J/A+A/635/A13 HD41248 Radial velocities and activity indicators (Faria+, 2020)
Decoding the radial velocity variations of HD 41248 with ESPRESSO.
Faria J.P., Adibekyan V., Amazo-Gomez E.M., Barros S.C.C., Camacho J.D.,
Demangeon O., Figueira P., Mortier A., Oshagh M., Pepe F., Santos N.C.,
Gomes da Silva J., Costa Silva A.R., Sousa S.G., Ulmer-Moll S., Viana P.T.P.
<Astron. Astrophys. 635, A13 (2020)>
=2020A&A...635A..13F 2020A&A...635A..13F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Radial velocities
Keywords: techniques: radial velocities - methods: data analysis -
planetary systems - stars: individual: HD 41248
Abstract:
Twenty-four years after the first exoplanet discoveries, the
radial-velocity (RV) method is still one of the most productive
techniques to detect and confirm exoplanets. But stellar magnetic
activity can induce RV variations large enough to make it difficult to
disentangle planet signals from the stellar noise. In this context,
HD 41248 is an interesting planet-host candidate, with RV observations
plagued by activity-induced signals. We report on ESPRESSO
observations of HD 41248 and analyse them together with previous
observations from HARPS, with the goal of evaluating the presence of
orbiting planets. Using different noise models within a general
Bayesian framework designed for planet detection in RV data, we test
the significance of the various signals present in the HD 41248 data
set. We use Gaussian processes as well as a first-order moving average
component to try to correct for activity-induced signals. At the same
time, we analyse photometry from the TESS mission, searching for
transits and rotational modulation in the lightcurve. The number of
significantly detected Keplerian signals depends on the noise model
employed, ranging from 0 with the Gaussian process model to 3 with a
white noise model. We find that the Gaussian process alone can explain
the RV data and allows for the stellar rotation period and active
region evolution timescale to be constrained. The rotation period
estimated from the RVs agrees with the value determined from the TESS
lightcurve. Based on the currently available data, we conclude that
the RV variations of HD 41248 can be explained by stellar activity
(using the Gaussian process model) in line with the evidence from
activity indicators and the TESS photometry.
Description:
Full set of radial velocities and activity indicators from both the
HARPS and ESPRESSO observations of HD41248
Objects:
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RA (2000) DE Designation(s)
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06 00 32.78 -56 09 42.6 HD 41248 = HIP 28460
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 78 250 Radial velocities and activity indicators
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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- 12 F12.6 d BJD Modified barycentric Julian day (BJD-2400000)
14- 20 F7.5 km/s BRV Barycentric radial velocity
22- 28 F7.5 km/s e_BRV BRV error
30- 36 F7.5 km/s FWHM CCF FWHM
38- 45 F8.5 m/s BIS CCF bisector span
47- 53 F7.5 --- ICaII Activity index based on the Ca II H & K lines
55- 61 F7.5 --- IHa Activity index based on the Halpha line
63- 69 F7.5 --- INaI Activity index based on the Na I lines
71- 78 A8 --- Inst Instrument (1)
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Note (1): Instrument column is either "HARPS" or "ESPRESSO"
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Acknowledgements:
Joao Pedro Faria, joao.faria(at)astro.up.pt
(End) Joao Pedro Faria [IA, Portugal], Patricia Vannier [CDS] 22-Nov-2019