Oxygen, Sodium, Magnesium and Aluminium as tracers of the Galactic Bulge Formation

Details Oxygen, Sodium, Magnesium and Aluminium as tracers of the Galactic Bulge Formation Oxygen, Sodium, Magnesium and Aluminium as tracers of the Galactic Bulge Formation

2006-10-12

arxiv.org/abs/astro-ph/0610346v1

Astronomy and Astrophysics

Astrophysics

36 pages, 7 tables, 14 figures. Accepted for publication in A&A

Scientific paper

10.1051/0004-6361:20066036

This paper investigates the peculiar behaviour of the light even (alpha-elements) and odd atomic number elements in red giants in the galactic bulge, both in terms of the chemical evolution of the bulge, and in terms of possible deep-mixing mechanisms in these evolved stars. Using UVES on VLT, we measure the abundances of the four light elements O, Na, Mg and Al in 13 red clump and 40 red giant branch stars in four fields spanning the bulge from b=-3 to -12\deg. We show that the resulting abundance patterns point towards a chemical enrichment dominated by massive stars at all metallicities. O, Mg and Al ratios with respect to iron are overabundant with respect to both galactic disks (thin and thick) for [Fe/H]$>-0.5$. A formation timescale for the galactic bulge shorter than for both the thin and thick disks is therefore inferred. Using Mg as a proxy for metallicity (instead of Fe) we further show that: (i) the bulge stars [O/Mg] ratio follows and extend to higher metallicities the decreasing trend of [O/Mg] found in the galactic disks. (ii) the [Na/Mg] ratio trend with increasing [Mg/H] is found to increase in three distinct sequences in the thin disk, the thick disk and the bulge. The bulge trend is well represented by the predicted metallicity-dependent yields of massive stars, whereas the galactic disks have too high Na/Mg ratios at low metallicities, pointing to an additional source of Na from AGB stars. (iii) Contrary to Na, there appears to be no systematic difference in the [Al/Mg] ratio between bulge and disk stars, and the theoretical yields by massive stars agree with the observed ratios, leaving no space for AGB contribution to Al.

Affiliated with

Also associated with

No associations

Rating

Oxygen, Sodium, Magnesium and Aluminium as tracers of the Galactic Bulge Formation does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Oxygen, Sodium, Magnesium and Aluminium as tracers of the Galactic Bulge Formation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oxygen, Sodium, Magnesium and Aluminium as tracers of the Galactic Bulge Formation will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-442347