J/A+A/691/A28 Tidal tails of open clusters (Kos, 2024)
Tidal tails of open clusters.
Kos J.
<Astron. Astrophys. 691, A28 (2024)>
=2024A&A...691A..28K 2024A&A...691A..28K (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Associations, stellar ; Optical ;
Proper motions ; Parallaxes, trigonometric ; Radial velocities
Keywords: methods: statistical - surveys - stars: kinematics and dynamics -
open clusters and associations: general
Abstract:
Open clusters that emerged from the star forming regions as
gravitationally bound structures are subjected to star evaporation,
ejection, and tidal forces throughout the rest of their lives.
Consequently they form tidal tails that can stretch kiloparsecs along
the cluster's orbit.
Cluster members are typically found by searching for overdensities in
some parameter space (positions and velocities or sometimes actions
and orbital parameters of stars). However, this method is not
effective in identifying stars located in the tidal tails far from the
open cluster cores. We present a probabilistic method for finding
distant cluster members without relying on searching for overdensities
and apply it to 476 open clusters.
First, we simulate the dissolution of a cluster and obtain a
probability distribution (likelihood) describing where cluster members
are to be found. The distribution of stars from the Gaia DR3 catalogue
in high likelihood regions is then compared to the simulated stellar
population of the Galaxy to define the membership probability of each
star.
The survey of cluster members included all stars with a magnitude of
G<17.5 and larger clusters with an age of >100Myr within 3kpc from the
Sun. We successfully find stars with high membership probabilities in
the tidal tails of most clusters, stretching more than a kiloparsec
from the cluster cores in some cases. We analyse the morphological
properties of tidal tails, demonstrate how properly normalised
membership probabilities aid systematic studies of open clusters and
publish a catalogue of stars found in the tidal tails.
Description:
We search for stars in the tidal tails of nearby open clusters. Stars
are found in the Gaia DR3 catalogue with the aid of simulations of
clusters dissolution and models of the Galactic stellar population. We
calculate membership probabilities for around one million stars that
are likely to be members of 476 open clusters. We also derive some
morphological properties of the recovered tidal tails.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
clusters.dat 552 476 Analysed clusters with basic parameters and
derived quantities for each cluster (table 1)
members.dat 728 1045223 Member stars of all clusters listed in
clusters.dat (table 3)
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: clusters.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- Cluster Common name of the cluster (Cluster)
19- 40 A22 --- SimbadName Name of the cluster recognised by Simbad
(SimbadName)
42- 61 F20.16 deg RAdeg [] Right ascension of cluster centre (ICRS)
(ra_icrs)
63- 83 F21.17 deg DEdeg Declination of cluster centre (ICRS)
(dec_icrs)
85-104 F20.16 kpc X Galactocentric X coordinate of cluster centre
(Sun is at X=-8.122) (X)
106-129 E24.16 kpc Y Galactocentric Y coordinate of cluster centre
(Sun is at Y=0.0) (Y)
131-154 E24.16 kpc Z Galactocentric Z coordinate of cluster centre
(Sun is at Z=0.0208) (Z)
156-177 F22.18 mas/yr pmRA Proper motion of cluster centre in R.A.,
pmRA*cosDE (pmracosdec)
179-200 F22.18 mas/yr pmDE Proper motion of cluster centre in
declination (pmdec)
202-221 F20.17 mas plx Parallax of cluster centre (parallax)
223-243 F21.17 km/s RV Radial velocity used in the simulation
(radial_velocity)
245-263 A19 --- r_RV Source of the radial velocity used in the
simulation. If empty, we used our value for
radial_velocity (radialvelocitysource)
265-270 F6.1 Myr Age Age of the cluster (age)
272-290 F19.14 --- N Number of members (sum of all membership
probabilities for one cluster) (n)
292-295 I4 --- Nmemb Number of stars with reported membership
probabilities (n_members)
297-300 I4 --- Nmemb50 Number of stars with membership
probability > 0.5 (nmembers50)
302-305 I4 --- Nmemb90 Number of stars with membership
probability > 0.9 (nmembers90)
307-324 F18.16 --- galaxCom Mean completeness of the Galaxia simulation
(galaxia_com)
326-348 E23.15 mag AG Mean extinction in Gaia G band for stars with
membership probability > 0.5 (A_G)
350-368 F19.16 --- MFIndex ?=- Index of the power law in the mass
function (massfuncindex)
370-388 F19.17 Msun MFCharm ?=- Characteristic mass of the mass function
(massfunccharm)
390-407 F18.16 --- MFTaper ?=- Tapering exponent in the mass function
(massfunctaper)
409-430 F22.19 --- MassSeg Mass segregation index (mass_segregation)
432-450 F19.17 --- CuspIndex ?=- Cusp index (cusp_index)
452-470 F19.17 kpc TailLen Length of the tidal tails (tail_len)
472-490 F19.17 --- AsymIndex ?=- Tail asymmetry index (asym_index)
492-509 F18.15 deg PAdaxis Positional angle of the major axis of the
tidal tails in the XY plane (padaxis)
511-531 F21.17 km/s RVmeas ?=- Radial velocity of the cluster core
measured by us (radialvelocitymeasured)
533-552 F20.17 km/s e_RVmeas ?=- Standard deviation of radial velocity
measured (radialvelocitystd)
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Byte-by-byte Description of file: members.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Cluster Common name of the cluster (Cluster)
19- 37 I19 --- GaiaDR3 Gaia DR3 source_id (source_id)
39- 61 E23.15 deg RAdeg Gaia DR3 Right ascension (ICRS) at Ep=2016.0
(ra_icrs)
63- 86 E24.16 deg DEdeg Gaia DR3 Declination (ICRS) at Ep=2016.0
(dec_icrs)
88-111 E24.16 mas/yr pmRA Gaia DR3 proper motion in R.A.,pmRA*cosDE
(pmra)
113-136 E24.16 mas/yr pmDE Gaia DR3 proper motion in declination (pmdec)
138-157 F20.17 mas plx Gaia DR3 parallax (parallax)
159-182 E24.16 km/s RV ?=- Gaia DR3 radial velocity (radial_velocity)
184-203 F20.16 kpc X Galactocentric X coordinate of the star
(Sun is at X=-8.122) (x)
205-228 E24.16 kpc Y Galactocentric Y coordinate of the star
(Sun is at Y=0.0) (y)
230-253 E24.16 kpc Z Galactocentric Z coordinate of the star
(Sun is at Z=0.0208) (z)
255-278 E24.16 kpc daxis Position along the dominant axis of the
cluster (d_axis)
280-303 E24.16 deg GLON Galactic longitude (l)
305-328 E24.16 deg GLAT Galactic latitude (b)
330-353 E24.16 deg d2d Distance from the cluster centre projected
on the sky (d_2d)
355-378 E24.16 mas/yr proj2d On-sky motion projected to the radial
direction from the cluster centre (proj_2d)
380-403 E24.16 mas/yr projPerp2d On-sky motion projected perpendicularly to
the radial direction from the cluster centre
(projperp2d)
405-428 E24.16 kpc d3d Distance from the cluster centre (d_3d)
430-453 E24.16 km/s proj3d ?=- Motion projected to the radial direction
from the cluster centre (proj_3d)
455-476 F22.18 km/s projPerp3d ?=- Motion projected perpendicularly to the
radial direction from the cluster centre
(projperp3d)
478-502 F25.18 --- like Likelihood for the star to be a member of
the cluster (likelihood)
504-527 E24.16 --- like6d Likelihood for the star to be a member of the
cluster calculated from a six dimensional
parameter space (likelihood_6d)
529-552 E24.16 --- pbint [0/1] Membership probability calculated with
the "integrated" method (probability_int)
554-577 E24.16 --- pbbin [0/1] Membership probability calculated with
the "bin" method (probability_bin)
579-597 F19.16 --- Gmag Gaia DR3 mean G magnitude (photgmean_mag)
599-617 F19.16 --- BPmag Gaia DR3 mean BP magnitude (photbpmean_mag)
619-637 F19.16 --- RPmag Gaia DR3 mean RP magnitude (photrpmean_mag)
639-662 E24.16 mag AG Gaia DR3 extinction in G band (ag_gspphot)
664-687 E24.16 mag E(BP-RP) Gaia DR3 colour excess E(BP-RP)
(ebpminrp_gspphot)
689-708 F20.17 --- RUWE Gaia DR3 RUWE index (ruwe)
710-728 F19.17 Msun Mass Stellar mass (mass)
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Acknowledgements:
Janez Kos, janez.kos(at)gmail.com
(End) Patricia Vannier [CDS] 10-Jul-2024