TY - JOUR
T1 - Kinematics of a globular cluster with an extended profile
T2 - NGC 5694
AU - Bellazzini, Michele
AU - Mucciarelli, Alessio
AU - Sollima, Antonio
AU - Catelan, M
AU - Dalessandro, Emanuele
AU - Correnti, M
AU - D'Orazi, V.
AU - Cortés, C.
AU - Amigo, P
PY - 2015
Y1 - 2015
N2 - We present a study of the kinematics of the remote globular cluster NGC 5694 based on GIRAFFE@VLT medium-resolution spectra. A sample of 165 individual stars selected to lie on the red giant branch in the cluster colour-magnitude diagram was considered. Using radial velocity and metallicity from Calcium triplet, we were able to select 83 bona fide cluster members. The addition of six previously known members leads to a total sample of 89 cluster giants with typical uncertainties ≤1.0 kms-1 in their radial velocity estimates. The sample covers a wide range of projected distances from the cluster centre, from~0.2 arcmin to 6.5 arcmin (minus tilde)(combining long vertical line 23 half-light radii (rh).We find only very weak rotation, as typical of metal-poor globular clusters. The velocity dispersion gently declines from a central value of s σ=6.1 kms-1 to s (minus tilde)(combining long vertical line 2.5 kms-1 at ~2 arcmin (minus tilde)(combining long vertical line 7.1rh, then it remains flat out to the next (and last) measured point of the dispersion profile, at ~4 arcmin (minus tilde)(combining long vertical line 14.0rh, at odds with the predictions of isotropic King models. We show that both isotropic single-mass non-collisional models and multimass anisotropic models can reproduce the observed surface brightness and velocity dispersion profiles.
AB - We present a study of the kinematics of the remote globular cluster NGC 5694 based on GIRAFFE@VLT medium-resolution spectra. A sample of 165 individual stars selected to lie on the red giant branch in the cluster colour-magnitude diagram was considered. Using radial velocity and metallicity from Calcium triplet, we were able to select 83 bona fide cluster members. The addition of six previously known members leads to a total sample of 89 cluster giants with typical uncertainties ≤1.0 kms-1 in their radial velocity estimates. The sample covers a wide range of projected distances from the cluster centre, from~0.2 arcmin to 6.5 arcmin (minus tilde)(combining long vertical line 23 half-light radii (rh).We find only very weak rotation, as typical of metal-poor globular clusters. The velocity dispersion gently declines from a central value of s σ=6.1 kms-1 to s (minus tilde)(combining long vertical line 2.5 kms-1 at ~2 arcmin (minus tilde)(combining long vertical line 7.1rh, then it remains flat out to the next (and last) measured point of the dispersion profile, at ~4 arcmin (minus tilde)(combining long vertical line 14.0rh, at odds with the predictions of isotropic King models. We show that both isotropic single-mass non-collisional models and multimass anisotropic models can reproduce the observed surface brightness and velocity dispersion profiles.
KW - Globular clusters: Individual: NGC 5694
KW - Stars: Abundances
UR - http://www.scopus.com/inward/record.url?scp=84985937176&partnerID=8YFLogxK
U2 - 10.1093/mnras/stu2303
DO - 10.1093/mnras/stu2303
M3 - Article
AN - SCOPUS:84985937176
SN - 0035-8711
VL - 446
SP - 3130
EP - 3138
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -