Possible chromospheric activity cycles in II Peg, UX Ari and V711 Tau

TL;DR

This study investigates chromospheric activity cycles in three RS CVn-type systems using IUE spectra, identifying potential long-term and flip-flop cycles through periodogram analysis.

Contribution

It presents the first evidence of possible long-term and flip-flop chromospheric cycles in II Peg, UX Ari, and V711 Tau based on spectral data analysis.

Findings

V711 Tau shows an 18-year cycle and a 3-year flip-flop cycle.

II Peg exhibits a 21-year cycle and a 9-year flip-flop cycle.

UX Ari suggests a 6-year chromospheric cycle.

Abstract

We study the Mount Wilson indices we obtained indirectly from IUE high and low resolution spectra of the RS CVn-type systems II Peg (K2IV), UX Ari (K0IV+G5V) and V711 Tau (K1IV+G5V), extensively observed by IUE from 1978 to 1996. We analyze the activity signatures, which correspond to the primary star, with the Lomb-Scargle periodogram. From the analysis of V711 Tau data, we found a possible chromospheric cycle with a period of 18 years and a shorter near 3-year cycle, which could be associated to a chromospheric flip-flop cycle. The data of II Peg also suggest a chromospheric cycle of near 21 years and a flip-flop cycle of 9 years approximately. Finally, we obtained a possible chromospheric cycle of near 6 years for UX Ari.