J/A+A/695/A277 Ariel space mission selected stellar calibrators (Tonucci+, 2025)
Analysing the flux stability of stellar calibrator candidates with TESS.
Tonucci E., Van Kempen T.A., Beaulieu J.-P., Bernard L.
<Astron. Astrophys. 695, A277 (2025)>
=2025A&A...695A.277T 2025A&A...695A.277T (SIMBAD/NED BibCode)
ADC_Keywords: Stars, standard ; Positional data ; Optical
Keywords: methods: data analysis - techniques: photometric - stars: solar-type -
stars: statistics - stars: variables: general
Abstract:
The ESA space mission Ariel requires bright sources that are stable at
the level of 100 ppm over 6 hours in order to accurately measure
exoplanet atmospheres through transmission spectroscopy. To ensure
this, in-flight instrument calibration can be performed by observing
stellar calibrators.
In this study, a stellar calibrator candidate list distributed over
the sky is created and a flux variability analysis is performed to
identify the best stellar calibrators for transit spectroscopy of
exoplanet atmospheres with Ariel.
A starting candidate sample of 1937 solar-type stars is created using
the all-sky surveys Two Micron All Sky Survey and Gaia. Using stellar
light curves from the Transit Exoplanet Survey Satellite (TESS), the
flux variability of each star is characterised by computing its
Lomb-Scargle periodogram and reduced chi-squared. This enables the
elimination of stars with detectable variability from the sample.
Approximately 22.2% of stars from the starting sample pass the
selection as potential calibrators. These do not all necessarily meet
Ariel's stability requirement, although some will. No correlation
between flux stability and stellar properties is found, as long as the
correct value ranges for the parameters are chosen, like a surface
temperature between 5000 and 6300K. The only exception is stellar
magnitude: Noise in TESS data increases as stars get dimmer, so, a
high percentage of faint stars passes the selection since their
variability is more likely hidden within the inherent TESS noise.
Contrarily, stars brighter than 5mag cannot be used as calibrators.
A list of 430 promising bright calibration targets distributed over
the sky has been selected. These can potentially be used as stellar
calibrators for the Ariel mission. Targets from this list will have to
be further studied to determine which ones possess a flux stability
better than 100 ppm over 6 hours.
Description:
Catalogue containing the stars passing all three selection criteria
from Tonucci et al. (2024, ESA's Ariel space mission). Currently, the
most promising stellar calibrators for ESA's Ariel's space mission.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 33 430 Selected stellar calibrator list
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See also:
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- TIC TESS Input Catalog identifier
11- 17 F7.3 deg RAdeg Right ascension (ICRS) at Ep=2000.0
19- 25 F7.3 deg DEdeg Declination (ICRS) at Ep=2000.0
27- 33 F7.3 ppm sigmaMdn Dispersion around the median of the light
curve time series observation in a
normalised unit
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 30-Jul-2025