Related papers: CN Bimodality at Low Metallicity: The Globular Clu…
We present a homogeneous survey of the CN and CH bandstrengths in eight Galactic globular clusters observed during the course of the Sloan Extension for Galactic Understanding and Exploration (SEGUE) sub-survey of the SDSS. We confirm the…
We present results from a study of 94 red giant stars in the globular cluster M53. We use low-resolution spectra to measure the strength of CN and CH features at $\sim$3800 and 4300 \r{A}, respectively. The strengths of these features are…
We present CH and CN index analysis and C and N abundance calculations based on the low-resolution blue spectra of red giant branch (RGB) stars in the Galactic globular cluster NGC 7089 (M 2). Our main goal is to investigate the C-N…
Abundance variations in moderately metal-rich globular clusters can give clues about the formation and chemical enrichment of globular clusters. CN, CH, Na, Mg and Al indices in spectra of 89 stars of the template metal-rich globular…
We present Ca-CN-CH-NH photometry for the well-known globular cluster (GC) M3 (NGC 5272). We show new evidence for two M3 populations with distinctly different carbon and nitrogen abundances, seen in a sharp division between CN-weak and…
We present a comparison of CN bandstrength variations in the high-metallicity globular clusters NGC 6356 and NGC 6528 with those measured in the old open clusters NGC 188, NCG 2158 and NGC 7789. Star-to-star abundance variations, of which…
Globular clusters show abundance variations for light elements that are not yet well understood. The preferred explanation involves a self-enrichment scenario, with two subsequent generations of stars. Observations of main sequence stars…
Spectra with a high signal-to-noise ratio of 50 stars which are just below the main sequence turnoff and are members of M13 are presented. They yield indices for the strength of the CH and the ultraviolet CN band. There is no evidence for a…
Low resolution SDSS/SEGUE spectra have been used to study the behavior of the strengths of the CN and CH molecular bands in stars at different evolutionary stages of the open cluster NGC 6791. We find a significant spread in the strengths…
NGC 5053 provides a rich environment to test our understanding of the complex evolution of globular clusters (GCs). Recent studies have found that this cluster has interesting morphological features beyond the typical spherical distribution…
We performed low-resolution spectroscopy for the red giant stars in the Galactic globular cluster (GC) NGC 5286, which is known to show intrinsic heavy element abundance variations. We found that the observed stars in this GC are clearly…
Among stars in Galactic globular clusters the carbon abundance tends to decrease with increasing luminosity on the upper red giant branch, particularly within the lowest metallicity clusters. While such a phenomena is not predicted by…
The behaviour of the Delta nu =2 CO bands around 2.3 micron was examined by comparing observed and synthetic spectra in stars in globular clusters of different metallicity. Changes in the 12C/13C isotopic ratio and the carbon abundances…
Recent observations have shown that a growing number of the most massive Galactic globular clusters contain multiple populations of stars with different [Fe/H] and neutron-capture element abundances. NGC 6273 has only recently been…
A combined effort utilizing spectroscopy and photometry has revealed the existence of a new globular cluster class. These "anomalous" clusters, which we refer to as "iron-complex" clusters, are differentiated from normal clusters by…
We present a chemical composition analysis of a sample of 20 giant branch stars in the "CN-bimodal" globular cluster M4 observed using high resolution echelle spectrographs at Lick & McDonald Observatories. M4, a mildly metal-poor ([Fe/H] ~…
An analysis of the CN and CH band strengths measured in a large sample of M71 and M13 main sequence stars by Cohen (1999a,b) is undertaken using synthetic spectra to quantify the underlying C and N abundances. In the case of M71 it is found…
Spectra with a high signal-to-noise ratio of 79 stars which are just below the main sequence turnoff of M71 are presented. They yield indices for the strength of the G band of CH and the ultraviolet CN band at 3885 \AA. These indices are…
We have observed 15 red giant stars in the relatively massive, metal-poor globular cluster NGC 4833 using the Magellan Inamori Kyocera Echelle spectrograph at Magellan. We calculate stellar parameters for each star and perform a standard…
In our recent investigation (Lim et al. 2015), we have shown that narrow-band photometry can be combined with low-resolution spectroscopy to effectively search for globular clusters (GCs) with supernovae (SNe) enrichments. Here we apply…