J/MNRAS/505/1342 Study of Cepheids in open clusters (Medina+, 2021)
A revisited study of Cepheids in open clusters in the Gaia era.
Medina G.E., Lemasle B., Grebel E.K.
<Mon. Not. R. Astron. Soc. 505, 1342-1366 (2021)>
=2021MNRAS.505.1342M 2021MNRAS.505.1342M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Milky Way ; Photometry, G band ;
Stars, standard ; Infrared sources
Keywords: methods: data analysis - catalogues - stars: kinematics and dynamics -
stars: variables: Cepheids - open clusters and associations: general
Abstract:
In this paper, we revisit the problem of identifying bona fide cluster
Cepheids by performing an all-sky search for Cepheids associated with
open clusters and making use of state-of-the-art catalogued
information for both Cepheids and clusters, based on the unparalleled
astrometric precision of the second and early third data releases of
the Gaia satellite. We determine membership probabilities by following
a Bayesian approach using spatial and kinematic information of the
potential cluster-Cepheid pairs. We confirm 19 Cepheid-cluster
associations considered in previous studies as bona fide, and question
the established cluster membership of six other associations. In
addition, we identify 138 cluster Cepheid candidates of potential
interest, mostly in recently discovered open clusters. We report on at
least two new clusters possibly hosting more than one Cepheid.
Furthermore, we explore the feasibility of using open clusters hosting
Cepheids to empirically determine the Cepheid period-age relation
through the use of Gaia and 2MASS photometry and a semiautomated
method to derive cluster ages. We conclude that the usage of cluster
Cepheids as tentative probes of the period-age relations still faces
difficulties due to the sparsely populated red giant branch and the
stochastically sampled main-sequence turn-off of the open clusters,
making age determinations a challenging task. This biases the
age-datable cluster selection for Cepheid period-age studies towards
older and high-mass clusters.
Description:
First, we construct by severals cross matched catalogues (mainly
Cat. B/ocl, J/A+A/558/A53 and I/345, see section. 2 on open clusters
sample), our final open clusters sample. After removing evident
repeated entries from this list (with astrometric parameters within
one standard deviation from each other), our final catalogue contains
a total of 4140 Galactic open clusters.
Secondly, we construct cepheids sample, we mainly rely for this on the
cross-survey validation performed by the OGLE team (Udalski et al.
2015AcA....65....1U 2015AcA....65....1U) and also including others cepheids surveys. Once
compiled, we cross-matched this catalogue against Gaia eDR3
Cat. I/350. Thus, our sample of Milky Way classical Cepheids
contains 2921 Cepheids.
Thirdly, we follow the Bayesian approach adopted by Anderson et al.
(A13, Anderson et al. 2013MNRAS.434.2238A 2013MNRAS.434.2238A) to address the membership
determination. The Bayesian approach enables us to quantify the
likelihood of a given Cepheid being a member of an open clusteWe refer
to a Cepheid-cluster pair as a 'combo', following the convention
initiated by A13 (e.g see the section 3. membership dertimination to
see the entire bayesian procedure with constraints and priors
settings using the parallaxes, proper motions and radial velocity).
Thus, giving birth to the outcomes tables. From 44 300 possible combos
for which we computed the likelihood of membership, we only keep a
small fraction which displays relatively high probabilities.
Cluster-Cepheid pairs with posterior probabilities higher than 0.10
are shown in table1.dat while those with membership probabilities from
0.01 to 0.10 can be found in the tablea1.dat. Additionally, in the
tablea2.dat, we exhibit convicing results of comparisons with
literature combos (see discussion in sections 5.1 and 5.4).
Knowing that a high likelihood is obviously not a guarantee of
membership, as it can in particular be driven by issues in the
determination of the astrometric parameters and/or large
uncertainties. Nevertheless, we highlight these cases as interesting
pairs to further investigate.
Consequently, we note that if we do not restrict ourselves to combos
with membership probabilities P(A|B) > 0.01, we find 258 additional
combos with likelihood P(B|A) > 0.85 listed in the tablea3.dat.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 87 67 Cluster - Cepheid pairs with membership
probabilities P(A|B) > 0.10
tablea1.dat 88 96 Cluster - Cepheid pairs with membership
probabilities P(A|B) between 0.01 and 0.10
tablea2.dat 126 25 Prior, likelihood and membership probability
for literature combos
tablea3.dat 82 258 Cluster - Cepheid pairs with low priors P(A),
but high likelihood (P(B|A) > 0.85)
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See also:
B/ocl : Optically visible open clusters and Candidates (Dias+ 2002-2015)
J/A+A/558/A53 : Milky Way global survey of star clusters. II.
(Kharchenko+, 2013)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Name Open cluster name (Open_cluster) (1)
15- 18 I4 --- MWSC ? MWSC Milky-Way ID number (MWSC_ID) (1)
20- 47 A28 --- Cepheid Cepheid name (Cepheid) (1)
49 A1 --- n_Cepheid [a] Uncertain Cepheid classification,
as noted by the OGLE team (Note)
51- 54 F4.2 --- Sep/r1 Angular Ratio (Sep/r1) (2)
56- 72 A17 --- Constr The list of constraints used to derive
the membership probability (Constraints)
74- 77 F4.2 --- P(A) The prior P(A) probability (P_A) (3)
79- 82 F4.2 --- P(B|A) The likelihood probability (P_B|A) (4)
84- 87 F4.2 --- P(A|B) The membership probability (P_A|B) (5)
--------------------------------------------------------------------------------
Note (1): Open clusters with identification names starting with UBC correspond
to clusters in references as:
Castro-Ginard et al. 2018A&A...618A..59C 2018A&A...618A..59C, Cat. J/A+A/627/A35,
Castro-Ginard et al. 2019A&A...627A..35C 2019A&A...627A..35C, Cat. J/A+A/627/A35,
Castro-Ginard et al. 2020A&A...635A..45C 2020A&A...635A..45C. Cat. J/A+A/635/A45.
The cluster names starting with LP are discoveries of
Liu & Pang 2019ApJS..245...32L 2019ApJS..245...32L, Cat. J/ApJS/245/32.
Whereas those starting with UFMG are from
Ferreira et al. 2021MNRAS.502L..90F 2021MNRAS.502L..90F, Cat. J/MNRAS/502/L90.
MWSC identification in the K13 catalogue
(Kharchenko N. V. et al. 2013yCat..35580053K, Cat. J/A+A/558/A53)
Cepheid names are taken from the International Variable Star Index
(VSX; Watson, Henden & Price 2015yCat....102027W 2015yCat....102027W, Cat. B/vsx),
or from the OGLE catalogue (Udalski et al. 2018AcA....68..315U 2018AcA....68..315U,
Cat. J/AcA/68/315).
Note (2): Ratio between angular separation of the pair Sep and the angular
radius of the central part of the cluster r1.
Note (3): P(A) reprensents probability distribution that expresses our belief
of membership before the evidence used for P(B|A) is considered.
Note (4): P(B|A) is the conditional probability of obtaining the cluster
and Cepheid data assuming that their association is real.
Note (5): P(A|B) is the membership probability computed from P(B|A)*P(A).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Name Open cluster name (Open_cluster) (1)
15- 18 I4 --- MWSC ? MWSC Milky-Way ID number (MWSC_ID) (1)
20- 47 A28 --- Cepheid Cepheid name (Cepheid) (1)
49 A1 --- n_Cepheid [a b] Note on Cepheid name (Note) (2)
51- 55 F5.2 --- Sep/r1 Angular Ratio (Sep/r1) (3)
57- 73 A17 --- Constr The list of constraints used to derive
the membership probability (Constraints)
75- 78 F4.2 --- P(A) The prior P(A) probability (P_A) (4)
80- 83 F4.2 --- P(B|A) The likelihood probability (P_B|A) (5)
85- 88 F4.2 --- P(A|B) The membership probability (P_A|B) (6)
--------------------------------------------------------------------------------
Note (1): Open clusters with identification names starting with UBC correspond
to clusters in references as:
Castro-Ginard et al. 2018A&A...618A..59C 2018A&A...618A..59C, Cat. J/A+A/627/A35,
Castro-Ginard et al. 2019A&A...627A..35C 2019A&A...627A..35C, Cat. J/A+A/627/A35,
Castro-Ginard et al. 2020A&A...635A..45C 2020A&A...635A..45C Cat. J/A+A/635/A45.
The cluster names starting with LP are discoveries of
Liu & Pang 2019ApJS..245...32L 2019ApJS..245...32L, Cat. J/ApJS/245/32.
Whereas those starting with UFMG are from
Ferreira et al. 2021MNRAS.502L..90F 2021MNRAS.502L..90F, Cat. J/MNRAS/502/L90.
MWSC identification in the K13 catalogue
(Kharchenko N. V. et al. 2013yCat..35580053K, Cat. J/A+A/558/A53)
Cepheid names are taken from the International Variable Star Index
(VSX; Watson, Henden & Price 2015yCat....102027W 2015yCat....102027W, Cat. B/vsx),
or from the OGLE catalogue (Udalski et al. 2018AcA....68..315U 2018AcA....68..315U,
Cat. J/AcA/68/315).
Note (2): Remarks as follows:
a = Uncertain Cepheid classification, as noted by the OGLE team.
b = Coincidence with a cluster in the catalogues of
Liu & Pang 2019ApJS..245...32L 2019ApJS..245...32L, Cat. J/ApJS/245/32 or
Sim et al. 2019 https://doi.org/10.5303/JKAS.2019.52.5.145,
according to Castro-Ginard et al. 2020A&A...635A..45C 2020A&A...635A..45C,
Cat. J/A+A/635/A45.
Note (3): Ratio between angular separation of the pair Sep and the angular
radius of the central part of the cluster r1.
Note (4): P(A) reprensents probability distribution that expresses our belief
of membership before the evidence used for P(B|A) is considered.
Note (5): P(B|A) is the conditional probability of obtaining the cluster
and Cepheid data assuming that their association is real.
Note (6): P(A|B) is the membership probability computed from P(B|A)*P(A).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 23 A23 --- Combo Remark about the combo membership (1)
25- 37 A13 --- Name Open cluster name (Open_cluster) (1)
39- 65 A27 --- Cepheid Cepheid name (Cepheid) (1)
67- 70 F4.2 --- Sep/r1 Angular Ratio (Sep/r1) (2)
72- 88 A17 --- Constr The list of constraints used to derive
the membership probability (Constraints)
90- 93 F4.2 --- P(A) The prior P(A) probability (P_A) (3)
95- 98 F4.2 --- P(B|A) The likelihood probability (P_B|A) (4)
100-103 F4.2 --- P(A|B) The membership probability (P_A|B) (5)
105-126 A22 --- Ref. Litterature references (Reference) (6)
--------------------------------------------------------------------------------
Note (1): For the bona fide combos recovered, which appear at least once in
Turner's database (only potential combos with open clusters),
Anderson R.I. 2013MNRAS.434.2238A 2013MNRAS.434.2238A, Cat. J/MNRAS/434/2238
(with P(A|B) > 0.10, from that work),
or Chen et al. 2015MNRAS.446.1268C 2015MNRAS.446.1268C, we obtain membership
probabilities superior to 1 per cent.
We included in this list the cluster Cepheids recently confirmed
by Clark et al. 2015A&A...584L..12C 2015A&A...584L..12C,
by Lohr et al. 2018MNRAS.478.3825L 2018MNRAS.478.3825L,
and Negueruela et al. 2020MNRAS.494.3028N 2020MNRAS.494.3028N.
As we considered them in the combo descriptions presented
in section 5.
Combos in the bottom part of this table are those considered missed,
and are listed as true associations in at least three of the
mentionned catalogues plus Rock 2012, Master thesis,
Univ. Heidelberg.
Note (2): Ratio between angular separation of the pair Sep and the angular
radius of the central part of the cluster r1.
Note (3): P(A) reprensents probability distribution that expresses our belief
of membership before the evidence used for P(B|A) is considered.
Note (4): P(B|A) is the conditional probability of obtaining the cluster
and Cepheid data assuming that their association is real.
Note (5): P(A|B) is the membership probability computed from P(B|A)*P(A).
Note (6): References where the Cepheid membership to the cluster is discussed,
as follows:
a = Lohr et al. 2018MNRAS.478.3825L 2018MNRAS.478.3825L
b = Negueruela et al. 2018MNRAS.477.2976N 2018MNRAS.477.2976N
c = Anderson et al. 2013MNRAS.434.2238A 2013MNRAS.434.2238A
d = Walker 1985MNRAS.213..889W 1985MNRAS.213..889W
e = An et al. 2007ApJ...671.1640A 2007ApJ...671.1640A
f = Turner 2010Ap&SS.326..219T 2010Ap&SS.326..219T
g = Majaess et al. 2011ApJ...741L..27M 2011ApJ...741L..27M
h = Chen et al. 2015MNRAS.446.1268C 2015MNRAS.446.1268C
i = Sandage 1958ApJ...128..150S 1958ApJ...128..150S
j = Mateo & Madore 1988ASPC....4..174M 1988ASPC....4..174M
k = Matthews et al. 1995AJ....110.2280M 1995AJ....110.2280M
l = Irwin J. B., 1955, MNSSA, 14, 38
m = Kholopov P. N., 1956, Peremennye Zvezdy, 11, 325
n = Feast 1957MNRAS.117..193F 1957MNRAS.117..193F
o = Pel J. W., 1985cto..conf....1P
p = Medina et al. 2021ASPC..529..334M 2021ASPC..529..334M
q = Turner et al. 1992AJ....104.1132T 1992AJ....104.1132T
r = Turner, Pedreros & Walker 1998AJ....115.1958T 1998AJ....115.1958T
s = Coulson & Caldwell 1985MNRAS.216..671C 1985MNRAS.216..671C
t = Walker 1985MNRAS.214...45W 1985MNRAS.214...45W
u = Hoyle et al. 2003MNRAS.345..269H 2003MNRAS.345..269H
v = Clark et al. 2015A&A...584L..12C 2015A&A...584L..12C
w = Flower 1978ApJ...224..948F 1978ApJ...224..948F
x = Turner 1981AJ.....86..231T 1981AJ.....86..231T
y = Negueruela et al. 1986AJ.....92..111T 1986AJ.....92..111T
z = Turner 1986AJ.....92..111T 1986AJ.....92..111T
alpha = Walker 1987MNRAS.229...31W 1987MNRAS.229...31W
beta = Turner 1976AJ.....81.1125T 1976AJ.....81.1125T
gamma = Schmidt 1982AJ.....87.1197S 1982AJ.....87.1197S
delta = Turner & Burke 2002AJ....124.2931T 2002AJ....124.2931T
epsilon = Turner 1982PASP...94.1003T 1982PASP...94.1003T
zeta = Claria et al. 1991MNRAS.249..193C 1991MNRAS.249..193C
heta = Turner et al. 2008MNRAS.388..444T 2008MNRAS.388..444T
teta = Turner & Pedreros 1985AJ.....90.1231T 1985AJ.....90.1231T
lota = Turner 1998AJ....116..274T 1998AJ....116..274T
kappa = Yilmaz 1966ZA.....64...54Y 1966ZA.....64...54Y
lambda = Turner 1980ApJ...240..137T 1980ApJ...240..137T
nu = Turner et al. 1993ApJS...85..119T 1993ApJS...85..119T
Xi = Turner et al. 1998JRASC..92..145T 1998JRASC..92..145T
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Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- Name Open cluster name (Open_cluster) (1)
18 A1 --- n_Name [a] Note on Cepheid name (Note) (2)
20- 23 I4 --- MWSC ? MWSC Milky-Way ID number (MWSC_ID) (1)
25- 52 A28 --- Cepheid Cepheid name (Cepheid) (1)
54- 59 F6.2 --- Sep/r1 Angular Ratio (Sep/r1) (3)
61- 77 A17 --- Constr The list of constraints used to derive
the membership probability (Constraints)
79- 82 F4.2 --- P(B|A) The likelihood probability (P_B|A) (4)
--------------------------------------------------------------------------------
Note (1): Open clusters with identification names starting with UBC correspond
to clusters in references as:
Castro-Ginard et al. 2018A&A...618A..59C 2018A&A...618A..59C,
Castro-Ginard et al. 2019A&A...627A..35C 2019A&A...627A..35C,
Castro-Ginard et al. 2020A&A...635A..45C 2020A&A...635A..45C.
The cluster names starting with LP are discoveries of
Liu & Pang 2019ApJS..245...32L 2019ApJS..245...32L, Cat. J/ApJS/245/32.
Whereas those starting with UFMG are from
Ferreira et al. 2021MNRAS.502L..90F 2021MNRAS.502L..90F, Cat. J/MNRAS/502/L90.
MWSC identification in the K13 catalogue
(Kharchenko N. V. et al. 2013A&A...558A..53K 2013A&A...558A..53K, Cat. J/A+A/558/A53)
Cepheid names are taken from the International Variable Star Index
(VSX; Watson, Henden & Price 2006SASS...25...47W 2006SASS...25...47W, Cat. B/vsx),
or from the OGLE catalogue (Udalski et al. 2018AcA....68..315U 2018AcA....68..315U,
Cat. J/AcA/68/315).
Note (2): Cluster with position and proper motion compatible with a cluster
in K13 catalogue (Kharchenko N. V. et al. 2013yCat..35580053K,
Cat. J/A+A/558/A53), based on Castro-Ginard et al.
2020A&A...635A..45C 2020A&A...635A..45C, Cat. J/A+A/635/A45).
Note (3): Ratio between angular separation of the pair Sep and the angular
radius of the central part of the cluster r1.
Note (4): P(B|A) is the conditional probability of obtaining the cluster
and Cepheid data assuming that their association is real.
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(End) Luc Trabelsi [CDS] 22-May-2024