instrumentation: spectrographs; methods: statistical; planets and satellites: detection; stars: activity; stars: rotation; techniques: radial velocities; Dwarf stars; Gaussian process regression; Instrumentation:spectrographs; Methods:statistical; Planet search; Planets and satellites: detections; Star: activity; Stars: Rotation; Stellars; Techniques: radial velocities; Astronomy and Astrophysics; Space and Planetary Science
Abstract :
[en] We present the discovery of three super-Earth candidates orbiting HD 48948, a bright K-dwarf star with an apparent magnitude of mV = 8.58 mag. As part of the HARPS-N Rocky Planet Search programme, we collect 189 high-precision radial velocity measurements using the HARPS-N spectrograph from 2013 October 6, to 2023 April 16. Various methodologies are applied to extract the radial velocities from the spectra, and we conduct a comprehensive comparative analysis of the outcomes obtained through these diverse extraction techniques. To ensure the robustness of our findings, we employ several methods to address stellar variability, with a focus on Gaussian Process regression. To account for the impact of stellar variability and correlated noise in the radial velocity data set, we include activity indicators, such as log RH́K and bisector span, in the multidimensional Gaussian Process regression. Our analysis reveals three planetary candidates with orbital periods of 7.3, 38, and 151 d, and minimum masses estimated at 4.88 ± 0.21 M, 7.27 ± 0.70 M, and 10.59 ± 1.00 M, respectively. The outermost planet resides within the (temperate) habitable zone, positioned at a projected distance of 0.029 arcsec from its star. Given the close proximity of this planetary system, situated at a distance of 16.8 parsecs, HD 48498 emerges as a promising target (closest super-Earth around FGK stars) for future high-contrast direct imaging and high-resolution spectroscopic studies.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Dalal, S.; Department of Astrophysics, University of Exeter, Exeter, United Kingdom
Rescigno, F. ; Department of Astrophysics, University of Exeter, Exeter, United Kingdom
Cretignier, M. ; Department of Physics, University of Oxford, Oxford, United Kingdom
Anna John, A. ; SUPA, School of Physics & Astronomy, University of St Andrews, St Andrews, United Kingdom
Majidi, F.Z. ; Dipartimento di Fisica e Astronomia ‘Galileo Galilei’, Università degli Studi di Padova, Padova, Italy ; INAF - Osservatorio Astrofisico di Torino, Pino Torinese, Italy ; Blue Skies Space, Italia SRL, Milano, Italy
Malavolta, L. ; Dipartimento di Fisica e Astronomia ‘Galileo Galilei’, Università degli Studi di Padova, Padova, Italy ; INAF - Osservatorio Astrofisico di Torino, Pino Torinese, Italy
Mortier, A. ; Department of Astrophysics, University of Birmingham, Birmingham, United Kingdom
Pinamonti, M. ; INAF - Osservatorio Astrofisico di Torino, Pino Torinese, Italy
Buchhave, L.A. ; DTU Space, Technical University of Denmark, Kgs. Lyngby, Denmark
Haywood, R.D.; Department of Astrophysics, University of Exeter, Exeter, United Kingdom
Sozzetti, A. ; INAF - Osservatorio Astrofisico di Torino, Pino Torinese, Italy
Dumusque, X.; Observatoire de Genève, Université de Genève, Versoix, Switzerland
Lienhard, F.; Astrophysics Group, Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom
Rice, K.; SUPA, Institute for Astronomy, The Royal Observatory, University of Edinburgh, Edinburgh, United Kingdom ; Centre for Exoplanet Science, University of Edinburgh, Edinburgh, United Kingdom
Vanderburg, A.; Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, United States
Lakeland, B.; Department of Astrophysics, University of Exeter, Exeter, United Kingdom
Cameron, A. Collier; Dipartimento di Fisica e Astronomia ‘Galileo Galilei’, Università degli Studi di Padova, Padova, Italy ; Centre for Exoplanet Science, University of St Andrews, St Andrews, United Kingdom
Damasso, M.; INAF - Osservatorio Astrofisico di Torino, Pino Torinese, Italy
Affer, L.; INAF –, Osservatorio Astronomico di Palermo, Palermo, Italy
Boschin, W.; Fundación Galileo Galilei – INAF (Telescopio Nazionale Galileo), Canary Islands, Spain ; Instituto de Astrofísica de Canarias, Canary Islands, Spain
Cooke, B.; Centre for Exoplanets and Habitability, University of Warwick, Coventry, United Kingdom ; Department of Physics, University of Warwick, Coventry, United Kingdom
Cosentino, R.; Departamento de Astrofísica, Universidad de La Laguna, Canary Islands, Spain
Di Fabrizio, L.; Fundación Galileo Galilei – INAF (Telescopio Nazionale Galileo), Canary Islands, Spain
Ghedina, A.; Fundación Galileo Galilei – INAF (Telescopio Nazionale Galileo), Canary Islands, Spain
Harutyunyan, A.; Fundación Galileo Galilei – INAF (Telescopio Nazionale Galileo), Canary Islands, Spain
Latham, D.W.; Center for Astrophysics, Harvard & Smithsonian, Cambridge, United States
López-Morales, M.; Center for Astrophysics, Harvard & Smithsonian, Cambridge, United States
Lovis, C.; Observatoire de Genève, Université de Genève, Versoix, Switzerland
Fiorenzano, A.F. Martínez; Fundación Galileo Galilei – INAF (Telescopio Nazionale Galileo), Canary Islands, Spain
Mayor, M.; Observatoire de Genève, Université de Genève, Versoix, Switzerland
Nicholson, B.; Centre for Astrophysics, University Of Southern Queensland, Toowoomba, Australia
Pepe, F.; Observatoire de Genève, Université de Genève, Versoix, Switzerland
Stalport, Manu ; Université de Liège - ULiège > Unités de recherche interfacultaires > Space sciences, Technologies and Astrophysics Research (STAR)
Udry, S.; Observatoire de Genève, Université de Genève, Versoix, Switzerland
Watson, C.A.; Astrophysics Research Centre, Queen’s University Belfast, Belfast, United Kingdom
Wilson, T.G.; Dipartimento di Fisica e Astronomia ‘Galileo Galilei’, Università degli Studi di Padova, Padova, Italy ; Centre for Exoplanet Science, University of St Andrews, St Andrews, United Kingdom
STFC - Science and Technology Facilities Council SNSF - Swiss National Science Foundation ESA - European Space Agency
Funding text :
The HARPS-N project was funded by the Prodex Program 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), the Italian National Astrophysical Institute (INAF), University of St. Andrews, Queen\u2019s University Belfast, and University of Edinburgh.SD acknowledges support from the STFC consolidated grant no. ST/V000721/1. FR is funded by the University of Exeter\u2019s College of Engineering, Maths and Physical Sciences, UK. ACC acknowledges support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant no. ST/R003203/1. KR is grateful for support from UK STFC via consolidated grant no. ST/V000594/1. RDH is funded by the UK Science and Technology Facilities Council (STFC)\u2019s Ernest Rutherford Fellowship (grant number ST/V004735/1). MC acknowledges the SNSF support under grant P500PT_211024. AS, ASB, and MD gratefully acknowledge support from the \u2018Programma di Ricerca Fondamentale INAF 2023\u2019 of the National Institute of Astrophysics (Large Grant 2023 EXODEMO). MP acknowledges support from the Italian Space Agency (ASI) under contract 2018-24-HH.0 \u2018The Italian participation to the Gaia Data Processing and Analysis Consortium (DPAC)\u2019 in collaboration with the Italian National Institute of Astrophysics. MP also acknowledges support from the European Union \u2013 NextGenerationEU (PRIN MUR 2022 20229R43BH) and the \u2018Programma di Ricerca Fondamentale INAF 2023\u2019. FPE and CLO would like to acknowledge the Swiss National Science Foundation (SNSF) for supporting research with HARPS-N through the SNSF grant numbers 140649, 152721, 166227, 184618, and 215190. The HARPS-N Instrument Project was partially funded through the Swiss ESA-PRODEX Programme.
Commentary :
Error in the computation of incident flux and equilibrium temperature of the planets, displayed in Table 3. An erratum to Table 3 is available in annex.
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