Improving PARSEC models for very low mass stars

• DOI: 10.1093/mnras/stu1605
• Publication Date: 2014-09-16T03:12:34Z
• Authors: Yang Chen; Léo Girardi; Alessandro Bressan; Paola Marigo; Mauro Barbieri; Xu Kong
• Keywords: Parsec; Effective temperature

Many stellar models present difficulties in reproducing basic observational relations of very low mass stars (VLMS), including the mass--radius relation and optical colour--magnitudes cool dwarfs. Here, we improve PARSEC on these points. We implement T--tau from PHOENIX BT-Settl model atmospheres as outer boundary conditions code, finding that this change alone reduces discrepancy 8 to 5 per cent. compare with multi--band photometry clusters Praesepe M67, showing use clearly improves description colours magnitudes. But anyway, using both Kurucz spectra, are still systematically fainter bluer than observations. then apply a shift above relations, increasing 0 at T_eff = 4730 K ~14% 3160 K, reproduce observed radius dwarf stars. Taking experiment calibration can near infrared CMDs old metal--poor globular NGC6397 47Tuc, intermediate--age young solar--metallicity open M67 Praesepe. Thus, extend calibration, providing VLMS more suitable for lower main sequence over wide range metallicities wavelengths. Both sets available webpage.