An H i study of the collisional ring galaxy NGC 922. Issue 4 (12th April 2018)

• Record Type: Journal Article
• Authors: Elagali, Ahmed; Wong, O Ivy; Oh, Se-Heon; Staveley-Smith, Lister; Koribalski, Bärbel S; Bekki, Kenji; Zwaan, Martin
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 476:Issue 4(2018)
• Page Start: 5681
• Page End: 5691
• Publication Date: 2018-04-12
• Subjects: galaxies: individual: NGC 922 -- galaxies: kinematics and dynamics -- galaxies: starburst -- radio lines: galaxies; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty741
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract : We present new atomic hydrogen (H i ) observations of the collisional ring galaxy NGC 922 obtained using the Australia Telescope Compact Array. Our observations reveal for the first time the vast extent of the H i disc of this galaxy. The H i morphology and kinematics of NGC 922 show that this galaxy is not the product of a simple drop-through interaction, but has a more complex interaction history. The integrated H i flux density of NGC 922 from our observations is 24.7 Jy km s −1, which is within the error of the flux value obtained using the 64-m Parkes radio telescope. This flux density translates to a total H i mass of 1.1 × 10 10 M⊙ and corresponds to an H i to total mass fraction ($M_{{H\, \small {I}}}$ / M tot ) of approximately 0.11. The gaseous structures of NGC 922 are more extended to the north and include an H i tail that has a projected physical length of 8 kpc. Gas warps are also evident in the velocity field of NGC 922 and are more prominent on the approaching and the western side of the disc. In comparison with a large sample of star-forming galaxies in the local Universe, NGC 922 possesses a high gas fraction relative to galaxies with a similar stellar mass of ∼10 10.4 M⊙, and exhibits a high specific star formation rate.