X-ray flare oscillations track plasma sloshing along star-disk magnetic tubes in Orion star-forming region

TL;DR

This study observes long-period X-ray pulsations in Orion PMS stars, modeling them as plasma sloshing in star-disk magnetic tubes, revealing insights into magnetic structures and plasma dynamics in young stellar objects.

Contribution

It provides the first detailed hydrodynamic modeling linking long-period X-ray pulsations to plasma sloshing in star-disk magnetic tubes in PMS stars.

Findings

Long-period (~3 hours) X-ray pulsations detected in Orion PMS stars.

Hydrodynamic models suggest plasma sloshing in magnetic tubes as the cause.

Magnetic tubes are as long as 20 solar radii, connecting star and disk.

Abstract

Pulsing X-ray emission tracks the plasma echo traveling in an extremely long magnetic tube that flares in an Orion Pre-Main Sequence (PMS) star. On the Sun, flares last from minutes to a few hours and the longest-lasting typically involve arcades of closed magnetic tubes. Long-lasting X-ray flares are observed in PMS stars. Large-amplitude (~20%) long-period (~3 hours) pulsations are detected in the light curve of day-long flares observed by the Advanced CCD Imaging Spectrometer (ACIS) on-board Chandra from PMS stars in the Orion cluster. Detailed hydrodynamic modeling of two flares observed on V772 Ori and OW Ori shows that these pulsations may track the sloshing of plasma along a single long magnetic tube, triggered by a sufficiently short (~1 hour) heat pulse. This magnetic tubes are as long (>= 20 solar radii) as to connect the star with the surrounding disk.