Examinando por Autor "Redaelli, E."

Mostrando 1 - 6 de 6

Acceso Abierto
A precise architecture characterization of the π Mensae planetary system
(EDP Sciences, 2020-10-01) Damasso, D.; Sozzetti, A; Lovis, C.; Barros, S. C. C.; Sousa, S. G.; Demangeon, O. D. S.; Faria, J. P.; Lillo Box, J.; Cristiani, S.; Pepe, F.; Rebolo, R.; Santos, N. C.; Zapatero Osorio, M. R.; Amate, M.; Pasquini, L.; Zerbi, Filippo M.; Adibekyan, V.; Abreu, M.; Affolter, M.; Alibert, Y.; Aliverti, M.; Allart, R.; Allende Prieto, C.; Álvarez, D.; Alves, D.; Ávila, G.; Baldini, V.; Bandy, T.; Benz, W.; Bianco, A.; Borsa, F.; Bossini, D.; Bourrier, V.; Bouchy, F.; Broeg, C.; Cabral, A.; Calderone, G.; Cirami, R.; Coelho, J.; Conconi, P.; Coretti, I.; Cumani, C.; Cupani, G.; D´Odorico, V.; Deiries, S.; Dekker, H.; Delabre, B.; Di Marcoantonio, P.; Dumusque, X.; Ehrenreich, D.; Figueira, P.; Fragoso, A.; Genolet, L.; Genoni, M.; Génova Santos, R.; Hughes, I.; Iwert, O.; Kerber, F.; Knudstrup, J.; Landoni, M.; Lavie, B.; Lizon, J. L.; Lo Curto, G.; Maire, C.; Martins, C. J. A. P.; Mégevand, D.; Mehner, A.; Micela, G.; Modigliani, A.; Molaro, P.; Monteiro, M. A.; Monteiro, M. J. P. F. G.; Moschetti, M.; Mueller, E.; Murphy, M. T.; Nunes, N.; Oggioni, L.; Oliveira, A.; Oshagh, M.; Pallé, E.; Pariani, G.; Poretti, E.; Rasilla, J. L.; Rebordao, J.; Redaelli, E.; Riva, M.; Santa Tschudi, S.; Santin, P.; Santos, P.; Ségransan, D.; Schmidt, T. M.; Segovia, A.; Sosnowska, D.; Spanò, P.; Suárez Mascareño, A.; Tabernero, H.; Tenegi, F.; Udry, S.; Zanutta, A.; González Hernández, Carmen; Swiss National Science Foundation (SNSF); Agenzia Spaziale Italiana (ASI); Fundação para a Ciência e a Tecnologia (FCT); Australian Research Council (ARC); Istituto Nazionale Astrofisica (INAF); 0000-0003-0987-1593; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The bright star pi Men was chosen as the first target for a radial velocity follow-up to test the performance of ESPRESSO, the new high-resolution spectrograph at the European Southern Observatory's Very Large Telescope. The star hosts a multi-planet system (a transiting 4 M-circle plus planet at similar to 0.07 au and a sub-stellar companion on a similar to 2100-day eccentric orbit), which is particularly suitable for a precise multi-technique characterization. Aims. With the new ESPRESSO observations, which cover a time span of 200 days, we aim to improve the precision and accuracy of the planet parameters and search for additional low-mass companions. We also take advantage of the new photometric transits of pi Men c observed by TESS over a time span that overlaps with that of the ESPRESSO follow-up campaign. Methods. We analysed the enlarged spectroscopic and photometric datasets and compared the results to those in the literature. We further characterized the system by means of absolute astrometry with HIPPARCOS and Gaia. We used the high-resolution spectra of ESPRESSO for an independent determination of the stellar fundamental parameters. Results. We present a precise characterization of the planetary system around pi Men. The ESPRESSO radial velocities alone (37 nightly binned data with typical uncertainty of 10 cm s(-1)) allow for a precise retrieval of the Doppler signal induced by pi Men c. The residuals show a root mean square of 1.2 m s(-1), which is half that of the HARPS data; based on the residuals, we put limits on the presence of additional low-mass planets (e.g. we can exclude companions with a minimum mass less than similar to 2 M-circle plus within the orbit of pi Men c). We improve the ephemeris of pi Men c using 18 additional TESS transits, and, in combination with the astrometric measurements, we determine the inclination of the orbital plane of pi Men b with high precision (i(b) =45.8(-1.1)(+1.4) deg). This leads to precise measurement of its absolute mass m(b) = =14.1(-0.4)(+0.5) M-Jup, indicating that pi Men b can be classified as a brown dwarf. Conclusions. The pi Men system represents a nice example of the extreme precision radial velocities that can be obtained with ESPRESSO for bright targets. Our determination of the 3D architecture of the pi Men planetary system and the high relative misalignment of the planetary orbital planes put constraints on and challenge the theories of the formation and dynamical evolution of planetary systems. The accurate measurement of the mass of pi Men b contributes to make the brown dwarf desert a bit greener.
Acceso Abierto
ESPRESSO at VLT On-sky performance and first results
(EDP Sciences, 2021-01-19) Pepe, F.; Cristiani, S.; Rebolo, R.; Santos, N. C.; Dekker, H.; Cabral, A.; Di Marcoantonio, P.; Figueira, P.; Lo Curto, G.; Lovis, C.; Mayor, M.; Mégevand, D.; Molaro, P.; Riva, M.; Zapatero Osorio, M. R.; Amate, M.; Manescau, A.; Pasquini, L.; Zerbi, Filippo M.; Adibekyan, V.; Abreu, M.; Affolter, M.; Alibert, Y.; Aliverti, M.; Allart, R.; Allende Prieto, C.; Álvarez, D.; Alves, D.; Ávila, G.; Baldini, V.; Bandy, T.; Barros, S. C. C.; Benz, W.; Bianco, A.; Borsa, F.; Bourrier, V.; Bouchy, F.; Broeg, C.; Calderone, G.; Cirami, R.; Coelho, J.; Conconi, P.; Coretti, I.; Cumani, C.; Cupani, G.; D´Odorico, V.; Damasso, M.; Deiries, S.; Delabre, B.; Demangeon, O. D. S.; Dumusque, X.; Ehrenreich, D.; Faria, J. P.; Fragoso, A.; Genolet, L.; Genoni, M.; Génova Santos, R.; Hughes, I.; Iwert, O.; Kerber, F.; Knudstrup, J.; Landoni, M.; Lavie, B.; Lillo Box, J.; Lizon, J. L.; Maire, C.; Martins, C. J. A. P.; Mehner, A.; Micela, G.; Modigliani, A.; Monteiro, M. A.; Monteiro, M. J. P. F. G.; Moschetti, M.; Murphy, M. T.; Nunes, N.; Oggioni, L.; Oliveira, A.; Oshagh, M.; Pallé, E.; Pariani, G.; Poretti, E.; Rasilla, J. L.; Rebordao, J.; Redaelli, E.; Santana Tschudi, S.; Santin, P.; Santos, P.; Ségransan, D.; Schmidt, T. M.; Segovia, A.; Sosnowska, D.; Sozzetti, A.; Sousa, S. G.; Spanò, P.; Suárez Mascareño, A.; Tabernero, H.; Tenegi, F.; Udry, S.; Zanutta, A.; González Hernández, Carmen; Swiss National Science Foundation (SNSF); Fundacao para a Ciencia e a Tecnologia (FCT); European Research Council (ERC); Agencia Estatal de Investigación (AEI); Australian Research Council; 0000-0002-9433-871X; 0000-0003-0513-8116; 0000-0002-4339-0550; 0000-0002-6728-244X; 0000-0003-2434-3625; 0000-0002-7504-365X; 0000-0002-7040-5498; 0000-0003-4422-2919; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. ESPRESSO is the new high-resolution spectrograph of ESO’s Very Large Telescope (VLT). It was designed for ultra-high radial-velocity (RV) precision and extreme spectral fidelity with the aim of performing exoplanet research and fundamental astrophysical experiments with unprecedented precision and accuracy. It is able to observe with any of the four Unit Telescopes (UTs) of the VLT at a spectral resolving power of 140 000 or 190 000 over the 378.2 to 788.7 nm wavelength range; it can also observe with all four UTs together, turning the VLT into a 16 m diameter equivalent telescope in terms of collecting area while still providing a resolving power of 70 000. Aims. We provide a general description of the ESPRESSO instrument, report on its on-sky performance, and present our Guaranteed Time Observation (GTO) program along with its first results. Methods. ESPRESSO was installed on the Paranal Observatory in fall 2017. Commissioning (on-sky testing) was conducted between December 2017 and September 2018. The instrument saw its official start of operations on October 1, 2018, but improvements to the instrument and recommissioning runs were conducted until July 2019. Results. The measured overall optical throughput of ESPRESSO at 550 nm and a seeing of 0.65″ exceeds the 10% mark under nominal astroclimatic conditions. We demonstrate an RV precision of better than 25 cm s−1 during a single night and 50 cm s−1 over several months. These values being limited by photon noise and stellar jitter shows that the performance is compatible with an instrumental precision of 10 cm s−1. No difference has been measured across the UTs, neither in throughput nor RV precision. Conclusions. The combination of the large collecting telescope area with the efficiency and the exquisite spectral fidelity of ESPRESSO opens a new parameter space in RV measurements, the study of planetary atmospheres, fundamental constants, stellar characterization, and many other fields.
Acceso Abierto
ESPRESSO high-resolution transmission spectroscopy of WASP-76 b
(EDP Sciences, 2021-02-19) Tabernero, H. M.; Zapatero Osorio, M. R.; Allart, R.; Borsa, F.; Casasayas Barris, N.; Demangeon, O. D. S.; Ehrenreich, D.; Lillo Box, J.; Lovis, C.; Pallé, E.; Sousa, S. G.; Rebolo, R.; Santos, N. C.; Pepe, F.; Cristiani, S.; Adibekyan, V.; Allende Prieto, C.; Alibert, Y.; Barros, S. C. C.; Bouchy, F.; Bourrier, V.; D´Odorico, V.; Dumusque, X.; Faria, J. P.; Figueira, P.; Genova Santos, R.; Hojjatpanah, S.; Lo Curto, G.; Lavie, B.; Martins, C. J. A. P.; Martins, J. H. C.; Mehner, A.; Micela, G.; Molaro, P.; Nunes, N. J.; Poretti, E.; Seidel, J. V.; Sozzetti, A.; Suárez Mascareño, A.; Udry, S.; Aliverti, M.; Affolter, M.; Alves, D.; Amate, M.; Ávila, G.; Bandy, T.; Benz, W.; Bianco, A.; Broeg, C.; Cabral, A.; Conconi, P.; Coelho, J.; Cumani, C.; Deiries, S.; Dekker, H.; Delabre, B.; Fragoso, A.; Genoni, M.; Genolet, L.; Hughes, I.; Knudstrup, J.; Kerber, F.; Landoni, M.; Lizon, J. L.; Maire, C.; Manescau, A.; Di Marcoantonio, P.; Mégevand, D.; Monteiro, M.; Moschetti, M.; Mueller, E.; Modigliani, A.; Oggioni, L.; Oliveira, A.; Pariani, G.; Pasquini, L.; Rasilla, J. L.; Redaelli, E.; Riva, M.; Santana Tschudi, S.; Santin, P.; Santos, P.; Segovia, A.; Sosnowska, D.; Spanò, P.; Tenegi, F.; Iwert, O.; Zanutta, A.; Zerbi, Filippo M.; González Hernández, Carmen; European Research Council (ERC); Fundacao para a Ciencia e a Tecnologia (FCT); Agencia Estatal de Investigación (AEI); Istituto Nazionale di Astrofisica (INAF); Cabral, A. [0000-0002-9433-871X]; Monteiro, M. J. [0000-0003-0513-8116]; Coelho, F. M. [0000-0002-4339-0550]; Faria, J. [0000-0002-6728-244X]; Santos, N. [0000-0003-4422-2919]
Aims. We report on ESPRESSO high-resolution transmission spectroscopic observations of two primary transits of the highly irradiated, ultra-hot Jupiter-sized planet, WASP-76b. We investigated the presence of several key atomic and molecular features of interest that may reveal the atmospheric properties of the planet. Methods. We extracted two transmission spectra of WASP-76b with R ≈ 140 000 using a procedure that allowed us to process the full ESPRESSO wavelength range (3800–7880 Å) simultaneously. We observed that at a high signal-to-noise ratio, the continuum of ESPRESSO spectra shows ‘wiggles’, which are likely caused by an interference pattern outside the spectrograph. To search for the planetary features, we visually analysed the extracted transmission spectra and cross-correlated the observations against theoretical spectra of different atomic and molecular species. Results. The following atomic features are detected: Li I, Na I, Mg I, Ca II, Mn I, K I, and Fe I. All are detected with a confidence level between 9.2 σ (Na I) and 2.8 σ (Mg I). We did not detect the following species: Ti I, Cr I, Ni I, TiO, VO, and ZrO. We impose the following 1 σ upper limits on their detectability: 60, 77, 122, 6, 8, and 8 ppm, respectively. Conclusions. We report the detection of Li I on WASP-76b for the first time. In addition, we confirm the presence of Na I and Fe I as previously reported in the literature. We show that the procedure employed in this work can detect features down to the level of ~0.1% in the transmission spectrum and ~10 ppm by means of a cross-correlation method. We discuss the presence of neutral and singly ionised features in the atmosphere of WASP-76b.
Acceso Abierto
Fundamental physics with ESPRESSO: Towards an accurate wavelength calibration for a precision test of the fine-structure constant
(EDP Sciences, 2021-02-19) Schmidt, T. M.; Molaro, P.; Murphy, M. T.; Lovis, C.; Cupani, G.; Cristiani, S.; Pepe, F. A.; Rebolo, R.; Santos, N. C.; Abreu, M.; Adibekyan, V.; Alibert, Y.; Aliverti, M.; Allart, R.; Allende Prieto, C.; Alves, D.; Baldini, V.; Broeg, C.; Cabral, A.; Calderone, G.; Cirami, R.; Coelho, J.; Coretti, I.; D´Odorico, V.; Di Marcoantonio, P.; Ehrenreich, D.; Figueira, P.; Genoni, M.; Génova Santos, R.; Kerber, F.; Londoni, M.; Leite, A. C. O.; Louis Lizon, J.; Lo Curto, G.; Manescau, A.; Martins, C. J. A. P.; Mégevand, D.; Mehner, A.; Micela, G.; Modigliani, A.; Monteiro, M.; Monteiro, M. J. P. F. G.; Mueller, E.; Nunes, N. J.; Oggioni, L.; Oliveira, A.; Pariani, G.; Pasquini, L.; Redaelli, E.; Riva, M.; Santos, P.; Sosnowska, D.; Sousa, S. G.; Sozzetti, A.; Suárez Mascareño, A.; Udry, S.; Zapatero Osorio, M. R.; Zerbi, Filippo M.; González Hernández, Carmen; Istituto Nazionale di Astrofisica (INAF); Australian Research Council (ARC); Swiss National Science Foundation (SNSF); Fundacao para a Ciencia e a Tecnologia (FCT); European Research Council (ERC); Schmidt, T. M. [0000-0002-4833-7273]; Molaro, P. [0000-0002-0571-4163]; Murphy, M. T. [0000-0002-7040-5498]; Cristiani, S. [0000-0002-2115-5234]; Pepe, F. A. [0000-0002-9815-773X]; Rebolo, R. [0000-0003-3767-7085]
Observations of metal absorption systems in the spectra of distant quasars allow one to constrain a possible variation of the fine-structure constant throughout the history of the Universe. Such a test poses utmost demands on the wavelength accuracy and previous studies were limited by systematics in the spectrograph wavelength calibration. A substantial advance in the field is therefore expected from the new ultra-stable high-resolution spectrograph ESPRESSO, which was recently installed at the VLT. In preparation of the fundamental physics related part of the ESPRESSO GTO program, we present a thorough assessment of the ESPRESSO wavelength accuracy and identify possible systematics at each of the different steps involved in the wavelength calibration process. Most importantly, we compare the default wavelength solution, which is based on the combination of Thorium-Argon arc lamp spectra and a Fabry-Pérot interferometer, to the fully independent calibration obtained from a laser frequency comb. We find wavelength-dependent discrepancies of up to 24 m s−1. This substantially exceeds the photon noise and highlights the presence of different sources of systematics, which we characterize in detail as part of this study. Nevertheless, our study demonstrates the outstanding accuracy of ESPRESSO with respect to previously used spectrographs and we show that constraints of a relative change of the fine-structure constant at the 10−6 level can be obtained with ESPRESSO without being limited by wavelength calibration systematics.
Restringido
Nightside condensation of iron in an ultrahot giant exoplanet
(Nature Research Journals, 2020-03-11) Ehrenreich, D.; Lovis, C.; Allart, R.; Zapatero Osorio, M. R.; Pepe, F.; Cristiani, S.; Rebolo, R.; Santos, N. C.; Borsa, F.; Demangeon, O. D. S.; Dumusque, X.; Casasayas Barris, N.; Séngrasan, D.; Sousa, S.; Abreu, M.; Adibekyan, V.; Affolter, M.; Allende Prieto, C.; Alibert, Y.; Aliverti, M.; Alves, D.; Amate, M.; Ávila, G.; Baldini, V.; Bandy, T.; Benz, W.; Bianco, A.; Bolmont, É.; Bouchy, F.; Bourrier, V.; Broeg, C.; Cabral, A.; Calderone, G.; Pallé, E.; Cegla, H. M.; Cirami, R.; Coelho, João M. P.; Conconi, P.; Coretti, I.; Cumani, C.; Cupani, G.; Dekker, H.; Delabre, B.; Deiries, S.; D´Odorico, V.; Di Marcoantonio, P.; Figueira, P.; Fragoso, A.; Genolet, L.; Genoni, M.; Génova Santos, R.; Harada, N.; Hughes, I.; Iwert, O.; Kerber, F.; Knudstrup, J.; Landoni, M.; Lavie, B.; Lizon, J. L.; Lendl, M.; Lo Curto, G.; Maire, C.; Manescau, A.; Martins, C. J. A. P.; Mégevand, D.; Mehner, A.; Micela, G.; Modigliani, A.; Molaro, P.; Monteiro, M.; Monteiro, M. A.; Moschetti, M.; Muller, N.; Nunes, N.; Oggioni, L.; Oliveira, A.; Pariani, G.; Pasquini, L.; Poretti, E.; Rasilla, J. L.; Redaelli, E.; Riva, M.; Santana Tschudi, S.; Santin, P.; Santos, P.; Segovia Milla, A.; Seidel, J. V.; Sosnowska, D.; Sozzetti, A.; Spanò, P.; Suárez Mascareño, A.; Tabernero, H.; Tenegi, F.; Udry, S.; Zanutta, A.; Zerbi, Filippo M.; González Hernández, Carmen; European Research Council (ERC); Swiss National Science Foundation (SNSF); Fundacao para a Ciencia e a Tecnologia (FCT); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Suárez Mascareño, A. [0000-0002-3814-5323]; Abreu, M. [0000-0002-0716-9568]; João M. P. Coelho. [0000-0002-4339-0550]; Monteiro, M. J. [0000-0003-0513-8116]; Tabernero, H. [0000-0002-8087-4298]; Nunes, N. J. [0000-0002-3837-6914]; Cabral, A. [0000-0002-9433-871X]; Molaro, P. [0000-0002-0571-4163]; Redaelli, E. M. A. [0000-0001-8185-2122]; Zapatero Osorio, M. R. [0000-0001-5664-2852]; Castro Alves, D. [0000-0001-7026-2514]; Seidel, J. V. [0000-0002-7990-9596]; Martins, C. J. A. P. [0000-0002-4886-9261]; Adibekyan, V. [0000-0002-0601-6199]; Zerbi, F. M. [0000-0002-9996-973X]; Monteiro, M. [0000-0001-5644-0898]; Mehner, A. [0000-0002-9564-3302]; Santos, N. [0000-0003-4422-2919]; Cegla, H. [0000-0001-8934-7315]; Sozzetti, A. [0000-0002-7504-365X]; Allart, R. [0000-0002-1199-9759]; Landoni, M. [0000-0001-5570-5081]; Coretti, I. [0000-0001-9374-3249]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Ultrahot giant exoplanets receive thousands of times Earth’s insolation1,2. Their high-temperature atmospheres (greater than 2,000 kelvin) are ideal laboratories for studying extreme planetary climates and chemistry3,4,5. Daysides are predicted to be cloud-free, dominated by atomic species6 and much hotter than nightsides5,7,8. Atoms are expected to recombine into molecules over the nightside9, resulting in different day and night chemistries. Although metallic elements and a large temperature contrast have been observed10,11,12,13,14, no chemical gradient has been measured across the surface of such an exoplanet. Different atmospheric chemistry between the day-to-night (‘evening’) and night-to-day (‘morning’) terminators could, however, be revealed as an asymmetric absorption signature during transit4,7,15. Here we report the detection of an asymmetric atmospheric signature in the ultrahot exoplanet WASP-76b. We spectrally and temporally resolve this signature using a combination of high-dispersion spectroscopy with a large photon-collecting area. The absorption signal, attributed to neutral iron, is blueshifted by −11 ± 0.7 kilometres per second on the trailing limb, which can be explained by a combination of planetary rotation and wind blowing from the hot dayside16. In contrast, no signal arises from the nightside close to the morning terminator, showing that atomic iron is not absorbing starlight there. We conclude that iron must therefore condense during its journey across the nightside.
Acceso Abierto
Revisiting Proxima with ESPRESSO
(EDP Sciences, 2020-07-13) Suárez Mascareño, A.; Faria, J. P.; Figueira, P.; Lovis, C.; Damasso, M.; Rebolo, R.; Cristiani, S.; Pepe, F.; Santos, N. C.; Zapatero Osorio, M. R.; Adibekyan, V.; Hojjatpanah, S.; Sozzetti, A.; Murgas Alcaino, F.; Abreu, M.; Affolter, M.; Alibert, Y.; Aliverti, M.; Allart, R.; Allende Prieto, C.; Alves, D.; Amate, M.; Ávila, G.; Baldini, V.; Bandi, T.; Barros, S. C. C.; Bianco, A.; Benz, W.; Bouchy, F.; Broeg, C.; Cabral, A.; Calderone, G.; Cirami, R.; Coelho, J.; Conconi, P.; Coretti, I.; Cumani, C.; Cupani, G.; D´Odorico, V.; Deiries, S.; Delabre, B.; Di Marcantonio, P.; Dumusque, X.; Ehrenreich, D.; Fragoso, A.; Genolet, L.; Genoni, M.; Génova Santos, R.; Hughes, I.; Iwert, O.; Kerber, F.; Knusdstrup, J.; Landoni, M.; Lavie, B.; Lillo Box, J.; Lizon, J.; Lo Curto, G.; Maire, C.; Manescau, A.; Martins, C. J. A. P.; Mégevand, D.; Mehner, A.; Micela, G.; Modigliani, A.; Molaro, P.; Monteiro, M. A.; Monteiro, M. J. P. F. G.; Moschetti, M.; Mueller, E.; Nunes, N. J.; Oggioni, L.; Oliveira, A.; Pallé, E.; Pariani, G.; Pasquini, L.; Poretti, E.; Rasilla, J. L.; Redaelli, E.; Riva, M.; Santana Tschudi, S.; Santin, P.; Santos, P.; Segovia, A.; Sosnowska, D.; Sousa, S.; Spanò, P.; Tenegi, F.; Udry, S.; Zanutta, A.; Zerbi, Filippo M.; González Hernández, Carmen; Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); Swiss National Science Foundation (SNSF); Fundacao para a Ciencia e a Tecnologia (FCT); European Research Council (ERC); Lillo Box, J. [0000-0003-3742-1987]; Faria, J. [0000-0002-6728-244X]; Nunes, N. J. [0000-0002-3837-6914]; Molaro, P. [0000-0002-0571-4163]; Mascareño, A. S. [0000-0002-3814-5323]; Cabral, A. [0000-0002-9433-871X]; Monteiro, M. J. P. F. G. [0000-0003-0513-8116]; Redaelli, E. M. A. [0000-0001-8185-2122]; Barros, S. [0000-0003-2434-3625]; Santos, N. [0000-0003-4422-2919]; Abreu, M. [0000-0002-0716-9568]; Coretti, I. [0000-0001-9374-3249]; Sozzetti, A. [0000-0002-7504-365X]; Adibekyan, V. [0000-0002-0601-6199]; Monteiro, M. [0000-0001-5644-0898]; Damasso, M. [0000-0001-9984-4278]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. The discovery of Proxima b marked one of the most important milestones in exoplanetary science in recent years. Yet the limited precision of the available radial velocity data and the difficulty in modelling the stellar activity calls for a confirmation of the Earth-mass planet. Aims. We aim to confirm the presence of Proxima b using independent measurements obtained with the new ESPRESSO spectrograph, and refine the planetary parameters taking advantage of its improved precision. Methods. We analysed 63 spectroscopic ESPRESSO observations of Proxima (Gl 551) taken during 2019. We obtained radial velocity measurements with a typical radial velocity photon noise of 26 cm s−1. We combined these data with archival spectroscopic observations and newly obtained photometric measurements to model the stellar activity signals and disentangle them from planetary signals in the radial velocity (RV) data. We ran a joint Markov chain Monte Carlo analysis on the time series of the RV and full width half maximum of the cross-correlation function to model the planetary and stellar signals present in the data, applying Gaussian process regression to deal with the stellar activity signals. Results. We confirm the presence of Proxima b independently in the ESPRESSO data and in the combined ESPRESSO+ HARPS+UVES dataset. The ESPRESSO data on its own shows Proxima b at a period of 11.218 ± 0.029 days, with a minimum mass of 1.29 ± 0.13 M⊕. In the combined dataset we measure a period of 11.18427 ± 0.00070 days with a minimum mass of 1.173 ± 0.086 M⊕. We get a clear measurement of the stellar rotation period (87 ± 12 d) and its induced RV signal, but no evidence of stellar activity as a potential cause for the 11.2 days signal. We find some evidence for the presence of a second short-period signal, at 5.15 days with a semi-amplitude of only 40 cm s−1. If caused by a planetary companion, it would correspond to a minimum mass of 0.29 ± 0.08 M⊕. We find that forthe case of Proxima, the full width half maximum of the cross-correlation function can be used as a proxy for the brightness changes and that its gradient with time can be used to successfully detrend the RV data from part of the influence of stellar activity. The activity-induced RV signal in the ESPRESSO data shows a trend in amplitude towards redder wavelengths. Velocities measured using the red end of the spectrograph are less affected by activity, suggesting that the stellar activity is spot dominated. This could be used to create differential RVs that are activity dominated and can be used to disentangle activity-induced and planetary-induced signals. The data collected excludes the presence of extra companions with masses above 0.6 M⊕ at periods shorter than 50 days.