Spectral analysis of four surprisingly similar hot hydrogen-rich subdwarf O stars

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Volume 609 (January 2018)

A&A, 609 (2018) A89

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Table 3

Atmospheric parameters and chemical composition of our sample of hot sdOs.


	Feige 34	Feige 67	AGK+81°266	LS II+18°9	Haas (1997) ^a	Bauer & Husfeld (1995) ^b


T_eff^c (K)	62 550 ± 600	61 050 ± 520	61 860 ± 870	60 010 ± 800	60 000 ± 4000	75 000 ± 5000
log g^c (cm s^-2)	5.99 ± 0.03	5.95 ± 0.03	6.07 ± 0.04	6.00 ± 0.06	...	5.2 ± 0.2
RV^d (km s^-1)	11.0 ± 7.7	27.0 ± 7.8	−27.8 ± 7.8	−49.5 ± 12.3	...	...


Element	Abundance (log N(X)/N(H))						Solar^e


He^d	−1.79 ± 0.04	−1.59 ± 0.04	−2.9 ± 0.2	−1.87 ± 0.07	...	−1.27 ± 0.25	−1.07
C	≲−6.7	≲−8.0	≲−6.7	≲−6.7	...	≲−4.50	−3.56
N	−4.9 ± 0.3	−4.9 ± 0.3	−6.0 ± 0.3	−4.9 ± 0.3	...	−4.85 ± 0.5	−4.17
O	−5.5 ± 0.5	−5.5 ± 0.5	≲−6.4	−5.5 ± 0.5	...	...	−3.31
Mg	≲−5.0	≲−5.0	≲−5.0	≲−5.0	...	...	−4.40
Si	−6.2 ± 0.3	≲−6.2	−5.0 ± 0.3	−6.2 ± 0.3	...	≲−5.5	−4.49
P	−6.7 ± 0.5	−6.7 ± 0.5	−5.5 ± 0.5	−6.7 ± 0.5	...	...	−6.59
S	−5.6 ± 0.3	−5.6 ± 0.3	−5.3 ± 0.3	−5.6 ± 0.3	...	...	−4.86
Cr	≲−5.3	≲−5.3	≲−5.3	≲−5.3	...	...	−6.36
Mn	≲−5.6	≲−5.6	≲−5.3	≲−5.6	...	...	−6.57
Fe	−3.1 ± 0.3	−3.1 ± 0.3	−3.1 ± 0.3	−3.1 ± 0.3	−3.5	...	−4.50
Co	≲−5.8	≲−5.8	≲−5.8	≲−5.8	...	...	−7.01
Ni	−4.0 ± 0.3	−4.0 ± 0.3	−4.0 ± 0.3	−4.0 ± 0.3	−3.9	...	−5.77

Notes.

^(a)

For Feige 34, Feige 67, and LS II+18°9, parameters such as log g and abundances of He, C, and N were kept fixed to the values derived by Bauer & Husfeld (1995) for Feige 67.

^(b)

For Feige 67.

^(c)

Our results are the averaged values of the different fits presented in Table 2.

^(d)

Derived from the optical spectra.

^(e)

Asplund et al. (2009).

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