Multiwavelength Campaign Observations of a Young Solar-type Star, EK Draconis. II. Understanding Prominence Eruption through Data-Driven Modeling and Observed Magnetic Environment

• Main Authors: Namekata, Kosuke, Ikuta, Kai, Petit, Pascal, Airapetian, Vladimir S, Vidotto, Aline A, Heinzel, Petr, Wollmann, Jiří, Maehara, Hiroyuki, Notsu, Yuta, Inoue, Shun, Marsden, Stephen, Morin, Julien, Jeffers, Sandra V, Neiner, Coralie, Paudel, Rishi R, Avramova-Boncheva, Antoaneta A, Gendreau, Keith, Shibata, Kazunari
• Format: Journal Article
• Language: English
• Published: 07-10-2024
• Subjects: Physics - Earth and Planetary Astrophysics; Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.2410.05523

EK Draconis, a nearby young solar-type star (G1.5V, 50-120 Myr), is known as
one of the best proxies for inferring the environmental conditions of the young
Sun. The star frequently produces superflares and Paper I presented the first
evidence of an associated gigantic prominence eruption observed as a
blueshifted H$\alpha$ Balmer line emission. In this paper, we present the
results of dynamical modeling of the stellar eruption and examine its
relationship to the surface starspots and large-scale magnetic fields observed
concurrently with the event. By performing a one-dimensional free-fall
dynamical model and a one dimensional hydrodynamic simulation of the flow along
the expanding magnetic loop, we found that the prominence eruption likely
occurred near the stellar limb (12$^{+5}_{-5}$-16$^{+7}_{-7}$ degrees from the
limb) and was ejected at an angle of 15$^{+6}_{-5}$-24$^{+6}_{-6}$ degrees
relative to the line of sight, and the magnetic structures can expand into a
coronal mass ejection (CME). The observed prominence displayed a terminal
velocity of $\sim$0 km s$^{-1}$ prior to disappearance, complicating the
interpretation of its dynamics in Paper I. The models in this paper suggest
that prominence's H$\alpha$ intensity diminishes at around or before its
expected maximum height, explaining the puzzling time evolution in
observations. The TESS light curve modeling and (Zeeman) Doppler Imaging
revealed large mid-latitude spots with polarity inversion lines and one polar
spot with dominant single polarity, all near the stellar limb during the
eruption. This suggests that mid-latitude spots could be the source of the
pre-existing gigantic prominence we reported in Paper I. These results provide
valuable insights into the dynamic processes that likely influenced the
environments of early Earth, Mars, Venus, and young exoplanets.