Stars and gas in the very large interacting galaxy NGC 6872

Abstract

The dynamical evolution of the large (> 100 kpc), barred spiral galaxy NGC 6872 and its small companion IC 4970 in the southern group Pavo is investigated. We present N-body simulations with stars and gas and 21 cm HI observations carried out with the Australia Telescope Compact Array of the large-scale distribution and kinematics of atomic gas. HI is detected toward the companion, corresponding to a gas mass of ca 1.3 10^9 Msun. NGC 6872 contains ca 1.4 10^{10} Msun of HI gas, distributed in an extended rotating disk. Massive concentrations of gas (10^9 Msun) are found at the tip of both tidal tails and towards the break seen in the optical northern arm near the companion. We detect no HI counterpart to the X-ray trail between NGC 6872 and NGC 6876, the dominant elliptical galaxy in the Pavo group located 8 arcmin to the southeast. At the sensitivity and the resolution of the observations, there is no sign in the overall HI distribution that NGC 6876 has affected the evolution of NGC 6872. There is no evidence of ram pressure stripping either. The X-ray trail could be due to gravitational focusing of the hot gas in the Pavo group behind NGC 6872 as the galaxy moves supersonically through the hot medium. The simulations of a gravitational interaction with a small nearby companion on a low-inclination prograde passage are able to reproduce most of the observed features of NGC 6872, including the general morphology of the galaxy, the inner bar, the extent of the tidal tails and the thinness of the southern tail.

arXiv comment12 pages, 11 figures. Accepted for publication in Astronomy & Astrophysics. The resolution of the figures has been greatly reduced. The paper with the original figures can found at http://www.oso.chalmers.se/~horellou/PAPERS/2006n6872.pdf

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Cited by in corpus (13)

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• Identikit 1: A Modeling Tool for Interacting Disk Galaxies
• Star Clusters in the Tidal Tails of Interacting Galaxies: Cluster Populations Across a Variety of Tail Environments
• Smooth and Starburst Tidal Tails in the GEMS and GOODS Fields
• Galaxy Flybys: Evolution of the Bulge, Disk, and Spiral Arms
• Star Formation Histories Across the Interacting Galaxy NGC 6872, the Largest-Known Spiral
• Attack of the Flying Snakes : Formation of Isolated HI Clouds By Fragmentation of Long Streams
• Under Pressure: Star Clusters and the Neutral Hydrogen Medium of Tidal Tails
• Early-type galaxies in low-density environments: NGC 6876 explored through its globular cluster system
• A Multiwavelength View of Star Formation in Interacting Galaxies in the Pavo Group
• The Active Nucleus of IC4970: A Nearby Example of Merger-Induced Cold-Gas Accretion
• Dark matter effect attributed to the inherent structure of cosmic space