Young stellar clumps in the interacting systems: Arp305

TL;DR

This study uses optical spectroscopy to analyze the gas kinematics and metallicity of a tidal dwarf galaxy candidate in Arp305, revealing its formation process and relation to the interacting galaxies.

Contribution

It provides detailed spectroscopic evidence of a TDG candidate, highlighting its metallicity, formation environment, and kinematic relationship with the parent galaxies in Arp305.

Findings

TDG is metal poor compared to parent galaxy.

TDG is forming at the intersection of gas flows.

Low velocity difference suggests a short-lived formation.

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.