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Title: | The HARPS-N Rocky Planet Search. I. HD 219134 b: A transiting rocky planet in a multi-planet system at 6.5 pc from the Sun | Authors: | Motalebi, F. Udry, S. Gillon, M. Lovis, C. Ségransan, D. Buchhave, L. A. Demory, B. O. Malavolta, Luca Dressing, C. D. Sasselov, D. Rice, K. Charbonneau, D. Collier Cameron, A. Latham, D. MOLINARI, Emilio Carlo Pepe, F. AFFER, Laura BONOMO, ALDO STEFANO Cosentino, R. Dumusque, X. Figueira, P. Fiorenzano, A. F. M. Gettel, S. Harutyunyan, A. Haywood, R. D. Johnson, J. Lopez, E. Lopez-Morales, M. Mayor, M. MICELA, Giuseppina Mortier, A. NASCIMBENI, VALERIO Philips, D. Piotto, G. Pollacco, D. Queloz, D. SOZZETTI, Alessandro Vanderburg, A. Watson, C. A. |
Issue Date: | 2015 | Journal: | ASTRONOMY & ASTROPHYSICS | Number: | 584 | First Page: | A72 | Abstract: | We know now from radial velocity surveys and transit space missions that planets only a few times more massive than our Earth are frequent around solar-type stars. Fundamental questions about their formation history, physical properties, internal structure, and atmosphere composition are, however, still to be solved. We present here the detection of a system of four low-mass planets around the bright (V = 5.5) and close-by (6.5 pc) star HD 219134. This is the first result of the Rocky Planet Search programme with HARPS-N on the Telescopio Nazionale Galileo in La Palma. The inner planet orbits the star in 3.0935 ± 0.0003 days, on a quasi-circular orbit with a semi-major axis of 0.0382 ± 0.0003 AU. Spitzer observations allowed us to detect the transit of the planet in front of the star making HD 219134 b the nearest known transiting planet to date. From the amplitude of the radial velocity variation (2.25 ± 0.22 ms^-1) and observed depth of the transit (359 ± 38 ppm), the planet mass and radius are estimated to be 4.36 ± 0.44 M<SUB>⊕</SUB> and 1.606 ± 0.086 R_⊕, leading to a mean density of 5.76 ± 1.09 g cm^-3, suggesting a rocky composition. One additional planet with minimum-mass of 2.78 ± 0.65 M_⊕ moves on a close-in, quasi-circular orbit with a period of 6.767 ± 0.004 days. The third planet in the system has a period of 46.66 ± 0.08 days and a minimum-mass of 8.94 ± 1.13 M_⊕, at 0.233 ± 0.002 AU from the star. Its eccentricity is 0.46 ± 0.11. The period of this planet is close to the rotational period of the star estimated from variations of activity indicators (42.3 ± 0.1 days). The planetary origin of the signal is, however, the preferred solution as no indication of variation at the corresponding frequency is observed for activity-sensitive parameters. Finally, a fourth additional longer-period planet of mass of 71 M_⊕ orbits the star in 1842 days, on an eccentric orbit (e = 0.34 ± 0.17) at a distance of 2.56 AU. The photometric time series and radial velocities used in this work are available in electronic form at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/584/A72">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/584/A72</A> | Acknowledgments: | The HARPS-N project was funded by the Prodex programme of the Swiss Space Office (SSO), the Harvard University Origin of Life Initiative (HUOLI), the Scottish Universities Physics Alliance (SUPA), the University of Geneva, the Smithsonian Astrophysical Observatory (SAO), and the Italian National Astrophysical Institute (INAF), University of St. Andrews, Queen’s University Belfast, and University of Edinburgh. The research leading to these results has received funding from the European Union Seventh Framework programme (FP7/2007- 2013) under grant agreement No. 313014 (ETAEARTH). C.D. is supported by a National Science Foundation Graduate Research Fellowship. P.F. acknowledges support by Fundaçao para a Ciência e a Tecnologia (FCT) through Investigador FCT contracts of reference IF/01037/2013 and POPH/FSE (EC) by FEDER funding through the programme “Programa Operacional de Factores de Competitividade – COMPETE”. This work has been carried out in the frame of the National Centre for Competence in Research “PlanetS” supported by the Swiss National Science Foundation (SNSF). S.U., C.L., D.S. and F.P. acknowledge the financial support of the SNSF. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA. M. Gillon is Research Associate at the Belgian Scientific Research Fund (F.R.S-FNRS), and he is extremely grateful to NASA and SSC Director for having supported his searches for RV planets with Spitzer . P.F. further acknowledges support from Fundação para a Ciência e a Tecnologia (FCT) in the form of an exploratory project of reference IF/01037/2013CP1191/CT0001. R.D.H. was supported by STFC studentship grant ST/J500744/1 during the course of this work. CAW acknowledges support from STFC grant ST/L000709/1. This publication was made possible by a grant from the John Templeton Foundation. The opinions expressed in this publication are those of the authors and do not necessarily reflect the views of the John Templeton Foundation. This material is based upon work supported by the National Aeronautics and Space Administration under Grant No. NNX15AC90G issued through the Exoplanets Research Program. | URI: | http://hdl.handle.net/20.500.12386/23547 | URL: | https://www.aanda.org/articles/aa/pdf/2015/12/aa26822-15.pdf | ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/201526822 | Bibcode ADS: | 2015A&A...584A..72M | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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