J/MNRAS/495/1888 Pulsation properties of λbootis stars I (Murphy+, 2020)
The pulsation properties of λ bootis stars I. The southern TESS sample.
Murphy S.J., Paunzen E., Bedding T.R., Walczak P., Huber D.
<Mon. Not. R. Astron. Soc., 495, 1888-1912 (2020)>
=2020MNRAS.495.1888M 2020MNRAS.495.1888M (SIMBAD/NED BibCode)
ADC_Keywords: Asteroseismology ; Stars, variable ; Stars, double and multiple ;
Effective temperatures ; Abundances, [Fe/H] ; Stars, masses ;
Rotational velocities ; Parallaxes, trigonometric ;
Stars, diameters ; Stars, ages ; Optical
Keywords: asteroseismology - stars: chemically peculiar - stars: oscillations
Abstract:
We analyse TESS light curves for 70 southern λ Boo stars to
identify binaries and to determine which of them pulsate as
δ Scuti stars. We find two heartbeat stars and two eclipsing
binaries among the sample. We calculate that 81 per cent of
λ Boo stars pulsate as δ Sct variables, which is about
twice that of normal stars over the same parameter space. We determine
the temperatures and luminosities of the λ Boo stars from
photometry and Gaia DR2 parallaxes. A subset of 40 λ Boo stars
have 2-min TESS data, reliable temperatures and luminosities, and
δ Sct pulsation. We use Petersen diagrams (period ratios),
echelle diagrams, and the period-luminosity relation to identify the
fundamental mode in 20 of those 40 stars and conclude that a further 8
stars are not pulsating in this mode. For the remaining 12, the
fundamental mode cannot be unambiguously identified. Further mode
identification is possible for 12 of the fundamental mode pulsators
that have regular sequences of pulsation overtones in their echelle
diagrams. We use stellar evolution models to determine statistically
that the λ Boo stars are only superficially metal weak. Simple
pulsation models also better fit the observations at a metallicity of
Z=0.01 than at Z=0.001. The TESS observations reveal the great
potential of asteroseismology on λ Boo stars, for determining
precise stellar ages and shedding light on the origin(s) of the
λBoo phenomenon.
Description:
The 70 λ Boo stars studied here originate from four sources: 27
confirmed λ Boo stars from the Murphy et al.
(2015PASA...32...36M 2015PASA...32...36M, Cat. J/other/PASA/32.36) catalogue, omitting the
probable or uncertain members, and omitting HD 198161 which is not
resolved from its neighbour HD 198160 in TESS pixels; 20 λ Boo
stars from the Tycho sample in Gray et al. (2017AJ....154...31G 2017AJ....154...31G, Cat.
J/AJ/154/31); nine from the 'Misc' sample in the same paper; and 14
from a survey for southern λ Boo stars from Siding Spring
Observatory (Murphy et al. 2020MNRAS.499.2701M 2020MNRAS.499.2701M). A few targets belong
to more than one source.
TESS observes each sector for 27d and the sectors have overlap near
the ecliptic poles. Stars can therefore fall in more than one sector
and have light curves of longer durations (in some multiple of 27d).
Of our 70 targets, 21 have observations in more than one sector. The
majority (56) of our TESS targets were observed at 2-min cadence and
the rest only have full-frame image (FFI) data at 30-min cadence. We
used all available TESS sectors for each λ Boo star unless they
had 2-min data in some sectors but only FFI data in others, in which
case we analysed only the 2-min data.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 129 71 Stellar parameters for the southern λ Boo
stars used in this paper
table1.dat 74 70 Pulsation properties, including frequencies and
amplitudes, of the 70 λ Boo stars in this
study
table3.dat 42 40 Most likely identification of the fundamental
mode for the 40 pulsating λ Boo stars
table4.dat 234 8 Parameters of the eight stars chosen for
pulsational analysis
table5.dat 64 46 Models of the eight target stars, fitting their
observed values of effective temperature,
luminosity, and rotational velocity
tablea1.dat 65 14 Known pulsation properties of λBoo stars
from the literature
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Star name
(HD NNNNNN except for BD-11 1239 and T Ori)
12- 16 F5.2 mag Vmag V-band magnitude
18- 22 I5 K Teff Effective temperature
24- 26 I3 K e_Teff Error on Teff
28- 33 F6.2 Lsun Lum ? Luminosity
35- 38 F4.2 Lsun E_Lum ? Upper error on Lum
40- 43 F4.2 Lsun e_Lum ? Lower error on Lum
45- 49 F5.2 mag VMAG ? Absolute V-band magnitude
51- 54 F4.2 mag E_VMAG ? Upper error on VMAG
56- 59 F4.2 mag e_VMAG ? Lower error on VMAG
61- 64 F4.2 [cm/s2] logg ? Surface gravity
66- 69 F4.2 [cm/s2] E_logg ? Upper error on logg
71- 74 F4.2 [cm/s2] e_logg ? Lower error on logg
76- 80 F5.2 [-] [Fe/H] ? Fe/H abundance ratio
82- 85 F4.2 [-] E_[Fe/H] ? Upper error on [Fe/H]
87- 90 F4.2 [-] e_[Fe/H] ? Lower error on [Fe/H]
92- 95 F4.2 Msun Mass ? Star mass
97- 100 F4.2 Msun E_Mass ? Upper error on Mass
102- 105 F4.2 Msun e_Mass ? Lower error on Mass
107- 110 F4.2 mag AV ? Extinction on the V-band
112- 116 F5.2 --- RUWE Renormalized Unit Weight Error
118 I1 --- good [0/1] Boolean flag indicating whether the
parameters are 'good' (=1) or not (=0)
120- 124 F5.2 mag Dm ? Magnitude difference from any companion in
the WDS catalogue
126- 129 F4.2 arcsec Sep ? Separation from any companion in the WDS
catalogue
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Star name
(HD NNNNNN except for BD-11 1239 and T Ori)
12- 17 F6.3 d-1 f1 ? Frequency of the first stronger peak above
4d-1
19- 24 F6.3 mmag a1 ? Amplitude associated to f1
26- 31 F6.3 d-1 f2 ? Frequency of the second stronger peak above
4d-1
33- 38 F6.3 mmag a2 ? Amplitude associated to f2
40- 45 F6.3 d-1 f3 ? Frequency of the third stronger peak above
4d-1
47- 51 F5.3 mmag a3 ? Amplitude associated to f3
53- 55 A3 --- FFIonly Flag indicating the 14 stars with only 30-min
FFI data
57- 61 F5.3 mmag limit ? Upper limit on any undetected pulsation mode
for the 16 λBoo stars that are not
δSct pulsators
63- 74 A12 --- Sector TESS sector in which each the target was
observed
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name (HD NNNNNN)
11- 16 F6.3 d-1 Fund ? Most likely identification of the fundamental
mode
18- 28 A11 --- f_Fund Flag on Fund (1)
30- 42 A13 --- Method Method(s) used in the identification
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Note (1): Flag as follows:
unclear = It was not possible to identify the mode
not excited = This star does not pulsate in the fundamental mode
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Star name (HD NNNNNN)
11- 16 F6.3 mag Vmag V-band magnitude
18- 20 I3 km/s vsini Projected surface rotation velocity
22- 27 F6.3 mas plx Gaia DR2 parallax
29- 33 F5.3 mas e_plx Error on plx
35- 40 F6.4 [K] logTeff Logarithm of the effective temperature
42- 47 F6.4 [K] e_logTeff Error on logTeff
49- 53 F5.3 [Lsun] logL Logarithm of the star luminosity
55- 59 F5.3 [Lsun] e_logL Error on logL
61- 64 F4.2 Rsun Rad Stellar radius
66- 69 F4.2 Rsun e_Rad Error on Rad
71- 234 A164 --- Ref Literature references to spectroscopic
abundance analyses
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Star name (HD NNNNNN)
11- 12 A2 --- ES Evolutionary stage (1)
14- 18 F5.3 --- Z Metallicity
20- 22 F3.1 --- Xini Initial Hydrogen abundance
24- 27 F4.2 --- fov Extent of overshooting
29- 31 I3 km/s Vrotini Initial rotational velocity on the zero-age
main sequence
33- 35 I3 km/s Vrot Current rotational velocity
37- 41 F5.3 Msun Mass Stellar mass
43- 50 E8.4 yr Age Star age
52- 57 F6.4 Rsun Rad Star radius
59- 64 F6.4 [cm/s2] logg Surface gravity
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Note (1): Evolutionary stage as follows:
MS = main sequence
CP = contraction phase
AL = after the loop
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Star name (HD NNNNNN)
11- 17 F7.4 d-1 Freq Frequency
19- 22 F4.1 mmag Ampl Amplitude
24- 28 A5 --- Filter Filter
30- 65 A36 --- Ref Reference
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 13-Jun-2023