WALLABY Pre-pilot Survey: The Effects of Tidal Interaction on Radial Distribution of Color in Galaxies of the Eridanus Supergroup.
Wang et al. 2022. ApJ, DOI:10.3847/1538-4357/ac4270
The Westerbork Coma Survey. A blind, deep, high-resolution H I survey of the Coma cluster.
Molnár et al. 2022 A&A, DOI: 10.1051/0004-6361/202142614
Dpt. Astronomía Extragaláctica
Instituto Astrofísica Andalucía
Glorieta de la Astronomía s/n
18008 Granada
Spain
Star formationIsolated Galaxies Compact Groups Star formation in outer disks
Hierarchical models for galaxy formation as well as N-body/SPH simulations of the evolution of individual disk galaxies, predict an inside-out formation scenario for galaxy disks (see Muñoz-Mateos et al. and references therein). According to this scenario the formation of stars in the outer parts of the disks would have taken place recently. Extreme examples of this inside-out growth are the extended UV (XUV) disks discovered in ~20% of the nearby spiral galaxy population (Thilker al. 2005, 2007, Gil de Paz et al. 2005, 2007). We study the Kennicutt-Schmidt star formation law and efficiency in the gaseous disk of the isolated galaxy CIG 96 (NGC 864), with special emphasis on its unusually large atomic gas (H I) disk (rHI/r25 = 3.5, r25 = 1.′85). We present deep GALEX near and far ultraviolet observations, used as a recent star forma- tion tracer, and we compare them with new, high resolution (16′′, or 1.6 kpc) VLA H I observations.
The UV and H I maps show good spatial correlation out- side the inner 1′, where the H I phase dominates over H2. Star-forming regions in the extended gaseous disk are mainly located along the enhanced H I emission within two (relatively) symmetric giant gaseous spiral arm-like features, which emulate a H Ipseudo-ring at a r ≃ 3′. Inside such structure, two smaller gaseous spiral arms extend from the NE and SW of the optical disk and connect to the previously mentioned H I pseudo-ring.
We discuss about possible mechanisms that might be trig- gering the star formation in the outskirts of this galaxy, and we suggest that the constant SFE for such large radii r > 2 r25 and at such low surface densities might be a common characteristic in extended UV disk galaxies. |