J/A+A/672/A187 Milky Way global survey of star clusters. VII. (Just+, 2023)
Global survey of star clusters in the Milky Way.
VII. Tidal parameters and mass function.
Just A., Piskunov A.E., Klos J.H., Kovaleva D.A., Polyachenko E.V.
<Astron. Astrophys., 672, A187 (2023)>
=2023A&A...672A.187J 2023A&A...672A.187J (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, open ; Morphology ; Stars, masses ;
Stars, distances ; Stars, ages
Keywords: Galaxy: evolution - open clusters and associations: general -
Galaxy: stellar content - galaxies: fundamental parameters -
galaxies: photometry - galaxies: star clusters: general
Abstract:
We built Galactic open star cluster mass functions (CMFs) for
different age sub-samples and spatial locations in the wider solar
neighbourhood. Here, we present a simple cluster formation and
evolution model to reproduce the main features of the CMFs.
We used an unbiased working sample of 2227 clusters of the Milky Way
Star Cluster (MWSC) catalogue, which occupy the heliocentric cylinders
with magnitude-dependent completeness radii of 1-5kpc. The MWSC
survey provides an extended set of open star cluster parameters,
including tidal radii, distances, and ages. From an analytic
three-component Galaxy model, we derived tidal masses of clusters with
a typical accuracy of about 70%. Our simple model includes a
two-section cluster initial mass function, constant cluster formation
rate, supervirial phase after a sudden expulsion of the remaining gas,
and cluster mass loss due to stellar evolution and the clusters'
gradual destruction in the Galactic tidal field. The dynamical
evolution model is based on previous N-body simulations.
The obtained tidal masses have been added to the MWSC catalogue. A
general CMF (GCMF), built for all cluster ages around the Sun, has a
bell-like shape and extends over four decades in mass. The high-mass
slope found for tidal mass logmt/M☉≥2.3 is equal to
1.14±0.07. The CMFs for different age groups show the same high-mass
slopes, while the low-mass slope is nearly flat for the youngest
sub-sample (clusters younger than 20Myr) and about -0.7 for the
others. The inner and outer sub-samples covering Galactocentric radii
R=4.2-8.1kpc and 8.9-13.5kpc, respectively, are consistent with the
GCMF, once the exponential decline of the Galactic disc density is
taken into account. The model suggests star formation with low
efficiency of 15-20%, where only 10% of stars remain bound in a
cluster after gas expulsion and subsequent violent relaxation. The
cluster formation rate required to reproduce the observed
distributions in age and mass is about 0.4M☉/pc2/Gyr.
The obtained high-mass slope of the GCMF for the wide neighbourhood of
the Sun is similar to slopes determined earlier in nearby galaxies for
more luminous clusters with logm/M☉>3.8. The MWSC catalogue
supports models with a low star-formation efficiency, where 90% of
stars are lost quickly after gas expulsion. The obtained cluster
formation rate corresponds to open clusters' contribution to the
stellar content of the thin disc at the level of 30%.
Description:
Basing on King structure parameters of 3017 open clusters derived
within MWSC project we calculate tidal masses of the clusters.
The catalogue presents tidal masses computed from an analytic
three-component Galaxy model and other relevant parameters including
King tidal radii, solarcentric distances and ages taken from the MWSC
catalogue (J/A+A/558/A53, J/A+A/568/A51, J/A+A/581/A39). This
computation is based on the assumption of equality of cluster King and
Jacoby radii and provides a typical accuracy of tidal masses of about
70 percent. The derived masses were used for construction of the
Galactic Cluster Mass Function.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
catalog.dat 136 3017 Tidal masses and other parameters for
Galactic star clusters
--------------------------------------------------------------------------------
See also:
J/A+A/543/A156 : Milky Way global survey of star clusters I (Kharchenko+ 2012)
J/A+A/558/A53 : Milky Way global survey of star clusters II (Kharchenko+ 2013)
J/A+A/568/A51 : Milky Way global survey of star clusters III (Schmeja+, 2014)
J/A+A/581/A39 : Milky Way global survey of star clusters IV (Scholz+, 2015)
J/A+A/585/A101 : Milky Way global survey of star clusters V (Kharchenko+, 2016)
Byte-by-byte Description of file: catalog.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- MWSC [1/5963] MWSC sequential number (1)
5- 14 F10.4 deg GLON Galactic longitude
15- 24 F10.4 deg GLAT Galactic latitude
25- 34 F10.4 kpc X Galactic rectangular coordinate X
35- 44 F10.4 kpc Y Galactic rectangular coordinate Y
45- 54 F10.4 kpc Z Galactic rectangular coordinate Z
55- 64 F10.4 kpc Rg Galactocentric distance
65- 74 F10.4 kpc dxy Distance from the Sun in the XY-plane
75- 84 F10.4 kpc dcmpl Completeness distance
85- 93 F9.3 mag I(Ks) Integrated magnitude in Ks (2)
94-102 F9.3 [yr] logt Logarithm of age
103-110 F8.2 pc rt King radius
111-118 F8.2 pc e_rt Error of the King radius
119-127 F9.3 [Msun] logmt Logarithm of tidal mass
128-136 F9.3 [Msun] e_logmt Error of logarithm of tidal mass
--------------------------------------------------------------------------------
Note (1): MWSC sequential numbers :
Numbers 1-3999 are from Kharchenko et al., 2013, Cat. J/A+A/558/A53,
Numbers 4000-4999 are from Scholz et al., 2015, Cat. J/A+A/581/A39,
Numbers 5000-5999 are from Schmeja et al., 2014, Cat. J/A+A/568/A51.
Note (2): I(Ks) is absolute integrated magnitude in photometric passband Ks.
--------------------------------------------------------------------------------
Acknowledgements:
Anatoly Piskunov, piskunov(at)inasan.ru
References:
Kharchenko et al., Paper I 2012A&A...543A.156K 2012A&A...543A.156K, Cat. J/A+A/543/156
Kharchenko et al., Paper II 2013A&A...558A..53K 2013A&A...558A..53K, Cat. J/A+A/558/A53
Schmeja et al., Paper III 2014A&A...568A..51S 2014A&A...568A..51S, Cat. J/A+A/568/A51
Scholz et al., Paper IV 2015A&A...581A..39S 2015A&A...581A..39S, Cat. J/A+A/581/A39
Kharchenko et al., Paper V 2016A&A...585A.101K 2016A&A...585A.101K, Cat. J/A+A/585/A101
Piskunov et al., Paper VI 2018A&A...614A..22P 2018A&A...614A..22P
(End) Patricia Vannier [CDS] 02-Aug-2023