Doppler Imaging of LQ Hya for 1998-2002

TL;DR

This study uses Doppler Imaging over four years to map surface spots on LQ Hya, revealing an activity cycle, spot concentration at certain latitudes, and complex long-term magnetic behavior.

Contribution

First application of Doppler Imaging to LQ Hya across multiple seasons, revealing detailed surface spot evolution and activity cycles.

Findings

Detected an activity cycle with varying spot coverage.

No persistent active longitudes over multiple seasons.

Spot activity concentrated at two latitudes.

Abstract

We study the spot distribution on the surface of LQ~Hya during the observing seasons October 1998 -- November 2002. We look for persistent active longitudes, trends in the level of spot activity and compare to photometric data, specifically to the derived time epochs of the lightcurve minima. We apply the Doppler Imaging technique on photospheric spectral lines using an inversion code to retrieve images of the surface temperature. We present new temperature maps using multiple spectral lines for a total of 7 seasons. We calculate spot coverage fractions from each map, and as a result we find a general trend that is interpreted to be an indication of a spot cycle. There is a minimum during the observing season of March 1999. After this the activity increases until November 2000, followed by a general decrease in activity again. We find no evidence for active longitudes persisting over multiple observing seasons. The spot activity appears to be concentrated to two latitude regions. The high latitude spots are particularly strong when the spot coverage is at a maximum. Using the currently accepted rotation period, we find spot structures to show a trend in the phase-time plot, indicative of a need for a longer period. We conclude that the long-term activity of LQ~Hya is more chaotic than that of some magnetically active binary stars analyzed with similar methods, but still with clear indications of an activity cycle.