# Spectral observations of the systems with the disturbed spiral arms: Arp 42, Arp 82 and Arp58

## TL;DR

This study uses spectral observations to analyze gas kinematics, metallicity, and star formation in three peculiar Arp galaxy systems with disturbed spiral arms, revealing velocity disturbances and shallow abundance gradients indicative of interactions.

## Contribution

It provides detailed spectral analysis of three peculiar galaxy systems, highlighting gas dynamics and metallicity patterns associated with spiral arm disturbances and interactions.

## Key findings

- All systems show velocity disturbances and enhanced gas velocity dispersion.
- Shallow radial metallicity gradients are observed, typical for interacting galaxies.
- Tidal features may be remnants of pre-existing spiral wave modes.

## Abstract

We study three Arp' systems of peculiar galaxies: Arp 42 (NGC 5829), Arp 82 (NGC 2535/36) and Arp 58 (UGC 4457), using the long-slit spectral observations carried out at the 6m telescope BTA of Special Astrophysical Observatory. Arp 82 and Arp 58 are the M51-type systems. In the third system - Arp 42, there are two extremely luminous kpc-sized clumps observed at the ends of the bifurcated spiral arm, however the source of perturbations remains unknown. From the emission line measurements we analyzed the distribution of gas line-of-sight (LOS) velocity, velocity dispersion and gas-phase metallicity along the slits estimated by different methods. A special attention is paid to the young regions of star formation at the peripheries of the galaxies and in tidal debris, their connection with gas kinematics and abundance. All three systems show the signs of velocity disturbances and the presence of regions of locally enhanced gas velocity dispersion, as well as the regions of diffuse ionized gas. A distribution of oxygen reveals shallow radial abundance gradients, typical for interacting systems. A faint spiral-like branches of tidal bridges which are observed in NGC 2535 and UGC 4457 may represent the remnants of pre-existing "old" mode of spiral waves.