Many stellar models present difficulties in reproducing basic observational relations of very low mass stars (VLMS), including the mass-radius relation and the optical colour-magnitudes of cool dwarfs. Here, we improve PARSEC (PAdova-TRieste Stellar Evolution Code) models on these points. We implement the T- � relations from PHOENIX BT-Settl model atmospheres as the outer boundary conditions in the PARSEC code, finding that this change alone reduces the discrepancy in the mass-radius relation from 8 to 5 per cent. We compare the models with multiband photometry of clusters Praesepe and M67, showing that the use of T- � relations clearly improves the description of the optical colours and magnitudes. But anyway, using both Kurucz and PHOENIX model spectra, model colours are still systematically fainter and bluer than the observations. We then apply a shift to the above T- � relations, increasing from 0 at Teff = 4730 K to ~14 per cent at Teff = 3160 K, to reproduce the observed mass-radius relation of dwarf stars. Taking this experiment as a calibration of the T- � relations, we can reproduce the optical and near-infrared colour-magnitude diagrams of low-mass stars in the old metal-poor globular clusters NGC 6397 and 47 Tuc, and in the intermediate-age and young solar-metallicity open clusters M67 and Praesepe. Thus, we extend PARSEC models using this calibration, providing VLMS models more suitable for the lower main-sequence stars over a wide range of metallicities and wavelengths. Both sets of models are available on PARSEC webpage. � 2014 The Authors.

Improving PARSEC models for very low mass stars / Chen, Yang; Girardi, L; Bressan, Alessandro; Marigo, P; Barbieri, M; Kong, X.. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 444:3(2014), pp. 2525-2543. [10.1093/mnras/stu1605]

Improving PARSEC models for very low mass stars

Chen, Yang;Bressan, Alessandro;
2014-01-01

Abstract

Many stellar models present difficulties in reproducing basic observational relations of very low mass stars (VLMS), including the mass-radius relation and the optical colour-magnitudes of cool dwarfs. Here, we improve PARSEC (PAdova-TRieste Stellar Evolution Code) models on these points. We implement the T- � relations from PHOENIX BT-Settl model atmospheres as the outer boundary conditions in the PARSEC code, finding that this change alone reduces the discrepancy in the mass-radius relation from 8 to 5 per cent. We compare the models with multiband photometry of clusters Praesepe and M67, showing that the use of T- � relations clearly improves the description of the optical colours and magnitudes. But anyway, using both Kurucz and PHOENIX model spectra, model colours are still systematically fainter and bluer than the observations. We then apply a shift to the above T- � relations, increasing from 0 at Teff = 4730 K to ~14 per cent at Teff = 3160 K, to reproduce the observed mass-radius relation of dwarf stars. Taking this experiment as a calibration of the T- � relations, we can reproduce the optical and near-infrared colour-magnitude diagrams of low-mass stars in the old metal-poor globular clusters NGC 6397 and 47 Tuc, and in the intermediate-age and young solar-metallicity open clusters M67 and Praesepe. Thus, we extend PARSEC models using this calibration, providing VLMS models more suitable for the lower main-sequence stars over a wide range of metallicities and wavelengths. Both sets of models are available on PARSEC webpage. � 2014 The Authors.
2014
444
3
2525
2543
https://doi.org/10.1093/mnras/stu1605
https://arxiv.org/abs/1409.0322
Chen, Yang; Girardi, L; Bressan, Alessandro; Marigo, P; Barbieri, M; Kong, X.
File in questo prodotto:
File Dimensione Formato  
MNRAS-2014-Chen-2525-43.pdf

accesso aperto

Tipologia: Versione Editoriale (PDF)
Licenza: Non specificato
Dimensione 2.99 MB
Formato Adobe PDF
2.99 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/14332
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 440
  • ???jsp.display-item.citation.isi??? 439
social impact