dwarf spectral indices at moderate resolution: accurate T-eff and [Fe/H] for 178 southern star

Autor(es)

Costa-Almeida, Ellen ^{[1, 2]} ; Porto de Mello, Gustavo F. ^[1] ; Giribaldi, Riano E. ^[3] ; Lorenzo-Oliveira, Diego ^[4] ; Ubaldo-Melo, Maria L. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Fed Rio de Janeiro, Observ Valongo, Ladeira Pedro Antonio 43, BR-20080090 Rio De Janeiro, RJ - Brazil

^[2] MCTI, Observ Nacl, Rua Gen Jose Cristino 77, BR-20921400 Rio De Janeiro, RJ - Brazil

^[3] Polish Acad Sci, Nicolaus Copernicus Astron Ctr, Bartycka 18, PL-00716 Warsaw - Poland

^[4] Univ Sao Paulo, Dept Astmn IAG, USP, Rua Matao 1226, Cidode Univ, BR-05508900 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 508, n. 4, p. 5148-5162, DEC 2021.
• Citações Web of Science: 0

Resumo

We present a spectroscopic and photometric calibration to derive effective temperatures T-eff and metallicities {[}Fe/H] for M dwarfs, based on a principal component analysis (PCA) of 147 spectral indices measured off moderate resolution (R similar to 11000), high S/N (>100) spectra in the lambda lambda 8390-8834 region, plus the J-H colour. Internal uncertainties, estimated by the residuals, are 81 K and 0.12 dex, respectively, for T-eff and {[}Fe/H], the calibrations being valid for 3050 K < T 4100 K and -0.45 < {[}Fe/H] 0.50 dex. The PCA calibration is a competitive model-independent method to derive T-eff and {[}Fe/H] for large samples of M dwarfs, well suited to the available database of far-red spectra. The median uncertainties are 105 K and 0.23 dex for T-eff and {[}Fe/H], respectively, estimated by Monte Carlo simulations. We compare our values to other works based on photometric and spectroscopic techniques and find median differences 75 +/- 273 K and 0.02 +/- 0.31 dex for T-eff and {[}Fe/H], respectively, achieving good accuracy but relatively low precision. We find considerable disagreement in the literature between atmospheric parameters for stars in common. We use the new calibration to derive T-eff and {[}Fe/H] for 178 K7-M5 dwarfs, many previously unstudied. Our metallicity distribution function for nearby M dwarfs peaks at {[}Fe/H]similar to-0.10 dex, in good agreement with the RAVE distribution for GK dwarfs. We present radial velocities (internal precision 1.4 kms(-1)) for 99 objects without previous measurements. The kinematics of the sample shows it to be fully dominated by thin/thick disc stars, excepting the well-known high-velocity Kapteyn's star. (AU)

• Processo FAPESP: 16/20667-8 - Cronômetros estelares: a conexão entre idade, atividade cromosférica, rotação e abundâncias de lítio em estrelas de tipo solar
• Beneficiário: Diego Lorenzo de Oliveira
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado