# The emission-line regions in the nucleus of NGC 1313 probed with GMOS-IFU: a supergiant/hypergiant candidate and a kinematically cold nucleus

## TL;DR

This study uses GMOS-IFU observations to analyze the nuclear emission-line regions of NGC 1313, identifying Wolf-Rayet stars, a potential hypergiant, and a kinematically cold nucleus, revealing insights into its stellar and gas dynamics.

## Contribution

First detailed emission-line analysis of NGC 1313's nucleus using integral field spectroscopy, identifying specific stellar populations and gas kinematics.

## Key findings

- Detection of Wolf-Rayet stars near the nucleus.
- Identification of a massive emission-line star candidate.
- Observation of a cold gas region with low velocity dispersion.

## Abstract

NGC 1313 is a bulgeless nearby galaxy, classified as SB(s)d. Its proximity allows high spatial resolution observations. We performed the first detailed analysis of the emission-line properties in the nuclear region of NGC 1313, using an optical data cube obtained with the Gemini Multi-object Spectrograph. We detected four main emitting areas, three of them (regions 1, 2 and 3) having spectra typical of H II regions. Region 1 is located very close to the stellar nucleus and shows broad spectral features characteristic of Wolf-Rayet stars. Our analysis revealed the presence of one or two WC4-5 stars in this region, which is compatible with results obtained by previous studies. Region 4 shows spectral features (as a strong H$\alpha$ emission line, with a broad component) typical of a massive emission-line star, such as a luminous blue variable, a B[e] supergiant or a B hypergiant. The radial velocity map of the ionized gas shows a pattern consistent with rotation. A significant drop in the values of the gas velocity dispersion was detected very close to region 1, which suggests that the young stars there were formed from this cold gas, possibly keeping low values of velocity dispersion. Therefore, although detailed measurements of the stellar kinematics were not possible (due to the weak stellar absorption spectrum of this galaxy), we predict that NGC 1313 may also show a drop in the values of the stellar velocity dispersion in its nuclear region.