The Search for Signatures of Transient Mass Loss in Active Stars

Abstract

General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. ABSTRACTThe habitability of an exoplanet depends on many factors. One such factor is the impact of stellar eruptive events on nearby exoplanets. Currently this is poorly constrained due to heavy reliance on solar scaling relationships and a lack of experimental evidence. Potential impacts of coronal mass ejections (CMEs), which are the large eruption of magnetic field and plasma from a star, are space weather and atmospheric stripping. A method for observing CMEs as they travel though the stellar atmosphere is the type II radio burst, and the new Low Frequency Array (LOFAR) provides a means of detection. We report on 15 hr of observation of YZ Canis Minoris (YZ CMi), a nearby M dwarf flare star, taken in LOFAR's beam-formed observation mode for the purposes of measuring transient frequency-dependent low-frequency radio emission. The observations utilized the Low Band Antenna (10-90 MHz) or High Band Antenna (110-190 MHz) for five three-hour observation periods. In this data set, there were no confirmed type II events in this frequency range. We explore the range of parameter space for type II bursts constrained by our observations. Assuming the rate of shocks is a lower limit to the rate at which CMEs occur, no detections in a total of 15 hr of observation places a limit of n < 0.0667 type II shocks/hrν CME for YZ CMi due to the stochastic nature of the events and the limits of observational sensitivity. We propose a methodology to interpret jointly observed flares and CMEs which will provide greater constraints to CMEs and test the applicability of solar scaling relations.

The MUSCLES Treasury Survey. IV. Scaling Relations for Ultraviolet, Ca ii K, and Energetic Particle Fluxes from M Dwarfs

“…Our new method of proton flux estimation due to stellar flares has important limitations, but it will be useful until advancements are made in the indirect detection of particles from stellar eruptive events (e.g., coronal dimming or Type II or III radio bursts; Crosley et al 2016;Harra et al 2016) or in our understanding of particle acceleration under kilogauss magnetic field strengths. The scaling relations are statistical and are relatively inaccurate for individual flares.…”

“…Coronal dimming, when EUV emission lines dim after part of the corona has been evacuated from a CME (Mason et al 2014), was not observed by the Extreme UltraViolet Explorer (EUVE), likely due to insufficient sensitivity. Type II radio bursts that trace shocks associated with CMEs (Winter & Ledbetter 2015) are being searched for but have not yet been detected on other stars (Crosley et al 2016), but other possible kinematic signatures of CMEs in observed M dwarf flares have been detected (e.g., Houdebine et al 1990;Cully et al 1994;Fuhrmeister & Schmitt 2004). Type III radio bursts are caused by the acceleration of suprathermal electrons from solar active regions and have been detected on the M3 dwarf AD Leo (Osten & Bastian 2006).…”

Coronal mass ejections and their sheath regions in interplanetary space

“…Such signals could be detected, e.g., with the Low Frequency Array (LOFAR) (e.g., Crosley et al 2016). However, the Sun will remain for a long time our only source of direct information on CMEs and the studies on CME-induced effects on exoplanets have to rely largely on scaling laws derived using flare-CME and CME-ICME relationships from the Sun and our Solar System.…”

Mass-loss Rates from Coronal Mass Ejections: A Predictive Theoretical Model for Solar-type Stars

“…There are multiple measurements of time-variable outflows from cool stars (Houdebine et al 1990;Cully et al 1994;Fuhrmeister & Schmitt 2004;Leitzinger et al 2011;Dupree et al 2014;Vida et al 2016;Korhonen et al 2017), but it is not yet clear whether these should be interpreted as magnetically driven events analogous to solar CMEs. It is possible that observing the extrasolar equivalents of Type II radio bursts (Crosley et al 2016) or the polarization signatures of off-limb prominences (Felipe et al 2017) could be promising avenues toward the goal of definitive exo-CME detection.…”