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We use high-resolution Hubble Space Telescope imaging data of dwarf galaxies in the Local Volume ($\lesssim 11$ Mpc) to parameterise 19 newly discovered nuclear star clusters (NSCs). Most of the clusters have stellar masses of…

Astrophysics of Galaxies · Physics 2023-02-01 Nils Hoyer , Nadine Neumayer , Anil C. Seth , Iskren Y. Georgiev , Jenny E. Greene

The measurement of stellar properties such as chemical compositions, masses and ages, through stellar spectra, is a fundamental problem in astrophysics. Progress in the understanding, calculation and measurement of atomic properties and…

Solar and Stellar Astrophysics · Physics 2016-06-08 Paul S. Barklem

(ABRIDGED) We assess the systematic uncertainties in (young) cluster age, mass, and - to a lesser extent - extinction and metallicity determinations, based on broad-band imaging observations with the Hubble Space Telescope. Our aim here is…

[ABRIDGED] The purpose of this work is to evaluate how several elements produced by different nucleosynthesis processes behave with stellar age and provide empirical relations to derive stellar ages from chemical abundances. We derive…

We discuss the way of increasing of the number of chemical elements, investigated in stellar spectra. We can reach it by using spectrum synthesis method, new atomic data and observation of stellar spectra with resolution comparable to solar…

Star clusters are key to understand the stellar and Galactic evolution. ASCC 123 is a little-studied, nearby and very sparse open cluster. We performed the first high-resolution spectroscopic study of this cluster in the framework of the…

The metal-rich Galactic globular cluster NGC 6366 is the fifth closest to the Sun. Despite its interest, it has received scarce attention, and little is known about its internal structure. Its kinematics suggests a link to the halo, but its…

Astrophysics of Galaxies · Physics 2018-03-30 Arthur A. Puls , Alan Alves-Brito , Fabíola Campos , Bruno Dias , Beatriz Barbuy

The light element abundance pattern from many planetary nebulae (PNe) covering the upper 4 mag. of the [O III] luminosity function was observed with ESO VLT FORS1 multi-slit. Spectra of 51 PNe over the wavelength range 3500-7500 Angstrom…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 J. R. Walsh , G. H. Jacoby , R. F. Peletier , N. A. Walton

Recently, several studies have shown that young, open clusters are characterised by a considerable over-abundance in their barium content. In particular, D'Orazi et al. (2009) reported that in some younger clusters [Ba/Fe] can reach values…

Solar and Stellar Astrophysics · Physics 2015-06-04 Valentina D'Orazi , Katia Biazzo , Silvano Desidera , Elvira Covino , Sergei M. Andrievsky , Raffaele G. Gratton

We present an abundance analysis of 101 subgiant branch (SGB) stars in the globular cluster M22. Using low resolution FLAMES/GIRAFFE spectra we have determined abundances of the neutron-capture strontium and barium and the light element…

If NGC 6397 contains a large fraction of "second generation" stars (>70% according to recent analysis), the helium abundance of its stars might also be affected, show some star-to-star variation, and be larger than the standard Big Bang…

Solar and Stellar Astrophysics · Physics 2015-05-14 M. Di Criscienzo , F. D'Antona , P. Ventura

We present new FLAMES@VLT spectroscopic observations of 30 stars in the field of the LMC stellar cluster NGC 1866. NGC 1866 is one of the few young and massive globular cluster that is close enough so that its stars can be individually…

Solar and Stellar Astrophysics · Physics 2015-05-20 A. Mucciarelli , S. Cristallo , E. Brocato , L. Pasquini , O. Straniero , E. Caffau , G. Raimondo , A. Kaufer , I. Musella , V. Ripepi , M. Romaniello , A. R. Walker

This paper presents the chemical abundance analysis of a sample of 27 red giant stars located in 4 popolous intermediate-age globular clusters in the Large Magellanic Cloud, namely NGC 1651, 1783, 1978 and 2173. This analysis is based on…

Astrophysics · Physics 2009-11-13 A. Mucciarelli , E. Carretta , L. Origlia , F. R. Ferraro

Abundance observations indicate the presence of often surprisingly large amounts of neutron capture (i.e., s- and r-process) elements in old Galactic halo and globular cluster stars. These observations provide insight into the nature of the…

Observed chemical (anti)correlations in proton-capture elements among globular cluster stars are presently recognized as the signature of self-enrichment from now extinct, previous generations of stars. This defines the multiple population…

We present the first comprehensive abundance study of the massive, outer halo globular cluster (GC) M 75 (NGC 6864). This unique system shows a very extended trimodal horizontal branch (HB), but no other clues for multiple populations have…

Astrophysics of Galaxies · Physics 2013-01-11 Nikolay Kacharov , Andreas Koch

We present a detailed chemical abundance study of three red horizontal branch and two red giant branch stars in the metal-rich globular cluster NGC 6637 (M69). The value of [Fe/H] derived from LTE calculations is $-$0.77 $\pm$ 0.02 dex. We…

Astrophysics · Physics 2007-05-23 Jae-Woo Lee , Mercedes Lopez-Morales

We used the Ultraviolet and Visual Echelle Spectrograph of the ESO-Very Large Telescope to obtain a high resolution and high signal-to-noise ratio spectrum of Stock 16-12, an early-type star which previous Delta-a photometric observations…

Solar and Stellar Astrophysics · Physics 2015-06-22 M. Netopil , L. Fossati , E. Paunzen , K. Zwintz , O. I. Pintado , S. Bagnulo

We present a chemical abundance analysis of the tidally disrupted globular cluster (GC) Palomar 5. By co-adding high-resolution spectra of 15 member stars from the cluster's main body, taken at low signal-to-noise with the Keck/HIRES…

Astrophysics of Galaxies · Physics 2017-05-24 Andreas Koch , Patrick Côté

Based on the spectrum fitting method applied to CI 5380, NI 7486, and OI 6156-8 lines, we determined the abundances of C, N, and O for 100 mostly A-type main-sequence stars (late B through early F at 11000K>Teff>7000K) comprising normal…

Solar and Stellar Astrophysics · Physics 2018-09-12 Yoichi Takeda , Satoshi Kawanomoto , Naoko Ohishi , Dong-Il Kang , Byeong-Cheol Lee , Kang-Min Kim , Inwoo Han