J/MNRAS/491/4752 Modelled parameters of Cepheid and RR Lyrae (Bellinger+, 2020)
When a period is not a full stop: Light-curve structure reveals fundamental
parameters of Cepheid and RR Lyrae stars.
Bellinger E.P., Kanbur S.M., Bhardwaj A., Marconi M.
<Mon. Not. R. Astron. Soc., 491, 4752-4767 (2020)>
=2020MNRAS.491.4752B 2020MNRAS.491.4752B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Magellanic Clouds ; Models ; Stars, masses ;
Stars, diameters ; Effective temperatures ; Optical
Keywords: stars: fundamental parameters - stars: oscillations -
stars: variables: Cepheids - stars: variables: RR Lyrae -
Magellanic Clouds - distance scale
Abstract:
The period of pulsation and the structure of the light curve for
Cepheid and RR Lyrae variables depend on the fundamental parameters of
the star: mass, radius, luminosity, and effective temperature. Here,
we train artificial neural networks on theoretical pulsation models to
predict the fundamental parameters of these stars based on their
period and light-curve structure. We find significant improvements to
estimates of these parameters made using light-curve structure and
period over estimates made using only the period. Given that the
models are able to reproduce most observables, we find that the
fundamental parameters of these stars can be estimated up to 60 per
cent more accurately when light-curve structure is taken into
consideration. We quantify which aspects of light-curve structure are
most important in determining fundamental parameters, and find, for
example, that the second Fourier amplitude component of RR Lyrae light
curves is even more important than period in determining the effective
temperature of the star. We apply this analysis to observations of
hundreds Cepheids in the Large Magellanic Cloud and thousands of RR
Lyrae in the Magellanic Clouds and Galactic bulge to produce
catalogues of estimated masses, radii, luminosities, and other
parameters of these stars. As an example application, we estimate
Wesenheit indices and use those to derive distance moduli to the
Magellanic Clouds of µLMC,CEP=18.688±0.093,
µLMC,RRL=18.52±0.14, and µSMC,RRL=18.88±0.17mag.
Description:
Our interest is in determining global stellar parameters of Cepheids
and RR Lyraes, such as M, L, Teff, and R and in constraining input
stellar physics. The period-mean density relation suggests that the
observable period is the most important quantity in constraining the
global stellar parameters. However, in this study, using recently
published pulsation models for Cepheids and RR Lyraes, we have used
modern data analysis methods to demonstrate that light-curve structure
plays a statistically significant part in determining these
parameters. Using these techniques, we have developed a catalogue of
predicted masses, luminosities, radii, and effective temperatures for
OGLE Cepheids and RR Lyraes. We have furthermore used the predicted
luminosities and hence predicted V- and I-band theoretical magnitudes
to construct a Wesenheit function and estimate the distance to the LMC
and SMC. Our calculated distances are statistically consistent with
the latest estimates from eclipsing binaries.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 107 325 Masses, radii, luminosities, effective
temperatures, I- and V-band magnitudes, colour,
and Wesenheit indices estimated using machine
learning for Cepheids in the LMC
table4.dat 115 9238 Masses, radii, luminosities, effective
temperatures, I- and V-band magnitudes, colour,
and Wesenheit indices estimated using machine
learning for RR Lyrae in the LMC
table5.dat 114 812 Masses, radii, luminosities, effective
temperatures, I- and V-band magnitudes, colour,
and Wesenheit indices estimated using machine
learning for RR Lyrae in the SMC
table6.dat 116 3504 Masses, radii, luminosities, effective
temperatures, I- and V-band magnitudes, colour,
and Wesenheit indices estimated using machine
learning for RR Lyrae in the Galactic bulge
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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- 17 A17 --- Name Star name (OGLE-LMC-CEP-NNNN)
19- 22 F4.2 Msun Mass Star mass
24- 27 F4.2 Msun e_Mass Error on Mass
29- 33 F5.3 [Rsun] logR Logaritm of star radius
35- 39 F5.3 [Rsun] e_logR Error on logR
41- 45 F5.3 [Lsun] logL Logarithm of star luminosity
47- 51 F5.3 [Lsun] e_logL Error on logL
53- 56 I4 K Teff Effective temperature
58- 60 I3 K e_Teff Error on Teff
62- 66 F5.2 mag IMAG Absolute I-band magnitude
68- 71 F4.2 mag e_IMAG Error on IMAG
73- 77 F5.2 mag VMAG Absolute V-band magnitude
79- 82 F4.2 mag e_VMAG Error on VMAG
84- 88 F5.3 mag V-I V-I colour index
90- 94 F5.3 mag e_V-I Error on V-I
96-101 F6.3 mag W Wesenheit index (W=I-1.55(V-I))
103-107 F5.3 mag e_W Error on W
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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- 20 A20 --- Name Star name (OGLE-LMC-RRLYR-NNNNN)
22- 26 F5.3 Msun Mass Star mass
28- 32 F5.3 Msun e_Mass Error on Mass
34- 38 F5.3 [Rsun] logR Logaritm of star radius
40- 44 F5.3 [Rsun] e_logR Error on logR
46- 50 F5.3 [Lsun] logL Logarithm of star luminosity
52- 56 F5.3 [Lsun] e_logL Error on logL
58- 61 I4 K Teff Effective temperature
63- 65 I3 K e_Teff Error on Teff
67- 72 F6.3 mag IMAG Absolute I-band magnitude
74- 78 F5.3 mag e_IMAG Error on IMAG
80- 84 F5.3 mag VMAG Absolute V-band magnitude
86- 90 F5.3 mag e_VMAG Error on VMAG
92- 96 F5.3 mag V-I V-I colour index
98-102 F5.3 mag e_V-I Error on V-I
104-109 F6.3 mag W Wesenheit index (W=I-1.55(V-I))
111-115 F5.3 mag e_W Error on W
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name Star name (OGLE-SMC-RRLYR-NNNN)
21- 25 F5.3 Msun Mass Star mass
27- 31 F5.3 Msun e_Mass Error on Mass
33- 37 F5.3 [Rsun] logR Logaritm of star radius
39- 43 F5.3 [Rsun] e_logR Error on logR
45- 49 F5.3 [Lsun] logL Logarithm of star luminosity
51- 55 F5.3 [Lsun] e_logL Error on logL
57- 60 I4 K Teff Effective temperature
62- 64 I3 K e_Teff Error on Teff
66- 71 F6.3 mag IMAG Absolute I-band magnitude
73- 77 F5.3 mag e_IMAG Error on IMAG
79- 83 F5.3 mag VMAG Absolute V-band magnitude
85- 89 F5.3 mag e_VMAG Error on VMAG
91- 95 F5.3 mag V-I V-I colour index
97-101 F5.3 mag e_V-I Error on V-I
103-108 F6.3 mag W Wesenheit index (W=I-1.55(V-I))
110-114 F5.3 mag e_W Error on W
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 20 A20 --- Name Star name (OGLE-BLG-RRLYR-NNNNN)
22- 26 F5.3 Msun Mass Star mass
28- 32 F5.3 Msun e_Mass Error on Mass
34- 38 F5.3 [Rsun] logR Logaritm of star radius
40- 44 F5.3 [Rsun] e_logR Error on logR
46- 50 F5.3 [Lsun] logL Logarithm of star luminosity
52- 56 F5.3 [Lsun] e_logL Error on logL
58- 61 I4 K Teff Effective temperature
63- 65 I3 K e_Teff Error on Teff
67- 72 F6.3 mag IMAG Absolute I-band magnitude
74- 78 F5.3 mag e_IMAG Error on IMAG
80- 85 F6.3 mag VMAG Absolute V-band magnitude
87- 91 F5.3 mag e_VMAG Error on VMAG
93- 97 F5.3 mag V-I V-I colour index
99-103 F5.3 mag e_V-I Error on V-I
105-110 F6.3 mag W Wesenheit index (W=I-1.55(V-I))
112-116 F5.3 mag e_W Error on W
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 21-Feb-2023