English

New luminous blue variable candidates in the NGC 247 galaxy

Solar and Stellar Astrophysics 2020-09-02 v1 Astrophysics of Galaxies

Abstract

We search for LBV stars in galaxies outside the Local Group. Here we present a study of two bright HαH\alpha sources in the NGC 247 galaxy. Object j004703.27-204708.4 (MV=9.08±0.15mM_V=-9.08 \pm 0.15^m) shows the spectral lines typical for well-studied LBV stars: broad and bright emission lines of hydrogen and helium He I with P Cyg profiles, emission lines of iron Fe II, silicon Si II, nitrogen N II and carbon C II, forbidden iron [Fe II] and nitrogen [N II] lines. The variability of the object is ΔB=0.74±0.09m\Delta B = 0.74\pm0.09^m and ΔV=0.88±0.09m\Delta V = 0.88\pm0.09^m, which makes it reliable LBV candidate. The star j004702.18-204739.93 (MV=9.66±0.23mM_V=-9.66 \pm 0.23^m) shows many emission lines of iron Fe II, forbidden iron lines [Fe II], bright hydrogen lines with broad wings, and also forbidden lines of oxygen [O I] and calcium [Ca II] formed in the circumstellar matter. The study of the light curve of this star also did not reveal significant variations in brightness (ΔV=0.29±0.09m\Delta V = 0.29\pm0.09^m). We obtained estimates of interstellar absorption, the photosphere temperature, as well as bolometric magnitudes Mbol=10.50.4+0.5M_\text{bol}=-10.5^{+0.5}_{-0.4} and Mbol=10.80.6+0.5M_\text{bol}=-10.8^{+0.5}_{-0.6}, which corresponds to bolometric luminosities log(Lbol/L)=6.110.16+0.20\log(L_\text{bol}/L_{\odot})=6.11^{+0.20}_{-0.16} and 6.240.25+0.206.24^{+0.20}_{-0.25} for j004703.27-204708.4 and j004702.18-204739.93 respectively. Thus, the object j004703.27-204708.4 remains a reliable LBV candidate, while the object j004702.18-204739.93 can be classified as B[e]-supergiant.

Keywords

Cite

@article{arxiv.2008.06215,
  title  = {New luminous blue variable candidates in the NGC 247 galaxy},
  author = {Y. Solovyeva and A. Vinokurov and A. Sarkisyan and K. Atapin and S. Fabrika and A. F. Valeev and A. Kniazev and O. Sholukhova and O. Maslennikova},
  journal= {arXiv preprint arXiv:2008.06215},
  year   = {2020}
}

Comments

Accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journal 2020 July 15