J/MNRAS/513/788 MW field and cluster RR Lyrae stars (Garofalo+, 2022)
New LZ and PW(Z) relations of RR Lyrae stars calibrated with Gaia EDR3
parallaxes.
Garofalo A., Delgado H.E., Sarro L.M., Clementini G., Muraveva T.,
Marconi M., Ripepi V.
<Mon. Not. R. Astron. Soc., 513, 788-806 (2022)>
=2022MNRAS.513..788G 2022MNRAS.513..788G (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, globular ; Stars, standard ;
Stars, variable ; Positional data ; Parallaxes, trigonometric ;
Photometry ; Optical ; Extinction ; Abundances, [Fe/H]
Keywords: methods: data analysis - methods: statistical - parallaxes -
stars: variables: RR Lyrae - globular clusters: general
Abstract:
We present new luminosity-metallicity (LZ ; MV-[Fe/H] and MG-[Fe/H])
and relations and, for the first time, empirical, Gaia three-band (G,
GBP, GRP) period-Wesenheit-metallicity (PWZ) relations of RR Lyrae
stars (RRLs) derived using a hierarchical Bayesian approach and new
accurate parallaxes published for these variables in the Gaia Early
Data Release 3 (EDR3). In a previous study, we obtained Bayesian
hierarchically derived LZ relations from a sample of about four
hundred Milky Way field RRLs with G-band light curves and
trigonometric parallaxes published in the Gaia Data Release 2 (DR2),
using V mean magnitudes, metallicities, absorptions, and pulsation
periods available in the literature. We now extend that study in two
directions. First, we update our previous results using trigonometric
parallaxes from Gaia EDR3 and incorporate the Bayesian analysis of a
first empirical PWZ relation derived using those field RRLs with G,
GBP and GRP time-series photometry available in Gaia DR2.
Secondly, we use Bayesian inference to derive LZ relations and
empirical PW Gaia three-band relations from 385 RRLs belonging to 15
Milky Way globular clusters (GC) with literature-compiled
spectroscopic metallicities ranging from -0.36 to -2.39 dex and prior
distances extending from 2.2 to 41.2 kpc. From the samples of RRLs
analysed in this paper we infer a mean Gaia EDR3 zero-point offset of
-0.028 mas with median values ranging from -0.033 (LZ and PWZ models
for field stars) to -0.024 mas (LZ model in the V band for GC RRLs).
Description:
To further investigate the metallicity dependence of the LZ and PW(Z)
relations we have exploited the EDR3 parallaxes available for RRLs in
two different environments: the MW field and a sample of Galactic
globular clusters (GCs). In this paper, we thus present new
LZ(MV-[Fe/H] and MG-[Fe/H]) and PWZ(PW(G,GBP,GRP)Z) relations
obtained for field RRLs and new LZ(MV-[Fe/H] and MG-[Fe/H]) and PW
relations obtained for cluster RRLs, using a hierarchical Bayesian
inference and the new and accurate Gaia EDR3 parallaxes of these
variable stars, (i.e see section Introduction for more details).
We construct two separate data samples: RRLs in the MW field and in
Galactic GCs used for the derivation of the corresponding LZ relations
in the V and G passbands and PWZ relations in the Gaia G, GBP, and
GRP bands. First, as explained in the section 2.1 Field RR Lyrae
stars, we have built our field RRL sample starting from the 401 MW
RRLs analysed in Muraveva et al. (2018MNRAS.481.1195M 2018MNRAS.481.1195M,
Cat. J/MNRAS/481/1195) which were based on the Dambis et al.
(2013MNRAS.435.3206D 2013MNRAS.435.3206D, Cat. J/MNRAS/435/3206) sample. We first replaced
their Gaia DR2 parallaxes with the new EDR3 values, which are
available for the whole sample. To restrict the sample of field RRLs
used to calibrate the LZ and PLZ relations only to sources with
best-quality parallaxes we took into account the re-normalized unit
weight error (RUWE) (Lindegren 2018,
http://www.rssd.esa.int/doc_fetch.php?id=3757412) and retained only
sources satisfying the condition ruwe < 1.4. We provide information
for the complete data-set of 291 MW field RRLs in tablea1.dat. To
derive the MV-[Fe/H] and MG-[Fe/H] relations, among the 291 field
RRLs, we have used 274 sources having V magnitude (i.e refer to
section 4.2 MV-[Fe/H] relation) and 223 sources with G magnitude
(i.e refer to section 4.3 MG-[Fe/H] relation), respectively. A
subsample of 190 field RRLs having G, GBP, and GRP magnitudes were
instead used to infer the PW(G,GBP,GRP)Z relation (i.e refer to
section 4.4 PWZ relations).
Secondly, as explicited in the section 2.2 RR Lyrae stars in Globular
Clusters, we select a sample of 15 Galactic GCs with distances ranging
from a few to ∼41 kpc around the Galactic centre and spatially
distributed. According to the literature, the selected GCs host a
total number of 709 RRLs. We cross-matched the 709 cluster RRLs
against the Gaia EDR3 catalogue using a cross-match radius of 2 arcsec
and retained only sources unambiguously classified by the literature
as RRLs. With this filtering the GC RRL sample reduced to 643 sources.
Finally, as done for the field RRLs we cleaned the GC RRLs discarding
sources with ruwe => 1.4. With this latter filtering the sample was
reduced to 385 stars. The complete data-set with the relevant
information is summarized in tablea2.dat. As for field stars sample,
we also use V and G magnitude to derive the MV-[Fe/H] and
MG-[Fe/H] relations, G, GBP, and GRP magnitudes to infer the
PW(G,GBP,GRP)Z relation.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
cluster.dat 10 15 Globular Clusters in our sample
tablea1.dat 290 291 Galactic field RRLs used in this study
tablea2.dat 263 385 Milky Way RRLs stars cluster used in this study
--------------------------------------------------------------------------------
See also:
J/MNRAS/435/3206 : Properties of field RR Lyrae variables (Dambis+, 2013)
J/MNRAS/481/1195 : Gaia DR2 RR Lyrae stars as standard candles (Muraveva+,2018)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
I/358 : Gaia DR3 Part 4. Variability (Gaia Collaboration, 2022)
Byte-by-byte Description of file: cluster.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Cluster Cluster name (Cluster)
9- 10 I2 --- Nbr Number of stars in the cluster
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name RR Lyrae name (Name)
11- 29 I19 --- GaiaEDR3 Gaia EDR3 source ID number (sourceidEDR3)
31- 51 F21.17 deg RAdeg Barycentric right ascension of the source
(ICRS) at Ep=2016.0 (ra_EDR3)
53- 74 F22.18 deg DEdeg Barycentric declination of the source (ICRS)
at Ep=2016.0 (dec_EDR3)
76- 97 F22.19 mas plx Absolute stellar parallax of the source at
the Ep=2016.0 (parallax)
99- 110 F12.10 mas e_plx Standard error of the stellar parallax at
Ep=2016.0 (parallax_error)
112- 113 A2 --- Type [AB C] RR Lyrae subclass types (RRt) (1)
115- 120 F6.4 d P Variation period of the luminosity from
Muraveva et al. 2018MNRAS.481.1195M 2018MNRAS.481.1195M
Cat. J/MNRAS/481/1195 (Per)
122- 127 F6.3 mag Vmag ? Mean V magnitude from Muraveva et al.
2018MNRAS.481.1195M 2018MNRAS.481.1195M Cat. J/MNRAS/481/1195
(<Vmag>)
129- 133 F5.3 mag e_Vmag ? Mean error on Vmag from Muraveva et al.
2018MNRAS.481.1195M 2018MNRAS.481.1195M, Cat. J/MNRAS/481/1195
(e_<Vmag>)
135- 139 F5.3 mag AV Extinction coefficient in V band (AV)
141- 161 F21.19 mag e_AV Mean error on Av (err_Av)
163- 180 F18.15 mag AmpGmag ? Intensity-averaged mean magnitudes in the G
bands from GaiaDR2 Cat. I/345/rrlyrae
(intaverageg)
182- 202 E21.19 mag e_AmpGmag ? Mean error on AmpGmag (intaverageg_error)
204- 221 F18.15 mag AmpBPmag ? Intensity-averaged mean magnitudes in the
BP bands from GaiaDR2 Cat. I/345/rrlyrae
(intaveragebp)
223- 243 E21.19 mag e_AmpBPmag ? Mean error on AmpBPmag
(intaveragebp_error)
245- 262 F18.15 mag AmpRPmag ? Intensity-averaged mean magnitudes in the
RP bands from GaiaDR2 Cat. I/345/rrlyrae
(intaveragerp)
264- 284 E21.19 mag e_AmpRPmag ? Mean error on AmpRPmag
(intaveragerp_error)
286- 290 F5.2 [Sun] [Fe/H] [-2.84/0.07] Iron abundance relative to the
sun from Muraveva et al. 2018MNRAS.481.1195M 2018MNRAS.481.1195M,
Cat. J/MNRAS/481/1195 ([Fe/H])
--------------------------------------------------------------------------------
Note (1): RR Lyrae stars have two subclasses as follows:
AB = ab-type with asymmetric ("saw tooth") light curves indicating
that the star is pulsating in multiple modes, fundamental mode
and often in the first overtone, 260 stars in our sample
C = c-type with asymmetric light curves with less complexity and
longer pulsation periods than AB-type light curves, 31 stars
in our sample
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Cluster Cluster name (Cluster)
9- 13 A5 --- Name RR Lyrae name (Name)
15- 33 I19 --- GaiaEDR3 Gaia EDR3 source ID number (sourceidEDR3)
35- 52 F18.14 deg RAdeg Barycentric right ascension of the source
(ICRS) at Ep=2016.0 (ra_EDR3)
54- 73 F20.16 deg DEdeg Barycentric declination of the source (ICRS)
at Ep=2016.0 (dec_EDR3)
75- 96 F22.19 mas plx Absolute stellar parallax of the source at
the Ep=2016.0 (parallax)
98-108 F11.9 mas e_plx Standard error of the stellar parallax at
Ep=2016.0 (parallax_error)
110-116 A7 --- Type RR Lyrae subclass types (RRt) (1)
118-127 F10.8 d P Variation period of the luminosity from
Muraveva et al. 2018MNRAS.481.1195M 2018MNRAS.481.1195M
Cat. J/MNRAS/481/1195 (Per)
129-136 F8.5 mag Vmag ? Mean V magnitude from Muraveva et al.
2018MNRAS.481.1195M 2018MNRAS.481.1195M Cat. J/MNRAS/481/1195
(<Vmag>)
138-142 F5.3 mag e_Vmag ? Mean error on Vmag from Muraveva et al.
2018MNRAS.481.1195M 2018MNRAS.481.1195M, Cat. J/MNRAS/481/1195
(e_<Vmag>)
144-161 F18.15 mag AmpGmag ? Intensity-averaged mean magnitudes in the G
bands from GaiaDR2 Cat. I/345/rrlyrae
(intaverageg)
163-182 E20.18 mag e_AmpGmag ? Mean error on AmpGmag (intaverageg_error)
184-201 F18.15 mag AmpBPmag ? Intensity-averaged mean magnitudes in the
BP bands from GaiaDR2 Cat. I/345/rrlyrae
(intaveragebp)
203-223 E21.19 mag e_AmpBPmag ? Mean error on AmpBPmag
(intaveragebp_error)
225-242 F18.15 mag AmpRPmag ? Intensity-averaged mean magnitudes in the
RP bands from GaiaDR2 Cat. I/345/rrlyrae
(intaveragerp)
244-263 E20.18 mag e_AmpRPmag ? Mean error on AmpRPmag
(intaveragerp_error)
--------------------------------------------------------------------------------
Note (1): RR Lyrae stars have two subclasses as follows:
RRAB = ab-type with asymmetric ("saw tooth") light curves
indicating that the star is pulsating in multiple modes,
fundamental mode and often in the first overtone, 236 stars
in our sample
RRAB Bl = Similar as RRAB, 13 stars in our sample
RRC = c-type with asymmetric light curves with less complexity and
longer pulsation periods than AB-type light curves, 130
stars in our sample
RRC Bl = Similar as RRC, 6 stars in our sample
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Luc Trabelsi [CDS] 20-Nov-2024