BRAINE, J.; FERGUSON, Annette M. N.; BERTOLDI, Frank; WILSON, Christine D.

doi:10.1086/524135

Métadonnées

Licence d’utilisation du document

BRAINE, J.
Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
Observatoire aquitain des sciences de l'univers [OASU]
Laboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]

FERGUSON, Annette M. N.
Department of Physics

BERTOLDI, Frank

Langue

Article de revue

Ce document a été publié dans

The Astrophysical Journal. 2007, vol. 669, n° 2, p. L73-L76

American Astronomical Society

Résumé en anglais

We present the results of a search for molecular gas emission via the CO line in the far outer disk of the nearby spiral, NGC 6946. The positions targeted were chosen to lie on or near previously-identified outer disk HII regions. Molecular gas was clearly detected out to 1.3 R$_{25}$, with a further tentative detection at 1.4 R$_{25}$. The CO detections show excellent agreement with the HI velocities and imply beam-averaged column densities of $0.3-9\times 10^{20}$ cm$^{-2}$ and molecular gas masses of (2-70)$\times 10^{5}$ M$_{\sun}$ per 21$''$ beam (560pc). We find evidence for an abrupt decrease in the molecular fraction at the edge of the optical disk, similar to that seen previously in the azimuthally-averaged areal star formation rate. Our observations provide new constraints on the factors that determine the presence and detectability of molecular gas in the outskirts of galaxies, and suggest that neither the HI column, the metallicity or the local heating rate alone plays a dominant role.< Réduire

Mots clés en anglais

galaxies: individual (NGC 6946)—galaxies: individual (NGC 1058) — galaxies: spiral — galaxies: ISM

ISM: molecules

radio lines: ISM

Métadonnées

Licence d’utilisation du document

The Detection of Molecular Gas in the Outskirts of NGC 6946

Langue

Ce document a été publié dans

Résumé en anglais

Mots clés en anglais

DOI

Origine

Unités de recherche