id:"swepub:oai:DiVA.org:uu-361994"
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- Amarsi, A. M.Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany (författare)
Effective temperature determinations of late-type stars based on 3D non-LTE Balmer line formation
- Artikel/kapitelEngelska2018
Förlag, utgivningsår, omfång ...
- 2018-07-27
- EDP Sciences,2018
- printrdacarrier
Nummerbeteckningar
- LIBRIS-ID:oai:DiVA.org:uu-361994
- https://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-361994URI
- https://doi.org/10.1051/0004-6361/201732546DOI
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- Språk:engelska
- Sammanfattning på:engelska &language:-1_t
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Anmärkningar
- Hydrogen Balmer lines are commonly used as spectroscopic effective temperature diagnostics of late-type stars. However, reliable inferences require accurate model spectra, and the absolute accuracy of classical methods that are based on one-dimensional (1D) hydrostatic model atmospheres and local thermodynamic equilibrium (LTE) is still unclear. To investigate this, we carry out 3D non-LTE calculations for the Balmer lines, performed, for the first time, over an extensive grid of 3D hydrodynamic STAGGER model atmospheres. For H alpha, H beta, and H gamma we find significant 1D non-LTE versus 3D non-LTE differences (3D effects): the outer wings tend to be stronger in 3D models, particularly for H gamma, while the inner wings can be weaker in 3D models, particularly for H alpha. For H alpha, we also find significant 3D LTE versus 3D non-LTE differences (non-LTE effects): in warmer stars (T-eff approximate to 6500 K) the inner wings tend to be weaker in non-LTE models, while at lower effective temperatures (T-eff approximate to 4500 K) the inner wings can be stronger in non-LTE models; the non-LTE effects are more severe at lower metallicities. We test our 3D non-LTE models against observations of well-studied benchmark stars. For the Sun, we infer concordant effective temperatures from H alpha, H beta, and H gamma; however the value is too low by around 50 K which could signal residual modelling shortcomings. For other benchmark stars, our 3D non-LTE models generally reproduce the effective temperatures to within 1 sigma uncertainties. For H alpha, the absolute 3D effects and non-LTE effects can separately reach around 100 K, in terms of inferred effective temperatures. For metal-poor turn-off stars, 1D LTE models of H alpha can underestimate effective temperatures by around 150 K. Our 3D non-LTE model spectra are publicly available, and can be used for more reliable spectroscopic effective temperature determinations.
Ämnesord och genrebeteckningar
- NATURVETENSKAP Fysik Astronomi, astrofysik och kosmologi hsv//swe
- NATURAL SCIENCES Physical Sciences Astronomy, Astrophysics and Cosmology hsv//eng
- radiative transfer
- line: formation
- line: profiles
- stars: atmospheres
- stars: late-type
Biuppslag (personer, institutioner, konferenser, titlar ...)
- Nordlander, T.Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia;ARC Ctr Excellence All Sky Astrophys 3 Dimens AST, Canberra, ACT, Australia (författare)
- Barklem, PaulUppsala universitet,Teoretisk astrofysik(Swepub:uu)pba11670 (författare)
- Asplund, M.Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia (författare)
- Collet, R.Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, Ny Munkegade 120, DK-8000 Aarhus C, Denmark (författare)
- Lind, KarinUppsala universitet,Teoretisk astrofysik,Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany(Swepub:uu)karli488 (författare)
- Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, GermanyAustralian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia;ARC Ctr Excellence All Sky Astrophys 3 Dimens AST, Canberra, ACT, Australia (creator_code:org_t)
Sammanhörande titlar
- Ingår i:Astronomy and Astrophysics: EDP Sciences6150004-63611432-0746
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- Amarsi, A. M.
- Nordlander, T.
- Barklem, Paul
- Asplund, M.
- Collet, R.
- Lind, Karin
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