J/A+A/676/A136 SED of Magellanic Clouds classical Cepheids (Groenewegen+, 2023)
Spectral energy distributions of classical Cepheids in the Magellanic Clouds.
Groenewegen M.A.T, Lub J.
<Astron. Astrophys. 676, A136 (2023)>
=2023A&A...676A.136G 2023A&A...676A.136G (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Stars, variable ; Stars, distances;
Parallaxes, trigonometric ; Optical
Keywords: stars: distances - stars: fundamental parameters -
stars: variables: Cepheids
Abstract:
The spectral energy distributions (SEDs) of a sample of 142 LMC and 77
SMC fundamental mode classical Cepheids (CCs) were constructed using
photometric data in the literature. The data was whenever possible
representative of mean light, or averaged over the light curve. The
sample was build from stars that have a metallicity determination from
high-resolution spectroscopy, have been used in Baade-Wesselink type
of analysis, have a radial velocity curve published in Gaia DR3, have
Walraven photometry, or have their light- and radial-velocity curves
modelled by pulsation codes.
The SEDs were fitted with stellar photosphere models to derive the
best-fitting luminosity and effective temperature. Distance and
reddening were taken from the literature.
The stars were plotted in a Hertzsprung-Russell diagram (HRD) and
compared to evolutionary tracks for CCs and to theoretical instability
strips. For the large majority of stars, the position in the HRD is
consistent with the instability strip. Period-luminosity (PL) and
period-radius relations are derived and compared to these relations in
the MW.
For a fixed slope, the zero point of the bolometric PL relation does
not depend on metallicity, contrary to recent findings of a
significant metallicity term when considering the PL relation in
different photometric bands.
The mass-luminosity (ML) relation is derived and it points to an over
luminosity of about +0.3dex with respect to a canonical ML relation.
The most intriguing result concerns the flux-weighted gravity (FWG, a
quantity derived from gravity and effective temperature) and its
relation to period and luminosity. Both relations agree with theory,
with the results for the MW, and with the independent estimates from
the six known LMC eclipsing binaries that contain CCs.
However, the FWG as determined from dedicated high-resolution
spectroscopy for the sample is too low by about 0.8dex in 90% of the
cases.
Recent work on time-series data on 20 CCs in the MW was analysed to
find a similar (but less extreme) offset in gravity and the FWG.
Importantly, other time-series data on the same 20 CCs are in full
agreement with the FWG-period relation however.
The observed time-series of spectroscopic data and from a
two-dimensional hydrodynamical cepheid model was used to investigate
the so-called effective gravity, that is, the gravity corrected for a
dynamical term related to the time derivative of the radial velocity.
There is a reasonable good correspondence between the predicted
effective gravity and the observed gravity as a function of pulsation
phase, which potentially would allow for an independent estimate of
the projection factor, but the dynamical term is too small to explain
the overall difference between the observed (flux weighted) gravity,
and the (flux weighted) gravity derived from the SED modelling and
stellar mass estimates.
Description:
The tabular material includes:
basic parameters for the sample of stars (Table 1),
epoch photometry in the Walraven system (Table A1),
mean magnitudes and amplitudes in the Walraven system (Table A2), and
different mass estimates for the sample of stars (Table B1).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 128 219 Sample of stars with parameters
tablea1.dat 60 1210 Individual Walraven observations for 46 stars
tablea2.dat 146 68 Mean VBLUW photometry
tableb1.dat 82 219 Different mass estimates
--------------------------------------------------------------------------------
See also:
J/AcA/65/297 : OGLE4 LMC and SMC Cepheids (Soszynski+, 2015)
J/ApJ/898/L7 : Predicted masses of Gal. Cepheids from Gaia (Marconi+, 2020)
J/AJ/163/152 : ∼650000 stars stellar parameters with APOGEE (Sprague+, 2022)
J/A+A/658/A29 : LMC classical Cepheids Fe and O content (Romaniello+, 2022)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name The identifier used in this paper, which is
related to the identifier used by OGLE (1)
11- 15 I5 --- HV ? Harvard variable (HV) identifier,
when available (SV* HV NNNNN in Simbad)
17- 23 F7.3 d Per Pulsation period.
25- 29 F5.2 kpc d The adopted distance. For the LMC objects this
includes the geometric correction
31- 34 F4.2 mag AV The adopted reddening value AV based on
Skowron at al, 2021ApJS..252...23S 2021ApJS..252...23S,
Cat. J/ApJS/252/23, see main text.
36- 39 I4 K Teff ? Effective temperature in the literature.
For references 3 and 6 an uncertainty of 100K
has been adopted
41- 43 I3 K e_Teff ? Effective temperature error
45- 48 F4.2 [cm/s2] logg ? log gravity in the literature.
For references 3, 4 and 6 an uncertainty of
0.1dex has been adopted
50- 53 F4.2 [cm/s2] e_logg ? log gravity error
55 I1 --- Ref ? Reference for Teff and logg (2)
57- 63 F7.1 Lsun Lum Luminosity with error bar from the SED fitting
65- 70 F6.1 Lsun e_Lum Luminosity with error bar from the SED fitting
72- 75 I4 K Teffp (photometric) effective temperature from
the SED fitting
77- 79 I3 K e_Teffp (photometric) effective temperature error bar
from the SED fitting
81- 85 F5.1 Rsun R Radius, derived from L and Teff
87- 90 F4.1 Rsun e_R Radius error bar, derived from L and Teff
92- 96 F5.2 Msun Mass Adopted stellar mass
98-101 F4.2 Msun e_Mass Adopted stellar mass errro
102 A1 --- n_Mass [)] ) for mass and (flux-weighted) gravity are
not used to calculate loggF
104-107 F4.2 [cm/s2] logg2 log gravity determined from mass and radius
109-112 F4.2 [cm/s2] e_logg2 log gravity determined from mass and radius
error
114-117 F4.2 [cm/s2] loggF Flux-weighted gravity calculated from from
the gravity and Teff (3)
119-122 F4.2 [cm/s2] e_loggF Flux-weighted gravity calculated from from
the gravity and Teff error
124-128 F5.1 --- rchi2 The reduced chi-square of the fit to the SED
--------------------------------------------------------------------------------
Note (1): The first entry, LMC0046, for example, would be known as
OGLE-LMC-CEP-0046, OGLE LMC-CEP-0046 in Simdab.
Note (2): References as follows:
1 = Romaniello et al., 2022A&A...658A..29R 2022A&A...658A..29R. Cat. J/A+A/658/A29,
re-analysed data from Romaniello et al. 2008A&A...488..731R 2008A&A...488..731R
(Tables 4 and 6)
2 = Romaniello et al., 2022A&A...658A..29R 2022A&A...658A..29R. Cat. J/A+A/658/A29
(new spectra, Tables 3 and 5)
3 = Romaniello et al. 2008A&A...488..731R 2008A&A...488..731R
4 = Lemasle et al., 2017A&A...608A..85L 2017A&A...608A..85L
5 = Sprague et al.. 2022AJ....163..152S 2022AJ....163..152S, Cat. J/AJ/163/152
6 = Ragosta et al., 2019MNRAS.490.4975R 2019MNRAS.490.4975R (LMC) and Marconi et al.,
2017MNRAS.466.3206M 2017MNRAS.466.3206M (SMC). The values are not determined from
high-resolution spectroscopy but from their best-fitting LC fitting
models.
Note (3): For a few stars the mass estimate is clearly too low given their
period and the value for the mass and (flux-weighted) gravity are not used
and the is a ")" in n_Mass column.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format UnitsLabel Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- HV HV number
7- 17 F11.5 d HJD Heliocentric Julian date (HJD-2400000.0)
19- 25 F7.4 mag Vmag Walraven V magnitude
27- 32 F6.4 mag V-B Walraven V-B colour index
34- 39 F6.4 mag B-U Walraven B-U colour index
41- 47 F7.4 mag U-W Walraven U-W colour index
49- 54 F6.4 mag B-L Walraven B-L colour index
56- 60 I5 --- QFlag Quality flag in the VBLUW bands, respectively (1)
--------------------------------------------------------------------------------
Note (1): This flag indicates the internal dispersion in the photometer signal
in each channel, and 0, 1, 2, ..., 9 implies, <1, 1-2, 2-4, ...,
256-512 promille variation, respectively.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- HV HV number (1)
8- 13 F6.3 mag Vmag Walraven V magnitude
15- 19 F5.3 mag e_Vmag Walraven V magnitude error
21- 25 F5.3 mag AmpV Amplitude in Walraven V magnitude
27- 31 F5.3 mag e_AmpV Amplitude in Walraven V magnitude
33- 34 I2 --- o_Vmag Number of data points in Walraven V filter
36- 41 F6.3 mag Bmag ? Walraven B magnitude
43- 47 F5.3 mag e_Bmag ? Walraven B magnitude error
49- 53 F5.3 mag AmpB ? Amplitude in Walraven B magnitude
55- 59 F5.3 mag e_AmpB ? Amplitude in Walraven B magnitude error
61- 62 I2 --- o_Bmag ? Number of data points in Walraven B filter
64- 69 F6.3 mag Lmag ? Walraven L magnitude
71- 75 F5.3 mag e_Lmag ? Walraven L magnitude error
77- 81 F5.3 mag AmpL ? Amplitude in Walraven L magnitude
83- 87 F5.3 mag e_AmpL ? Amplitude in Walraven L magnitude error
89- 90 I2 --- o_Lmag ? Number of data points in Walraven L filter
92- 97 F6.3 mag Umag ? Walraven U magnitude
99-103 F5.3 mag e_Umag ? Walraven U magnitude error
105-109 F5.3 mag AmpU ? Amplitude in Walraven U magnitude
111-115 F5.3 mag e_AmpU ? Amplitude in Walraven U magnitude error
117-118 I2 --- o_Umag ? Number of data points in Walraven U filter
120-125 F6.3 mag Wmag ? Walraven W magnitude
127-131 F5.3 mag e_Wmag ? Walraven W magnitude error
133-137 F5.3 mag AmpW ? Amplitude in Walraven W magnitude
139-143 F5.3 mag e_AmpW ? Amplitude in Walraven W magnitude error
145-146 I2 --- o_Wmag ? Number of data points in Walraven W filter
--------------------------------------------------------------------------------
Note (1): 270100 refers to HDE 270100 Van Genderen & Hadiyanto Nitihardjo
(1989A&A...221..230V 1989A&A...221..230V).
The first entries (HV 824 - 5655) are the stars with new observations,
the latter part (HDE 270100 - HV 12815) are the stars from
Van Genderen (1983A&AS...52..423V 1983A&AS...52..423V) (and Van Genderen & Hadiyanto Nitihardjo
(1989A&A...221..230V 1989A&A...221..230V) for HDE 270100) with any new data added in the
analysis.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Name Identifier (sources are sorted by period)
10- 15 F6.2 d Per Period
17- 21 F5.2 Msun Mass1 Mass estimate from the
period-luminosity-mass-effective_temperature-
metallicity relation (1)
23- 26 F4.2 Msun e_Mass1 Error on Mass1
28- 32 F5.2 Msun Mass2 Mass estimate from Eq. (1), based on the
models of Anderson et al.
(2016A&A...591A...8A 2016A&A...591A...8A)
34- 37 F4.2 Msun e_Mass2 Error on Mass2
39- 43 F5.2 Msun Mass3 Mass estimate from the relation in
Ragosta et al. (2019MNRAS.490.4975R 2019MNRAS.490.4975R)
45- 48 F4.2 Msun e_Mass3 Error on Mass3
50- 54 F5.2 Msun Mass4 Mass estimate from the relation in
Pilecki et al. (2018ApJ...862...43P 2018ApJ...862...43P)
56- 59 F4.2 Msun e_Mass4 Error on Mass4
61- 65 F5.2 Msun Mass5 Mass estimate from the relation in
Marconi et al. (2020ApJ...898L...7M 2020ApJ...898L...7M,
Cat. J/ApJ/898/L7)
67- 70 F4.2 Msun e_Mass5 Error on Mass5
72- 76 F5.2 Msun Mass Adopted mass based on the median and the MAD
(see text)
78- 81 F4.2 Msun e_Mass Error on Mass
82 A1 --- n_Mass [)] Note on Mass (2)
--------------------------------------------------------------------------------
Note (1): derived in Groenewegen and Jurkovic (2017A&A...604A..29G 2017A&A...604A..29G,
Cat. J/A+A/604/A29) based on the the models in Bono et al.
(2000ApJ...529..293B 2000ApJ...529..293B).
Note (2): Note as follows:
) = Mass value deemed unreliable and have not been used in the analysis of
the mass-luminosity relation and in the calculation of the evolutionary
logg and FWG values
--------------------------------------------------------------------------------
Acknowledgements:
Martin Groenewegen, martin.groenewegen(at)oma.be
(End) Patricia Vannier [CDS] 18-Jul-2023