2018/11/30 by D. Rosado-Belza, U. Lisenfeld, J. E. Hibbard +9
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Galaxy merger #Irregular galaxy #Lenticular galaxy #Physics #Spiral galaxy #Star formation #Stellar mass #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1051/0004-6361/201833896
published as A&A 623, A154 (2019) · 17 pages, 11 figures, in press (Astronomy & Astrophysics)
arxiv created 2018/12/10 · openalex publication_date 2019/02/18 · arxiv updated 2019/03/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Minor mergers play a crucial role in galaxy evolution. UGC 10214 (the Tadpole galaxy) is a prime example of this process in which a dwarf galaxy has interacted with a large spiral galaxy ∼250 Myr ago and produced a perturbed disc and a giant tidal tail. We used a multi-wavelength dataset that partly consists of new observations (H α , HI, and CO) and partly of archival data 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 high-mass (stellar mass M ⋆ = 1.28 × 10 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 global SFR compared to its stellar mass places UGC 10214 on the galaxy main sequence (MS). The comparison of the molecular gas mass and current SFR gives a molecular gas depletion time of about ∼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, and also from spectral energy distribution 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 where a pronounced peak of the H α emission is visible. 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 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 that resulted in a moderate increase of the SFR, but it has not perturbed the gas significantly so that the molecular depletion time remains normal.