2014A&A...563A..15B -
Astronomy and Astrophysics, volume 563A, 15-15 (2014/3-1)
Metallicity and kinematics of the bar in situ.
BABUSIAUX C., KATZ D., HILL V., ROYER F., GOMEZ A., ARENOU F., COMBES F., DI MATTEO P., GILMORE G., HAYWOOD M., ROBIN A.C., RODRIGUEZ-FERNANDEZ N., SARTORETTI P. and SCHULTHEIS M.
Abstract (from CDS):
Constraints on the Galactic bulge and bar structures and on their formation history from stellar kinematics and metallicities mainly come from relatively high-latitude fields (|b|>4°) where a complex mix of stellar population is seen. We aim here to constrain the formation history of the Galactic bar by studying the radial velocity and metallicity distributions of stars in situ (|b|≤1°). We observed red clump stars in four fields along the bar's major axis as radial velocity trends with distance. We observe an increase in the radial velocity dispersion near the Galactic plane. We detect the streaming motion of the stars induced by the bar in fields at l=±6°, the highest velocity components of this bar stream being metal-rich ([Fe/H]∼0.2dex). Our data is consistent with a bar that is inclined at 26±3° from the Sun-Galactic centre line. We observe a significant fraction of metal-poor stars, in particular in the field at l=0°, b=1°. We confirm the flattening of the metallicity gradient along the minor axis when getting closer to the plane, with a hint that it could actually be inverted. Our stellar kinematics corresponds to the expected behaviour of a bar issued from the secular evolution of the Galactic disc. The mix of several populations, seen further away from the plane, is also seen in the bar in situ since our metallicity distributions highlight a different spatial distribution between metal-poor and metal-rich stars, the more metal-poor stars being more centrally concentrated.
Abstract Copyright:
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Journal keyword(s):
Galaxy: bulge - Galaxy: formation - Galaxy: abundances - Galaxy: kinematics and dynamics
VizieR on-line data:
<Available at CDS (J/A+A/563/A15): table2.dat>
Nomenclature:
Table 2: [BKH2014] 9P NNNNN N=92 among (Nos 00002-00182), [BKH2014] 5PN NNNNN N=101 among (Nos 00003-00193), [BKH2014] C32 NNNNN N=107 among (Nos 00004-00326), [BKH2014] 5NN NNNNN N=99 among (Nos 00001-00271).
Simbad objects:
404
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