Chemical Similarities Between Galactic Bulge And Local Thick Disk Red Giant Stars

By Jorge Meléndez, Martin Asplund, A. Alves-Brito, Katia Cunha, B. Barbuy, M. Bessell, C. Chiappini, Kenneth C. Freeman, I. Ramírez, V. Smith and 1 more. 2008

158 citations recorded by the source corpus.

Context. The evolution of the Milky Way bulge and its relationship with the other Galactic populations is still poorly understood. The bulge has been suggested to be either a merger-driven classical bulge or the product of a dynamical instability of the inner disk. Aims. To probe the star formation history, the initial mass function and stellar nucleosynthesis of the bulge, we performed an elemental abundance analysis of bulge red giant stars. We also completed an identical study of local thin disk, thick disk and halo giants to establish the chemical differences and similarities between the various populations. Methods. High-resolution infrared spectra of 19 bulge giants and 49 comparison giants in the solar neighborhood were acquired with Gemini/Phoenix. All stars have similar stellar parameters but cover a broad range in metallicity. A standard 1D local thermodynamic equilibrium analysis yielded the abundances of C, N, O and Fe. A homogeneous and differential analysis of the bulge, halo, thin disk and thick disk stars ensured that systematic errors were minimized. Results. We confirm the well-established differences for [O/Fe] (at a given metallicity) between the local thin and thick disks. For the elements investigated, we find no chemical distinction between the bulge and the local thick disk, which is in contrast to previous studies relying on literature values for disk dwarf stars in the solar neighborhood. Conclusions. Our findings suggest that the bulge and local thick disk experienced similar, but not necessarily shared, chemical evolution histories. We argue that their formation timescales, star formation rates and initial mass functions were similar.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/ef4c04e33bb874314754f6ca5f60e276734b94e4

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In Astronomy and Astrophysics

1. P. Hopkins
2. L. Hernquist
3. A. Dekel
4. I. Minchev
5. Hans-Walter Rix
6. T. Naab
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In Instrumentation

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2. A. Dekel
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6. T. Naab
7. Frédéric Bournaud
8. A. Burkert

Citations in the corpus

• The metallicity distribution of bulge clump giants in Baade’s window (2011, result): “This result confirms, but with better statistics, the results found for the oxygen by Meléndez et al. (2008) in the same metallicity regime.”
• From Rings to Bulges: Evidence for Rapid Secular Galaxy Evolution at z ~ 2 from Integral Field Spectroscopy in the SINS Survey (2008, background): “In support of this conjecture, Melendez et al. (2008) have found that the /Fe element abundances of the old Galactic bulge are more or less identical to those of the thick disk, implying that these two components are coeval and both formed rapidly.”
• Gaia FGK benchmark stars: Effective temperatures and surface gravities (2015, unknown): “On the other hand, Meléndez et al. (2008) used more recent model isochrones, similar to the ones used in the current work, for Arcturus and HD 107328, and derived log g values closer to the fundamental ones.”
• THE MOST METAL-POOR STARS. II. CHEMICAL ABUNDANCES OF 190 METAL-POOR STARS INCLUDING 10 NEW STARS WITH [Fe/H] ⩽ −3.5,, (2012, background): “The reason for separating the dwarfs from giants is that we want to compare, as best we can, stars with similar stellar parameters to minimize systematic errors (e.g., Cayrel et al. 2004; Meléndez et al. 2008; Bonifacio et al. 2009; Alves-Brito et al. 2010; Nissen & Schuster 2010)16.”
• Chemical similarities between Galactic bulge and local thick disk red giants: O, Na, Mg, Al, Si, Ca, and Ti (2010, methodology): “Since this is identical to the estimated error in [O/Fe] from OH found in Meléndez et al. (2008), the uncertainties in our stellar parameters arelikely somewhat overestimated, as already discussed above.”
• ARGOS - III. Stellar populations in the Galactic bulge of the Milky Way (2012, background): “Several authors have argued that the bulge is anα-enhanced metal-rich population (Zoccali et al. 2008; Fulbright, McWilliam, & Rich 2007; Lecureur et al. 2007; Meléndez et al. 2008).”
• THE THICK DISKS OF SPIRAL GALAXIES AS RELICS FROM GAS-RICH, TURBULENT, CLUMPY DISKS AT HIGH REDSHIFT (2009, background): “Other chemical similarities between the bulge and the thick disk of the Milky Way were discussed by Meléndez et al. (2008).”
• Origin and structure of the Galactic disc(s) (2009, background): “Meléndez et al. (2008) remarked that the thick disc has similar properties to the Galactic bulge.”
• Insights on the Milky Way bulge formation from the correlations between kinematics and metallicity (2010, background): “Meléndez et al. (2008), Ryde et al. (2010), Bensby et al. (2010) and Alves-Brito et al. (2010) observed similarities between the metallicity of the bulge and the metallicity of thick disc stars for metal-poor stars.”
• Chemodynamics of the Milky Way - I. The first year of APOGEE data (2013, result): “…et al. (2006), Fulbright et al. (2007) and Lecureur et al. (2007), are somewhat different from the more recent homogeneous abundance analyses of Meléndez et al. (2008), Alves-Brito et al. (2010)20 and Gonzalez et al. (2011) who find a similar abundance pattern for bulge and thick disc giants…”
• Gaia FGK benchmark stars: Metallicity (2013, background): “Edvardsson et al. (1993), for example, considered the solar chemical abundances of Anders & Grevesse (1989) while Meléndez et al. (2008) refered to the solar abundances of Asplund et al. (2005).”
• Through thick and thin: kinematic and chemical components in the solar neighbourhood (2010, background): “Another potential challenge may arise from the fact that at least some metal-rich stars in the inner Galaxy seem to be α-enriched (Meléndez et al. 2008) whereas those in the solar neighbourhood are not.”
• Alpha element abundances and gradients in the Milky Way bulge from FLAMES-GIRAFFE spectra of 650 K giants (2011, methodology): “The sample for thick and thin disk RGB stars in the local neighborhood consists of the same spectra analyzed in Meléndez et al. (2008) and Alves-Brito et al. (2010, hereafter AB10).”
• A FIRST CONSTRAINT ON THE THICK DISK SCALE LENGTH: DIFFERENTIAL RADIAL ABUNDANCES IN K GIANTS AT GALACTOCENTRIC RADII 4, 8, AND 12 kpc (2011, background): “…evidence of a connection between the metal-poor bulge and the thick disk, regarding their abundance patterns, metallicity distribution functions, ages and a flat radial abundance gradient in the thick disk (Meléndez et al. 2008; Alves-Brito et al. 2010; Bensby et al. 2010b, 2011, this work).”