TY - JOUR
T1 - Search for extra-tidal RR Lyrae stars in Milky Way globular clusters from Gaia DR2
AU - Kundu, Richa
AU - Minniti, Dante
AU - Singh, Harinder P.
N1 - Funding Information:
The authors thank the reviewer for a thorough review and highly appreciate the comments and suggestions, which significantly contributed to improving the content. RK is thankful to the Council of Scientific and Industrial Research, New Delhi, for a Senior Research Fellowship (SRF). RK would also like to thank Miss Alessia Garofalo for helping her with the Gaia data during VOSS 2018. DM gratefully acknowledges support provided by the BASAL Center for Astrophysics and Associated Technologies (CATA) through grant PFB-06, and the Ministry for the Economy, Development and Tourism, Programa Iniciativa Científica Milenio grant IC120009, awarded to the Millennium Institute of Astrophysics (MAS), and from project Fondecyt No. 1170121. HPS and RK thank the Indo-US Science and Technology Forum for funding the Indo-US virtual joint network centre on ‘Theoretical analyses of variable star light curves in the era of large surveys’. RK and DM are also very grateful for the hospitality of the Vatican Observatory, where this work was started.
PY - 2019/1/1
Y1 - 2019/1/1
N2 - We used extra-tidal RR Lyrae stars to study the dynamics of Galactic globular clusters and know how effects like dynamical friction and tidal disruption affect these clusters. The Gaia DR2 catalogue for RR Lyrae stars (Clementini et al. 2018) is used along with the proper motions and tidal radii data for the globular clusters compiled from literature. A sample of 56 Galactic globular clusters is analysed. Out of these 56 Galactic globular clusters, only 11 have extra-tidal RR Lyrae stars. However, only two clusters, namely, NGC 3201 and NGC 5024, have enough extra-tidal RR Lyrae stars to draw interesting conclusions. NGC 3201 has 13 extra-tidal RR Lyrae stars which are asymmetrically distributed around its centre with more number of stars in its trailing zone than its leading part. We conclude that these asymmetrical tidal tails are due to the combined effect of tidal disruption and the stripped debris from the cluster. On the other hand, NGC 5024 has five extra-tidal RR Lyrae stars, four of them are concentrated in a region which is at a distance of about three times the tidal radius from its centre. These may be the stars that are being ripped apart from the cluster due to tidal disruption. The presence of these extra-tidal RR Lyrae stars in the clusters can be an indication that more cluster stars are present outside their tidal radii which may be revealed by deep wide field colour-magnitude diagrams of the clusters.
AB - We used extra-tidal RR Lyrae stars to study the dynamics of Galactic globular clusters and know how effects like dynamical friction and tidal disruption affect these clusters. The Gaia DR2 catalogue for RR Lyrae stars (Clementini et al. 2018) is used along with the proper motions and tidal radii data for the globular clusters compiled from literature. A sample of 56 Galactic globular clusters is analysed. Out of these 56 Galactic globular clusters, only 11 have extra-tidal RR Lyrae stars. However, only two clusters, namely, NGC 3201 and NGC 5024, have enough extra-tidal RR Lyrae stars to draw interesting conclusions. NGC 3201 has 13 extra-tidal RR Lyrae stars which are asymmetrically distributed around its centre with more number of stars in its trailing zone than its leading part. We conclude that these asymmetrical tidal tails are due to the combined effect of tidal disruption and the stripped debris from the cluster. On the other hand, NGC 5024 has five extra-tidal RR Lyrae stars, four of them are concentrated in a region which is at a distance of about three times the tidal radius from its centre. These may be the stars that are being ripped apart from the cluster due to tidal disruption. The presence of these extra-tidal RR Lyrae stars in the clusters can be an indication that more cluster stars are present outside their tidal radii which may be revealed by deep wide field colour-magnitude diagrams of the clusters.
KW - Globular clusters: individual: NGC 3201, NGC 5024
KW - Proper motion
KW - Stars: variables: RR Lyrae
UR - http://www.scopus.com/inward/record.url?scp=85067076592&partnerID=8YFLogxK
U2 - 10.1093/mnras/sty3239
DO - 10.1093/mnras/sty3239
M3 - Article
AN - SCOPUS:85067076592
SN - 0035-8711
VL - 483
SP - 1737
EP - 1743
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -