Star formation and gas in the minor merger UGC 10214

D. Rosado-Belza; U. Lisenfeld; J. Hibbard; K. Kniermann; J. Ott; S. Verley; M. Boquien; T. Jarrett; C. K. Xu

doi:10.1051/0004-6361/201833896

paper

Star formation and gas in the minor merger UGC 10214

arXiv:1811.12417 · doi:10.1051/0004-6361/201833896

Abstract

UGC 10214 is a minor merger in which a dwarf galaxy has interacted with a large spiral galaxy $\sim$ 250 Myr ago and produced a perturbed disk and a giant tidal tail. We use a multiwavelength dataset in order to study the present and past star formation rate (SFR) and its relation to the gas and stellar mass at a spatial resolution down to 4 kpc. UGC 10214 is a very massive (stellar mass $M_{⋆}$ = $1.28 \times 1 0^{11}$ $M_{⊙}$ ) galaxy with a low gas fraction ( $M_{gas}$ / $M_{⋆}$ = 0.24), a high molecular gas fraction ( $M_{H_{2}}$ / $M_{HI}$ = 0.4) and a modest SFR (2-5 $M_{⊙}$ yr $^{- 1}$ ). The comparison of the molecular gas mass and current SFR gives a molecular gas depletion time of about $\sim$ 2 Gyr (based on H $α$ ), comparable to those of normal spiral galaxies. Both from a comparison of the H $α$ emission, tracing the current SFR, and far-ultraviolet (FUV) emission, tracing the recent SFR during the past tens of Myr, as well as from spectral energy distribution (SED) fitting with CIGALE, we find that the SFR has increased by a factor of about 2-3 during the recent past. This increase is particularly noticeable in the centre of the galaxy. A pixel-to-pixel comparison of the SFR, molecular gas mass and stellar mass shows that the central region has had a depressed FUV-traced SFR, both compared to the molecular gas and the stellar mass, whereas the H $α$ -traced SFR shows a normal level. The atomic and molecular gas distribution is asymmetric, but the position-velocity diagram along the major axis shows a pattern of regular rotation. We conclude that the minor merger has most likely caused variations in the SFR in the past resulting in a moderate increase of the SFR, but it has not perturbed the gas significantly so that the molecular depletion time remains normal.

arXiv comment17 pages, 11 figures, in press (Astronomy & Astrophysics)

Star formation and gas in the minor merger UGC 10214

Abstract

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