M54 + SAGITTARIUS = ω CENTAURI

AAOmega maps the ISM towards ω Centauri

The Stellar Dynamics of ω Centauri

The stellar dynamics of ω Centauri are inferred from the radial velocities of 469 stars measured with CORAVEL (Mayor et al. 1997). Rather than fit the data to a family of models, we generate estimates of all dynamical functions nonparametrically, by direct operation on the data. The cluster is assumed to be oblate and edge-on but mass is not assumed to follow light. The mean motions are consist...

Elemental Abundances in Five Stars in M54, a Globular Cluster Associated with the Sagittarius Galaxy

Chemical abundances in Ðve stars in M54, a globular cluster associated with the Sagittarius dwarf galaxy, have been determined using high-resolution echelle spectra. We Ðnd the cluster to have [Fe/H]\ [1.55 and possibly halo-normal abundance patterns, although the [O/Fe] and [a/Fe] ratios lie between solar and the normal halo values. One star shows the combination of low oxygen and enhanced Na ...

The Globular Cluster M54 and the Star Formation History of the Sagittarius Dwarf Galaxy

We present a deep color-magnitude diagram in the V I passbands of the globular cluster M54, a member of the Sagittarius dwarf galaxy. The data extend below the cluster’s main sequence turn-off, allowing us to estimate the cluster’s age. We find that M54 is 0.5–1.5 gigayears older than the Galactic globulars M68 and M5. In absolute terms, the age is comparable to the published age estimates of t...

Stellar populations in ω Centauri: a multivariate analysis

We have performed multivariate statistical analyses of photometric and chemical abundance parameters of three large samples of stars in the globular cluster ω Centauri. The statistical analysis of a sample of 735 stars based on seven chemical abundances with the method of Maximum Parsimony (cladistics) yields the most promising results: seven groups are found, distributed along three branches w...