2011A&A...534A...3G


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.03CET06:33:41

2011A&A...534A...3G - Astronomy and Astrophysics, volume 534A, 3-3 (2011/10-1)

Reddening and metallicity maps of the Milky Way bulge from VVV and 2MASS. I. The method and minor axis maps.

GONZALEZ O.A., REJKUBA M., ZOCCALI M., VALENTI E. and MINNITI D.

Abstract (from CDS):

The Milky Way bulge is the nearest galactic bulge and the best laboratory for studies of stellar populations in spheroids based on individual stellar abundances and kinematics. The observed properties point to a very complex nature, which is hard to extrapolate from a few fields. We present a method of obtaining reddening maps and tracing structure and metallicity gradients of the bulge using data from the recently started ESO public survey Vista Variables in the Via Lactea (VVV). The method is used to derive properties of the fields along the minor axis. We derived the mean J-Ks color of the red clump (RC) giants in 1835 subfields in the bulge region with -8°<b←0.4° and 0.2°<l<1.7°, and compare it to the color of RC stars in Baade's window, for which we adopt E(B-V)=0.55. This allows us to derive the reddening map on a small enough scale to minimize the problems arising from differential extinction. The dereddened magnitudes were then used to build the bulge luminosity function in regions of ∼0.4°x0.4° to obtain the mean RC magnitudes. These were used as distance indicator in order to trace the bulge structure. Finally, for each subfield the derived distance and extinction values were used to obtain photometric metallicities through interpolation of red giant branch colors on a set of empirical ridge lines. The photometric metallicity distributions were compared to metallicity distributions obtained from high-resolution spectroscopy in the same regions. The reddening determination is sensitive to small-scale variations, which are clearly visible in our maps. Our results agree within the errors with literature values based on different methods, although our maps have much higher resolution and more complete coverage. The luminosity function clearly shows the double RC recently discovered in 2MASS and OGLE III datasets, thereby allowing the X-shape morphology of the bulge to be traced. Finally, the mean of the derived photometric metallicity distributions are in remarkable agreement with those obtained from spectroscopy. The VVV survey is a unique tool for mapping the bulge properties by means of the consistent method presented here. The remarkable agreement between our results and those presented in literature for the minor axis allows us to safely extend our method to the whole region covered by the survey.

Abstract Copyright:

Journal keyword(s): stars: abundances - Galaxy: bulge - dust, extinction

Simbad objects: 10

goto Full paper

goto View the reference in ADS

Number of rows : 10

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NGC 362 GlC 01 03 14.26 -70 50 55.6     6.58     ~ 965 0
2 M 92 GlC 17 17 07.39 +43 08 09.4     6.52     ~ 1933 0
3 NGC 6440 GlC 17 48 52.67 -20 21 34.5   12.01 10.10     ~ 480 1
4 NAME Baade Window reg 18 03.5 -30 01           ~ 549 3
5 NGC 6528 GlC 18 04 49.61 -30 03 20.8   12.12 10.65     ~ 475 0
6 M 69 GlC 18 31 23.10 -32 20 53.1   9.32 8.31     ~ 416 1
7 NGC 6752 GlC 19 10 52.11 -59 59 04.4   6.96 6.28     ~ 1835 0
8 NGC 6791 OpC 19 20 53 +37 46.3   10.52 9.5     ~ 899 0
9 M 55 GlC 19 39 59.71 -30 57 53.1     6.49     ~ 776 0
10 NAME Galactic Bulge reg ~ ~           ~ 3532 0

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2011A&A...534A...3G and select 'bookmark this link' or equivalent in the popup menu


2021.03.03-06:33:41

© Université de Strasbourg/CNRS

    • Contact