2000A&A...359..907L


Query : 2000A&A...359..907L

2000A&A...359..907L - Astronomy and Astrophysics, volume 359, 907-931 (2000/7-3)

Tidal tails around 20 Galactic globular clusters. Observational evidence for gravitational disk/bulge shocking.

LEON S., MEYLAN G. and COMBES F.

Abstract (from CDS):

Large-field multi-color images of 20 galactic globular clusters are used to investigate the presence of tidal tails around these stellar systems. Field and cluster stars are sorted with the help of color-magnitude diagrams, and star-count analysis is performed on the selected cluster stars in order to increase the signal-to-noise ratio of their surface density. We study the overdensities of these stars using the wavelet transform of the star counts in order to filter the background density noise and to detect the weak structures, at large scale, formed by the numerous stars previously members of the clusters. We associate these stellar overdensities with the stars evaporated from the clusters because of dynamical relaxation and/or tidal stripping from the clusters by the galactic gravitational field. We take into account the strong observational biases induced by the clustering of galactic field stars and of background galaxies, along with the fluctuations of the background due to dust extinction. Most of the globular clusters in our sample display strong evidence of tidal interactions with the galactic plane in the form of large and extended deformations. These tidal tails exhibit projected directions preferentially towards the galactic center. All the clusters observed, which do not suffer from strong observational biases, present such tidal tails, tracing their dynamical evolution (evaporation, tidal shocking, tidal torquing, and bulge shocking) in the Galaxy. The clusters exhibit different regimes of mass loss rate, detected using the radial density slope in the outer parts of the clusters. For NGC 5139 (ω Centauri), we estimate, taking into account the possible presence of mass segregation in its outer parts, that about 0.6 to 1% of its mass has been lost during the current disk shocking event. In the case of NGC 6254, we tentatively estimate, in the cluster reference frame, for the radial diffusion velocity of the stars stripped, a value of the order of the velocity dispersion in the cluster itself. The sizes and orientations of these observed tidal tails are perfectly reproduced by N-body simulations of globular clusters in the galactic potential well. We present these results in a companion paper (Combes et al., 1999A&A...352..149C). As a by-product of this study, we detect several new galaxy clusters towards the different fields studied at high galactic latitude. The estimation of the tidal radius of some of the globular clusters could have been overestimated because of these galaxy clusters.

Abstract Copyright:

Journal keyword(s): techniques: image processing - ISM: dust, extinction - Galaxy: globular clusters: general - Galaxy: structure - cosmology: large-scale structure of Universe

Simbad objects: 25

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Number of rows : 25
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 NGC 104 GlC 00 24 05.359 -72 04 53.20   5.78 4.09     ~ 3723 0
2 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11798 1
3 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10204 1
4 NGC 288 GlC 00 52 45.24 -26 34 57.4   10 8.13     ~ 984 0
5 NGC 362 GlC 01 03 14.26 -70 50 55.6     6.58     ~ 1012 0
6 NGC 1261 GlC 03 12 16.21 -55 12 58.4     8.63     ~ 470 0
7 NGC 1851 GlC 05 14 06.76 -40 02 47.6           ~ 1330 0
8 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16002 1
9 M 79 GlC 05 24 10.59 -24 31 27.3   9.21 8.16     ~ 762 0
10 NGC 2298 GlC 06 48 59.41 -36 00 19.1   10.77 8.89     ~ 459 0
11 NGC 4372 GlC 12 25 45.43 -72 39 32.7   10.86 9.85     ~ 282 0
12 NGC 5139 GlC 13 26 47.28 -47 28 46.1   6.12 5.33     ~ 3231 0
13 M 3 GlC 13 42 11.62 +28 22 38.2     6.39     ~ 2374 0
14 NGC 5694 GlC 14 39 36.52 -26 32 18.0   11.58 10.89     ~ 284 0
15 NGC 5824 GlC 15 03 58.612 -33 04 06.70   10.28 9.56     ~ 378 0
16 NAME Serpens Dwarf GlC 15 16 05.30 -00 06 41.0   15.1       ~ 682 1
17 M 5 GlC 15 18 33.22 +02 04 51.7   7.34 5.95     ~ 1872 0
18 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1758 0
19 M 13 GlC 16 41 41.634 +36 27 40.75     5.8     ~ 2099 0
20 M 10 GlC 16 57 09.05 -04 06 01.1     4.98     ~ 741 0
21 NGC 6397 GlC 17 40 42.09 -53 40 27.6   7.39 5.17     ~ 1876 1
22 NGC 6535 GlC 18 03 50.51 -00 17 51.5   11.35 9.85     ~ 266 0
23 M 55 GlC 19 39 59.71 -30 57 53.1     6.49     ~ 807 0
24 Cl Pal 12 GlC 21 46 38.84 -21 15 09.4     11.89     ~ 487 0
25 NGC 7492 GlC 23 08 26.68 -15 36 41.3     10.48     ~ 279 0

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2022.05.26-02:50:41

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