlated to CMEs. We investigate more than 3700 hours of on-source time of in total 425 dF-dK stars. We find no signatures of CMEs and only few flares. To explain this low level of activity we derive upper limits for the non detections of CMEs and compare those with empirically modelled CME rates. To explain the low number of detected flares we adapt a flare power law derived from EUV data to the Hα regime, yielding more realistic results for Hα observations. In addition we examine the detectability of flares from the stars by extracting Sun-as-a-star Hα light curves. The extrapolated maximum numbers of observable CMEs are below the observationally determined upper limits, which indicates that the on-source times were mostly too short to detect stellar CMEs in Hα. We conclude that these non detections are related to observational biases in conjunction with a low level of activity of the investigated dF-dK stars.

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“…While strong flares are routinely detected in active stars, particularly M-dwarfs (see Schmidt et al 2019 and references therein), recent studies have shown that the solar flare-CME paradigm might be different in the stellar regime, such that the occurrence rate of CMEs and their associated kinetic energies are reduced dramatically (Vida et al 2019, Moschou et al 2019. The recent direct detection of a stellar CME by Argiroffi et al (2019) follows the same trend.…”

Section: Introductionmentioning

confidence: 86%

Coronal Response to Magnetically Suppressed CME Events in M-dwarf Stars

Alvarado‐Gómez

Drake

Moschou

et al. 2019

ApJL

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We report the results of the first state-of-the-art numerical simulations of Coronal Mass Ejections (CMEs) taking place in realistic magnetic field configurations of moderately active M-dwarf stars. Our analysis indicates that a clear, novel, and observable, coronal response is generated due to the collapse of the eruption and its eventual release into the stellar wind. Escaping CME events, weakly suppressed by the large-scale field, induce a flare-like signature in the emission from coronal material at different temperatures due to compression and associated heating. Such flare-like profiles display a distinctive temporal evolution in their Doppler shift signal (from red to blue), as the eruption first collapses towards the star and then perturbs the ambient magnetized plasma on its way outwards. For stellar fields providing partial confinement, CME fragmentation takes place, leading to rise and fall flow patterns which resemble the solar coronal rain cycle. In strongly suppressed events, the response is better described as a gradual brightening, in which the failed CME is deposited in the form of a coronal rain cloud leading to a much slower rise in the ambient high-energy flux by relatively small factors (∼ 2 − 3). In all the considered cases (escaping/confined) a fractional decrease in the emission from mid-range coronal temperature plasma occurs, similar to the coronal dimming events observed on the Sun. Detection of the observational signatures of these CME-induced features requires a sensitive next generation X-ray space telescope.

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The Stellar CME–Flare Relation: What Do Historic Observations Reveal?

Cited by 111 publications

References 155 publications

Atmospheric Escape Processes and Planetary Atmospheric Evolution

Atmospheric Escape Processes and Planetary Atmospheric Evolution

A census of coronal mass ejections on solar-like stars

Coronal Response to Magnetically Suppressed CME Events in M-dwarf Stars

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