Outer structure of the Galactic warp and flare: explaining the Canis Major over-density

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dc.creatorMomany, Y.
dc.creatorZaggia, S.
dc.creatorGilmore, G.
dc.creatorPiotto, G.
dc.creatorCarraro, G.
dc.creatorBedin, L. R.
dc.creatorDe Angeli, F.
dc.date2006-03-15
dc.date.accessioned2026-07-07T07:01:07Z
dc.date.available2026-07-07T07:01:07Z
dc.description(Abridged) We derive the structure of the Galactic stellar Warp and Flare using 2MASS RC and RGB stars, selected at mean heliocentric distances of 3, 7 and 17 kpc. Our results are: (i) a clear stellar warp signature is derived for the 3 selected rings; (ii) the derived stellar warp is consistent (both in amplitude and phase-angle) with that for the Galactic interstellar dust and HI gas; (iii) the Sun seems not to fall on the line of nodes. The stellar warp phase-angle orientation (+15 degrees) is close to the orientation angle of the Galactic bar and this produces an asymmetric warp for the inner rings; (iv) a Northern/Southern warp symmetry is observed only for the ring at 17 kpc; (v) treating a mixture of thin and thick disk populations we trace the disk flaring and derive a constant scale-height (~0.65 kpc) within R(GC)~15 kpc. Further out, the disk flaring increase gradually reaching a mean scale-height of ~1.5 kpc at R(GC)~23 kpc; and (vi) these results provide further robust evidence that there is no disk radial truncation at R(GC)~14 kpc. In the particular case of the Canis Major over-density we confirm its coincidence with the Southern stellar maximum warp occurring near l=240. We present evidence to conclude that all observed parameters (e.g. number density, radial velocities, proper motion etc) of CMa are consistent with it being a normal Milky Way outer-disk population, thereby leaving no justification for a more complex interpretations of its origin. The present analysis does not provide a conclusive test of the structure or origin of the Monoceros Ring. Nevertheless, we show that a warped flared Milky Way contributes significantly at the locations of the Monoceros Ring.
dc.description25 pages, 22 figures, accepted for publication in A&A. A higher resolution pdf file is available at http://wwwuser.oat.ts.astro.it/zaggia/public_html/warp/
dc.identifierhttps://arxiv.org/abs/astro-ph/0603385
dc.identifierhttp://arxiv.org/abs/astro-ph/0603385
dc.identifierAstron.Astrophys. 451 (2006) 515-538
dc.identifierdoi:10.1051/0004-6361:20054081
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/108180
dc.subjectAstrophysics
dc.titleOuter structure of the Galactic warp and flare: explaining the Canis Major over-density
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