Searching for the in-plane Galactic bar and ring in DENIS

Abstract

New evidence for a long thin Galactic bar (in contradistinction to the bulge), as well as for the existence of the ring and the truncation of the inner disc, are sought in the DENIS survey. First, we examine DENIS and Two Micron Galactic Survey star counts for the characteristic signatures of an in-plane bar and ring. The star counts in the plane for 30 deg.>l>-30 deg. are shown to be highly asymmetric with considerably more sources at positive than at negative longitudes. At |b|\approx 1.5 deg., however, the counts are nearly symmetric. Therefore, the asymmetry is not due to the disc, which is shown to have an inner truncation, or to the bulge, so there has to be another major component in the inner Galaxy that is causing the asymmetries. This component provides up to 50% of the detected sources in the plane between the bulge and l=27 deg. or l=-14 deg. This component is shown to be consistent with an in-plane bar with a position angle of 40 deg. and half-length of 3.9 kpc. However, there is also a major peak in the counts at l=-22 deg., which coincides with the tangential point of the so-called 3 kpc arm. This is shown to be most probably a ring or a pseudo-ring. The extinction in the plane is also shown to be asymmetric with more extinction at negative than at positive longitudes. For l<8 deg. the extinction is shown to be slightly tilted with respect to b=0 deg. in the same manner as the HI disc. We conclude that the Galaxy is a fairly typical ringed barred spiral galaxy.

15 pages, 10 figures, accepted in A&A

Cited by in corpus (30)

• Old stellar Galactic disc in near-plane regions according to 2MASS: scales, cut-off, flare and warp
• Stellar populations in the Milky Way bulge region : Towards solving the Galactic bulge and bar shapes using 2MASS data
• Gas flow models in the Milky Way embedded bars
• Using Cepheids to determine the galactic abundance gradient I. The solar neighbourhood
• The structure of the Galactic bar
• Infrared stellar populations in the central parts of the Milky Way galaxy
• Tracing the long bar with red-clump giants
• The Long Bar in the Milky Way. Corroboration of an old hypothesis
• A Distinct Structure Inside the Galactic Bar
• The long Galactic bar as seen by UKIDSS Galactic Plane Survey
• A boxy bulge in the Milky Way. Inversion of the stellar statistics equation with 2MASS data
• Another bar in the Bulge
• Offset between stellar spiral arms and gas arms of the Milky Way
• 3D outer bulge structure from near infrared star counts
• Major structures of the inner Galaxy delineated by 6.7-GHz methanol masers
• 86 GHz SiO maser survey of late-type stars in the Inner Galaxy. I. Observational data
• The 3D structure of the Galactic bulge
• The start of the Sagittarius spiral arm (Sagittarius origin) and the start of the Norma spiral arm (Norma origin) - model-computed and observed arm tangents at galactic longitudes -20 degrees < l < +23 degrees
• Evidence for a deficit of young and old stars in the Milky Way inner in-plane disc
• Stellar density distribution in the NIR on the Galactic plane at longitudes 15-27 deg. Clues for the Galactic bar ?
• Quantifying the (X/peanut)-shaped Structure of the Milky Way - New Constraints on the Bar Geometry
• An analysis of star formation with Herschel in the Hi-GAL Survey. II. The tips of the Galactic bar
• The ISOGAL field FC--01863+00035: Mid-IR interstellar extinction and stellar populations
• A Galactic Ring of Minimum Stellar Density Near the Solar Orbit Radius
• A search for late-type supergiants in the inner regions of the Milky Way
• The long bar as seen by the VVV Survey: II. Star counts
• Metallicity distribution of red giants in the Inner Galaxy from Near Infrared spectra
• Three-dimensional decomposition of galaxies with bulge and long bar
• Systematic motions in the Galactic plane found in the Hipparcos Catalogue using Herschel's Method
• Bar-driven injection of intergalactic matter into galactic halos