J/A+A/642/A133 V830 Tau VI light curves and RV curves (Damasso+, 2020)
The GAPS Programme at TNG. XXVII. Reassessment of a young planetary system with
HARPS-N: is the hot Jupiter V830 Tau b really there?
Damasso M., Lanza A.F., Benatti S., Rajpaul V.M., Mallonn M., Desidera S.,
Biazzo K., D'Orazi V., Malavolta L., Nardiello D., Rainer M., Borsa F.,
Affer L., Bignamini A., Bonomo A.S., Carleo I., Claudi R., Cosentino R.,
Covino E., Giacobbe P., Gratton R., Harutyunyan A., Knapic C., Leto G.,
Maggio A., Maldonado J., Mancini L., Micela G., Molinari E., Nascimbeni V.,
Pagano I., Piotto G., Poretti E., Scandariato G., Sozzetti A.,
Capuzzo Dolcetta R., Di Mauro M.P., Carosati D., Fiorenzano A.,
Frustagli G., Pedani M., Pinamonti M., Stoev H., Turrini D.
<Astron. Astrophys. 642, A133 (2020)>
=2020A&A...642A.133D 2020A&A...642A.133D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry ; Optical ;
Radial velocities
Keywords: stars: individual: V830 Tau - stars: individual: EPIC 247822311 -
planets and satellites: detection - techniques: radial velocities -
techniques: photometric
Abstract:
Detecting and characterising exoworlds around very young stars
(age≤10Myr) are key aspects of exoplanet demographic studies,
especially for understanding the mechanisms and timescales of planet
formation and migration. Any reliable theory for such physical
phenomena requires a robust observational database to be tested.
However, detection using the radial velocity method alone can be very
challenging because the amplitude of the signals caused by the
magnetic activity of such stars can be orders of magnitude larger than
those induced even by massive planets. We observed the very young
(∼2Myr) and very active star V830 Tau with the HARPS-N spectrograph
between October 2017 and March 2020 to independently confirm and
characterise the previously reported hot Jupiter V830 Tau b
(Kb=68±11ms; mbsinib=0.57±0.10Mjup; Pb=4.927±0.008d).
Because of the observed ∼1km/s radial velocity scatter that can
clearly be attributed to the magnetic activity of V830 Tau, we
analysed radial velocities extracted with different pipelines and
modelled them using several state-of-the-art tools. We devised
injection-recovery simulations to support our results and characterise
our detection limits. The analysis of the radial velocities was aided
by a characterisation of the stellar activity using simultaneous
photometric and spectroscopic diagnostics. Despite the high quality of
our HARPS-N data and the diversity of tests we performed, we were
unable to detect the planet V830 Tau b in our data and cannot confirm
its existence. Our simulations show that a statistically significant
detection of the claimed planetary Doppler signal is very challenging.
It is important to continue Doppler searches for planets around young
stars, but utmost care must be taken in the attempt to overcome the
technical difficulties to be faced in order to achieve their detection
and characterisation. This point must be kept in mind when assessing
their occurrence rate, formation mechanisms, and migration pathways,
especially without evidence of their existence from photometric
transits.
Description:
Photometry collected with the STELLA telescope; radial velocities and
stellar activity diagnostics extracted from HARPS-N spectra.
Objects:
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RA (ICRS) DE Designation(s)
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04 33 10.03 +24 33 43.3 V830 Tau = EPIC 247822311
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 25 125 STELLA V-band photometry (relative flux)
tablea2.dat 25 122 STELLA I-band photometry (relative flux)
tableb1.dat 54 144 Spectroscopic activity diagnostics
tablec1.dat 51 144 Radial velocities (m/s)
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Byte-by-byte Description of file: tablea1.dat tablea2.dat
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Bytes Format Units Label Explanations
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1- 11 F11.6 d Time Epoch of observation (BJD-2450000)
13- 18 F6.4 --- Flux Relative photometry
20- 25 F6.4 --- e_Flux Relative photometry error
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 11 F11.6 d Time Epoch of observation (BJD-2450000)
13- 19 F7.1 m/s FWHM CCF FWHM
21- 30 F10.1 m/s BIS CCF bisector span
32- 36 F5.3 --- CaHK Chromospheric CaHK index
38- 42 F5.3 --- e_CaHK Chromospheric CaHK index error
44- 48 F5.3 --- Halpha Chromospheric H-alpha index
50- 54 F5.3 --- e_Halpha Chromospheric H-alpha index error
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Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
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1- 11 F11.6 d Time Epoch of observation (BJD-2450000)
13- 19 F7.1 m/s RVTerra TERRA radial velocity
21- 24 F4.1 m/s e_RVTerra TERRA radial velocity error
26- 32 F7.1 m/s RVDRS DRS radial velocity
34- 37 F4.1 m/s e_RVDRS DRS radial velocity error
39- 45 F7.1 m/s RVRaj20 Rajpaul et al. (2020MNRAS.492.3960R 2020MNRAS.492.3960R)
radial velocity
47- 51 F5.1 m/s e_RVRaj20 Rajpaul et al. (2020MNRAS.492.3960R 2020MNRAS.492.3960R)
radial velocity error
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Acknowledgements:
Mario Damasso, mario.damasso(at)inaf.it
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(End) Mario Damasso [INAF, Italy], Patricia Vannier [CDS] 31-Aug-2020