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Radial O/H abundance gradients derived from HII regions, hot stars and planetary nebulae are combined with [Fe/H] gradients from open cluster stars in order to derive an independent [O/Fe] x [Fe/H] relation for the galactic disk. A…

Astrophysics · Physics 2007-05-23 W. J. Maciel

We explore the origin of the observed decline in [O/Fe] (and [Mg/Fe]) with Galactocentric distance for high-metallicity stars ([Fe/H] > -1.1), based on a sample of halo stars selected within the Apache Point Observatory Galactic Evolution…

We present an analysis of the photometric parallaxes of stars in 21 BATC fields carried out with the National Astronomical Observatories (NAOC) 60/90 cm Schmidt Telescope in 15 intermediate-band filters from 3000 to 10000 {\AA}. In this…

Astrophysics · Physics 2009-11-11 Cuihua Du , Jun Ma , Zhenyu Wu , Xu Zhou

We investigate if there is a difference in the lithium abundances of stars belonging to two halo populations of F and G main-sequence stars previously found to differ in [alpha/Fe] for the metallicity range -1.4 < [Fe/H] < -0.7. Li…

Astrophysics of Galaxies · Physics 2015-06-05 P. E. Nissen , W. J. Schuster

We performed an extensive non-LTE analysis of the neutral sodium lines of Na {\sc i} 5683/5688, 5890/5896, 6154/6161, and 8183/8195 for disk/halo stars of F--K type covering a wide metallicity range ($-4 \la$ [Fe/H] $\la 0.4$), based on our…

Astrophysics · Physics 2014-10-13 Yoichi Takeda , Gang Zhao , Masahide Takada-Hidai , Yu-Qin Chen , Yu-ji Saito , Hua-Wei Zhang

We present the first fluorine measurements in 12 normal giants belonging to the Galactic thin and thick disks using spectra obtained with the Phoenix infrared spectrometer on the 2.1m telescope at Kitt Peak. Abundances are determined from…

Astrophysics of Galaxies · Physics 2024-06-06 K. E. Brady , C. A. Pilachowski , V. Grisoni , Z. G. Maas , K. A. Nault

(Abridged) We have used the atmospheric parameters, [alpha/Fe] abundances and radial velocities, determined from the Gaia-ESO Survey GIRAFFE spectra of FGK-type stars (iDR1), to provide a chemo-kinematical characterisation of the disc…

Stellar halos are the only major stellar component of disk galaxies that lack systematic observational characterization, yet they encode critical information about galaxy merger histories. We present the first systematic census of stellar…

Astrophysics of Galaxies · Physics 2026-02-25 Bojun Tao , Hong-Xin Zhang , Wenting Wang , Enci Wang , Guangwen Chen , Huiyuan Wang , Lijun Chen , Qian-Hui Chen , Song Huang , Xu Kong , Yu Rong

[ABRIDGED] In order to trace the origin and evolution of carbon in the Galactic disk we have determined carbon abundances in 51 nearby F and G dwarf stars. The sample is divided into two kinematically distinct subsamples with 35 and 16…

Astrophysics · Physics 2009-11-11 T. Bensby , S. Feltzing

The Milky Way is home to a thin disk that can be defined via kinematics and/or elemental abundances. The elemental abundance-defined thin disk, also called the low-alpha disk, is generally thought to be comprised of stars on planar,…

We use a series of high-resolution simulations of a `Milky-Way' halo coupled to semi-analytic methods to study the formation of our own Galaxy and of its stellar halo. The physical properties of our model Milky Way, as well as the age and…

Astrophysics · Physics 2009-11-13 Gabriella De Lucia , Amina Helmi

Oxygen abundances are derived in a sample of 13 field F and G dwarfs and subgiants with metallicities in the range of -0.75 < [Fe/H] < +0.15. This is the same sample of stars for which boron abundances have been derived earlier from…

Astrophysics · Physics 2009-11-06 Verne V. Smith , Katia Cunha , Jeremy R. King

Abundances of 18 elements are determined for the common proper-motion pair, HD134439 and HD134440, which shows high [Mn/Fe] and low [\alpha/Fe] ratios as compared to normal halo stars. Moreover, puzzling abundances are indicated from…

Astrophysics · Physics 2009-11-11 Y. Q. Chen , G. Zhao

New uvby-\beta data are provided for 442 high-velocity and metal-poor stars; 90 of these stars have been observed previously by us, and 352 are new. When combined with our previous two photometric catalogues, the data base is now made up of…

Astrophysics · Physics 2009-11-11 W. J. Schuster , A. Moitinho , A. Marquez , L. Parrao , E. Covarrubias

We measure the orbital properties of halo stars using 7-dimensional information provided by Gaia and the Sloan Digital Sky Survey. A metal-rich population of stars, present in both local main sequence stars and more distant blue horizontal…

Astrophysics of Galaxies · Physics 2018-08-01 Alis J. Deason , Vasily Belokurov , Sergey E. Koposov , Lachlan Lancaster

We study the metal abundances of F and G type stars in the Galactic disk and halo using the Canada-France-Hawaii Telescope Legacy Survey D4 field. For a sample of stars within 7 kpc of the Galactic plane, we derive mean abundance values of…

Astrophysics · Physics 2009-11-13 Y. Karatas , M. Kilic , O. Gunes , F. Limboz

We determine relative abundance ratios for the neutron-capture elements Zr, La, Ce, Nd, and Eu for a sample of 27 Galactic dwarf stars with -1.5 < [Fe/H] <-0.8. We also measure the iron-peak element Sc. These stars separate into three…

Solar and Stellar Astrophysics · Physics 2017-01-18 C. K. Fishlock , D. Yong , A. I. Karakas , A. Alves-Brito , J. Melendez , P. E. Nissen , C. Kobayashi , A. R. Casey

We estimated the galactic model parameters for a set of 20 intermediate-latitude fields with galactic longitudes 0<l<100 and 160<l<240, included in the currently available Data Release 6 (DR6) of SDSS, to explore their possible variation…

Astrophysics of Galaxies · Physics 2015-05-13 E. Yaz , S. Karaali

The origin of the Galactic halo is one of the fundamental topics linking the study of galaxy formation and evolution to cosmology. We aim at deriving precise and accurate stellar parameters, Mg abundances, and ages for a sample of…

Astrophysics of Galaxies · Physics 2025-06-04 Riano E. Giribaldi , Laura Magrini , Martina Rossi , Anish M. Amarsi , Donatella Romano , Davide Massari

We present a statistical analysis of halo emission for a sample of 1047 edge-on disk galaxies imaged in five bands by the Sloan Digital Sky Survey (SDSS). Stacking the homogeneously rescaled images of the galaxies, we can measure surface…

Astrophysics · Physics 2009-09-25 Stefano Zibetti , Simon D. M. White , Jon Brinkmann
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