J/A+A/674/A106 8 solar-like pulsating stars (Gonzalez-Cuesta+, 2023)
Multi-campaign asteroseismic analysis of eight solar-like pulsating stars
observed by the K2 mission.
Gonzalez-Cuesta L., Mathur S., Garcia R.A., Perez Hernandez F.,
Delsanti V., Breton S.N., Hedges C., Jimenez A., Della Gaspera A.,
El-issami M., Fox V., Godoy-Rivera D., Pitot S., Proust N.
<Astron. Astrophys., 674, A106 (2023)>
=2023A&A...674A.106G 2023A&A...674A.106G (SIMBAD/NED BibCode)
ADC_Keywords: Asteroseismology ; Stars, G-type ; Optical
Keywords: asteroseismology - stars: activity - stars: fundamental parameters -
stars: oscillations
Abstract:
The NASA K2 mission that succeeded the nominal Kepler mission observed
several hundred thousand stars during its operations. While most of
the stars were observed in single campaigns of ∼80 days, some of them
were targeted for more than one campaign. We perform an asteroseismic
study of a sample of eight solar-like stars observed during K2
Campaigns 6 and 17, allowing us access to up to 160 days of data. With
these two observing campaigns, we determine not only the stellar
parameters but also study the rotation and magnetic activity of these
stars. We first extract the light curves for the two campaigns using
two different pipelines, EVEREST and Lightkurve. The seismic analysis
is done on the combined light curve of C6 and C17, where the gap
between them was removed and the two campaigns were 'stitched'
together. We determine the global seismic parameters of the solar-like
oscillations using two different methods: one using the A2Z pipeline
and the other the Bayesian apollinaire code. With the latter, we also
perform the peak-bagging of the modes to characterize their individual
frequencies. By combining the frequencies with the Gaia DR2 effective
temperature and luminosity, and metallicity for five of the targets,
we determine the fundamental parameters of the targets using the
IACgrids based on the MESA (Modules for Experiments in Stellar
Astrophysics) code. We find that four of the stars are on the main
sequence, two stars are about to leave it, and two stars are more
evolved (a subgiant and an early red giant). While the masses and
radii of our targets probe a similar parameter space compared to the
Kepler solar-like stars, with detailed modeling, we find that for a
given mass our more evolved stars seem to be older than previous
seismic stellar ensembles. We calculate the stellar parameters using
two different grids of models, one incorporating and one excluding the
treatment of diffusion, and find that the results agree generally
within the uncertainties, except for the ages. The ages obtained using
the models that exclude diffusion are older, with differences of
greater than 10% for most stars. The seismic radii and the Gaia DR2
radii present an average difference of 4% with a dispersion of 5%.
Although the agreement is relatively good, the seismic radii are
slightly underestimated compared to Gaia DR2 for our stars, the
disagreement being greater for the more evolved ones. Our rotation
analysis provides two candidates for potential rotation periods but
longer observations are required to confirm them.
Description:
We present the asteroseismic analysis of eight solar-like stars using
photometric data of the C6 and C17 observation campaigns of the K2
mission. By concatenating the EVEREST C6 light curve and the C17 light
curve produced by an adapted version of the Lightkurve package, we
obtain light curves of ∼160 days in observation length.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 113 8 Atmospheric and global seismic parameters for
our sample of stars with their corresponding
letter references from A to H
tablec1.dat 26 32 Individual frequencies for HD 115680
(A, EPIC 212478598)
tablec2.dat 26 33 Individual frequencies for HD 116832
(B, EPIC 212485100)
tablec3.dat 26 41 Individual frequencies for HD 114558
(C, EPIC 212487676)
tablec4.dat 24 42 Individual frequencies for HD 115427
(D, EPIC 212509747), not analyzed in
Ong et al. (2021ApJ...922...18O 2021ApJ...922...18O)
tablec5.dat 26 33 Individual frequencies for HD 120746
(E, EPIC 212516207)
tablec6.dat 24 34 Individual frequencies for HD 117779
(F, EPIC 212617037), not analyzed in
Ong et al. (2021ApJ...922...18O 2021ApJ...922...18O)
tablec7.dat 26 30 Individual frequencies for HD 119026
(G, EPIC 212683142)
tablec8.dat 24 41 Individual frequencies for HD 119038
(H, EPIC 212772187), not analyzed in
Ong et al. (2021ApJ...922...18O 2021ApJ...922...18O)
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See also:
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 A1 --- Ref [A-H] Reference letter for star
3- 11 I9 --- EPIC EPIC number
13- 18 I6 --- HD HD number
20- 23 A4 --- SpType Spectral type
25- 29 F5.3 mag Kpmag Kepler magnitude (1)
31- 34 I4 K Teff Effective temperature from Gaia DR2
(Cat. I/345)
36- 38 I3 K e_Teff Effective temperature error
40- 44 F5.3 Lsun Lum Luminosity from Gaia DR2 (Cat. I/345)
46- 50 F5.3 Lsun e_Lum Luminosity error
52- 57 F6.3 [-] [M/H] ?=- Metallicity from Ong et al.
(2021ApJ...922...18O 2021ApJ...922...18O) when available
59- 62 F4.2 [-] e_[M/H] ? Metallicity error
64- 67 I4 uHz numax Maximum frequency
69- 70 I2 uHz e_numax Maximum frequency error
72- 76 F5.2 uHz Deltanu Amplitude of variation
78- 81 F4.2 uHz e_Deltanu Amplitude of variation error
83- 86 F4.2 [cm/s2] logg Surface gravity
88- 91 F4.2 [cm/s2] e_logg Surface gravity error
93- 96 F4.2 --- eps Phase offset
98-101 F4.2 --- e_eps Phase offset error
103-113 A11 --- Table Name of the table with individual frequencies
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Note (1): Kepler magnitude (Kp) is from the K2 Ecliptic Plane Input Catalog
(EPIC, Cat. IV/34, see Huber et al. 2016ApJS..224....2H 2016ApJS..224....2H, Cat. J/ApJS/224/2).
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Byte-by-byte Description of file: tablec?.dat
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Bytes Format Units Label Explanations
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1 I1 --- l [0/3] Mode degree
3- 5 I3 --- n Radial order
7- 15 F9.4 --- nu(ln) Frequency of the mode, νl,n
17- 22 F6.4 --- e_nu(ln) Frequency of the mode error
24 I1 --- Flag [0/1] Flag (1)
26 I1 --- FO [0/1]? Fitted by Ong et al.
(2021ApJ...922...18O 2021ApJ...922...18O) (2)
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Note (1): Mode used to find the best-fit stellar evolution models as follows:
1 = mode was used
2 = mode was not used
Note (2): Flag as follows:
1 = fitted by Ong et al. 2021ApJ...922...18O 2021ApJ...922...18O)
0 = new mode from our analysis
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 14-Aug-2023