J/A+A/684/A170 BL Her stars Gaia PL relation (Das+, 2024)
Theoretical framework for BL Her stars.
II. New period-luminosity relations in Gaia passbands.
Das S., Molnar L., Kanbur S.M., Joyce M., Bhardwaj A., Singh H.P.,
Marconi M., Ripepi V., Smolec R.
<Astron. Astrophys. 684, A170 (2024)>
=2024A&A...684A.170D 2024A&A...684A.170D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Models ; Abundances ; Photometry ; Optical
Keywords: hydrodynamics - methods: numerical - stars: low-mass -
stars: oscillations - stars: Population II -
stars: variables: Cepheids
Abstract:
In the era of the Hubble tension, it is crucial to obtain a precise
calibration of the period-luminosity (PL) relations of classical
pulsators. Type II Cepheids (T2Cs; often exhibiting negligible or weak
metallicity dependence on PL relations) used in combination with RR
Lyraes and the tip of the red giant branch may prove useful as an
alternative to classical Cepheids for the determination of
extragalactic distances.
We present new theoretical period-luminosity (PL) and period-Wesenheit
(PW) relations for a fine grid of convective BL Her, the shortest
period T2Cs, models computed using MESA-RSP and compare our results
with the empirical relations from Gaia DR3. We use the
state-of-the-art 1D non-linear radial stellar pulsation tool MESA-RSP
to compute models of BL Her stars over a wide range of input
parameters - metallicity (-2.0dex≤[Fe/H]≤0.0dex), stellar mass
(0.5M☉-0.8M☉), stellar luminosity (50L☉-300L☉)
and effective temperature (full extent of the instability strip; in
steps of 50K).
The BL Her stars in the All Sky region exhibit statistically different
PL slopes compared to the theoretical PL slopes computed using the
four sets of convection parameters. We find the empirical PL and PW
slopes from BL Her stars in the Magellanic Clouds to be statistically
consistent with the theoretical relations computed using the different
convection parameter sets in the Gaia passbands. There is negligible
effect of metallicity on the PL relations in the individual Gaia
passbands. However, there exists a small but significant negative
coefficient of metallicity in the PWZ relations for the BL Her models
using the four sets of convection parameters. This could be attributed
to the increased sensitivity of bolometric corrections to
metallicities at wavelengths shorter than the V band. Our BL Her
models also suggest a dependence of the mass-luminosity relation on
metallicity. We found the observed Fourier parameter space to be
covered well by our models. Higher mass models (>0.6M☉) may be
needed to reliably model the observed light curves of BL Her stars in
the All Sky region. We also found the theoretical light curve
structures (especially the Fourier amplitude parameters) to be
affected by the choice of convection parameters.
Description:
Light curve parameters of BL Her models computed using MESA-RSP and of
observed BL Her stars from the Gaia DR3 catalogue.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 86 30816 Light curve parameters of BL Her models
computed using MESA-RSP
table4.dat 110 1483 Light curve parameters of observed BL Her stars
from the Gaia DR3 catalogue
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 F7.5 --- Z Mass fraction of heavy elements
9- 15 F7.5 --- X Mass fraction of hydrogen
17- 18 A2 --- lambda Gaia passband: G, Gbp, Grp
20- 23 F4.2 Msun M Stellar mass in units of solar mass
25- 26 A2 --- Mode Mode of pulsation (FU=Fundamental)
28- 31 I4 K Teff Effective temperature
33- 35 I3 [Lsun] logL Stellar luminosity in units of solar luminosity
37- 41 F5.3 [d] logP Logarithmic pulsation period
43- 47 F5.3 mag Amp Amplitude of the theoretical light curve
49- 54 F6.3 mag m0 Mean magnitude
56- 60 F5.3 --- R21 Fourier amplitude parameter R21
62- 66 F5.3 --- R31 Fourier amplitude parameter R31
68- 72 F5.3 --- phi21 Fourier phase parameter phi21
74- 78 F5.3 --- phi31 Fourier phase parameter phi31
80- 84 F5.3 [Rsun] logR Stellar radius in units of solar radius
86 A1 --- Set Convection set used
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Sub-region Gaia DR3 sub-region (All Sky, LMC, SMC)
9- 10 A2 --- lambda Gaia passband: G, Gbp, Grp
12- 30 I19 --- GaiaDR3 Gaia DR3 Source ID
32- 37 F6.3 [d] logP Logarithmic pulsation period
39 I1 --- Order Order of Fourier fit (N= 4 to 8)
41- 46 F6.3 mag Amp Amplitude of the observed light curve
48- 53 F6.3 mag m0 Mean magnitude
55- 60 F6.3 mag e_m0 Error in mean magnitude
62- 66 F5.3 --- R21 Fourier amplitude parameter R21
68- 72 F5.3 --- e_R21 Error in the Fourier amplitude parameter R21
74- 78 F5.3 --- R31 Fourier amplitude parameter R31
80- 84 F5.3 --- e_R31 Error in the Fourier amplitude parameter R31
86- 90 F5.3 --- phi21 Fourier phase parameter phi21
92- 97 F6.3 --- e_phi21 Error in the Fourier phase parameter phi21
99-103 F5.3 --- phi31 Fourier phase parameter phi31
105-110 F6.3 --- e_phi31 Error in the Fourier phase parameter phi31
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Acknowledgements:
Susmita Das, susmita.das(at)csfk.org
References:
Das et al., Paper I 2021MNRAS.501..875D 2021MNRAS.501..875D
(End) Patricia Vannier [CDS] 07-Feb-2024