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Titolo: LTE spectrum synthesis in magnetic stellar atmospheres - The interagreement of three independent polarised radiative transfer codes
Autore: Wade, GA; Bagnulo, S; Kochukhov, O; Landstreet, JD; Piskunov, N; Stift, MJ;
- Indirizzi:
- Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada Univ Montreal Montreal PQ Canada H3C 3J7 ys, Montreal, PQ H3C 3J7, Canada Univ Vienna, Inst Astron, A-1180 Vienna, Austria Univ Vienna Vienna Austria A-1180 a, Inst Astron, A-1180 Vienna, Austria European So Observ, Santiago 19, Chile European So Observ Santiago Chile19 opean So Observ, Santiago 19, Chile Uppsala Astron Observ, S-75120 Uppsala, Sweden Uppsala Astron Observ Uppsala Sweden S-75120 rv, S-75120 Uppsala, Sweden Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada Univ Western Ontario London ON Canada N6A 3K7 London, ON N6A 3K7, Canada
- Titolo Testata:
- ASTRONOMY & ASTROPHYSICS
fascicolo: 1,
volume: 374,
anno: 2001,
pagine: 265 - 279
- SICI:
- 1432-0746(200107)374:1<265:LSSIMS>2.0.ZU;2-F
- Fonte:
- ISI
- Lingua:
- ENG
- Soggetto:
- LINEAR POLARIMETRY; AP STARS; PARTITION-FUNCTIONS; FIELDS; PECULIAR; PROFILES; MODEL; SAFE;
- Keywords:
- line : profiles; polarisation; stars : magnetic fields; stars : atmospheres;
- Tipo documento:
- Article
- Natura:
- Periodico
- Settore Disciplinare:
- Physical, Chemical & Earth Sciences
- Citazioni:
- 54
- Recensione:
- Indirizzi per estratti:
- Indirizzo: Wade, GA Univ Montreal, Dept Phys, CP 6128 Succ Ctr Ville, Montreal, PQ H3C 3J7, Canada Univ Montreal CP 6128 Succ Ctr Ville Montreal PQ Canada H3C 3J7 a
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- Citazione:
- G.A. Wade et al., "LTE spectrum synthesis in magnetic stellar atmospheres - The interagreement of three independent polarised radiative transfer codes", ASTRON ASTR, 374(1), 2001, pp. 265-279
Abstract
With the aim of establishing a benchmark for the detailed calculation of the polarised line profiles of magnetic stars, we describe an intercomparison of LTE Stokes profiles calculated using three independent, state-of-the-art magnetic spectrum synthesis codes: Cossam, Invers10 and Zeeman2. We find, upon establishing a homogeneous basis for the calculations (identical definitions of the Stokes parameters and the magnetic and stellar reference frames, identical input model stellar atmosphere, identical input atomic data, and identical chemical element abundances and magnetic field distributions), that local and disc-integrated Stokes IQUV profiles of Fe II lambda 4923.9 calculated using the three codes agree very well. For the illustrative case of disc-integrated profiles calculated for abundance log n(Fe)/n(tot) = 4.60, dipole magnetic field intensity B-d = 5 kG, and projected rotational velocity v(e) sin i = 20 km s(-1), Stokes I profiles (depth similar to 40% of the continuum flux I-c) agree to within about 0.05% rms of I-c, StokesV profiles (full amplitude similar to 10%) to within about 0.02% rms of I-c, and Stokes Q and U profiles (full amplitudes similar to2%) at the sub-0.01% rms level. These differences are sufficiently small so as to allow for congruent interpretation of the best spectropolarimetric data available, aswell as for any data likely to become available during the near future. This indicates that uncertainties in modeling Stokes profiles result overwhelmingly from uncertainties in input atomic and physical data, especially thestate and structure of model stellar atmospheres.
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Documento generato il 25/05/13 alle ore 13:52:06