J/A+A/653/A41       L 98-59 (TOI-175) ESPRESSO observations   (Demangeon+, 2021)

Warm terrestrial planet with half the mass of Venus transiting a nearby star. Demangeon O.D.S., Zapatero Osorio M.R., Alibert Y., Barros S.C.C., Adibekyan V., H.M.Tabernero, Antoniadis-Karnavas A., Camacho J.D., Suarez Mascareno A., Oshagh M., Micela G., Sousa S.G., Lovis C., Pepe F.A., Rebolo R., Cristiani S., Santos N.C., Allart R., AllendePrieto C., Bossini D., Bouchy F., Cabral A., Damasso M., Di Marcantonio P., D'Odorico V., D.Ehrenreich, Faria J., Figueira P., Genova Santos R., Haldemann J., Hara N., Gonzalez Hernandez J.I., Lavie B., Lillo-Box J., Lo Curto G., Martins C.J.A.P., Megevand D., Mehner A., Molaro P., Nunes N.J., Palle E., Pasquini L., Poretti E., Sozzetti A., Udry S. <Astron. Astrophys. 653, A41 (2021)> =2021A&A...653A..41D 2021A&A...653A..41D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Radial velocities Keywords: techniques: radial velocities - techniques: photometric - planet and satellites: detection - planets and satellites: terrestrial planets - planets and satellites: composition - stars: individual: L 98-59 Abstract: In recent years, the advent of a new generation of radial velocity instruments has allowed us to detect lower and lower mass planets, breaking the one Earth-mass barrier. Here we report a new milestone in this context, by announcing the detection of the lightest planet measured so far using radial velocities: L 98-59 b, a rocky planet with half the mass of Venus which is part of a system composed of three known transiting terrestrial planets (planets b to d). We announce the discovery of a fourth non-transiting planet with a minimum mass of 3.06-0.37+0.33M{Earth) and an orbital period of 12.796-0.019+0.020 days and report hints for the presence of a fifth non-transiting terrestrial planet. If confirmed, with a minimum mass of 2.46-0.82+0.66M and an orbital period 23.15-0.17+0.60 days, this planet would sit in the middle of the habitable zone of the L 98-59 system. L 98-59 is a bright M-dwarf located 10.6pc away. Positioned at the border of the continuous viewing zone of the James Webb space telescope, this system is destined to become a corner stone for comparative exoplanetology of terrestrial planets. The three transiting planets have transmission spectrum metrics ranging from 49 to 255 which undoubtedly make them prime targets for atmospheric characterization with the James Webb space telescope, the Hubble space telescope, Ariel or ground-based facilities like NIRPS or ESPRESSO. With equilibrium temperature ranging from 416 to 627K, they offer a unique opportunity to study the diversity of warm terrestrial planets without the unknowns associated with different host stars. L 98-59 b and c have densities of 3.6-1.5+1.4 and 4.57-0.85+0.77g/cm3 respectively and have very similar bulk compositions with a small iron core, representing only 12 to 14% of the total mass, and a small amount of water. However, with a density of 2.95-0.51+0.79g/cm3 and despite a similar core mass fraction, up to 30% of L 98-59 d's mass could be made of water. Description: We present the measurements from our radial velocity campaign of L 98-59 realized with the ESPRESSO spectrograph. From these data and the HARPS and TESS data available in the literature, we performed the characterization of the L 98-59 planetary system. Objects: ---------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------- 08 18 07.62 -68 18 46.8 L 98-59 = TOI 175 ---------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file espresso.dat 181 66 Radial velocities and activity indicators measurement on L 98-59 with the ESPRESSO spectrograph -------------------------------------------------------------------------------- See also: J/A+A/629/A111 : L 98-59 (TOI 175) HARPS observations https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html : TESS data Byte-by-byte Description of file: espresso.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 18 F18.12 d Time Time of the measurement, UTC (BJD-2400000) 20- 32 F13.6 m/s RV Radial velocity 34- 43 F10.6 m/s e_RV Uncertainty on the radial velocity (1 sigma) 45- 56 F12.6 m/s FWHM Full width at half maximum of the cross-correlation function 58- 67 F10.6 m/s e_FWHM Uncertainty on the full width at half maximum (1 sigma) 69- 80 F12.6 m/s BIS Bisector span of the cross-correlation function 82- 91 F10.6 m/s e_BIS Uncertainty on the bisector span (1 sigma) 93-101 F9.6 --- Contrast Contrast of the cross-correlation function 103-110 F8.6 --- e_Contrast Uncertainty on the contrast (1 sigma) 112-119 F8.6 --- Sindex Mont-Wilson S index 121-128 F8.6 --- e_Sindex Uncertainty on the S index (1 sigma) 130-138 F9.6 --- Halpha Depth of the Halpha line 140-147 F8.6 --- e_Halpha Uncertainty on the depth of the Halpha line (1 sigma) 149-157 F9.6 --- NaD Depth of the sodium doublet lines 159-166 F8.6 --- e_NaD Uncertainty on the depth of the sodium doublet lines (1 sigma) 168-176 F9.6 m/s BERV Barycentric Earth Radial Velocity 178-181 A4 --- Inst String indicating if the measurement has been acquired before (Pre) or after (Post) the June 2019 replacement of the fiber-link of ESPRESSO -------------------------------------------------------------------------------- Acknowledgements: Olivier Demangeon, olivier.demangeon(at)astro.up.pt
(End) Patricia Vannier [CDS] 15-Jul-2021
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