V. A. Checha | Searcharxiv

arXiv2026

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

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.

astro-ph.SR↗

arXiv2025

Photometric and spectroscopic variability of the blue supergiant rho Leo

Context. The post-main-sequence evolution of massive stars remains poorly understood, particularly for blue supergiants. These objects play a crucial role in the dynamical and chemical evolution of galaxies and exhibit pronounced photometric and spectroscopic variability, often quasi-periodic rather than strictly periodic. Aims. We investigate the variability of the evolved B-type star rho Leo to determine its physical properties, identify the underlying mechanisms driving its variability, and constrain its evolutionary stage. Methods. We analyse long-term spectroscopic and photometric datasets obtained from multiple sources, including the TESS and Kepler space missions and observations with the 1.5 m telescope in Estonia. Period analysis is performed using the Generalized Lomb-Scargle periodogram, Lomb-Scargle pre-whitening, and the Weighted Wavelet Z-Transform. Fundamental stellar parameters are derived by fitting synthetic line profiles computed with the FastWind code to the HARPS spectrum, while the stellar rotation inclination is estimated using the ZPEKTR code. Results. The He I 6678.151 A line shows significant radial-velocity and line-profile moment variations. We detect a set of periods and harmonics spanning approximately 0.8 to 35 days. Some periods remain stable over time, whereas others vary between observing seasons. A comparison of spectroscopic and photometric variability, together with phase-curve morphology, allows us to constrain the origin of several signals. In particular, the approximately 11 day period is attributed to stellar rotation, while the approximately 17 day period is linked to radial pulsations. Conclusions. Although the variability is quasi-periodic, most detected periods persist across multiple seasons. The wide range of timescales suggests that rho Leo is likely evolving along a blue loop following the red supergiant phase.

astro-ph.SR↗