Multi-Observatory Research of Young Stellar Energetic Flares (MORYSEF): X-ray Flare Related Phenomena and Multi-epoch Behavior

TL;DR

This study investigates the multi-epoch X-ray and multi-wavelength behavior of young stellar flares in the Orion Nebula, revealing the ubiquity of mega-flares and their implications for protoplanetary environments.

Contribution

It provides the first detailed correlations between flare energies and stellar properties in PMS stars, and demonstrates the widespread occurrence of mega-flares in young stellar objects.

Findings

Most PMS stars exhibit minor long-term X-ray variations.

Correlations between flare energies and stellar mass/size are identified.

X-ray mega-flares are common, affecting protoplanetary disks and planet formation.

Abstract

The most powerful stellar flares driven by magnetic energy occur during the early pre-main sequence (PMS) phase. The Orion Nebula represents the nearest region populated by young stars, showing the greatest number of flares accessible to a single pointing of Chandra. This study is part of a multi-observatory project to explore stellar surface magnetic fields (with HET-HPF), particle ejections (VLBA), and disk ionization (ALMA) immediately following the detection of PMS super-flares with Chandra. In December 2023, we successfully conducted such a multi-telescope campaign. Additionally, by analyzing Chandra data from 2003, 2012, and 2016, we examine the multi-epoch behavior of PMS X-ray emission related to PMS magnetic cyclic activity and ubiquitous versus sample-confined mega-flaring. Our findings follow. 1) We report detailed stellar quiescent and flare X-ray properties for numerous HET/ALMA/VLBA targets, facilitating ongoing multi-wavelength analyses. 2) For numerous moderately energetic flares, we report correlations (or lack thereof) between flare energies and stellar mass/size (presence/absence of disks) for the first time. The former is attributed to the correlation between convection-driven dynamo and stellar volume, while the latter suggests the operation of solar-type flare mechanisms in PMS stars. 3) We find that most PMS stars exhibit minor long-term baseline variations, indicating the absence of intrinsic magnetic dynamo cycles or observational mitigation of cycles by saturated PMS X-rays. 4) We conclude that X-ray mega-flares are ubiquitous phenomena in PMS stars, which suggests that all protoplanetary disks and nascent planets are subject to violent high-energy emission and particle irradiation events.