Comparative modelling of the spectra of cool giants

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Table 12

Experiment 1: parameters determined for α Tau (Star 1) from the best fits to the optical spectra by the various participating teams.

	Starting parameters from photometry			Best fit parameters from spectroscopy				Additional quantities
Code	T _eff	log g	[Fe/H]	T _eff	log g	[Fe/H]	[Ca/Fe]	RV	v _mic	v _mac
	(K)	(g (cm s^-2))		(K)	(g (cm s^-2))			(km s^-1)	(km s^-1)	(km s^-1)

M1			−0.3^a	3800 ± 100	0.75 ± 0.25	−0.3 ± 0.25		54	2.5^f	3^f
M2	3850/4000^b			3850	1.25	0.0	0.0 ± 0.1	54.5	1–2^f	4.5
M3a				3994 ± 100	1.54 ± 0.20	−0.15 ± 0.10		53.9 ± 0.9	2^f	^g
M3b				3839 ± 80	0.94 ± 0.15	−0.35 ± 0.10	−0.2 ± 0.1^c	53.9 ± 0.9	2^f	^g
M4				4000^d	1.5^d	0.0^d		55	2^f	0^f
				3900^d	1.0^d	−0.25^d		55	2^f	0^f
M6	3750–4250^e	1.0–1.5^e		4000 ± 200	1.0 ± 1.0	0.0 ± 0.5	−0.3 ± 0.1	54.3 ± 0.5	2^f
A1	3900	0.0	1.0	3950 ± 100	1.5	−0.67 ± 0.08	−0.23 ± 0.17		2	–ⁱ
A2				4788 ± 92	1.5 ± 0.1	−0.4 ± 0.1		54.1 ± 0.4	2^f
A4				3900	1.0	0.0		54.3	1.3	1.5
A5				4000 ± 200	1.0 ± 0.25	−0.29			1.6 ± 0.5
P				3910 ± 45^d	1.75 ± 0.25^d	0.0^d		54.71	3^h	0
				3800 ± 30^d	1.75 ± 0.25^d	−0.5^d		54.71	3^h	0

Notes. Methods for photometric parameter determination: M1, M2: MARCS models. Theoretical colour (V − K and J − K) – T_eff calibrations (Bessell et al. 1998; van Eck et al. 2011). M6: Houdashelt et al. (2000). A1: Kučinskas et al. (2005).

^(a)

Photometric colours used to resolve a T_eff[Fe/H] degeneracy after spectral fitting.

^(b)

T_eff(V − K)/T_eff(J − K).

^(c)

[α/Fe].

^(d)

Degeneracy in T_eff and [Fe/H].

^(e)

Ranges.

^(f)

Fixed value(s).

^(g)

Not taken into account.

^(h)

Microturbulence increased from 2.0 to 4.0 km s^-1 as log g decreased from 2.5 to 1.0.

⁽ⁱ⁾

Not determined.

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