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MWSC - Milky Way Star Clusters Catalog |
HEASARC Archive |
This table contains the list of 3,006 Milky Way stellar clusters (MWSC) found in the 2MAst (2MASS with Astrometry) catalog presented in Paper II of this series (these clusters have source numbers below 4000), together with an additional 139 new open clusters (these clusters have source numbers between 5000 and 6000) found by the authors at high Galactic latitudes (|b_II_| > 18.5 degrees) which were presented in Paper III of the series, and an additional 63 new open clusters (these clusters have source numbers between 4000 and 5000) which were presented in Paper IV of the series.
The target list in Paper II from which the 3,006 open clusters was contained was compiled on the basis of present-day lists of open, globular and candidate clusters. The list of new high-latitude open clusters in Paper III was obtained from a target list of 714 density enhancements found using the 2MASS Catalog. The list of new open clusters in Paper IV was obtained from an initial list of 692 compact cluster candidates which were found by the authors by conducting an almost global search of the sky (they excluded the portions of the sky with |b_II_| < 5 degrees) in the PPMXL and the UCAC4 proper-motion catalogs.
For confirmed clusters, the authors determined a homogeneous set of astrophysical parameters such as membership, angular radii of the main morphological parts, mean cluster proper motions, distances, reddenings, ages, tidal parameters, and sometimes radial velocities.
Global survey of star clusters in the Milky Way. I. The Pipeline and fundamental parameters in the second quadrant. Kharchenko N.V., Piskunov A.E., Schilbach E., Roeser S., Scholz R.-D. <Astron. Astrophys. 543, A156 (2012)> =2012A&A...543A.156K (SIMBAD/NED BibCode) Global survey of star clusters in the Milky Way. II. The catalogue of basic parameters. Kharchenko N.V., Piskunov A.E., Roeser S., Schilbach E., Scholz R.-D. <Astron. Astrophys. 558, A53 (2013)> =2013A&A...558A..53K (SIMBAD/NED BibCode) Global survey of star clusters in the Milky Way. III. 139 new open clusters at high Galactic latitudes. Schmeja S., Kharchenko N.V., Piskunov A.E., Roeser S., Schilbach E., Froebrich D., Scholz R.-D. <Astron. Astrophys. 568, A51 (2014)> =2014A&A...568A..51S (SIMBAD/NED BibCode) Global survey of star clusters in the Milky Way. IV. 63 new open clusters detected by proper motions. Scholz R.-D., Kharchenko N.V., Piskunov A.E., Roeser S., Schilbach E. <Astron. Astrophys. 581, A39 (2015)> =2015A&A...581A..39S (SIMBAD/NED BibCode)
The CDS describes the atlas files as follows:
For each cluster we prepared two EPS-pages with diagrams: Page 1 contains the cluster map as the basic panel (file MWSC_Name_map.eps.gz), Page 2 contains the Ks,(J-Ks) and Ks,(J-H) CMDs as basic panels (file MWSC_Name_cmd.eps.gz). The legend on each page gives the cluster name, MWSC number, (COCD number); equatorial RAJ2000, DecJ2000, and galactic l, b coordinates of the cluster center; apparent cluster sizes r0, r1, r2, [number of 1sigma-members within the corresponding radius]; weighted average components PM_(X,Y) of proper motion with their rms errors, [number of stars used to compute the average]; the average radial velocity, RV with their rms error, [the number of stars used to compute the average]; distance to the cluster, d, distance modulus, (Ks-M_Ks); NIR color-excesses, E(J-H), E(J-Ks), interstellar extinction, A(Ks); cluster age, its rms error, [the number of stars used to compute the average age, or it is -1 if a manual isochrone fit was applied]. Additionally we show in the 2nd pages: an empirical correction Delta_H for a better isochrone fit in the Ks,(J-H) diagram. Symbols and their colors have the same meaning in all plots. Stars are shown as colored circles or dots. Cyan symbols mark stars outside the cluster radius r2, green symbols are stars within r2. The most probable kinematic and photometric members (1sigma-members) are indicated in black, red, or blue. Black is for members located within r1 (the visible radius of the central part), red for members between r1 and r2, and blue for stars outside r2 (the probabilities are formal). Cyan bars show the uncertainty for 1sigma-members. Description of files MWSC_Name_map.eps.gz (Page 1): Page 1 contains five diagrams with spatial information. The right panel is a map of the cluster neighborhood (MAP), the left panels show (from top to bottom) relations depending on the distance from the cluster center, r, for: -magnitude Ks (Ks vs. r), -proper motions (PM vs. r), -density profile diagram (DPD). MAP: Stars are displayed as small circles. The circle size corresponds to the stellar magnitude ranged in six Ks mag intervals: < 6.0, 6.0 - 8.0, 8.0 - 10.0, 10.0 - 12.0, 12.0 - 14.0, > 14.0. Blue cross : cluster center selected in this study; Blue plus : cluster center from the literature; Magenta pluses : centers of other clusters (from target list) visible (if any) in the map; Dotted blue large circle : cluster core border (r0); Solid blue large circle : inner cluster border (r1); Dashed blue large circle : cluster corona border (r2). The left panels: Blue vertical dotted, solid, dashed lines mark r0, r1, r2, respectively. PM vs. r: Magenta horizontal lines correspond to the average proper motion of the cluster determined in this paper; DPD: Density profiles (Log of Number of stars per 1 sq.deg) are shown for all stars (green line), 3sigma-members (blue line), 2sigma-members (magenta line) and 1sigma-members (black line). Description of files MWSC_Name_cmd.eps.gz (Page 2): Page 2 contains diagrams with kinematic and photometric information. The three left panels are: -two PM_(X,Y) vs. Ks relations, i.e. PM-magnitude equation diagrams (MEDs); -the vector point diagram of proper motions (VPD). The two upper right panels are: -relations (Ks,(J-H) and Ks,(J-Ks), i.e. the color-magnitude diagrams (CMDs). The bottom right panels: -color-color diagrams (CCDs); -reddening-independent parameter Q-color diagrams (QCDs). The CCDs and QCDs are separated into two sub-panels (as well as CMDs and MEDs are separated into two parts via a broken line). The division is made with respect to the Ksmc magnitude: in the bottom sub-panels we place data for Ks > Ksmc, in the upper ones - for Ks < Ksmc, where Ksmc is the Ks-magnitude at the bluest color (J-Ks) of the isochrone closest to the determined cluster age. CMDs: Magenta curve: the apparent isochrone closest to the determined cluster age; Solid blue lines: left and right borders of a domain of 100% photometric cluster members; Solid red lines: ZAMS and TAMS (shown only in the Ks,(J-Ks) diagram), the borders of the evolved Main Sequence stars; Magenta dashed line: corresponds to the Ks_mc; Thick yellow circles: stars selected for age determination; Black arrows: increasing interstellar extinction vectors. MED: Magenta solid lines correspond to the average proper motion of the cluster; the magenta dashed line corresponds to the Ks_mc. CCD and QCD: The Magenta curve corresponds to the apparent isochrone (observed magnitudes and colors); the cyan curve corresponds to the intrinsic isochrone.
Around each confirmed object from their target list, the authors defined a circular area with a radius of ra = r2 + radd where r2 is an initial estimate of the cluster radius, and radd = 0.3 deg. In these areas, they selected in 2MAst only those stars with flags Rflg (the 2nd triple of the flags in 2MASS) set to 1, 2, or 3 in each band, i.e. the stars with the best quality detections in photometric and astrometric data. The 63 sky areas with confirmed clusters contain about 0.49 million 2MAst stars with best quality detections in photometric and astrometric data. The authors selected the most probable members and determined - with a homogeneous method/pipeline - the angular sizes of the main morphological parts, heliocentric distances, color-excesses, mean proper motions, ages, tidal parameters.
This work represents the second extension of the MWSC survey (Kharchenko et al. 2012, Paper I, 2013, Paper II), which had an original input list of 3784 targets. After the first extension by Schmeja et al. (2014, Paper III), who investigated 782 further candidates, the present authors analyzed 692 new candidates. They have adopted for them MWSC numbers starting with 4001.
The basic stellar data were taken from the all-sky catalog 2MAst (2Mass with Astrometry), that was extracted from the all-sky catalogs PPMXL (Roeser et al. 2010, CDS Cat. I/317) and 2MASS (Cutri et al. 2003, CDS Cat. II/246). Additionally, the authors incorporated data on radial velocities from Kharchenko et al. (2007, CDS Cat. III/254) and spectral types from ASCC-2.5 (Kharchenko & Roeser 2009, CDS Cat. I/280).
Around each object from their target list, the authors defined a circular area with a radius of ra = r2 + radd where r2 is the cluster radius, and radd = 0.3 degrees. In these areas, they selected in 2MAst only those stars with flags Rflg (the second triple of the flags in 2MASS) set to 1, 2, or 3 in each band, i.e. the stars with the best quality detections in photometric and astrometric data.
Of the 3,784 targets in their object list, the authors confirmed 3,006 clusters and/or associations. These 3,006 sky areas contain about 63.5 million 2MAst stars with best quality detections in photometric and astrometric data. The authors selected about 0.14 million most probable members located in the central cluster regions and determined - with a homogeneous method/pipeline - the angular sizes of the main morphological parts, heliocentric distances, color-excesses, mean proper motions, ages, tidal parameters, sometimes radial velocities and metallicities.
Around each confirmed object from their target list they defined a circular area with a radius of ra = r2 + radd where r2 is initial estimate of cluster radius, and radd = 0.3 degrees. In these areas they selected in 2MAst only those stars with flags Rflg (the 2nd triple of the flags in 2MASS) set to 1, 2, or 3 in each band, i.e. the stars with the best quality detections in photometric and astrometric data.
The 139 sky areas with confirmed clusters contain about 0.52 million 2MAst stars with best quality detections in photometric and astrometric data. The authors selected the most probable members and determined - with a homogeneous method/pipeline - the angular sizes of the main morphological parts, their heliocentric distances, color excesses, mean proper motions, ages and tidal parameters.
Paper III extends the MWSC project's initial Paper II input list of 3784 targets by 714 new candidates. The authors have adopted for them an MWSC numbering starting with source number 5001. Since the search was performed for Northern and Southern hemispheres separately, the candidate numbering is discontinuous: the numbers 5001 <= MWSC < 5499 are assigned for b > +18.5 degrees, and 5500 <= MWSC < 5999 designate candidates for b < -18.5 degrees.
Source_Number
A running identification number for each cluster or cluster candidate in
order of increasing J2000.0 Right Ascension, from 1 to 3,784 for objects from
Paper II, from 5004 to 5963 for objects from Paper III, and from 4005 to 4688
for objects from Paper IV. Some of the source numbers were assigned to
candidates which turned out not to be clusters and are thus not contained in
this present table, which lists only the 3,208 confirmed clusters.
Name
The NGC, IC or other common designation for the cluster. The new clusters
from paper III have been given names using the 'MWSC' prefix and their source
number, e.g., 'MWSC 5004'.
Broad_Type
This flag parameter indicates the object type as follows:
(blank) = open cluster a = association g = globular cluster m = moving group n = nebulosity/presence of nebulosity r = remnant cluster s = asterism
Cluster_Status
This flag parameter is set only for 739 objects which are not open clusters
(i.e., broad_type != ' '): 'c' means candidate and 'o' means object,
according to the CDS documentation.
RA
The Right Ascension of the adopted cluster center in the selected equinox.
This was given in J2000.0 coordinates to a precision of 0.0001 hours (0.36
seconds of time) in the original table.
Dec
The Declination of the adopted cluster center in the selected equinox. This
was given in J2000.0 coordinates to a precision of 0.001 degrees (3.6
arcseconds) in the original table.
LII
The Galactic Longitude of the adopted cluster center.
BII
The Galactic Latitude of the adopted cluster center.
Core_Radius
The angular radius of the core of the cluster, r0, in degrees. The authors
assumed a centrally symmetric distribution of the cluster members and
introduced three empirical structural parameters r0 < r1 < r2
describing the shape of the radial density profile (RDP), which were fitted
by eye. The visible core radius r0 corresponds to the distance from the
cluster center where the slope of the RDP becomes flatter, the visible radius
of the central part r1 is the distance where the decrease of the stellar
density stops abruptly, and the actual (total) visible radius of a cluster
r2 is defined as the distance from the cluster center where the surface
density of stars becomes equal to the average density of the surrounding
field. r0 is a new feature considered here, while in their previous work
with the COCD the authors determined only r1 and r2. Based on visual
inspection of the corresponding data, r0, r1, and r2 give empirical
descriptions of cluster sizes, without a direct association to e.g., King's
parameters rc and rt (see Section. 3.4.4. of Paper I). However, the
authors found that the relations r0 < rc < r1 and rt > r2 are
generally obeyed.
Central_Radius
The angular radius of the central part of the cluster, r1, in degrees. (See
the core_radius description above for more details).
Cluster_Radius
The angular radius of the cluster, r2, in degrees. (See the core_radius
description above for more details).
PM_RA
The average cluster proper motion in the Right Ascension direction, muRA *
cos(Dec), in milliarcseconds per year (mas/yr).
PM_Dec
The average cluster proper motion in the Declination direction, muDec, in
milliarcseconds per year (mas/yr).
PM_Tot_Error
The standard error in the average cluster total proper motion, mu, in
milliarcseconds per year (mas/yr).
Rad_Vel
The average radial velocity of the selected stars in the cluster, in km/s.
Rad_Vel_Error
The standard error in the average radial velocity of the selected stars in
the cluster, in km/s.
Num_Rad_Vel_Stars
The number of cluster stars used for the radial velocity calculation.
Num_Core_Stars
The number of most probable (so-called 1-sigma) members stars within the core
region radius, r0. The membership probabilities for the individual stars in
the cluster are given in the associated stars file for the cluster at CDS
(see Data Products section above for more details).
Num_Central_Stars
The number of most probable (so-called 1-sigma) members stars within the
central region radius, r1. The membership probabilities for the individual
stars in the cluster are given in the associated stars file for the cluster
at CDS (see Data Products section above for more details).
Num_Cluster_Stars
The number of most probable (so-called 1-sigma) members stars within the
cluster radius, r2. The membership probabilities for the individual stars
in the cluster are given in the associated stars file for the cluster at CDS
(see Data Products section above for more details).
Distance
The cluster distance, D, from the Sun, in parsecs (pc). The methodology used
to estimate D is discussed in Section 3.4.3 of Paper I. The authors consider
the distances to be accurate to within +/- 16%. For young clusters, which
have almost vertical and poorly populated main sequences, the accuracy of
this parameter is considerably lower.
E_BV
The reddening (color excess), E(B-V), towards the cluster, in magnitudes. The
methodology used to estimate E(B-V) is discussed in Section 3.4.3 of Paper I.
The authors consider the reddening values to be accurate to within +/- 0.06
magnitudes (+/- ~ 10%). For young clusters, which have almost vertical and
poorly populated main sequences, the accuracy of this parameter is
considerably lower.
Distance_Modulus
The apparent distance modulus of the cluster in the 2MASS Ks band, i.e.,
the quantity [(5 * log (D)) - 5.0 + A_Ks_], where D is the distance to the
cluster, in parsecs, and AKs is the extinction in the 2MASS Ks band
towards the cluster. A standard interstellar reddening law is assumed, e.g.,
AV = 3.1 * E(B-V), AK = 0.95 * AKs, and AKs = 0.670 * E(J-Ks)
(Cardelli et al.1989, ApJ, 345, 245; Dutra & Bica 2001, A&A, 376, 434). The
authors consider the distance moduli to be accurate to within +/- 0.35
magnitudes. For young clusters, which have almost vertical and poorly
populated main sequences, the accuracy of this parameter is considerably
lower.
E_JK
The reddening (color excess), E(J-Ks), towards the cluster, in magnitudes.
E_JH
The reddening (color excess), E(J-H), towards the cluster, in magnitudes.
Delta_H
The correction to the H magnitude of the fitted isochrone, Delta-H. The
authors found that the theoretical isochrones usually fitted the observed
sequences in the Ks,(J - Ks)-diagrams better than in the Ks, (J - H)
one. They observed a (J - H) color shift that is typically of about a few
hundreds of a magnitude but it varied from cluster to cluster. They attribute
this effect to a lack of a global calibration of the H-band in 2MASS and,
additionally, to spatial variations of the properties of the absorbing dust
that affect the H-band. Therefore, they introduced this empirical correction
Delta-H to provide a better isochrone fit in the Ks, (J - H) diagram.
Log_Age
The logarithm of the average age of the stars in the cluster, log t, in
years. The methodology used to estimate cluster ages and their accuracy are
discussed in Section 3.4.3 of Paper I.
Log_Age_Error
The standard error in the logarithm of the average age of the stars in the
cluster, log t, in years.
Num_Log_Age_Stars
The number of cluster stars used for the average cluster age calculation. A
value of -1 for this parameter indicates that the age of the cluster was set
manually.
King_Core_Radius
The core radius, rc, of a King model fit to the cluster RDP, in parsecs.
This was estimated using the same technique as was applied earlier to COCD
clusters (see Piskunov et al. 2007, A&A, 468, 151 for more details). The
method is based on a three-parameter fit (rc, rt and a normalization
factor) of cumulative King profiles to the observed density distribution of
the cluster members.
King_Core_Radius_Error
The standard error in the core radius, rc, of a King model fit to the
cluster RDP, in parsecs.
King_Tidal_Radius
The tidal radius, rt. of a King model fit to the cluster RDP, in parsecs.
This was estimated using the same technique as was applied earlier to COCD
clusters (see Piskunov et al. 2007, A&A, 468, 151 for more details). The
method is based on a three-parameter fit (rc, rt and a normalization
factor) of cumulative King profiles to the observed density distribution of
the cluster members.
King_Tidal_Radius_Error
The standard error in the tidal radius, rt, of a King model fit to the
cluster RDP, in parsecs.
King_Norm_Factor
The normalization factor of a King model fit to the cluster RDP, in
parsecs-2. This was estimated using the same technique as was applied
earlier to COCD clusters (see Piskunov et al. 2007, A&A, 468, 151 for more
details). The method is based on a three-parameter fit (rc, rt and a
normalization factor) of cumulative King profiles to the observed density
distribution of the cluster members.
King_Norm_Factor_Error
The standard error in the normalization factor of a King model fit to the
cluster RDP, in parsecs-2.
Reference_Code
The reference source for the MWSC list and input parameters for the cluster
coded as follows:
COCD = Kharchenko et al. (2005, CDS Cats. J/A+A/438/1163, J/A+A/440/403) DIAS = Dias et al. (2002, CDS Cat. B/ocl), Version 3.1, 24/nov/2010 DREM = Dias et al. (2002, CDS Cat. B/ocl), Version 3.1, 24/nov/2010, removed MELN = Melnik & Dambis (2009, CDS Cat. J/MNRAS/400/518), associations FPRO = Froebrich et al. (2007, J/MNRAS/374/399), probable FPOS = Froebrich et al. (2007, J/MNRAS/374/399), possible BOPN = Bica et al. (2003, CDS Cat. J/A+A/404/223), Dutra et al. (2003, CDS Cat. J/A+A/400/533), New objects in the area of optical nebulae BIRN = Bica et al. (2003, CDS Cat. J/A+A/404/223), Dutra et al. (2003, CDS Cat. J/A+A/400/533) 2003, New objects in the area of radio/IR nebulae LLEM = Lada & Lada (2003ARA&A..41...57L), Embedded clusters in Molecular Clouds BIEM = Bica et al. (2003, CDS Cat. J/A+A/404/223); IR star clusters and stellar groups catalog HARR = Harris (1996AJ....112.1487H, CDS Cat. VII/202), edition 2010, 2010arXiv1012.3224H, www.physics.mcmaster.ca/~harris/mwgc.dat ARIn = Objects from Paper III with b > +18.5 degrees ARIs = Objects from Paper III with b < -18.5 degrees AIPk = Objects from Paper IVTwo Paper III objects, 'MWSC 5901' and 'MWSC 5963', had reference_code values of 'ARIa' in the CDS table which are undocumented, and the HEASARC believes them to be erroneous. Based on their Galactic latitudes, the HEASARC has corrected these values to 'ARIn' and 'ARIs', respectively.
Cluster_Type
The source object cluster type, coded as follows:
ass = stellar association ast = Dias: possible asterism/dust hole/star cloud dub = Dias: dubious, objects considered doubtful by the DSS images inspection emb = embedded open cluster/cluster associated with nebulosity glo = globular cluster/possible globular cluster irc = infrared cluster irg = infrared stellar group mog = Dias: possible moving group non = Dias: "non-existent NGC"/ objects not found in DSS images inspection rem = Possible cluster remnant var = clusters with variable extinction
Metallicity
The metallicity of the cluster, [Fe/H]. These values were copied from Conrad
et al. (2014, A&A, 562, A54) or Dias et al. (2002, A&A, 389, 871), Version
3.1, 24/nov/2010; for globular clusters, they are taken from the revised
Harris (1996, AJ, 112.1487, CDS Cat. VII/202) Catalog, 2010 edition, or are
newly determined.
Metallicity_Error
The standard error in the metallicity, [Fe/H].
Num_Metallicity_Stars
The number of cluster stars used for the derived metallicity.
Comments
This parameter contains notes for many (but not all) of the objects.
Class
The HEASARC Browse object classification, based on the value of the
broad_type parameter.