2010A&A...509A..20R


Query : 2010A&A...509A..20R

2010A&A...509A..20R - Astronomy and Astrophysics, volume 509, A20-20 (2010/1-1)

Chemical abundances of 11 bulge stars from high-resolution, near-IR spectra.

RYDE N., GUSTAFSSON B., EDVARDSSON B., MELENDEZ J., ALVES-BRITO A., ASPLUND M., BARBUY B., HILL V., KAEUFL H.U., MINNITI D., ORTOLANI S., RENZINI A. and ZOCCALI M.

Abstract (from CDS):

It is debated whether the Milky Way bulge has characteristics more similar to those of a classical bulge than those of a pseudobulge. Detailed abundance studies of bulge stars are important when investigating the origin, history, and classification of the bulge. These studies provide constraints on the star-formation history, initial mass function, and differences between stellar populations. Not many similar studies have been completed because of the large distance and high variable visual extinction along the line-of-sight towards the bulge. Therefore, near-IR investigations can provide superior results. To investigate the origin of the bulge and study its chemical abundances determined from near-IR spectra for bulge giants that have already been investigated with optical spectra. The optical spectra also provide the stellar parameters that are very important to the present study. In particular, the important CNO elements are determined more accurately in the near-IR. Oxygen and other α elements are important for investigating the star-formation history. The C and N abundances are important for determining the evolutionary stage of the giants and the origin of C in the bulge. High-resolution, near-infrared spectra in the H band were recorded using the CRIRES spectrometer mounted on the Very Large Telescope. The CNO abundances are determined from the numerous molecular lines in the wavelength range observed. Abundances of the α elements Si, S, and Ti are also determined from the near-IR spectra. The abundance ratios [O/Fe], [Si/Fe], and [S/Fe] are enhanced to metallicities of at least [Fe/H]=-0.3, after which they decline. This suggests that the Milky Way bulge experienced a rapid and early burst of star formation similar to that of a classical bulge. However, a similarity between the bulge trend and the trend of the local thick disk seems to be present. This similarity suggests that the bulge could have had a pseudobulge origin. The C and N abundances suggest that our giants are first-ascent red-giants or clump stars, and that the measured oxygen abundances are those with which the stars were born. Our [C/Fe] trend does not show any increase with [Fe/H], which is expected if W-R stars contributed substantially to the C abundances. No ``cosmic scatter'' can be traced around our observed abundance trends: the measured scatter is expected, given the observational uncertainties.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: carbon - Galaxy: bulge - infrared: stars - stars: late-type

Simbad objects: 15

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Number of rows : 15
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 * alf Boo RG* 14 15 39.67207 +19 10 56.6730 2.46 1.18 -0.05 -1.03 -1.68 K1.5IIIFe-0.5 2245 0
2 ISOGAL-P J180323.6-300159 AB* 18 03 23.5582252344 -30 01 59.005714548     13.804   11.744 ~ 35 0
3 Cl* NGC 6522 ARP 4329 RG* 18 03 28.4320629024 -29 58 41.691364068     15.110 14.58 13.282 ~ 31 0
4 NAME Baade Window reg 18 03.5 -30 01           ~ 583 3
5 2MASS J18033691-3007047 RG* 18 03 36.9106653672 -30 07 04.745611884     18.387   14.272 K 19 0
6 Cl* NGC 6522 ARP 1322 RG* 18 03 49.3866105024 -30 01 54.191622504   16.46 14.467   12.532 ~ 30 0
7 UCAC4 300-175366 * 18 03 51.8482129224 -30 06 28.428365088     16.42 15.39 14.430 K 13 0
8 [LHZ2007] B3-b1 * 18 08 15.8385193824 -25 42 09.855737172       15.82   K 11 0
9 2MASS J18082459-2548444 RG* 18 08 24.5996840952 -25 48 44.483739336     18.915   16.488 K 12 0
10 NGC 6553 GlC 18 09 15.68 -25 54 27.9   9.08       ~ 578 0
11 2MASS J18091653-2549261 RG* 18 09 16.5364901832 -25 49 26.057581428     18.659   16.355 K 12 0
12 [LHZ2007] B6-b8 * 18 09 55.9582700568 -31 45 46.287594144     18.397   16.290 K 14 0
13 [LHZ2007] B6-f1 * 18 10 04.4608354104 -31 41 45.275386416     17.901   15.960 K 14 0
14 [LHZ2007] B6-f7 * 18 10 52.3070057160 -31 46 42.144199248     17.841   15.950 K 14 0
15 NAME Galactic Bulge reg ~ ~           ~ 3967 0

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2022.11.29-16:03:17

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