STRUCTURE AND KINEMATICS OF THE STELLAR HALOS AND THICK DISKS OF THE MILKY WAY BASED ON CALIBRATION STARS FROM SLOAN DIGITAL SKY SURVEY DR7

By Daniela Carollo, Timothy C. Beers, M. Chiba, J. Norris, Kenneth C. Freeman, Y. S. Lee, Željko Ivezic´, C. Rockosi, Brian Yanny. Proceedings of the International Astronomical Union, 2009

370 citations recorded by the source corpus.

The structure and kinematics of the recognized stellar components of the Milky Way are explored, based on well-determined atmospheric parameters and kinematic quantities for 32360 “calibration stars” from the Sloan Digital Sky Survey (SDSS) and its first extension, SDSS-II, which included the sub-survey Sloan Extension for Galactic Understanding and Exploration (SEGUE). Full space motions for a sub-sample of 16,920 stars, exploring a local volume within 4 kpc of the Sun, are used to derive velocity ellipsoids for the inner- and outer-halo components of the Galaxy, as well as for the canonical thick-disk and proposed metal-weak thick-disk (MWTD) populations. This new sample of calibration stars represents an increase of 60% relative to the numbers used in a previous analysis. We first examine the question of whether the data require the presence of at least a two-component halo in order to account for the rotational behavior of likely halo stars in the local volume, and whether more than two components are needed. We also address the question of whether the proposed MWTD is kinematically and chemically distinct from the canonical thick disk, and point out that the Galactocentric rotational velocity inferred for the MWTD, as well as its mean metallicity, appear quite similar to the values derived previously for the Monoceros stream, suggesting a possible association between these structures. In addition, we consider the fractions of each component required to understand the nature of the observed kinematic behavior of the stellar populations of the Galaxy as a function of distance from the plane. Scale lengths and scale heights for the thick-disk and MWTD components are determined. Spatial density profiles for the inner- and outer-halo populations are inferred from a Jeans theorem analysis. The full set of calibration stars (including those outside the local volume) is used to test for the expected changes in the observed stellar metallicity distribution function with distance above the Galactic plane in situ, due to the changing contributions from the underlying stellar populations. The above issues are considered, in concert with theoretical and observational constraints from other Milky-Way-like galaxies, in light of modern cold dark matter galaxy formation models.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/57a67c2c4acc12a82a29e6e5e614fa62e7bdae4c

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

Citations in the corpus

The Close Binary Fraction of Solar-type Stars Is Strongly Anticorrelated with Metallicity (2018, background): “Such old, low-mass giants tend to be metal-poor (Ratnatunga & Yoss 1991; Carollo et al. 2010; Mackereth et al. 2017).”
KINEMATICAL AND CHEMICAL VERTICAL STRUCTURE OF THE GALACTIC THICK DISK. II. A LACK OF DARK MATTER IN THE SOLAR NEIGHBORHOOD, (2012, background): “…et al. (1998, 1999); Siegel et al. (2002); Cabrera-Lavers et al. (2005, 2007); Bilir et al. (2008); Jurić et al. (2008); de Jong et al. (2010); Carollo et al. (2010); Chang et al. (2011) If the hypothesis (VIII) is dropped and a non-flat rotation curve is considered, the additional term…”
Near-Field Cosmology with Extremely Metal-Poor Stars (2015, background): “…component, but contains substructure resulting from accretion events, superimposed on a dichotomy of inner and outer components (Hartwick 1987, Norris & Ryan 1989, Carollo et al. 2007, 2010, 2014, de Jong et al. 2010, Deason, Belokurov & Evans 2011, Beers et al. 2012, and references therein).”
The GALAH survey: scientific motivation (2015, methodology): “For discussions on the state of the Galactic halo based on Sloan Digital Sky Survey, see e.g. Carollo et al. (2007), Carollo et al. (2010), Beers et al. (2012), Fermani & Schönrich (2013), Kafle et al. (2013) and Schönrich, Asplund & Casagrande (2014).”
A-type stars in the Canada–France Imaging Survey – II. Tracing the height of the disc at large distances with Blue Stragglers (2018, background): “…of the Galaxy that formed in situ and the fraction that originally came from the Galactic disc (e.g. Eggen, Lynden-Bell & Sandage 1962; Searle & Zinn 1978; Carollo et al. 2007, 2010; Font et al. 2011; Rodriguez-Gomez et al. 2016; Deason et al. 2017; Belokurov et al. 2018; Pillepich et al. 2018).”
THE SEGUE STELLAR PARAMETER PIPELINE. V. ESTIMATION OF ALPHA-ELEMENT ABUNDANCE RATIOS FROM LOW-RESOLUTION SDSS/SEGUE STELLAR SPECTRA (2010, result): “…et al. 2006, 2007, 2008, 2010) are quite similar to those observed for stars in the Galactic halo with [Fe/H] < −2.5, strengthening the argument of Carollo et al. (2007, 2010) and Frebel et al. (2010) that dSphs may well have contributed to (at least) the formation of the outer-halo component…”
THE STELLAR POPULATION STRUCTURE OF THE GALACTIC DISK (2015, background): “The 6 youngest part of the disk, as well as components more metal-poor than the bulk of the disk (e.g., Carollo et al. 2010) are therefore not represented in the sample; however, most of the disk mass satisfies these constraints.”