Stellar rotation is closely linked to both the age and the magnetic activity of stars. Through gyrochronology, studying stellar rotation provides a means to estimate stellar ages and trace the evolution of planetary systems, and it is also a crucial means to constrain and correct stellar activity effects for robust exoplanet detection and characterisation. CARMENES is a dual-channel, high-resolution (mathcal R > 80000) spectrograph that has been highly successful in detecting exoplanets around M-dwarf stars using the radial-velocity technique, and it also enables precise measurements of the projected rotational velocity (v i) from spectral line broadening. We present an oversampled convolution method that incorporates a realistic limb-darkening model to determine v . We applied our method to 392 M dwarfs observed with CARMENES and it yielded v ) with a median relative uncertainty of 6.8,%, which is substantially smaller than the 15.4,% reported in the literature. This work provides the largest uniform catalogue of v i from CARMENES spectra by comparing observed spectra with that of a template star. The advantages over existing methods in the literature have been assessed using high-resolution synthetic spectra that span effective temperatures of 2500--4000,K and projected rotational velocities of up to 50,km,s -1 i measurements (or upper limits at 2,km,s -1 i measurements for M dwarfs, including significantly updated values for several targets, along with 36 new targets.
Varas et al. (2026) studied this question.