J/ApJ/709/168 Eccentric orbits in exoplanets (Anglada-Escude+, 2010)
How eccentric orbital solutions can hide planetary systems in 2:1 resonant
orbits.
Anglada-Escude G., Lopez-Morales M., Chambers J.E.
<Astrophys. J., 709, 168-178 (2010)>
=2010ApJ...709..168A 2010ApJ...709..168A
ADC_Keywords: Planets ; Binaries, orbits ; Stars, double and multiple
Keywords: celestial mechanics - planetary systems -
techniques: radial velocities
Abstract:
The Doppler technique measures the reflex radial motion of a star
induced by the presence of companions and is the most successful
method to detect exoplanets. If several planets are present, their
signals will appear combined in the radial motion of the star, leading
to potential misinterpretations of the data. Specifically, two planets
in 2:1 resonant orbits can mimic the signal of a single planet in an
eccentric orbit. We quantify the implications of this statistical
degeneracy for a representative sample of the reported single
exoplanets with available data sets, finding that (1) around 35% of
the published eccentric one-planet solutions are statistically
indistinguishable from planetary systems in 2:1 orbital resonance,
(2) another 40% cannot be statistically distinguished from a circular
orbital solution, and (3) planets with masses comparable to Earth
could be hidden in known orbital solutions of eccentric super-Earths
and Neptune mass planets.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 70 252 List of eccentric planets and the amplitudes of
their correspondent eccentric harmonics
table3.dat 75 161 Statistical comparison of circular, resonant,
and eccentric orbital solutions
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See also:
B/eso : ESO Science Archive Catalog (ESO, 2012)
J/MNRAS/414/1278 : Eccentricities of transiting planets (Pont+, 2011)
J/ApJS/182/97 : Radial velocities of multi-planet systems (Wittenmyer+,
2009)
J/A+A/485/871 : Transiting planet HD 17156b (Gillon+, 2008)
J/A+A/426/695 : Radial velocities of HD 41004A/B (Zucker+, 2004)
http://exoplanet.eu/ : The extrasolar planets encyclopaedia
http://oklo.org/ : Systemic project web page maintained by G. Laughlin
http://exoplanetarchive.ipac.caltech.edu/ : NASA Exoplanet archive (NStED
database)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Star name
15 A1 --- m_Name [b-f] Planet designation
21- 27 F7.2 --- msin(i) Planet sin(i) mass
29- 35 F7.2 d P Planet orbital period
37- 40 F4.2 --- e Planet eccentricity
42- 48 F7.2 m/s K Planet radial velocity semi-amplitude
50- 55 F6.2 m/s Ke Semi-amplitude of first eccentric harmonic
57- 62 F6.2 m/s Ke2 Semi-amplitude of second order harmonic
64- 70 F7.2 Mgeo mhsin(i) Mass of the possible inner companion
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Star name
18 A1 --- f_Name [c] Individual notes (1)
20- 25 F6.2 --- chi.c (χ2)0.5 of circular orbital solution
27- 31 F5.2 --- chi.r (χ2)0.5 of resonant orbital solution
33- 37 F5.2 --- chi.e (χ2)0.5 of eccentric orbital solution
39- 43 F5.2 % Conf Confidence level (2)
45- 47 I3 --- Nobs Number of observations
49 A1 --- l_Nreq [+] Limit flag on Nreq
50- 53 I4 --- Nreq ? Estimated number of required observations to
detect the second harmonic (3)
54 A1 --- f_Nreq [ab] Flag on Nreq (1)
56- 64 A9 --- Pref Preferred solution (Circular, Eccentric or
Resonant)
66 A1 --- u_FAP [~] Uncertainty flag on FAP
67- 71 F5.2 % FAP ? False alarm probability (FAP) of the favored
solution
73- 75 A3 --- Qual [U* ] Significance of the solution (4)
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Note (1): Flag as follows:
a = Other data sets and astrometry seem to confirm the eccentricity. Very
noisy star.
b = The obtained solution differs from the published one significantly.
c = According to (Bean et al. 2007AJ....134..749B 2007AJ....134..749B), astrometric observations
indicate that the candidate is a star indeed with an orbital inclination
close to 0.
Note (2): To decide which of the orbital solutions is the best, we apply the
confidence level test given by Lucy & Sweeney (1971AJ.....76..544L 1971AJ.....76..544L)
and Lucy (2005A&A...439..663L 2005A&A...439..663L). We only accept one of the non-circular
solutions if the confidence level (c.l.) is better than 95%.
Note (3): Nreq is only given if the orbital solution is significantly
non-circular.
Note (4): Quality flag according to false alarm probability (FAP) as follows:
*** = secure solution (FAP<0.1%)
** = FAP<1%
* = FAP<5%
U = undecided (the solutions are not significantly different: FAP>5%)
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 23-Feb-2012