Dust and molecular shells in asymptotic giant branch stars - Mid-infrared interferometric observations of R Aquilae, R Aquarii, R Hydrae, W Hydrae, and V Hydrae

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Volume 545 (September 2012)

A&A, 545 (2012) A56

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Table 5

Summary of the results.

Target:	R Aql	R Aqr	R Hya	W Hya	V Hya


Best model:	relative	FDD +	relative	relative	FDD +
	FDD	Gaussian	FDD	FDD	Gaussian
ϵ_FDD layer^a	0.77 ± 0.02	0.35 ± 0.03	0.84 ± 0.01	0.78 ± 0.01	0.23 ± 0.03
θ_FDD layer^a (mas):	21.3 ± 2.0	20.9 ± 3.5	46.6 ± 0.6	79.0 ± 1.2	19.3 ± 3.5
	(4.7 AU)	(5.2 AU)	(6.1 AU)	(7.1 AU)	(6.9 AU)
θ_G dust^a,b (mas):	>1000	105 ± 8	>1000	>1000	105 ± 4
	(>220 AU)	(26.3 AU)	(>130 AU)	(>90 AU)	(37.8 AU)


assumed θ_phot^c (mas):	9.6 ± 1.2	13.8 ± 2.5	20.4 ± 1.0	35.7 ± 2.7	12.1 ± 0.3
assumed θ_SiO^d (mas):	24.2 ± 2.7	31.7 ± 1.2	−	77.3 ± 10.5	−


θ_FDD,12μm / θ_FDD,10μm:	(31 ± 15)%	(24 ± 34)%	(24 ± 2)%	(31 ± 3)%	(18 ± 5)%^e
θ_SiO / θ_phot:	2.5 ± 0.4	2.3 ± 0.4	−	2.2 ± 0.3	−
θ_FDD,10μm / θ_phot:	2.2 ± 0.3	1.5 ± 0.4	2.3 ± 0.1	2.2 ± 0.2	1.6 ± 0.3
θ_G,10μm / θ_phot^b:	>100	7.6 ± 1.5	>49	>28	8.7 ± 0.4


Phase-to-phase variations:
/:	(18 ± 12)%	(14 ± 19)%	(8 ± 3)%	(13 ± 4)%	−
/:	(13 ± 10)%	(18 ± 23)%	(10 ± 10)%	(7 ± 10)%	−


Cycle-to-cycle variations:	−	−	(5 ± 3)%	(5 ± 4)%	−


Asymmetry:	no	yes	no	yes	yes

Notes.

^(a)

At 10 μm.

^(b)

Lower limits of the dust shell diameter (not Gaussian) for R Aql, R Hya and W Hya are obtained from FoV restrictions (cf. Sect. 4.2).

^(c)

Assumed photospheric diameter derived from the K-band diameter (Table 1) divided by 1.2 (cf. e.g. Millan-Gabet et al. 2005).

^(d)

Assumed SiO ring diameter (average of the values given in Sect. 2, but see also Sect. 4.4).

^(e)

For V Hya, θ_{G,12 μm} / θ_{G,8 μm} is given.

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