J/MNRAS/493/1388 Asteroseismology of luminous red giants with Kepler (Yu+, 2020)
Asteroseismology of luminous red giants with Kepler. I:
long-period variables with radial and non-radial modes.
Yu J., Bedding T.R., Stello D., Huber D., Compton D.L., Gizon L., Hekker S.
<Mon. Not. R. Astron. Soc., 493, 1388-1403 (2020)>
=2020MNRAS.493.1388Y 2020MNRAS.493.1388Y (SIMBAD/NED BibCode)
ADC_Keywords: Asteroseismology ; Stars, late-type ; Stars, variable ;
Effective temperatures ; Parallaxes, trigonometric ; Optical
Keywords: techniques: photometric - stars: evolution - stars: late-type -
stars: oscillations
Abstract:
While long-period variables (LPVs) have been extensively investigated,
especially with MACHO and OGLE data for the Magellanic Clouds, there
still exist open questions in their pulsations regarding the
excitation mechanisms, radial order, and angular degree assignment.
Here, we perform asteroseismic analyses on LPVs observed by the 4-year
Kepler mission. Using a cross-correlation method, we detect
unambiguous pulsation ridges associated with radial fundamental modes
(n=1) and overtones (n≥2), where the radial order assignment is made
using theoretical frequencies and observed frequencies. Our results
confirm that the amplitude variability seen in semiregulars is
consistent with oscillations being solar-like. We identify that the
dipole modes, l=1, are dominant in the radial orders of 3=<n=<6, and
that quadrupole modes, l=2, are dominant in the first overtone n=2. A
test of seismic scaling relations using Gaia DR2 parallaxes reveals
the possibility that the relations break down when νmax~<3µHz
(R≳40R☉, or logL/L☉≳2.6). Our homogeneous measurements
of pulsation amplitude and period for 3213 LPVs will be valuable for
probing effects of pulsation on mass-loss, in particular in those
stars with periods around 60d, which has been argued as a threshold of
substantial pulsation-triggered mass-loss.
Description:
To construct a sample of LPVs, we selected 4296 Kepler red giants from
Mathur et al. (2017ApJS..229...30M 2017ApJS..229...30M, Cat. J/ApJS/229/30) with surface
gravity logg<2.0dex, equivalent to a period ≳1d. We added known
Kepler M giants from the literature, namely, Banyai et al.
(2013MNRAS.436.1576B 2013MNRAS.436.1576B), Stello et al. (2014ApJ...788L..10S 2014ApJ...788L..10S), and Yu et
al. (2018ApJS..236...42Y 2018ApJS..236...42Y, Cat. J/ApJS/236/42). For the sample in Yu et
al. (2018ApJS..236...42Y 2018ApJS..236...42Y, Cat. J/ApJS/236/42), we applied a cut-off
νmax=<15µHz.
From the sample of 4724 stars selected above, we excluded the stars
with marginal pulsation detections. This is because 75 per cent of
them have too short light curves for our analyses, i.e. they were
observed for fewer than four quarters, and/or too faint, the Kepler
magnitudes Kp>14mag. For the other 25 per cent of the excluded stars,
no clear pulsation signal is found. Our final sample comprised 3213
LPVs, as listed in Table 1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 126 3213 Asteroseismic parameters and stellar properties
of Kepler M giants
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJS/229/30 : Revised stellar properties of Q1-17 Kepler targets
(Mathur+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC [892738/12984227] KIC source identifier
10- 15 A6 --- LCs Type of light-curve used in this work (PDCSAP
or SAP) (1)
17- 20 F4.1 --- Q ? Number of quarters of Kepler light curves
22- 27 F6.2 --- Pext ? Approximation of the period of the light
curve (2)
29- 32 I4 K Teff ? Effective temperature from Mathur et al.
(2017ApJS..229...30M 2017ApJS..229...30M, Cat. J/ApJS/229/30)
34- 36 I3 K e_Teff ? Error on Teff
38- 47 F10.2 umag Amp ? Dominant mode amplitude
49- 54 F6.2 d Period ? Dominant mode period
56 I1 --- Order ? Radial order
58- 62 F5.2 uHz numax ? Frequency of maximum power
64- 67 F4.2 uHz e_numax ? Error on numax
69- 72 F4.2 uHz Dnu ? Mean larger frequency separation
74- 77 F4.2 uHz e_Dnu ? Error on Dnu
79- 83 F5.2 mas plx ? Gaia DR2 parallax with an offset of 0.03mas
added
85- 88 F4.2 mas e_plx ? Error on plx
90- 95 F6.3 kpc Dist ? Distance
97-101 F5.3 kpc e_Dist ? Error on Dist
103-110 F8.2 Lsun L ? Luminosity
112-121 F10.2 Lsun e_L ? Error on L
123-126 F4.2 mag Av ? Extinction
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Note (1): For some M giants pulsating at a long period, such as Mira variables,
PDCSAP time series were overcorrected, by treating intrinsic
pulsations as 'systematic errors'. For these stars, we adopted
'simple aperture photometry' (SAP) light curves.
Note (2): To determine the stars for which the PDCSAP light curves were safe to
use, we used a measure, Pextrema, which approximates a typical
period of a light curve. It is defined as:
Pextrema=2Nδt/Nextrema,
where Nextrema is the number of turning points, N is the total
number of data points of a light curve, and δt is the sampling
interval of the long-cadence Kepler data (29.4min).
We found Pextrema=6d is an appropriate threshold to select the
light-curve source (PDCSAP if Pextrema<6d and SAP otherwise).
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History:
From electronic version of the journal
References:
Yu et al., Paper II 2021MNRAS.501.5135Y 2021MNRAS.501.5135Y
(End) Ana Fiallos [CDS] 12-Apr-2023