J/A+A/650/A66 DS Tuc A radial velocity curve (Benatti+, 2021)
Constraints on the mass and on the atmospheric composition and evolution of the
low-density young planet DS Tucanae A b.
Benatti S., Damasso M., Borsa F., Locci D., Pillitteri I., Desidera S.,
Maggio A., Micela G., Wolk S., Claudi R., Malavolta L.,
Modirrousta-Galian D.
<Astron. Astrophys. 650, A66 (2021)>
=2021A&A...650A..66B 2021A&A...650A..66B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, G-type ; Exoplanets ;
Radial velocities
Keywords: planets and satellites: individual: DS Tuc A -
planets and satellites: atmospheres - techniques: radial velocities -
techniques: spectroscopic - X-rays: individuals: DS Auc
Abstract:
The observations of young close-in exoplanets are providing first
indications of the characteristics of the population and, in turn,
clues on the early stages of their evolution. Transiting planets at
young ages are also key benchmarks for our understanding of planetary
evolution through the verification of atmospheric escape models.
We performed a radial velocity (RV) monitoring of the 40Myr old star
DS Tuc A with HARPS at the ESO-3.6m to determine the planetary mass of
its 8.14-days planet, first revealed by the NASA TESS satellite. We
also observed two planetary transits with HARPS and ESPRESSO at
ESO-VLT, to measure the Rossiter-McLaughlin (RM) effect and
characterise the planetary atmosphere. We measured the high-energy
emission of the host with XMM-Newton observations to investigate
models for atmospheric evaporation.
We employed Gaussian Processes (GP) regression to model the high level
of the stellar activity, which is more than 40 times larger than the
expected RV planetary signal. GPs were also used to correct the
stellar contribution to the RV signal of the RM effect.
We extracted the transmission spectrum of DS Tuc A b from the ESPRESSO
data and searched for atmospheric elements/molecules either by
single-line retrieval and by performing cross-correlation with a set
of theoretical templates. Through a set of simulations, we evaluated
different scenarios for the atmospheric photo-evaporation of the
planet induced by the strong XUV stellar irradiation.
While the stellar activity prevented us from obtaining a clear
detection of the planetary signal from the RVs, we set a robust mass
upper limit of 14.4Me for DS Tuc A b. We also confirm that the
planetary system is almost (but not perfectly) aligned. The strong
level of stellar activity hampers the detection of any atmospheric
compounds, in line with other studies presented in the literature. The
expected evolution of DS Tuc A b from our grid of models indicates
that the planetary radius after the photo-evaporation phase will be
1.8-2.0Re, falling within the Fulton gap.
The comparison of the available parameters of known young transiting
planets with the distribution of their mature counterpart confirms
that the former are characterised by a low density, with DS Tuc A b
being one of the less dense. A clear determination of their
distribution is still affected by the lack of a robust mass
measurement, in particular for planets younger than ∼100Myr.
Description:
HARPS at ESO-3.6m and ESPRESSO at VLT radial velocities for DS Tuc A.
HARPS table includes the time series of the RV monitoring for the
young planet-host DS Tuc A, obtained in ESO P103. It also contains the
transit series obtained on Aug 10th, 2019. ESPRESSO table includes the
transit series of DS Tuc A obtained on Oct 6th, 2019.
Objects:
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RA (2000) DE Designation(s)
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23 39 39.48 -69 11 44.7051 DS Tuc A = HD 222259
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 64 106 HARPS dataset (RV monitoring and transit)
table2.dat 53 97 ESPRESSO dataset (transit)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 F13.8 d BJD Barycentric Julian day (TDB) (BJD-24500000.0)
15- 21 F7.2 m/s RV Radial Velocity (TERRA)
23- 27 F5.2 m/s e_RV Radial Velocity Error (TERRA)
29- 33 F5.3 --- CaII Calcium Index (ACTIN)
35- 39 F5.3 --- e_CaII Calcium Index Error (ACTIN)
41- 46 F6.4 --- Halpha Halpha Index (ACTIN)
48- 53 F6.4 --- e_Halpha Halpha Index Error (ACTIN)
55- 61 F7.4 km/s BIS Bisector (HARPS DRS)
63- 64 A2 --- Flag [RV T] RV = regular RV monitoring;
T = RV transit series
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 F13.8 d BJD Barycentric Julian day (TDB) (BJD-24500000.0)
15- 20 F6.4 km/s RV Radial Velocity (ESPRESSO DRS)
22- 27 F6.4 km/s e_RV Radial Velocity Error (ESPRESSO DRS)
29- 33 F5.3 --- CaII Calcium Index (ACTIN)
35- 39 F5.3 --- e_CaII Calcium Index Error (ACTIN)
41- 46 F6.4 --- Halpha Halpha Index (ACTIN)
48- 53 F6.4 --- e_Halpha Halpha Index Error (ACTIN)
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Acknowledgements:
Serena Benatti, serena.benatti(at)inaf.it
(End) Patricia Vannier [CDS] 29-Mar-2021