J/A+A/675/A52 TOI-244 photometry and spectroscopy (Castro-Gonzalez+, 2023)
An unusually low-density super-Earth transiting the bright early-type
M-dwarf GJ 1018 (TOI-244).
Castro-Gonzalez A., Demangeon O.D.S., Lillo-Box J., Lovis C., Lavie B.,
Adibekyan V., Acuna L., Deleuil M., Aguichine A., Zapatero Osorio M.R.,
Tabernero H.M., Davoult J., Alibert Y., Santos N., Sousa S.G.,
Antoniadis-Karnavas A., Borsa F., Winn J.N., Allende Prieto C., Figueira P.,
Jenkins J.M., Sozzetti A., Damasso M., Silva A.M., Astudillo-Defru N.,
Barros S.C.C., Bonfils X., Cristiani S., Di Marcantonio P.,
Gonzalez Hernandez J.I., Lo Curto G., Martins C.J.A.P., Nunes N.J.,
Palle E., Pepe F., Seager S., Suarez Mascareno A.
<Astron. Astrophys. 675, A52 (2023)>
=2023A&A...675A..52C 2023A&A...675A..52C (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Radial velocities ;
Photometry ; Optical
Keywords: planets and satellites: individual: TOI-244 b -
planets and satellites: detection -
planets and satellites: composition -
stars: individual: GJ 1018 - techniques: radial velocities -
techniques: photometric
Abstract:
Small planets located at the lower mode of the bimodal radius
distribution are generally assumed to be composed of iron and
silicates in a proportion similar to that of the Earth. However,
recent discoveries are revealing a new group of low-density planets
that are inconsistent with that description.
We intend to confirm and characterize the TESS planet candidate
TOI-244.01, which orbits the bright (K=7.97mag), nearby (d=22pc), and
early-type (M2.5 V) M-dwarf star GJ 1018 with an orbital period of 7.4
days. We used Markov Chain Monte Carlo methods to model 57 precise
radial velocity measurements acquired by the ESPRESSO spectrograph
together with TESS photometry and complementary HARPS data. Our model
includes a planetary component and Gaussian Processes aimed at
modeling the correlated stellar and instrumental noise.
We find TOI-244 b to be a super-Earth with a radius of
Rp=1.52±0.12R☉ and a mass of Mp=2.66±0.31M☉. These
values correspond to a density of ρ=4.2±1.1g/cm3, which is
below what would be expected for an Earth-like composition. We find
that atmospheric loss processes may have been efficient to remove a
potential primordial hydrogen envelope, but high mean-molecular weight
volatiles such as water could have been retained. Our internal
structure modeling suggests that TOI-244 b has a 479+128-96km
thick hydrosphere over a 1.17±0.09R☉ solid structure composed
of a Fe-rich core and a silicate-dominated mantle compatible with that
of the Earth. On a population level, we find two tentative trends in
the density-metallicity and density-insolation parameter space for the
low-density super-Earths, which may hint at their composition.
With a 8% precision in radius and 12% precision in mass, TOI-244 b is
among the most precisely characterized super-Earths, which, together
with the likely presence of an extended hydrosphere, makes it a key
target for atmospheric observations.
Description:
Detection and characterization of the low-density super-Earth
TOI-244 b with high-precision radial velocity and photometry.
Objects:
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RA (2000) DE Designation(s)
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00 42 16.74 -36 43 04.71 TOI-244 = TIC 118327550 = GJ 1018
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 88 33219 TESS photometry of GJ 1018
tablea2.dat 213 57 ESPRESSO radial velocities and activity
indicators of GJ 1018
tablea3.dat 94 15 HARPS radial velocities and activity indicators
of GJ 1018
tablea4.dat 31 1110 ASAS-SN photometry of GJ 1018 (Table A4)
tablea5.dat 63 89 Absolute fluxes of GJ 1018 in different filters
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 18 F18.10 d BJD Barycentric Julian date
20- 29 F10.4 e-/s PDCSAP TESS PDCSAP
31- 40 F10.7 e-/s e_PDCSAP TESS PDCSAP uncertainty
42- 59 F18.16 --- PDCSAPdet Detrended TESS PDCSAP from biweight method
61- 81 F21.19 --- e_PDCSAPdet Detrended TESS PDCSAP uncertainty
from biweight method
83- 88 A6 --- Sector Sector
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 18 F18.12 d RJD Reduced Julian Date (JD-2400000)
20- 31 F12.6 m/s RV Radial velocity
33- 40 F8.6 m/s e_RV Radial velocity uncertainty
42- 52 F11.6 m/s FWHM FWHM of the CCF
54- 61 F8.6 m/s e_FWHM FWHM of the CCF uncertainty
63- 79 F17.13 10-4 Sindex S-index multiplied by a x1000 factor
81- 98 F18.16 10-4 e_Sindex S-index uncertainty
multiplied by a x1000 factor
100-108 F9.6 % Contrast Contrast of the CCF
110-117 F8.6 % e_Contrast Contrast of the CCF uncertainty
119-135 F17.13 10-4 Halpha H-alpha activity indicator
multiplied by a x1000 factor
137-155 F19.17 10-4 e_Halpha H-alpha activity indicator uncertainty
multiplied by a x1000 factor
157-173 F17.14 10-4 NaD NaD activity indicator
multiplied by a x1000 factor
175-193 F19.17 10-4 e_NaD NaD activity indicator uncertainty
multiplied by a x1000 factor
195-204 F10.6 --- BIS BIS-SPAN of the CCF
206-213 F8.6 --- e_BIS BIS-SPAN of the CCF uncertainty
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 18 F18.12 d RJD Reduced Julian Date (JD-2400000)
20- 37 F18.12 m/s RV Radial velocity
39- 56 F18.16 m/s e_RV Radial velocity uncertainty
58- 75 F18.13 m/s FWHM FWHM of the CCF
77- 94 F18.16 m/s e_FWHM FWHM of the CCF uncertainty
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Byte-by-byte Description of file: tablea4.dat
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Bytes Format Units Label Explanations
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1- 13 F13.5 d HJD Heliocentric Julian Date
15- 20 F6.3 mJy Flux Observed flux
22- 26 F5.3 mJy e_Flux Observed flux uncertainty
28- 29 A2 --- Camera Camera
31 A1 --- Filter Filter
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Byte-by-byte Description of file: tablea5.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Filter Filter
19- 40 E22.16 10mW/m2/nm Absflux Absolute flux (in erg/cm2/s/Å)
42- 63 E22.16 10mW/m2/nm e_Absflux Absolute flux uncertainty
(in erg/cm2/s/Å)
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Acknowledgements:
Amadeo Castro-Gonzalez, acastro(at)cab.inta-csic.es
(End) Patricia Vannier [CDS] 07-May-2023