Bibcode
Herrera-Endoqui, M.; Salo, H.; Laurikainen, E.; Knapen, J. H.
Bibliographical reference
Astronomy and Astrophysics, Volume 599, id.A43, 23 pp.
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2
2017
Journal
Citations
10
Refereed citations
10
Description
Aims: We aim to study the colors and orientations of structures
in low and intermediate inclination barred galaxies. We test the
hypothesis that barlenses, roundish central components embedded in bars,
could form part of the bar in a similar manner to boxy/peanut bulges in
the edge-on view. Methods: A sample of 79 barlens galaxies was
selected from the Spitzer Survey of Stellar Structure in Galaxies
(S4G) and the Near IR S0 galaxy Survey (NIRS0S), based on
previous morphological classifications at 3.6 μm and 2.2 μm
wavelengths. For these galaxies the sizes, ellipticities, and
orientations of barlenses were measured, parameters which were used to
define the barlens regions in the color measurements. In particular, the
orientations of barlenses were studied with respect to those of the
"thin bars" and the line-of-nodes of the disks. For a subsample of 47
galaxies color index maps were constructed using the Sloan Digital Sky
Survey (SDSS) images in five optical bands, u, g, r, i, and z. Colors of
bars, barlenses, disks, and central regions of the galaxies were
measured using two different approaches and color-color diagrams
sensitive to metallicity, stellar surface gravity, and short lived stars
were constructed. Color differences between the structure components
were also calculated for each individual galaxy, and presented in
histogram form. Results: We find that the colors of barlenses are
very similar to those of the surrounding bars, indicating that most
probably they form part of the bar. We also find that barlenses have
orientations closer to the disk line-of-nodes than to the thin bars,
which is consistent with the idea that they are vertically thick, in a
similar manner as the boxy/peanut structures in more inclined galaxies.
Typically, the colors of barlenses are also similar to those of normal
E/S0 galaxies. Galaxy by galaxy studies also show that in spiral
galaxies very dusty barlenses also exist, along with barlenses with
rejuvenated stellar populations. The central regions of galaxies are
found to be on average redder than bars or barlenses, although galaxies
with bluer central peaks also exist.
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