2009/01/31 by J. I. González Hernández, J. I. Gónzalez Hernández, P. Bonifacio · 3 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Effective temperature #Giant star #Infrared #Metallicity #Photometric system #Photometry (optics) #Physics #Scale of temperature #Stars #Stellar, planetary, and galactic studies #Subgiant #astro-ph.SR
paper · pdf · doi:10.1051/0004-6361/200810904
Accepted for publication in A&A. This paper contains online data that will be available at the CDS. Updated version
openalex publication_date 2009/03/05 · arxiv created 2009/03/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
<i>Context. <i/>The effective temperature scale of FGK stars, especially at the lowest metallicities remains a major problem in the chemical abundance analysis of metal-poor stars.<i>Aims. <i/>We present a new implementation of the infrared flux method (IRFM) using the 2MASS catalogue.<i>Methods. <i/>We computed the theoretical quantities in the 2MASS <i>JHK<i/><sub>s<sub/> filters by integrating theoretical fluxes computed from ATLAS models, and compare them directly with the observed 2MASS <i>JHK<i/><sub>s<sub/> magnitudes. This is the main difference between our implementation of the IRFM and that of Ramírez & Meléndez (2005, ApJ, 626, 446, hereafter RM05), since to introduce new stars at the lowest metallicities they transform the 2MASS <i>JHK<i/><sub>s<sub/> magnitudes into the TCS photometric system. We merge in our sample the stars from Alonso et al. (1996, A&AS, 117, 227, hereafter AAM96; 1999, A&AS, 139, 335, hereafter AAM99), and other studies to appropriately cover a wide range of metallicities, ending up with 555 dwarf and subgiant field stars and 264 giant field stars. We derived a new bolometric flux calibration using the available Johnson-Cousins and the 2MASS <i>JHK<i/><sub>s<sub/> photometry. We also computed new versus colour empirical calibrations using our extended sample of stars.<i>Results. <i/>We derived effectives temperatures for almost all the stars in the AAM96 and AAM99 samples and find that our scales of temperature are hotter by K ( K, dwarfs) and K with a K ( giants). The same comparison with the sample of RM05 for stars with [Fe/H] provides a difference of –87 K ( K, dwarf stars) and K ( K, giant stars). <i>Conclusions. <i/>Our temperature scale is slightly hotter than that of AAM96 and RM05 for metal-rich dwarf stars but cooler than that of RM05 for metal-poor dwarfs. We have performed an fully self-consistent IRFM in the 2MASS photometric system. For those who wish to use 2MASS photometry and colour-temperature calibrations to derive effective temperatures, especially for metal-poor stars, we recommend our calibrations over others available in the literature. In our implementation we avoid the transformation of the 2MASS magnitudes to a different photometric system and thus fully exploit the excellent internal consistency of the 2MASS photometric system.