Young stellar clumps in the interacting system Arp 305

Abstract

We present the results of optical long-slit spectral observations of interacting system Arp305 carried out at the 6m telescope BTA at the SAO RAS: the radial variation of gas kinematics and oxygen abundance. This study continues the series of spectral observations of tidal debris in the interacting galaxies. Here we pay special attention to the star-forming region between the interacting galaxies -a tidal dwarf galaxy (TDG) candidate. This star-forming system appears to be gravitationally bound or close to this condition. We show that TDG is metal poor in comparison to the parental galaxy. It can indicate that either the origin of star-forming gas of TDG was very far from the centre of parent galaxy or its gas has been diluted by the accretion of metal poor intergalactic gas. Nevertheless the region of the brightest emission clump in TDG where a current star formation takes place reveals a noticeable colour excess evidencing a local gas concentration. We pay attention that TDG is situated in the region of intersection of two gas flows and is in a process of formation probably caused by the collision of these flows. Low velocity difference between TDG, NGC 4017 and the gaseous bridge between them evidences that the lifetime of TDG is restricted by the time of its fall back onto the parent galaxy.

Spectral observations of the systems with the disturbed spiral arms: Arp 42, Arp 82, and Arp 58

“…A procedure of data processing was described step-bystep in our earlier papers (Zasov et al 2015(Zasov et al , 2016(Zasov et al , 2017(Zasov et al , 2018. To process the data we used the -based pipeline.…”

“…In this paper we continue to describe the results of spectral observations at the 6m telescope BTA of Special Astrophysical Observatory of disturbed galaxies with local regions of star formation in the periphery of discs or in the intergalactic space which we started in Zasov et al (2015Zasov et al ( , 2016Zasov et al ( , 2017Zasov et al ( , 2018. Here we focus on the three Arp systems Arp 42, Arp 82, and Arp 58.…”

Observational insights on the origin of giant low surface brightness galaxies

“…The formation of this spiral arm could have been induced by the interaction with neighbouring galaxies. Another similarly perturbed galaxy is NGC 4017 surrounded by the tidal debris resulting from the recent interaction, where one of the tidal tails lies on the continuation of the spiral arm (Sengupta et al 2017;Zasov et al 2018). These examples demonstrate the possibility of the giant LSB disc formation by gravitational interactions (flybys).…”

NGC 90: a hidden jelly-fish galaxy?

“…In this paper which is a continuation of our series of works on the interacting systems (Zasov et al 2015(Zasov et al , 2016(Zasov et al , 2017(Zasov et al , 2018(Zasov et al , 2019 we describe the results of optical spectral observations of NGC 90 with a long-slit aimed to study its Sengupta et al (2015). Left: the zoomed region around NGC 90 in DECaLS r-filter with H contours and overplotted positions of the slit and the apertures considered in photometric analysis.…”