397 citations · 5.3k across the 92 of their papers we have counts for
24 papers · 1 filter
Hunting for UVdim stars in Galactic Open clusters. Clues from ultraviolet photometry
G. Cordoni, A. P. Milone, L. Casagrande +7
Split main-sequences (MSs) and extended main-sequence turn-offs (eMSTOs) have been observed in nearly all Magellanic Clouds clusters younger than 2 Gyr. More recently, Hubble Space…
High-resolution spectroscopic study of extremely metal-poor stars in the Large Magellanic Cloud
W. S. Oh, T. Nordlander, G. S. Da Costa +2
We present detailed abundance results based on UVES high dispersion spectra for 7 very and extremely metal-poor stars in the Large Magellanic Cloud. We confirm that all 7 stars, tw…
The SkyMapper search for extremely metal-poor stars in the Large Magellanic Cloud
W. S. Oh, T. Nordlander, G. S. Da Costa +2
We present results of a search for extremely metal-poor (EMP) stars in the Large Magellanic Cloud, which can provide crucial information about the properties of the first stars as…
A high-resolution spectroscopic search for multiple populations in the 2 Gyr old cluster NGC 1846
Wei Shen Oh, Thomas Nordlander, Gary Da Costa +1
We present detailed C, O, Na, Mg, Si, Ca, Ti, V, Fe, Zr, Ba, and Eu abundance measurements for 20 red giant branch (RGB) stars in the LMC star cluster NGC 1846 ([Fe/H] = -0.59). Th…
R-Process elements from magnetorotational hypernovae
D. Yong, C. Kobayashi, G. S. Da Costa +11
Neutron-star mergers were recently confirmed as sites of rapid-neutron-capture (r-process) nucleosynthesis. However, in Galactic chemical evolution models, neutron-star mergers alo…
Spectroscopy and photometry of the least-massive Type-II globular clusters: NGC1261 AND NGC6934
A. F. Marino, A. P. Milone, A. Renzini +10
Recent work has revealed two classes of Globular Clusters (GCs), dubbed Type-I and Type-II. Type-II GCs are characterized by a blue- and a red- red giant branch composed of stars w…
THOR 42: A touchstone 24 Myr-old eclipsing binary spanning the fully-convective boundary
Simon J. Murphy, Warrick A. Lawson, Christopher A. Onken +7
We present the characterization of CRTS J055255.7004426 (=THOR 42), a young eclipsing binary comprising two pre-main sequence M dwarfs (combined spectral type M3.5). This nearby…
Photometry and spectroscopy of multiple populations along the AGB of NGC2808 and NGC6121 (M4)
A. F. Marino, A. P. Milone, D. Yong +8
We present a photometric and spectroscopic study of multiple populations along the asymptotic-giant branch (AGB) of the intermediate-metallicity globular clusters (GCs) NGC2808 and…
Scl-1013644: a CEMP-s star in the Sculptor Dwarf Spheroidal Galaxy
C. Salgado, G. S Da Costa, D. Yong +1
Recent studies of the Milky Way and its satellites have paid special attention to the importance of carbon-enhanced metal-poor (CEMP) stars due to their involvement in Galactic for…
The Ca II triplet in red giant spectra: [Fe/H] determinations and the role of [Ca/Fe]
G. S. Da Costa
Measurements are presented and analyzed of the strength of the Ca II triplet lines in red giants in Galactic globular and open clusters, and in a sample of red giants in the LMC di…
The Gaia-ESO Survey: the most metal-poor stars in the Galactic bulge
L. Howes, M. Asplund, A. R. Casey +39
We present the first results of the EMBLA survey (Extremely Metal-poor BuLge stars with AAOmega), aimed at finding metal-poor stars in the Milky Way bulge, where the oldest stars s…
The s-Process Enrichment of the Globular Clusters M4 and M22
Luke J. Shingles, Amanda I. Karakas, Raphael Hirschi +4
We investigate the enrichment in elements produced by the slow neutron-capture process (-process) in the globular clusters M4 (NGC 6121) and M22 (NGC 6656). Stars in M4 have hom…
The halo+cluster system of the Galactic globular cluster NGC1851
A. F. Marino, A. P. Milone, D. Yong +17
NGC1851 is surrounded by a stellar component that extends more than ten times beyond the tidal radius. Although the nature of this stellar structure is not known, it has been sugge…
Iron and neutron-capture element abundance variations in the globular cluster M2 (NGC 7089)
David Yong, Ian U. Roederer, Frank Grundahl +8
We present CN and CH indices and CaII triplet metallicities for 34 giant stars and chemical abundances for 33 elements in 14 giants in the globular cluster M2. Assuming the program…
A single low-energy, iron-poor supernova as the source of metals in the star SMSS J 031300.36-670839.3
S. C. Keller, M. S. Bessell, A. Frebel +11
The element abundance ratios of four low-mass stars with extremely low metallicities indicate that the gas out of which the stars formed was enriched in each case by at most a few,…
Deriving Metallicities from Calcium Triplet Spectroscopy in combination with Near Infrared Photometry
F. Mauro, C. Moni Bidin, D. Geisler +7
Context. [...] One of the most efficient methods is the measurement of the equivalent width (EW) of the Calcium II Triplet (CaT), corrected for the luminosity and temperature effec…
NGC 5824: a luminous outer halo globular cluster with an intrinsic abundance spread
G. S. Da Costa, E. V. Held, I. Saviane
We present a detailed study of the strengths of the calcium triplet absorption lines in the spectra of a large sample of red giant members of the luminous outer Galactic halo globu…
Hunting the Parent of the Orphan Stream II: The First High-Resolution Spectroscopic Study
Andrew Casey, Stefan Keller, Gary Da Costa +2
We present the first high-resolution spectroscopic study on the Orphan Stream for five stream candidates, observed with the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on…
The Aquarius Co-Moving Group is Not a Disrupted Classical Globular Cluster
Andrew R. Casey, Stefan Keller, Alan Alves-Brito +8
We present a detailed analysis of high-resolution, high S/N spectra for 5 Aquarius stream stars observed with the MIKE spectrograph on the Magellan Clay telescope. Our sample repre…
Finding RR Lyrae Stars with SkyMapper: an Observational Test
S. Akhter, G. S. Da Costa, S. C. Keller +3
One of the major science goals of the SkyMapper Survey of the Southern Hemisphere sky is the determination of the shape and extent of the halo of the Galaxy. In this paper we quant…
The dynamics of the outer parts of omega Centauri
G. S. Da Costa
The multi-object fibre-fed spectrograph AAOmega at the Anglo-Australian Telescope has been used to establish and measure accurate (<1 kms-1) radial velocities for a new sample of m…
Kinematics & Chemistry of Halo Substructures: The Vicinity of the Virgo Over-Density
A. R. Casey, S. C. Keller, G. Da Costa
We present observations obtained with the AAT's 2dF wide field spectrograph AAOmega of K-type stars located within a region of the sky which contains the Virgo Over-Density and the…
The two metallicity groups of the globular cluster M22: a chemical perspective
A. F. Marino, C. Sneden, R. P. Kraft +11
We present a detailed chemical composition analysis of 35 red giant stars in the globular cluster M22. High resolution spectra for this study were obtained at five observatories, a…
Abundances of C, N, Sr and Ba on the red giant branch of omega Centauri
Laura M. Stanford, Gary S. Da Costa, John E. Norris
Abundances relative to iron for carbon, nitrogen, strontium and barium are presented for 33 stars on the red giant branch of the globular cluster omega Centauri. They are based on…