000007557 001__ 7557
000007557 005__ 20260108155838.0
000007557 0247_ $$2DOI$$a10.1051/0004-6361/202553673
000007557 037__ $$aSCART-2025-0126
000007557 100__ $$aFrasca, Antonio
000007557 245__ $$aLAMOST medium-resolution observations of the Pleiades
000007557 260__ $$c2025
000007557 520__ $$aAims. In this work, we present the results of our analysis of medium-resolution LAMOST spectra of late-type candidate members of the Pleiades with the aim of determining the stellar parameters, activity level, and lithium abundance. Methods. We used the ROTFIT code to determine the atmospheric parameters (Teff, log g, and [Fe/H]), along with the radial velocity (RV) and projected rotation velocity (v sin i). Moreover, for late-type stars (Teff ≤ 6500 K), we also calculated the Hα and Li Iλ6708 net equivalent width by means of the subtraction of inactive photospheric templates. We also used the rotation periods from the literature and we purposely determined them for 89 stars by analyzing the available Transiting Exoplanet Survey Satellite (TESS) photometry. Results. We derived the RV, v sin i, and atmospheric parameters for 1581 spectra of 283 stars. Literature data were used to assess the accuracy of the derived parameters. The RV distribution of the cluster members peaks at 5.0 km s‑1 with a dispersion of 1.4 km s‑1, while the average metallicity is [Fe/H]=‑0.03±0.06, in line with previous determinations. Fitting empirical isochrones of Li depletion to EW measures of stars with Teff ≤ 6500 K, we obtained a reliable age for the Pleiades of 118±6 Myr, in agreement with the recent literature. The activity indicators Hα line flux (FHα) and luminosity ratio (R'Hα) show the hottest stars to be less active (on average) than the coldest ones, as expected for a 100-Myr old cluster. When plotted against the Rossby number, RO, our R'Hα values display a typical activity-rotation trend, with a steep decay for RO ≥ 0.2 and a nearly flat (saturated) activity level for smaller values. However, we still see a slight dependence on RO in the saturated regime, which is well fitted by a power law with a slope of ‑1.18 ± 0.02; this is in agreement with a number of previous works. For three sources with multi-epoch data, we had access to LAMOST spectra acquired during flares, which are characterized by strong and broad Hα profiles and the presence of the He I λ6678 Å emission line. Among our targets, we identified 39 possible SB1 and ten SB2 systems. We have also shown the potential of the LAMOST-MRS spectra in allowing us to refine the orbital solution of a number of binaries and to discover a new double-lined binary as well.
000007557 594__ $$aNO
000007557 6531_ $$aStars: abundances
000007557 6531_ $$aStars: activity
000007557 6531_ $$aBinaries: spectroscopic
000007557 6531_ $$aStars: flare
000007557 6531_ $$aStars: fundamental parameters
000007557 6531_ $$aOpen clusters and associations: individual: Pleiades
000007557 6531_ $$aSolar and Stellar Astrophysics
000007557 700__ $$aZhang, Jiayi
000007557 700__ $$aAlonso-Santiago, Javier
000007557 700__ $$aFu, Jian-Ning
000007557 700__ $$aMolenda-Żakowicz, Joanna
000007557 700__ $$aDe Cat, Peter
000007557 700__ $$aCatanzaro, Giovanni
000007557 773__ $$c1--17$$nA7$$pAstronomy & Astrophysics$$v698$$y2025
000007557 8560_ $$fpeter.decat@ksb-orb.be
000007557 8564_ $$s45787521$$uhttps://publi2-as.oma.be/record/7557/files/Frasca2025_AA698_7.pdf
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000007557 905__ $$apublished in
000007557 980__ $$aREFERD