New luminous blue variable candidates in the NGC 247 galaxy
Monthly Notices of the Royal Astronomical Society(2020)
摘要
We search for LBV stars in galaxies outside the Local Group. Here we present a study of two bright $H\\alpha$ sources in the NGC 247 galaxy. Object j004703.27-204708.4 ($M_V=-9.08 \\pm 0.15^m$) 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 $\\Delta B = 0.74\\pm0.09^m$ and $\\Delta V = 0.88\\pm0.09^m$, which makes it reliable LBV candidate. The star j004702.18-204739.93 ($M_V=-9.66 \\pm 0.23^m$) 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 ($\\Delta V = 0.29\\pm0.09^m$). We obtained estimates of interstellar absorption, the photosphere temperature, as well as bolometric magnitudes $M_\\text{bol}=-10.5^{+0.5}_{-0.4}$ and $M_\\text{bol}=-10.8^{+0.5}_{-0.6}$, which corresponds to bolometric luminosities $\\log(L_\\text{bol}/L_{\\odot})=6.11^{+0.20}_{-0.16}$ and $6.24^{+0.20}_{-0.25}$ 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.
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关键词
stars: emission-line, Be,stars: massive,stars: variables: S Doradus,galaxies: individual: NGC247
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