J/A+A/563/A45 Pleiades cluster membership probabilities (Sarro+, 2014)
Cluster membership probabilities from proper motions and multi-wavelength
photometric catalogues.
I. Method and application to the Pleiades cluster.
Sarro L.M., Bouy H., Bertin E., Moraux E., Bouvier J., Cuillandre J.-C.,
Barrado D., Solano E.
<Astron. Astrophys. 563, A45 (2014)>
=2014A&A...563A..45S 2014A&A...563A..45S
ADC_Keywords: Clusters, open ; Proper motions ; Photometry
Keywords: methods: data analysis - methods: statistical - catalogs -
stars: low-mass - open clusters and associations: general
Abstract:
With the advent of deep wide surveys, large photometric and
astrometric catalogues of literally all nearby clusters and
associations have been produced. The unprecedented accuracy and
sensitivity of these data sets and their broad spatial, temporal and
wavelength coverage make obsolete the classical membership selection
methods that were based on a handful of colours and luminosities. We
present a new technique designed to take full advantage of the high
dimensionality (photometric, astrometric, temporal) of such a survey
to derive self-consistent and robust membership probabilities of the
Pleiades cluster.
We aim at developing a methodology to infer membership probabilities
to the Pleiades cluster from the DANCe multidimensional
astro-photometric data set in a consistent way throughout the entire
derivation. The determination of the membership probabilities has to
be applicable to censored data and must incorporate the measurement
uncertainties into the inference procedure.
We use Bayes-theorem and a curvilinear forward model for the
likelihood of the measurements of cluster members in the
colour-magnitude space, to infer posterior membership probabilities.
The distribution of the cluster members proper motions and the
distribution of contaminants in the full multidimensional
astro-photometric space is modelled with a mixture-of-Gaussians
likelihood.
We analyse several representation spaces composed of the proper
motions plus a subset of the available magnitudes and colour indices.
We select two prominent representation spaces composed of variables
selected using feature relevance determination techniques based in
Random Forests, and analyse the resulting samples of high probability
candidates. We consistently find lists of high probability (p>0.9975)
candidates with ∼1000 sources, 4 to 5 times more than obtained in the
most recent astro-photometric studies of the cluster.
Multidimensional data sets require statistically sound multivariate
analysis techniques to fully exploit their scientific information
content. Proper motions in particular are, as expected, critical for
the correct separation of contaminants. The methodology presented here
is ready for application in data sets that include more dimensions,
such as radial and/or rotational velocities, spectral indices, and
variability.
Description:
Astrometry and photometry from the DANCe project is used to derive
statistical models of the distribution of sources in the Pleiades
region of the sky, in the space of proper motions, colours and
magnitudes. These models are subsequently used to estimate membership
probabilities to the Pleaides cluster. This catalog contains the
original data from the DANCe project and the infered membership
probabilities obtained in various setups.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 228 1972245 Positions, proper motions, photometry and
membership probabilities of sources in the
Pleiades region of the sky
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See also:
I/258 : Pleiades positions and proper motions (Wang+, 1996)
J/A+A/320/74 : Radial velocities of Pleiades members (Mermilliod+ 1997)
J/A+A/329/101 : Masses of Pleiades members (Raboud+ 1998)
J/A+A/332/575 : Pleiades member list (Belikov+ 1998)
J/MNRAS/380/712 : ZYJHK photometry in Pleiades (Lodieu+, 2007)
J/MNRAS/422/1495 : UKIDSS Galactic Clusters Survey Pleiades members
(Lodieu+ 2013)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 7 I7 --- DANCe DANCe identifier (Dynamical Analysis of Nearby
ClustErs)
9- 19 F11.8 deg RAdeg Right ascension (J2000.0)
21- 31 F11.8 deg DEdeg Declination (J2000.0)
33- 44 F12.8 mas/yr pmRA Proper motion in RA axis (accuracy 0.3mas/yr)
46- 57 F12.8 mas/yr pmDE Proper motion in DE axis (accuracy 0.3mas/yr)
59- 67 F9.6 mag umag ?=- u magnitude
69- 77 F9.6 mag gmag ?=- g magnitude
79- 87 F9.6 mag rmag ?=- r magnitude
89- 97 F9.6 mag imag ?=- i magnitude
99-107 F9.6 mag Jmag ?=- J magnitude
109-117 F9.6 mag Hmag ?=- H magnitude
119-127 F9.6 mag Kmag ?=- K magnitude
129-137 F9.6 mag Ymag ?=- Y magnitude
139-147 F9.6 mag zmag ?=- z magnitude
149-156 F8.6 --- pAMa [0/1] Membership probability AM, pin=0.9545 (1)
158-165 F8.6 --- pAMb [0/1] Membership probability AM, pin=0.975 (1)
167-174 F8.6 --- pAMc [0/1] Membership probability AM, pin=0.9975 (1)
176-183 F8.6 --- pRF2a [0/1] Membership probability RF2, pin=0.9545 (1)
185-192 F8.6 --- pRF2b [0/1] Membership probability RF2, pin=0.975 (1)
194-201 F8.6 --- pRF2c [0/1] Membership probability RF2, pin=0.9975 (1)
203-210 F8.6 --- pRF3a [0/1] Membership probability RF3, pin=0.9545 (1)
212-219 F8.6 --- pRF3b [0/1] Membership probability RF3, pin=0.975 (1)
221-228 F8.6 --- pRF3c [0/1] Membership probability RF3, pin=0.9975 (1)
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Note (1): The membership probabilities are calculated for 3
representation spaces:
* AM (apparent magnitudes) = pmRA, pmDE, r, i, J, H, K, Y, Z
* RF-2 = pmRA, pmDE, r J, H, K, (i-Z), (r-Y), (r-i)
* RF-3 = pmRA, pmDE, J, H, K, (i-K), (r-K), (Y-J)
and 3 probability thresholds pin (0.9545, 0.975, and 0.9975).
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Acknowledgements:
Luis M. Sarro, lsb(at)dia.uned.es
References:
Bouy et al., 2013A&A...554A.101B 2013A&A...554A.101B , DANCe project
History:
* 05-Mar-2014: on-line version of the catalog
* 22-Jul-2014: corrected version (positions) of the catalog, from authors
(End) Luis M. Sarro [UNED, Spain], Patricia Vannier [CDS] 04-Mar-2014