Issue |
A&A
Volume 381, Number 1, JanuaryI 2002
|
|
---|---|---|
Page(s) | 219 - 226 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361:20011541 | |
Published online | 15 January 2002 |
Low-extinction windows in the inner Galactic Bulge
1
Universidade Federal do Rio Grande do Sul, IF, CP 15051, Porto Alegre 91501–970, RS, Brazil
2
Instituto Astronomico e Geofisico da USP, CP 3386, São Paulo 01060-970, SP, Brazil
Corresponding author: B. X. Santiago, santiago@if.ufrgs.br
Received:
9
March
2001
Accepted:
30
October
2001
We built K band extinction maps in the area of two candidate
low-extinction windows in the inner Bulge: W0.2–2.1 at
() = (0.25°, -2.15°), and W359.4–3.1 at
(
) = (359.40°, -3.10°). We employed
JHKs photometry from the 2MASS Point Source Catalog.
Extinction values were determined by fitting the upper giant branch found
in the present 2MASS Ks (
) diagrams to a de-reddened
bulge stellar population reference giant branch. We tested
the method on the well known Baade's and Sgr I windows: the 2MASS
mean extinction values in these fields agreed well with those of
previous studies.
We confirm the existence of low-extinction windows in the regions studied,
as local minima in the AK maps reaching AK values about 2 standard deviations below
the mean values found in the neighbouring areas. Schlegel et al.'s ([CITE]) FIR extinction maps, which integrate dust
contributions throughout the Galaxy, are structurally similar to
those derived with 2MASS
photometry in the two studied windows. We thus conclude that
the dust clouds affecting the 2MASS and FIR maps in these directions
are basically the same and are located
on foreground of the bulk of bulge stars. However, the AK
absolute values differ significantly. In particular, the
FIR extinction values for W359.4–3.1 are a factor
1.45 larger
than those derived from
the 2MASS photometry. Possible explanations of this effect are discussed.
The lower Galactic latitudes of the low-extinction
windows W359.4–3.1 and W0.2–2.1, as compared to Baade's Window, make
them promising targets for detailed studies of more central bulge regions.
Key words: Galaxy: interstellar medium: dust
© ESO, 2002
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