J/A+A/687/A259 Altair light curves (Rieutord+, 2024)
An improved asteroseismic age of the rapid rotator Altair from TESS data.
Rieutord M., Reese D.R., Mombarg J.S.G., Charpinet S.
<Astron. Astrophys. 687, A259 (2024)>
=2024A&A...687A.259R 2024A&A...687A.259R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, early-type ; Photometry ; Optical
Keywords: stars: rotation - stars: variable: delta Scuti
Abstract:
Understanding the effects of rotation in stellar evolution is key to
modelling early-type stars, half of which have equatorial velocities
over 100km/s. The nearby star Altair is an example of such
fast-rotating stars, and furthermore, it has the privilege of being
modelled by a detailed 2D concordance model that reproduces most of
its observables.
The aim of this paper is to include new asteroseismic frequencies to
improve our knowledge of Altair, especially its age.
We processed images of Altair obtained during July 2022 by the
Transiting Exoplanet Survey Satellite using the halo photometry
technique to obtain its light curve over this observation period.
By analysing the light curve, we derived a set of 22 new frequencies
in the oscillation spectrum of Altair and confirmed 12 previously
known frequencies. Compared with model predictions, we could associate
ten frequencies with ten axisymmetric modes. This identification is
based on the modelled visibility of the modes. Moreover, nine of the
modelled frequencies can be adjusted to simultaneously match their
corresponding observed frequencies, once the core hydrogen mass
fraction of the concordance model is set to Xcore/Xini≃0.972,
with Xini=0.739. Using the combined results of a 1D MESA model
computing the pre-main sequence and a 2D time-dependent ESTER model
computing the main sequence, we find that this core hydrogen abundance
sets the age of Altair to 88±10Myrs, which is slightly younger than
previous estimates.
Description:
Using the halo photometry technique (White et al.,
2017MNRAS.471.2882W 2017MNRAS.471.2882W), we processed the TESS images of Altair and
derived its light curve during the observation period from 10 July to
5 August 2022. Using the FELIX code (Charpinet et al.
2010A&A...516L...6C 2010A&A...516L...6C; Zong et al., 2016A&A...594A..46Z 2016A&A...594A..46Z), we derived the
power spectrum of the light curve and exhibited 34 frequencies.
Objects:
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RA (2000) DE Designation(s)
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19 50 46.99 +08 52 05.9 Altair = 53 Aql
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
unfilt.dat 26 12939 Raw result halo photometry subtracted
filt.dat 26 12939 *Filtered photometry
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Note on filt.dat: A polynomial fit of degree 9 has been to each part of the
light curve to remove drifts at the end of each subsequence.
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Byte-by-byte Description of file: filt.dat unfilt.dat
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Bytes Format Units Label Explanations
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1- 12 F12.9 d Time Time (Barycentric TESS Julian Date) origin
is t0=2769.8986175
15- 26 F12.9 --- Flux Relative variation of the flux
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Acknowledgements:
Michel Rieutord, mrieutord(at)irap.omp.eu
(End) Patricia Vannier [CDS] 23-May-2024