Long Term Spectral Monitoring of TW Hya
Abstract
We present the analysis of 174 high resolution independent spectroscopic data of TW Hya observed with FEROS over several years. TW Hya has near pole-on configuration, which allows for the continuous monitoring of its high latitude regions where the accretion columns are more likely to be located. We examine the He I, Ca II, Mg II, Li I, and Hα lines, correlating spectral features impacting continua and line emission. The excess continuum is calculated separately using a large sample of weak and strong absorption lines. We find that the excess of continuum emission originates in two independent regions, one stellar, and another dependent on disk accretion. Excess emission obtained from strong absorption lines correlates with Ca II and Mg II, indicating a dependency on the level of chromospheric activity. Excess continuum emission derived from weak absorption lines do not correlate with chromospheric emission as indicated by Ca II and Mg II emission, but does correlate with classical tell-tales of accretion features, such as Hα and He I. The lithium absorption line remains constant throughout the observed range of mass accretion, while both broad and narrow He I line components correlate with disk accretion. The barycenter of the He I broad appears red shifted in over 80% of the sample, consistent with originating in material falling along the accretion column. The He I narrow component shows remarkable correlation with veiling. Quasi-periodic behavior of 3.7± .5 days was examined with mean veiling on data taken over a 30 night viewing.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23530827S