Star formation in the nearby dwarf galaxy DDO 53: interplay between gas accretion and stellar feedback

Abstract

We present the results of a multiwavelength study of the nearby dwarf galaxy DDO 53 – a relatively isolated member of the M 81 group. We analyse the atomic and ionised gas kinematics (based on the observations with Fabry-Perot interferometer in Hα line and archival data in H i 21 cm line), distribution, excitation and oxygen abundance of the ionised gas (based on the long-slit and integral-field spectroscopy and on imaging with narrow-band filters), and their relation with the young massive stars (based on archival HST data). We detect a faint 2-kpc sized supershell of ionised gas surrounding the galaxy. Most probably, this structure represents a large-scale gas outflow, however it could be also created by the ionising quanta leaking from star-forming regions to the marginally detected atomic hydrogen surrounding the galactic disc. We analyse the properties of the anomalous H i in the north part of the galaxy and find that its peculiar kinematics is also traced by ionised gas. We argue that this H i feature is related to the accreting gas cloud captured from the intergalactic medium or remaining after the merger event occurred >1 Gyr ago. The infalling gas produces shocks in the interstellar medium and could support the star formation activity in the brightest region in DDO 53.

The H i gas disc thickness of the ultra-diffuse galaxy AGC 242019

“…AGC 242019 and dwarf irregulars are isolated systems so that their disk thickness is not likely caused by environmental effects, although some dwarfs show faint tidal tails (i.e Hunter & Elmegreen 2006;Zhang et al 2012). On the other hand, the stellar feedback is found to be important for dwarf galaxies: Hunter et al (1993) found that NGC 2366, DDO 50, and DDO 53 have shell structures; Egorov et al (2021) identified six expanding superbubbles in DDO 53; DDO 50 contains many H holes (Puche et al 1992;Iorio et al 2017); Zhang et al (2012) derived star formation histories (SFH) with the SED fitting method and found that most of them have went through active star formation phases. Stellar feedback is also proposed to be important to expand the disk sizes for H -bearing UDGs (Jiang et al 2019;Liao et al 2019), which could thicken the disk as well (Sánchez-Janssen et al 2010;Di Cintio et al 2017;Jiang et al 2019;Liao et al 2019).…”

A kinematical study of the dwarf irregular galaxy NGC 1569 and its supernova remnants

“…In the case of NGC 1569, the 'O' region is located where the monochromatic image displays rather low intensity values (right panel of Figure 1) displaying a similar trend of the one mentioned by the authors above. The presence of double components in the Hα profiles in the central parts of dwarf irregular galaxies has also been studied by Egorov et al (2021). In their work, the analysis of the small-scale kinematics of the ionised gas indicated that the presence of composite profiles seemed to be associated with star-formation (SF) related phenomena (see their Figure 8).…”

“…However, the angular resolution of HI observations is not very large. Combining the RCs obtained for central regions of galaxies from ionised gas data with the results from neutral hydrogen data for the more external regions is becoming more frequent (Moiseev 2014;Egorov et al 2021). On the other hand, it is rather difficult to measure the RC of gas in dwarf galaxies.…”

“…The ionising radiation of OB stars, as well as the kinetic energy of stellar winds and supernova explosions can heat the gas, forming bubbles, shells, outflows and chaotic turbulent motions in the gaseous disc. In some cases, these motions dominate the kinematics and dynamics in the inner parts of dwarf galaxies, so a reliable RC that properly describes or traces the potential well of the galaxy cannot be derived from the ionised gas as suggested by Moiseev & Lozinskaya (2012); Moiseev et al (2015); Egorov et al (2021).…”

Measurements of the Expansion Velocities of Ionized-Gas Superbubbles in Nearby Galaxies Based on Integral Field Spectroscopy Data

“…This effect is often apparent in observations. Thus one can efficiently search for expanding superbubbles in nearby galaxies by analyzing (I-σ) diagrams in the Hα line (Muñoz-Tuñón et al, 1996;Moiseev and Lozinskaya, 2012;Egorov et al, 2017Egorov et al, , 2021, where such objects can be distinguished by their increased velocity dispersion. Compact nebulae around individual energetic objects (WR, LBV stars) and unresolved supernova remnants also stand out on the (I-σ)-diagram as regions with high intensity and high velocity dispersion (Moiseev and Lozinskaya, 2012).…”