Doppler Images and Chromospheric Variability of TWA 17

TL;DR

This study uses Doppler imaging and Balmer line analysis to map surface spots and chromospheric activity of TWA 17, revealing a polar spot, extended spots, and a high-altitude prominence.

Contribution

It provides the first Doppler map of TWA 17's surface spots and characterizes its chromospheric variability, including a slingshot prominence.

Findings

Presence of a polar spot with equatorial spots

Detection of a slingshot prominence 3 stellar radii above surface

Chromospheric variability consistent with active magnetic phenomena

Abstract

We present Doppler imaging and a Balmer line analysis of the weak-line T Tauri star TWA 17. Spectra were taken in 2006 with the UCL Echelle Spectrograph on the Anglo-Australian Telescope. Using least-squares deconvolution to improve the effective signal-to-noise ratio we produced a Doppler map of the surface spot distribution. This shows similar features to maps of other rapidly rotating T Tauri stars, i.e. a polar spot with more spots extending out of it down to the equator. In addition to the photospheric variability, the chromospheric variability was studied using the Balmer emission. The mean H-alpha profile has a narrow component consistent with rotational broadening and a broad component extending out to +/-220 km/s. The variability in H-alpha suggests that the chromosphere has at least one slingshot prominence 3 stellar radii above the surface.