2008/02/18 by I. Dicaire, Isabelle Dicaire, C. Carignan +10 · 39 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Galactic halo #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy rotation curve #Geometry #Globular cluster #Halo #Milky Way #Physics #Rotation (mathematics) #Stars #Thick disk #astro-ph
paper · pdf · doi:10.1088/0004-6256/135/6/2038
published in The Astronomical Journal 135(6), 2038-2047 (Institute of Physics) · 28 pages, 8 figures. Accepted for publication in AJ
arxiv created 2008/02/18 · openalex publication_date 2008/05/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Deep Hα observations of the Sculptor Group galaxy NGC 7793 were obtained on the ESO 3.60 m and the Marseille 36 cm telescopes at La Silla, Chile. Hα emission is detected all the way to the edge of the H i disk, making the H ii disk of NGC 7793 one of the largest ever observed in a quiet non-active galactic nucleus (AGN) late-type system. Even in the very outer parts, the H ii ionizing sources are probably mainly internal (massive stars in the disk) with an unlikely contribution from the extragalactic ionizing background. The Hα kinematics confirms what had already been seen with the H i observations: NGC 7793 has a truly declining rotation curve. However, the decline is not Keplerian and a dark halo is still needed to explain the rotation velocities in the outer parts.