Flaring and warping of the Milky Way disk: not only in the gas

Abstract

This paper presents an investigation of the outer disk structure by using data from a recent release of the 2 micron sky survey (2MASS). This 2MASS data show unambiguously that the stellar disk thickens with increasing distance from the Sun. In one of the field (longitude l$=$240) there is also strong evidence of an assymetry associated with the Galactic warp. This flaring and warping of the stellar disk is very similar to the features observed in the HI disk. The thickening of the stellar disk explains the drop in density observed near the Galactic plane: stars located at lower Galactic latitudes are re-distributed to higher latitudes. It is no longer necessary to introduce a disk cut-off to explain the drop in density. It is also not clear how this flaring disk is distinct from the thick disk in the outer disk region. At least, for lines of sight in the direction of the outer disk, the thickening of the disk is sufficient to account for the excess in star counts attributed by some models to the thick disk.

arXiv comment9 pages, 20 figure, submited to MNRAS

Cited by in corpus (3)

• The thick disks of spiral galaxies as relics from gas-rich, turbulent, clumpy disks at high redshift
• Flare in the Galactic stellar outer disc detected in SDSS-SEGUE data
• Warp and flare of the old Galactic disc as traced by the red clump stars