Doppler imaging of the young late-type star LO Pegasi (BD +22 4409) in September 2003

TL;DR

This paper presents a Doppler imaging study of the young star LO Pegasi, revealing persistent high-latitude spots and evolving smaller spots, using enhanced spectral analysis techniques to improve image reconstruction accuracy.

Contribution

The study applies an improved Least Square Deconvolution method with a reference spectrum, producing consistent Doppler images over a decade and revealing detailed starspot distributions.

Findings

Persistent high-latitude polar cap observed since 1993.

Detection of evolving small spots between 10 and 60 degrees latitude.

Confirmation of long-term stability of the polar cap feature.

Abstract

A Doppler image of the ZAMS late-type rapidly rotating star LO Pegasi, based on spectra acquired between 12 and 15 September 2003, is presented. The Least Square Deconvolution technique is applied to enhance the signal-to-noise ratio of the mean rotational broadened line profiles extracted from the observed spectra. In the present application, a unbroadened spectrum is used as a reference, instead of a simple line list, to improve the deconvolution technique applied to extract the mean profiles. The reconstructed image is similar to those previously obtained from observations taken in 1993 and 1998, and shows that LO Peg photospheric activity is dominated by high-latitude spots with a non-uniform polar cap. The latter seems to be a persistent feature as it has been observed since 1993 with little modifications. Small spots, observed between ~ 10 and ~ 60 degrees of latitude, appears to be different with respect to those present in the 1993 and 1998 maps.