Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-04-04
Astronomy and Astrophysics
Astrophysics
Accepted for publication in ApJ Letters
Scientific paper
10.1086/518653
About 25% of the Milky Way globular clusters (GCs) exhibit unusually extended color distribution of stars in the horizontal-branch (HB) phase. This phenomenon is now best understood as due to the presence of helium enhanced second generation subpopulations, which has raised a possibility that these peculiar GCs might have a unique origin. Here we show that these GCs with extended HB are clearly distinct from other normal GCs in kinematics and mass. The GCs with extended HB are more massive than normal GCs, and are dominated by random motion with no correlation between kinematics and metallicity. Surprisingly, however, when they are excluded, most normal GCs in the inner halo show clear signs of dissipational collapse that apparently led to the formation of the disk. Normal GCs in the outer halo share their kinematic properties with the extended HB GCs, which is consistent with the accretion origin. Our result further suggests heterogeneous origins of GCs, and we anticipate this to be a starting point for more detailed investigations of Milky Way formation, including early mergers, collapse, and later accretion.
Casetti-Dinescu Dana I.
Gim Hansung B.
Lee Young-Wook
No associations
LandOfFree
Kinematic Decoupling of Globular Clusters with Extended Horizontal-Branch does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Kinematic Decoupling of Globular Clusters with Extended Horizontal-Branch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Kinematic Decoupling of Globular Clusters with Extended Horizontal-Branch will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-213298