J/A+A/625/A14 Reclassification of Cepheids in the Gaia DR2 (Ripepi+, 2019)
Reclassification of Cepheids in the Gaia Data Release 2.
Period-luminosity and period-Wesenheit relations in the Gaia passbands.
Ripepi V., Molinaro R., Musella I., Marconi M., Leccia S., Eyer L.
<Astron. Astrophys. 625, A14 (2019)>
=2019A&A...625A..14R 2019A&A...625A..14R (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Parallaxes, trigonometric ; Photometry
Keywords: stars: distances - stars: variables: Cepheids - distance scale
Abstract:
Classical Cepheids are the most important primary indicators for the
extragalactic distance scale. Establishing the precise zero points of
their Period-Luminosity and Period-Wesenheit (PL/PW) relations has
profound consequences on the estimate of H0. Type II Cepheids are
also important distance indicator and tracers of old stellar
populations. The recent Data Release 2 (DR2) of the Gaia Spacecraft
includes photometry and parallaxes for thousands of classical and type
II cepheids. We aim at reviewing the classification of Gaia DR2
Cepheids and to derive precise PL/PW for Magellanic Cloud (MCs) and
Galactic Cepheids. Information from the literature and the Gaia
astrometry and photometry are adopted to assign DR2 Galactic Cepheids
to the classes: Classical, Anomalous and Type II Cepheids. We
re-classify the DR2 Galactic Cepheids and derive new precise PL/PW
relations in the Gaia passbands for the MCs and Milky Way Cepheids. We
investigated for the first time the dependence on metallicity of the
PW relation for Classical Cepheids in the Gaia bands, finding
non-conclusive results. According to our analysis, the zero point of
the Gaia DR2 parallaxes as estimated from Classical and Type II
Cepheids seems to be likely underestimated by ∼0.07mas, in full
agreement with recent literature. The next Gaia data releases are
expected to fix this zero point offset to eventually allow a
determination of H0 to less than 1%.
Description:
Reclassification of the Cepheids published in the Gaia Data Release 2.
The different tables show: Table 2, the comparison with literature
results; Table 5, the reclassification; Table 7, the association of
the Cepheids with star clusters or galaxies of the Local Group; Table
8, the reddening and metallicity estimates for Classical Cepheids
adopted in the paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 233 1416 Comparison with literature classification
table5.dat 182 2116 Reclassification of the Cepheids in Gaia DR2
table7.dat 81 195 Association of the Cepheids in Gaia DR2 with
star clusters or galaxies of the Local Group
table8.dat 65 301 Values of reddening and metallicity for Classical
Cepheids adopted in this work
(and relative references)
refs.dat 264 31 References
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- SourceId Gaia DR2 source identification
21- 29 F9.5 deg RAdeg Right ascension (ICRS) at epoch 2015.5
31- 39 F9.5 deg DEdeg Declination (ICRS) at epoch 2015.5
41- 50 A10 --- DR2Class Variability classification according
to Gaia DR2
52- 85 A34 --- LitName Name of the object in the literature
87-111 A25 --- LitClass Type(s) of variability found in
the literature
113-144 A32 --- e_LitClass Source for the different type of
variability, inrefs.dat file (1)
146-155 F10.5 d P1 ? Period present in the literature
157-165 F9.4 d P2 ? Period present in the literature
168-175 F8.4 d P3 ? Period present in the literature
177-200 A24 --- r_P1 Source of the period P1, inrefs.dat file (1)
202-219 A18 --- r_P2 Source of the period P2, inrefs.dat file (1)
221-233 A13 --- r_P3 Source of the period P3, inrefs.dat file (1)
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Note (1): separated by a "/" or "//" depending whether or not the period
estimates of the two or more sources agree.
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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 I19 --- SourceId Gaia DR2 source identification
21- 29 F9.5 deg RAdeg Right ascension (ICRS) at epoch 2015.5
31- 39 F9.5 deg DEdeg Declination (ICRS) at epoch 2015.5
41- 43 I3 --- o_Gmag Number of epochs in G
45- 47 I3 --- o_GBPmag Number of epochs in GBP
49- 51 I3 --- o_GRPmag Number of epochs in GRP
53- 63 F11.6 d Per Period
65- 70 F6.3 mag Gmag Intensity averaged magnitudes in G
72- 77 F6.3 mag GBPmag Intensity averaged magnitudes in GBP
79- 84 F6.3 mag GRPmag Intensity averaged magnitudes in GRP
86- 91 F6.3 --- R21 ?=99.999 Fourier amplitude ratio R21
93- 98 F6.3 --- R31 ?=99.999 Fourier amplitude ratio R31
100-105 F6.3 rad Phi21 ?=99.999 Fourier phase difference Phi21
107-112 F6.3 rad Phi31 ?=99.999 Fourier phase difference Phi31
114-120 F7.3 mas Plx Parallax
122-127 F6.3 mas e_Plx Error on parallax
129-134 F6.3 --- E(BP/RP) Excess of flux in the BP and RP integrated
photometry with respect to the G band
136-141 F6.3 mas epsi Excess noise of the source
143-150 F8.3 --- Signiepsi Significance of epsi
152-157 F6.3 mas RUWE Renormalised unit weight error
159-171 A13 --- Class Variability classification from from
present work
173 A1 --- New [N] Flag "N" to denote a cepheid not known
in the literature
175-182 A8 --- Notes Notes (1)
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Note (1): Notes as follows:
a = wrong period in DR2, used the literature or derived in this work
b = uncertain period
c = uncertain astrometry
d = incomplete LC
e = scattered LC
f = bad astrometric solution (see text)
g = classification based on the LC shape
h = adopted literature classification
i = uncertain classification of LC shape
NC: = not classifiable
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
-------------------------------------------------------------------------------
1- 19 I19 --- SourceId Gaia DR2 source identification
21- 47 A27 --- LitName Name of the object in the literature
49- 58 A10 --- Class Variability classification according to
this work
60- 71 A12 --- HostSystem Host system
73- 81 A9 --- r_HostSystem Source of the association of the variable
with the stellar system, in refs.dat file
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Literature name
11- 17 A7 --- Class Variability classification according to
this work
19- 37 I19 --- SourceId Gaia DR2 source identification
40- 44 F5.3 mag E(B-V) Color excess due to extinction
47- 51 F5.3 mag e_E(B-V) Error on E(B-V)
53- 57 F5.2 [-] [Fe/H] ? Metallicity
61 I1 --- r_E(B-V) [1/4] Source for E(B-V) value (1)
65 I1 --- r_[Fe/H] [2/5]? Source for [Fe/H] value (1)
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Note (1): References as follows:
1 = Fernie, 1990ApJS...72..153F 1990ApJS...72..153F
2 = Ngeow, 2012, Cat. J/ApJ/747/50
3 = Majaess et al., 2008MNRAS.390.1539M 2008MNRAS.390.1539M
4 = Kashuba et al., 2016, Cat. J/MNRAS/461/839
5 = Genovali et al. 2013, Cat. J/A+A/554/A132; 2014, Cat. J/A+A/566/A37;
2015, Cat. J/A+A/580/A17
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Ref Reference code
16- 34 A19 --- BibCode BibCode
36- 58 A23 --- Aut Author's name
60-264 A205 --- Com Comments
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Acknowledgements:
Vincenzo Ripepi, vincenzo.ripepi(at)inaf.it
(End) Vincenzo Ripepi [INAF, Italy], Patricia Vannier [CDS] 18-Mar-2019