The long bar as seen by the VVV Survey

Abstract

Context. There is still some debate about the presence and the morphological properties of the long bar in the inner Galaxy. Aims. We investigate the morphological properties of the long Galactic bar using the VVV survey extending star counts at least 3 mag deeper than 2MASS. Our study covers the relatively unexplored negative longitudes of the Galactic bar. We obtain a detailed description of the spatial distribution of star counts towards the long Galactic bar as well as to measure its parameters. Methods. We performed star counts towards −20 • < < 0, |b| ≤ 2 • using VVV, 2MASS, and GLIMPSE data. We applied an average interstellar extinction correction. We also adjusted latitudinal profiles to obtain the centroid variation and bar thickness. Results. We probe the structure of long Galactic bar, as well as its far edge at ≈ −14 • . The differences between counts with and without extinction correction allow us to produce a crude extinction map showing regions with high extinction, mainly beyond the end of long Galactic bar. The latitudinal profiles show evidence of the centroid vertical variation with Galactic longitude reaching a minimum at ≈ −13.8 • . The bar has an inclination angle α = 43 • ± 5 • with respect to the line Sun-Galactic center. In addition, we have determined the bar parameters, such as thickness, length, and stellar distribution.

The Milky Way Bulge: Observed Properties and a Comparison to External Galaxies

“…The position angle of this longer component has been constrained to ∼45 degrees in such studies (e.g. López-Corredoira et al, 2007;Cabrera-Lavers et al, 2007;Hammersley et al, 2000;Churchwell et al, 2009;Amôres et al, 2013). On the other hand, the recent model of the global distribution of red-clump stars from Wegg and Gerhard (2013) provided a precise measurement for the B/P Bulge position angle of 27 ± 2 degrees, in agreement with the studies done at larger distances from the Galactic plane.…”

The 3D Structure of the Galactic Bulge

“…• -45 • ) and half-length (3.7 -4.4 kpc) (see Benjamin et al 2005;López-Corredoira et al 2007;CabreraLavers et al 2007CabreraLavers et al , 2008Vallenari, Ragaini, & Bertelli 2008;Churchwell et al 2009;Amôres et al 2013). Moreover, the vast majority of these studies favour the thesis for which the Milky Way hosts two bars: the main bar confined in the bulge within |l| ≤ 10…”

An analysis of star formation withHerschelin the Hi-GAL Survey

“…The black dotted circles indicate the heliocentric distance, while the green dashed circles indicate the galactocentric radius. The long bar as from Amores et al (2013) is shown in gray, and the black rectangles indicate the sources considered at the edges of the bar in the present paper. The Sun is at the bottom of the image (orange circle) and the GC is represented by the black cross at the position (0,0).…”

“…According to the information about the MW structure currently available, mostly based on spectroscopic observations of the ISM and star counts (see, for example Benjamin et al (2005); Rodriguez-Fernandez & Combes (2008)), the MW is a barred spiral Galaxy with two main arms and several secondary arms. The long in-plane Galactic bar (Lopez-Corredoira et al 2001;Benjamin et al 2005;López-Corredoira et al 2007;Amores et al 2013) has length, horizontal and vertical thickness of approximately 7.8 kpc × 1.2 kpc × 0.2 kpc, respectively. The major axis is inclined by an angle of approximatley 42…”