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As part of a large investigation with Hubble Space Telescope to study the faintest stars within the globular cluster Omega Centauri, in this work we present early results on the multiplicity of its main sequence (MS) stars, based on deep…

Solar and Stellar Astrophysics · Physics 2017-05-31 A. P. Milone , A. F. Marino , L. R. Bedin , J. Anderson , D. Apai , A. Bellini , P. Bergeron , A. J. Burgasser , A. Dotter , J. M. Rees

Omega Cen is composed of several stellar populations. Their history might allow us to reconstruct the evolution of this complex object. We performed a statistical cluster analysis on the large data set provided by Johnson and Pilachowski…

Astrophysics of Galaxies · Physics 2015-05-28 Raffaele Gratton , Christian I. Johnson , Sara Lucatello , Valentina D'Orazi , Catherine A. Pilachowski

We model the evolution of manganese relative to iron in the progenitor system of the globular cluster Omega Centauri by means of a self-consistent chemical evolution model. We use stellar yields that already reproduce the measurements of…

Astrophysics of Galaxies · Physics 2015-05-28 Donatella Romano , Gabriele Cescutti , Francesca Matteucci

Historically, photometry has been largely used to identify stellar populations (MPs) in Globular Clusters (GCs) by using diagrams that are based on colours and magnitudes that are mostly sensitive to stars with different metallicities or…

Solar and Stellar Astrophysics · Physics 2020-07-29 A. P. Milone , A. F. Marino , A. Renzini , C. Li , S. Jang , E. P. Lagioia , M. Tailo , G. Cordoni , M. Carlos , E. Dondoglio

We study the multiple populations of $\omega$ Cen by using the abundances of Fe, C, N, O, Mg, Al, Si, K, Ca, and Ce from the high-resolution, high signal-to-noise (S/N$>$70) spectra of 982 red giant stars observed by the SDSS-IV/APOGEE-2…

Recent wide-field photometric surveys (Lee et al.; Pancino et al.) have shown the existence of a previously unknown metal-rich ([Fe/H] -0.6) stellar population in the galactic globular cluster omega Centauri. The discovery of this new…

Astrophysics · Physics 2009-11-07 F. R. Ferraro , M. Bellazzini , E. Pancino

The most massive and complex globular clusters in the Galaxy are thought to have originated as the nuclear cores of now tidally disrupted dwarf galaxies, but the connection between globular clusters and dwarf galaxies is tenuous with the…

Solar and Stellar Astrophysics · Physics 2020-05-13 Christian I. Johnson , Andrea K. Dupree , Mario Mateo , John I. Bailey , Edward W. Olszewski , Matthew G. Walker

Copper abundances are presented for 40 red-giant stars in Omega Cen as well as 15 red-giant members of the globular clusters NGC288, NGC362, NGC3201, NGC6752, and M4. A comparison with the halo field star pattern indicates that, unlike the…

Astrophysics · Physics 2016-08-30 K. Cunha , V. V. Smith , N. B. Suntzeff , J. E. Norris , G. S. Da Costa , B. Plez

We derive homogeneous abundances of Fe, O, Na and alpha-elements from high resolution FLAMES spectra for 76 red giant stars in NGC 6715 (M 54) and for 25 red giants in the surrounding nucleus of the Sagittarius (Sgr) dwarf galaxy. Our main…

Astrophysics of Galaxies · Physics 2015-05-18 E. Carretta , A. Bragaglia , R. G. Gratton , S. Lucatello , M. Bellazzini , G. Catanzaro , F. Leone , Y. Momany , G. Piotto , V. D'Orazi

We analysed high-resolution UVES spectra of six stars belonging to the subgiant branch of omega Centauri, and derived abundance ratios of 19 chemical elements (namely Al, Ba, C, Ca, Co, Cr, Cu, Fe, La, Mg, Mn, N, Na, Ni, Sc, Si, Sr, Ti, and…

Solar and Stellar Astrophysics · Physics 2015-05-20 E. Pancino , A. Mucciarelli , L. Sbordone , M. Bellazzini , L. Pasquini , L. Monaco , F. R. Ferraro

We have used high resolution observations obtained at the AAT with UHRF (R ~ 100,000) and at Gemini-S with b-HROS (R ~ 150,000) to determine magnesium isotope ratios for seven omega Centauri red giants that cover a range in iron abundance…

Astrophysics of Galaxies · Physics 2015-06-15 G S Da Costa , John E Norris , David Yong

Abundance ratios relative to iron for carbon, nitrogen, strontium and barium are presented for a metal-rich main sequence star ([Fe/H]=--0.74) in the globular cluster omega Centauri. This star, designated 2015448, shows depleted carbon and…

Astrophysics · Physics 2009-11-11 Laura M. Stanford , G. S. Da Costa , John E. Norris , Russell D. Cannon

We take advantage of the Gaia-ESO Survey iDR4 bulge data to search for abundance anomalies that could shed light on the composite nature of the Milky Way bulge. The alpha-elements (Mg, Si, and whenever available, Ca) abundances, and their…

CCD vby Stroemgren photometry of a statistically complete sample of red giants and stars in the main sequence turn-off region in omega Centauri has been used to analyse the apparently complex star formation history of this cluster. From the…

Astrophysics · Physics 2009-10-05 Michael Hilker , Tom Richtler

Among the multiple stellar populations in globular clusters (GCs) the very high-temperature H-burning regime, able to produce elements up to potassium, is still poorly explored. Here we present the first abundance analysis of K in 42 giants…

Astrophysics of Galaxies · Physics 2022-09-15 Eugenio Carretta

We have determined stellar parameters and abundances for 221 giant branch stars in the globular cluster {\omega} Centauri. A combination of photometry and lower-resolution spectroscopy was used to determine temperature, gravity,…

Solar and Stellar Astrophysics · Physics 2015-06-11 Jeffrey D. Simpson , P. L. Cottrell , C. C. Worley

We present the abundance analysis for a sample of 17 red giant branch stars in the metal-poor globular cluster M28 based on high resolution spectra. This is the first extensive spectroscopic study of this cluster. We derive abundances of O,…

Astrophysics of Galaxies · Physics 2016-10-12 S. Villanova , C. Moni Bidin , F. Mauro , C. Munoz , L. Monaco

We derive [Cu/Fe] for 117 giant stars in ten globular clusters (M3, M4, M5, M10, M13, M15, M71, NGC 7006, NCG 288, and NGC 362) and find that globular cluster Cu abundances appear to follow [Cu/Fe] trends found in the field. This result is…

Having shown in a recent paper that the main sequence of omega Centauri is split into two distinct branches, we now present spectroscopic results showing that the bluer sequence is_less_ metal-poor. We have carefully combined GIRAFFE@VLT…

We present new spectroscopic metal abundances for 74 RR Lyrae stars in omega Cen obtained with FLAMES. The well-known metallicity spread is visible among the RR Lyrae variables. The metal-intermediate (MInt) RR Lyrae stars ([Fe/H] ~ -1.2)…

Astrophysics · Physics 2009-11-11 A. Sollima , J. Borissova , M. Catelan , H. A. Smith , D. Minniti , C. Cacciari , F. R. Ferraro