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arXiv · 2608.28039

A decade of radial-velocity monitoring of rho Leo: moment analysis and periodic variability

V. A. Checha·A. Aret·I. Kolka·T. Liimets·V. Mitrokhina·A. Kasikov·T. Eenmäe·S. P. D. Borthakur·H. Ramler
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Abstract

We investigate the origin of long-term spectroscopic and photometric variability in the blue supergiant rho Leo, with particular emphasis on distinguishing between intrinsic pulsations and variability induced by a possible companion. Our analysis is based on an 11.5-year spectroscopic time series obtained at Tartu Observatory, complemented by high-cadence, high-resolution spectroscopy from the Hertzsprung SONG telescope and space-based photometry from TESS. We studied line-profile variability using normalised moments of the HeI 6678, HeI 5875, and SiIII 4552 lines. Periodic signals were identified using the generalised Lomb-Scargle periodogram with iterative pre-whitening, and their temporal stability was examined with the weighted wavelet Z-transform. We detect a persistent periodic signal at P = 16.46 d in the first and third moments, present throughout the full observing interval, with a radial-velocity amplitude of 3.9 km/s. This signal is also present in the SONG data and is visible in multiple spectral lines, indicating a global origin. Photometric observations reveal a dominant variability timescale near 33 d, approximately twice the spectroscopic period. The stable 16.46-day period, present throughout the entire observing interval, most likely results from non-radial pulsations of the supergiant. A binary origin of the signal is not excluded, but distinguishing between these scenarios is complicated by the supergiant's complex variability pattern.

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V. A. Checha, A. Aret, I. Kolka, T. Liimets, V. Mitrokhina, A. Kasikov, T. Eenmäe, S. P. D. Borthakur, H. Ramler. 2026-08-28. A decade of radial-velocity monitoring of rho Leo: moment analysis and periodic variability. https://arxiv.org/abs/2608.28039

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