# DDO68-V1: an extremely metal-poor LBV in a void galaxy

## TL;DR

This paper studies DDO68-V1, an extremely metal-poor luminous blue variable star in a void galaxy, analyzing its 30-year lightcurve and documenting a rare giant eruption event.

## Contribution

It provides the first detailed long-term lightcurve of DDO68-V1, revealing a rare giant eruption in an extremely metal-poor LBV, advancing understanding of low-metallicity massive star evolution.

## Key findings

- DDO68-V1 experienced a giant eruption with 4.5 mag amplitude.
- The star's metallicity is Z=Zo/35, one of the lowest known.
- The lightcurve spans over 30 years, showing rare variability.

## Abstract

The lowest metallicity massive stars in the Local Universe with Z~(Zo/50-Zo/30) are the crucial objects to test the validity of assumptions in the modern models of very low-metallicity massive star evolution. These models, in turn, have major implications for our understanding of galaxy and massive star formation in the early epochs. DDO68-V1 in a void galaxy DDO68 is a unique extremely metal-poor massive star. Discovered by us in 2008 in the HII region Knot3 with Z = Zo/35 [12+log(O/H)=7.14], DDO68-V1 was identified as an LBV star. We present here the LBV lightcurve in V band, combining own new data and the last archive and/or literature data on the light of Knot3 over the 30 years. We find that during the years 2008-2011 the LBV have experienced a very rare event of `giant eruption' with V-band amplitude of 4.5 mag (V~24.5-20 mag).