MUSE crowded field 3D spectroscopy in NGC 300 II. Quantitative spectroscopy of BA-type supergiants

TL;DR

This study uses MUSE integral field spectroscopy to analyze BA-type supergiants in NGC 300, extending the flux-weighted gravity-luminosity relationship to lower luminosities and providing detailed stellar parameters.

Contribution

It presents the first detailed spectroscopic analysis of lower-luminosity BA supergiants in NGC 300, extending the FGLR method and demonstrating its applicability at these luminosities.

Findings

Most stars follow the established FGLR.

Increased scatter observed at lower luminosities.

Derived stellar parameters for 16 stars, including temperature and mass.

Abstract

A quantitative spectral analysis of BA-type supergiants and bright giants in an inner spiral arm region of the nearby spiral galaxy NGC 300 is presented, based on observations with the Multi Unit Spectroscopic Explorer (MUSE) on the European Southern Obsevatory, Very Large Telescope (ESO, VLT). The flux-weighted gravity-luminosity relationship (FGLR), a stellar spectroscopic distance determination method for galaxies, is extended towards stars at lower luminosities. Point spread function fitting 3D spectroscopy was performed with PampelMUSE on the datacube. The 16 stars with the highest signal-to-noise ratios ($S/N s$) are classified with regard to their spectral type and luminosity class using Galactic templates. They were analysed using hybrid non-local thermodynamic equilibrium (non-LTE) model spectra to fit the strongest observed hydrogen, helium, and metal lines in the intermediate-resolution spectra. Supplemented by photometric data, this facilitates fundamental stellar parameters and interstellar reddening which have yet to be determined. Effective temperatures, surface gravities, reddening $E(B-V)$, bolometric magnitudes and luminosities, as well as radii and masses are presented for the sample stars. The majority of the objects follow the FGLR as established from more luminous BA-type supergiants in NGC 300. An increase in the scatter in the flux-weighted gravity-luminosity plane is observed at these lower luminosities, which is in line with predictions from population synthesis models.