Elemental abundance survey of the Galactic thick disc
By B. E. Reddy, D. Lambert, Carlos Allende Prieto Iia, Bangalore, U. Texas, Austin. 2005
657 citations recorded by the source corpus.
We have performed an abundance analysis for F- and G- dwarfs of the Galactic thick-disc component. A sample of 176 nearby (d≤ 150 pc) thick-disc candidate stars was chosen from the Hipparcos catalogue and subjected to a high-resolution spectroscopic analysis. Using accurate radial velocities combined with the Hipparcos astrometry, kinematics (U, V and W) and Galactic orbital parameters were computed. We estimate the probability for a star to belong to the thin disc, the thick disc or the halo. With a probability P≥ 70 per cent taken as certain membership, we assigned 95 stars to the thick disc, 13 to the thin disc, and 20 to the halo. The remaining 48 stars in the sample cannot be assigned with reasonable certainty to one of the three components. Abundances of C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Ba, Ce, Nd and Eu have been obtained. The abundances for the thick-disc stars are compared with those for the thin-disc members from Reddy et al. The ratios of α-elements (O, Mg, Si, Ca and Ti) to iron for thick-disc stars show a clear enhancement compared to thin-disc members in the range −0.3 < [Fe/H] < −1.2. There are also other elements – Al, Sc, V, Co, and possibly Zn – which show enhanced ratios to iron in the thick disc relative to the thin disc. The abundances of Na, Cr, Mn, Ni and Cu (relative to Fe) are very similar for thin- and thick-disc stars. The dispersion in abundance ratios [X/Fe] at given [Fe/H] for thick-disc stars is consistent with the expected scatter due to measurement errors, suggesting a lack of ‘cosmic’ scatter. A few stars classified as members of the thick disc by our kinematic criteria show thin-disc abundances. These stars, which appear older than most thin-disc stars, are also, on average, younger than the thick-disc population. They may have originated early in the thin-disc history, and been subsequently scattered to hotter orbits by collisions. The thick disc may not include stars with [Fe/H] > −0.3. The observed compositions of the thin and thick discs seem to be consistent with the models of galaxy formation by hierarchical clustering in a Lambda cold dark matter (ΛCDM) universe.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/4949878ef67f34e985040a6dfeb9fe6890aa2c62
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
Citations in the corpus
- Origin and structure of the Galactic disc(s) (2009, methodology): “Many authors consider the thick disc to be a relic of a turbulent era of Galactic history in which the thick disc formed from accreted satellites and/or a thin disc was violently heated by one or more merger events (for a discussion see e.g. Reddy et al. 2006).”
- Alpha element abundances and gradients in the Milky Way bulge from FLAMES-GIRAFFE spectra of 650 K giants (2011, result): “Since those previous studies were done comparing bulge giants to local disk dwarfs from other works (Bensby et al. 2005; Reddy et al. 2006), Meléndez et al. (2008) claim that differences between thick disk and bulge stars might be explained by systematic errors when comparing dwarfs to giants or…”
- Chemical abundance analysis of the open clusters Cr 110, NGC 2099 (M 37), NGC 2420, NGC 7789, and M 67 (NGC 2682) (2009, methodology): “For the Milky Way field stars, we use the Thick and Thin Disc measurements from Reddy et al. (2003) and Reddy et al. (2006), who performed homeogeneous abundance calculations of a few hundred F/G dwarfs selected from th Hipparcos catalogue.”
- The metallicity distribution of bulge clump giants in Baade’s window (2011, methodology): “In contrast, several authors (Reddy et al. 2006; Fuhrmann 2008) argue that the thick disc does not extend significantly in this metallicity regime and that there is no evidence of decreasing [α/Fe] in the thick disc at all.”
- Through thick and thin: kinematic and chemical components in the solar neighbourhood (2010, methodology): “…older and more highly enriched in α elements than their thin disk counterparts supports the twocomponent nature of the Galactic disk (Gratton et al. 1996; Fuhrmann 1998; Prochaska et al. 2000; Bensby et al. 2003; Gilmore & Wyse 1985; Reddy et al. 2006; Bensby et al. 2007; Fuhrmann 2008).”
- NLTE abundances of Mn in a sample of metal-poor stars ⋆ (2008, background): “We find a more or less smooth increase in [Mn/Fe] with [Fe/H] in the results of Prochaska & McWilliam (2000), Nissen et al. (2000), Reddy et al. (2003), Reddy et al. (2006), and Feltzing et al. (2007).”
- CHEMICAL CARTOGRAPHY WITH APOGEE: METALLICITY DISTRIBUTION FUNCTIONS AND THE CHEMICAL STRUCTURE OF THE MILKY WAY DISK (2015, background): “…stars in the [α/Fe] versus [Fe/H] plane shows two distinct stellar populations in the solar neighborhood (e.g., Fuhrmann 1998; Prochaska et al. 2000; Reddy et al. 2006; Adibekyan et al. 2012; Haywood et al. 2013; Anders et al. 2014; Bensby et al. 2014; Nidever et al. 2014; Snaith et al. 2014),…”
- Exploring the Milky Way stellar disk - A detailed elemental abundance study of 714 F and G dwarf stars in the solar neighbourhood (2013, methodology): “…even with these very extreme definitions of the samples there is a significant overlap in the sense that there are stars with either classification that fall on the abundance trend normally associated with the other population (see also, e.g., Fuhrmann 1998; Bensby et al. 2003; Reddy et al. 2006).”
- Distribution functions for the Milky Way (2009, background): “Studies of the chemistry of the thick disc depend heavily on identifying nearby, bright stars that belong to the thick disc as targets of medium-dispersion spectroscopy (Fuhrmann 1998; Bensby et al. 2003; Venn et al. 2004; Bensby et al. 2005; Gilli et al. 2006; Reddy et al. 2006).”