J/MNRAS/495/2844 Mode identification in 3 pulsating hot subdwarfs (Sahoo+, 2020)
Mode identification in three pulsating hot subdwarfs observed with TESS
satellite.
Sahoo S.K., Baran A.S., Heber U., Ostrowski J., Sanjayan S., Silvotti R.,
Irrgang A., Uzundag M., Reed M.D., Shoaf K.A., Raddi R., Vuckovic M.,
Ghasemi H., Zong W., Bell K.J.
<Mon. Not. R. Astron. Soc., 495, 2844-2857 (2020)>
=2020MNRAS.495.2844S 2020MNRAS.495.2844S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, B-type ; Stars, subdwarf ; Asteroseismology ;
Effective temperatures ; Stars, distances ; Stars, diameters ;
Parallaxes, trigonometric ; Stars, masses ; Spectra, optical
Keywords: asteroseismology - stars: oscillations (including pulsations) -
subdwarfs
Abstract:
We report on the detection of pulsations of three pulsating subdwarf B
stars observed by the Transiting Exoplanet Survey Satellite (TESS)
satellite and our results of mode identification in these stars based
on an asymptotic period relation. SB 459 (TIC 067584818), SB 815 (TIC
169285097), and PG 0342+026 (TIC 457168745) have been monitored during
single sectors resulting in 27d coverage. These data sets allowed for
detecting, in each star, a few tens of frequencies that we interpreted
as stellar oscillations. We found no multiplets, though we partially
constrained mode geometry by means of period spacing, which recently
became a key tool in analyses of pulsating subdwarf B stars. Standard
routine that we have used allowed us to select candidates for trapped
modes that surely bear signatures of non-uniform chemical profile
inside the stars. We have also done statistical analysis using
collected spectroscopic and asteroseismic data of previously known
subdwarf B stars along with our three stars. Making use of high
precision trigonometric parallaxes from the Gaia mission and spectral
energy distributions we converted atmospheric parameters to stellar
ones. Radii, masses, and luminosities are close to their canonical
values for extreme horizontal branch stars. In particular, the stellar
masses are close to the canonical one of 0.47M☉ for all three
stars but uncertainties on the mass are large. The results of the
analyses presented here will provide important constrains for
asteroseismic modelling.
Description:
In case of SB 459, the only available quantitative spectral analysis
was carried out by Heber et al. (1984A&A...130..119H 1984A&A...130..119H). Therefore, it
was considered worthwhile to revisit the star and to take another
spectrum with more advanced instruments than before. The ESO Faint
Object Spectrograph and Camera 2 (EFOSC2) spectrograph at the 3.58-m
New Technology Telescope (NTT) at the La Silla Observatory was used.
The single spectrum was obtained on 2019 June with grism #7, a slit
of 1arcsec covering the wavelength range from 3270 to 5240Å.
SB 459 was also observed with Boller & Chivens Spectrograph at the
2.5-m Irene Du Pont Telescope at the Las Campanas Observatory. The
single spectrum was taken on 2019 October 31 using the following
instrument setup, the grating of 600 lines/mm corresponding to the
central wavelength of 5000Å covering a wider wavelength range from
3427 to 6573Å.
PG 0342+026 was observed in 2012 November-December with Harps-N at the
Telescopio Nazionale Galileo (TNG, La Palma) in the context of a
program to search for sdB low-mass companions (see Silvotti, Ostensen
& Telting 2020arXiv200204545S 2020arXiv200204545S for more details). Four high-resolution
spectra were collected with a mean signal-to-noise ratio of 71 at
4700Å.
Photometric measurements allow the angular diameters to be determined
along with the interstellar extinction, once the atmospheric
parameters are known. We constructed spectral energy distributions
from photometric measurements ranging from the ultraviolet (IUE) to
the infrared.
Objects:
-----------------------------------------------------------
RA (ICRS) DE Designation(s)
-----------------------------------------------------------
01 08 26.77 -32 43 11.6 SB 459 = TIC 67584818
23 44 22.00 -34 27 00.3 SB 815 = TIC 169285097
03 45 34.57 +02 47 52.7 PG 0342+026 = TIC 457168745
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 141 8 Basic information of the targets
table2.dat 129 1 SB 459: Angular diameters, interstellar
reddening parameter, Gaia parallax, and stellar
parameters
table3.dat 129 1 SB 815: Angular diameters, interstellar
reddening parameter, Gaia parallax, and stellar
parameters
table4.dat 129 1 PG 0342+026: Angular diameters, interstellar
reddening parameter, Gaia parallax, and stellar
parameters
table5.dat 65 22 List of frequencies detected in SB 459
table6.dat 65 43 List of frequencies detected in SB 815
table7.dat 65 27 List of frequencies detected in PG 0342+026
table8.dat 43 29 Effective temperature and average period
spacing data for known sdBVs
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See also:
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- TIC TESS Input Catalog identifier
11- 21 A11 --- Name Star name
23 I1 --- Sector TESS Sector
25- 29 I5 K Teff Effective temperature
31- 34 I4 K e_Teff Error on Teff
36 A1 --- f_Teff [a] Flag on Teff (1)
38- 41 F4.2 [cm/s2] logg Surface gravity
43- 46 F4.2 [cm/s2] e_logg Error on logg
48 A1 --- f_logg [a] Flag on logg (1)
50- 54 F5.2 --- lognHe Logarithm of the Helium abundance
(log(nHe/n_H))
56- 59 F4.2 --- e_lognHe Error on lognHe
61 A1 --- f_lognHe [a] Flag on lognHe (1)
63- 66 F4.1 mag Gmag ? Gaia DR2 G-band magnitude
68- 70 I3 pc Dist ? Distance
72- 73 I2 pc e_Dist ? Error on Dist
75- 141 A67 --- Ref Reference for Teff and logg
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Note (1): Flag as follows:
a = Symmetric errors are given instead of the original asymmetric ones.
Systematic errors are not accounted for.
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Byte-by-byte Description of file: table[234].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Star name
13- 20 F8.4 [rad] logtheta Logarithm of the angular diameter
22- 27 F6.4 [rad] E_logtheta Upper error on logtheta
29- 34 F6.4 [rad] e_logtheta Lower error on logtheta
36- 41 F6.4 mag E(B-V) Colour excess
43- 48 F6.4 mag E_E(B-V) Upper error on E (B-V)
50- 55 F6.4 mag e_E(B-V) Lower error on E (B-V)
57- 60 F4.2 --- RUWE Renormalized unit weight error
62- 65 F4.2 mas plx Gaia DR2 parallax
67- 70 F4.2 mas e_plx Error on plx
72- 76 I5 K Teff Effective temperature
78- 81 I4 K e_Teff Error on Teff
83- 86 F4.2 [cm/s2] logg Surface gravity
88- 91 F4.2 [cm/s2] e_logg Error on logg
93- 97 F5.2 [-] lognHe Logarithm of the Helium abundance (log
(nHe/n_H))
99- 103 F5.3 Rsun Rad Star radius
105- 109 F5.3 Rsun e_Rad Error on Rad
111- 114 F4.2 Msun Mass Star mass
116- 119 F4.2 Msun e_Mass Error on Mass
121- 124 F4.2 [Lsun] logL Logarithm of the star luminosity
126- 129 F4.2 [Lsun] e_logL Error on logL
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table[567].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- ID Frequency ID
5- 13 F9.4 uHz freq Frequency value
15- 20 F6.4 uHz e_freq Error on freq
22- 31 F10.4 s Period Period
33- 38 F6.4 s e_Period Error on Period
40- 44 F5.3 10-3 Amp Amplitude (in parts per thousand)
46- 50 F5.3 10-3 e_Amp Error on Amp
52- 55 F4.1 --- S/N Signal to noise ratio
57- 59 A3 --- l Pulsation mode
61- 65 A5 --- n Radial order
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Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Star name
16- 21 F6.2 s DP Period spacing
23- 26 F4.2 s e_DP ? Error on DP
28- 33 F6.3 kK Teff Effective temperature
35- 39 F5.3 kK e_Teff ? Error on Teff
41 I1 --- r_DP Reference for DP (1)
43 I1 --- r_Teff Reference fot Teff (1)
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Note (1): Reference as follows:
1 = Reed et al. (2018OAst...27..157R 2018OAst...27..157R)
2 = Silvotti et al. (2019MNRAS.489.4791S 2019MNRAS.489.4791S)
3 = Reed et al. (2011MNRAS.414.2885R 2011MNRAS.414.2885R)
4 = Holdsworth et al. (2017MNRAS.466.5020H 2017MNRAS.466.5020H)
5 = Sanjayan et al. (2022MNRAS.509..763S 2022MNRAS.509..763S)
6 = Charpinet et al. (2019A&A...632A..90C 2019A&A...632A..90C)
7 = Reed et al. (2020MNRAS.493.5162R 2020MNRAS.493.5162R)
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 16-Jun-2023