NLTE Radiative Transfer in Cool Stars
Abstract
The interpretation of observed spectra of stars in terms of fundamental stellar properties is a key problem in astrophysics. For FGK-type stars, the radiative transfer models are often computed using the assumption of local thermodynamic equilibrium (LTE). Its validity is often questionable and needs to be supported by detailed studies, which build upon the consistent framework of NLTE. In this review, we outline the theory of NLTE. The processes causing departures from LTE are introduced qualitatively by their physical interpretation, as well as quantitatively by their impact on the models of stellar spectra and element abundances. We also compile and analyse the most recent results from the literature. In particular, we examine the NLTE effects for 24 chemical elements for six well-studied FGK-type stars.
Keywords
Line: formation Radiation mechanisms: general Radiative transfer Stars: atmospheres Stars: late-typeNotes
Acknowledgments
Figure 3 has been kindly provided by Rob Rutten; http://www.staff.science.uu.nl/~rutte101.
References
- Asplund M (2005) Ann Rev A&A 43:481CrossRefGoogle Scholar
- Baumueller D, Gehren T (1997) A&A 325:1088Google Scholar
- Bergemann M (2011) MNRAS 413:2184CrossRefGoogle Scholar
- Bergemann M, Cescutti G (2010) A&A 522:A9CrossRefGoogle Scholar
- Bergemann M, Gehren T (2008) A&A 492:823CrossRefGoogle Scholar
- Bergemann M, Pickering JC, Gehren T (2010) MNRAS 401:1334CrossRefGoogle Scholar
- Bergemann M, Hansen CJ, Bautista M, Ruchti G (2012a) A&A 546:A90CrossRefGoogle Scholar
- Bergemann M, Lind K, Collet R, Magic Z, Asplund M (2012b) MNRAS 427:27CrossRefGoogle Scholar
- Bergemann M, Kudritzki RP, Würl M, Plez B, Davies B, Gazak Z (2013) ApJ 764:115CrossRefGoogle Scholar
- Bruls JHMJ, Rutten RJ, Shchukina NG (1992) A&A 265:237Google Scholar
- Caffau E, Maiorca E, Bonifacio P, Faraggiana R, Steffen M, Ludwig HG, Kamp I, Busso M (2009) A&A 498:877CrossRefGoogle Scholar
- Fabbian D, Asplund M, Carlsson M, Kiselman D (2006) A&A 458:899CrossRefGoogle Scholar
- Gehren T, Butler K, Mashonkina L, Reetz J, Shi J (2001) A&A 366:981CrossRefGoogle Scholar
- Gehren T, Shi JR, Zhang HW, Zhao G, Korn AJ (2006) A&A 451:1065CrossRefGoogle Scholar
- Johnson HR, Milkey RW, Ramsey LW (1974) ApJ 187:147CrossRefGoogle Scholar
- Kiselman D, Carlsson M (1996) A&A 311:680Google Scholar
- Kunc JA, Soon WH (1991) J Chem Phys 95:5738CrossRefGoogle Scholar
- Lind K, Asplund M, Barklem PS (2009) A&A 503:541CrossRefGoogle Scholar
- Lind K, Asplund M, Barklem PS, Belyaev AK (2011) A&A 528:A103CrossRefGoogle Scholar
- Lind K, Bergemann M, Asplund M (2012) MNRAS 427:50CrossRefGoogle Scholar
- Lind K, Melendez J, Asplund M, Collet R, Magic Z (2013) A&A 554:A96CrossRefGoogle Scholar
- Mashonkina L, Gehren T, Bikmaev I (1999) A&A 343:519Google Scholar
- Mashonkina L, Korn AJ, Przybilla N (2007) A&A 461:261CrossRefGoogle Scholar
- Mashonkina L, Zhao G, Gehren T, Aoki W, Bergemann M, Noguchi K, Shi JR, Takada-Hidai M, Zhang HW (2008) A&A 478:529CrossRefGoogle Scholar
- Mashonkina L, Ryabtsev A, Frebel A (2012) A&A 540:A98CrossRefGoogle Scholar
- Mihalas D (1978) Stellar atmospheres, 2nd edn. W. H. Freeman and Co, San FranciscoGoogle Scholar
- Mihalas D, Athay RG (1973) Ann Rev A&A 11:187CrossRefGoogle Scholar
- Reetz JK (1998) Sauerstoff in kühlen Sternen und die chemische Entwicklung der GalaxisGoogle Scholar
- Rybicki GB, Hummer DG (1992) A&A 262:209Google Scholar
- Sitnova TM, Mashonkina LI, Ryabchikova TA (2013) Astron Lett 39:126CrossRefGoogle Scholar
- Takeda Y, Zhao G, Chen YQ, Qiu HM, Takada-Hidai M (2002) PASJ 54:275Google Scholar
- Takeda Y, Hashimoto O, Taguchi H, Yoshioka K, Takada-Hidai M, Saito Y, Honda S (2005) PASJ 57:751Google Scholar
- Wijbenga JW, Zwaan C (1972) Solar Phys 23:265CrossRefGoogle Scholar
- Würl M (2012) NLTE analysis of silicon lines in solar-type stars and red super-giantsGoogle Scholar
- Zhang HW, Gehren T, Zhao G (2008) A&A 481:489CrossRefGoogle Scholar
- Zhao G, Butler K, Gehren T (1998) A&A 333:219Google Scholar