The CARMENES search for exoplanets around M dwarfs Characterization of the nearby ultra-compact multiplanetary system YZ Ceti
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Stock, S.
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The CARMENES search for exoplanets around M dwarfs Characterization of the nearby ultra-compact multiplanetary system YZ Ceti
Author
- Stock, S.;
- Kemmer, J.;
- Reffert, S.;
- Trifonov, T.;
- Kaminski, A.;
- Dreizler, S.;
- Quirrenbach, A.;
- Caballero, J. A.;
- Reiners, A.;
- Jeffers, S. V.;
- Anglada Escudé, G.;
- Ribas, I.;
- Amado, P. J.;
- Barrado, D.;
- Barnes, J. R.;
- Bauer, F. F.;
- Modroño Berdiñas, Zaira;
- Béjar, V. J. S.;
- Coleman, G. A. L.;
- Cortés Contreras, M.;
- Díez Alonso, E.;
- Domínguez Fernández, A. J.;
- Espinoza, N.;
- Haswell, C. A.;
- Hatzes, A.;
- Henning, T.;
- Jenkins, James S.;
- Jones, H. R. A.;
- Kossakowski, D.;
- Kürster, M.;
- Lafarga, M.;
- Lee, M. H.;
- López González, M. J.;
- Montes, D.;
- Morales, J. C.;
- Morales, N.;
- Pallé, E.;
- Pedraz, S.;
- Rodríguez, E.;
- Rodríguez López, C.;
- Zechmeister, M.;
Abstract
Context. The nearby ultra-compact multiplanetary system YZ Ceti consists of at least three planets, and a fourth tentative signal. The orbital period of each planet is the subject of discussion in the literature due to strong aliasing in the radial velocity data. The stellar activity of this M dwarf also hampers significantly the derivation of the planetary parameters.
Aims. With an additional 229 radial velocity measurements obtained since the discovery publication, we reanalyze the YZ Ceti system and resolve the alias issues.
Methods. We use model comparison in the framework of Bayesian statistics and periodogram simulations based on a method by Dawson and Fabrycky to resolve the aliases. We discuss additional signals in the RV data, and derive the planetary parameters by simultaneously modeling the stellar activity with a Gaussian process regression model. To constrain the planetary parameters further we apply a stability analysis on our ensemble of Keplerian fits.
Results. We find no evidence for a fourth possible companion. We resolve the aliases: the three planets orbit the star with periods of 2.02 d, 3.06 d, and 4.66 d. We also investigate an effect of the stellar rotational signal on the derivation of the planetary parameters, in particular the eccentricity of the innermost planet. Using photometry we determine the stellar rotational period to be close to 68 d and we also detect this signal in the residuals of a three-planet fit to the RV data and the spectral activity indicators. From our stability analysis we derive a lower limit on the inclination of the system with the assumption of coplanar orbits which is i(min) = 0.9 deg. From the absence of a transit event with TESS, we derive an upper limit of the inclination of i(max) = 87.43 deg.
Conclusions. YZ Ceti is a prime example of a system where strong aliasing hindered the determination of the orbital periods of exoplanets. Additionally, stellar activity influences the derivation of planetary parameters and modeling them correctly is important for the reliable estimation of the orbital parameters in this specific compact system. Stability considerations then allow additional constraints to be placed on the planetary parameters.
Patrocinador
German Research Foundation (DFG)
FOR2544
RE 2694/4-1
German Max-Planck-Gesellschaft (MPG)
Consejo Superior de Investigaciones Cientificas (CSIC)
European Union through FEDER/ERF
FICTS -2011 -02
Spanish Ministry of Economy
German Science Foundation through the Major Research Instrumentation Programme
Klaus Tschira Stiftung
state of Baden-Wurttemberg
state of Niedersachsen
Junta de Andalucia
High Performance and Cloud Computing Group at the Zentrum fur Datenverarbeitung of the University of Tubingen
state of Baden-Wurttemberg through bwHPC
German Research Foundation (DFG)
INST 37/935 -1 FUGG
European FEDER/ERF funds
AYA2015-69350-C3-2-P
AYA2016-79425-C3-1/2/3-P
ESP2017-87676-C5-2-R
ESP2017-87143-R
Centre of Excellence "Severo Ochoa" award
SEV-2015-0548
Centre of Excellence "Maria de Maeztu" award
SEV-2015-0548
Instituto de Astrofisica de Andalucia
SEV-2017-0709
Centro de Astrobiologia
MDM-2017-0737
Generalitat de Catalunya/CERCA programme
Science & Technology Facilities Council (STFC)
ST/M001008/1
ST/P000584/1
Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)
CONICYT FONDECYT
1161218
Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)
PB06
Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)
CONICYT FONDECYT
3180405
Hong Kong RGC grant
HKU 17305618
European Research Council under the Horizon 2020 Framework Program via the ERC
83 24 28
Max-Planck-Institut fur Astronomie
Instituto de Astrofisica de Andalucia
Landessternwarte Konigstuhl
Institut de Ciencies de l'Espai
Insitut fur Astrophysik Gottingen
Universidad Complutense de Madrid
Thuringer Landessternwarte Tautenburg
Instituto de Astrofisica de Canarias
Hamburger Sternwarte
Centro de Astrobiologia
Centro Astronomico Hispano -Aleman
Agencia Estatal de Investigacion of the Ministerio de Ciencia, Innovacion y Universidades
AYA2015-69350-C3-2-P
AYA2016-79425-C3-1/2/3-P
ESP2017-87676-C5-2-R
ESP2017-87143-R
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Artículo de publicación ISI Artículo de publicación SCOPUS
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A&A 636, A119 (2020)
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