Disentangling 2:1 resonant radial velocity orbits from eccentric ones and a case study for HD 27894

Home

All issues

Volume 577 (May 2015)

A&A, 577 (2015) A103

Full HTML

Free Access

Table 3

Orbital parameters for the HD 27894 system for the various applied models.

	1-planet models		2-planet models
	Moutou et al.	This work	This work
	(2005)		2:1-RCO	2-pl. circular
	Single	Single	e₁ = e₂ = 0	e₁ = e₂ = 0	Double
	Keplerian	Keplerian	P₁ = 2P₂	P₁ ≠ 2P₂	Keplerian

N _par	6	6	6	7	11

P ₁ [ d ]	17.991 ± 0.007	17.9904 ± 0.0077	17.9915 ± 0.0071	17.9919 ± 0.0070	17.99 ± 0.35
P ₂ [ d ]	–	–		8.276 ± 0.035	8.27 ± 0.99
t _p,1 [ BJD−2 450 000 ]	2933.7 ± 0.5 ^a	2933.64 ± 0.55	–	–	2928.2 ± 1.6
t _p,2 [ BJD−2 450 000 ]	–	–	–	–	2933.8 ± 5.9
t _max,1 [ BJD−2 450 000 ]	–	–	2926.98 ± 0.16	2927.03 ± 0.16	–
t _max,2 [ BJD−2 450 000 ]	–	–	2939.40 ± 0.25	2941.60 ± 1.75	–
e ₁	0.049 ± 0.008	0.0486 ± 0.0086			0.057 ± 0.021
e ₂	–	–			0.532 ± 0.076
ω₁[ °]	132.9 ± 9.7	132 ± 11	–	–	20.1 ± 24.6
ω₂[ °]	–	–	–	–	30.8 ± 8.0
K or κ₁^b[ m s^-1 ]	58.1 ± 0.5	58.13 ± 0.50	58.02 ± 0.50	58.28 ± 0.49	57.57 ± 0.60
κ₂ or K₂^b[ m s^-1 ]	–	–	3.00 ± 0.51	5.17 ± 0.62	8.24 ± 1.33
γ [ km s^-1 ]	82.9023	82.90033	82.90225	82.90231	82.90179
	± 0.0003	± 0.00057	± 0.00036	± 0.00039	± 0.00053

m₁sini ^c [ M_Jup ]	0.62	0.645	0.645	0.648	0.639
m₂sini ^c [ M_Jup ]	–	–	0.026	0.044	0.060
m₂sini ^c [ M_Earth ]	–	–	8.4	14	19
a ₁ ^c [ AU ]	0.122	0.125	0.125	0.125	0.125
a ₂ ^c [ AU ]	–	—	0.079	0.074	0.074

rms [ m s^-1 ]	4.0	4.21	4.17	3.20	2.42
	not given	8.706	8.581	5.444	2.522
d.o.f.	14	14	14	13	9
	not given	2.69 × 10^-19	5.92 × 10^-19	2.37 × 10^-19	6.91 × 10^-3

Stability	n.a.	n.a.	Yes	Yes	No^d

Notes. N_par is the number of model parameters and d.o.f. = N_data − N_par the number of degrees of freedom (with N_data the number of data points). All model parameters from P₁ to γ are as defined for Eqs. (1)–(4). Framed values were held fixed for the fits. m₁sini and m₂sini are the derived minimum masses of the outer and inner planet, respectively, a₁ and a₂ the pertinent semi-major axes of the orbits.

^(a)

Moutou et al. (2005) quoted a value of 3275.5 ± 0.5, which is later by 19 revolutions of the planet.

^(b)

As in the text, K stands for the semi-amplitude of the single Keplerian, wheras κ₁ and κ₂ stand for the semi-amplitudes of the circular orbits of the outer and inner planet, respectively; K₂ is meant to denote the semi-amplitude of the inner planet in the double Keplerian fit (last column).

^(c)

All determinations of msini and a made in this work use a stellar mass of 0.8 M_⊙. Contrary to their claim of having used the same value, Moutou et al. (2005) must have adopted 0.75 M_⊙ in order to arrive at their somewhat smaller m₁sini and a₁.

^(d)

Stable only if e₂ is constrained to < 0.3 (for the case i₁ = i₂ = 90°).

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.