Search for LBVs in the Local Volume galaxies: study of two stars in NGC 1156

Abstract

We continue the search for luminous blue variables (LBVs) in Local Volume galaxies in order to study their fundamental parameters. In this paper, we report the discovery of two new LBVs in the dwarf irregular galaxy NGC 1156. Both stars exhibit spectral variability simultaneously with strong brightness variations: $\Delta {\text{R}}_c=0.84\pm 0.23^m$ for J025941.21+251412.2 and $\Delta {\text{R}}_c=2.59\pm 0.10^m$ for J025941.54+251421.8. The bolometric luminosities of the stars are in the range of L${}_{\text{Bol}}\approx (0.8-1.6)\times 10^6$ L${}_{\odot }$. These values are corrected for reddening A${}_{\text{V}}\approx 0.9$ and are given for the distance to the galaxy D=7.0$\pm$0.4 Mpc, which we have measured by the TRGB method. Both stars are above the Humphreys-Davidson limit in the region of relatively low temperatures, T${}_{\text{eff}}\lesssim 10$ kK on the temperature-luminosity diagram. J025941.54+251421.8 had a temperature below the hydrogen ionisation threshold at maximum brightness, exhibiting behaviour very similar to that of the known LBV R71 during its 2012 outburst. We have estimated the masses of the detected LBVs and studied the properties of their stellar environment. We discuss our results within the framework of both a single star and a binary system evolution scenario for LBVs.

References in corpus (18)

• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• New PARSEC evolutionary tracks of massive stars at low metallicity: testing canonical stellar evolution in nearby star forming dwarf galaxies
• Luminous Blue Variables are Antisocial: Their Isolation Implies that they are Kicked Mass Gainers in Binary Evolution
• Luminous Blue Variables as the progenitors of supernovae with quasi-periodic radio modulations
• SN 2005 gj: Evidence for LBV supernovae progenitors?
• Luminous and Variable Stars in M31 and M33. II. Luminous Blue Variables, Candidate LBVs, Fe II Emission Line Stars, and Other Supergiants
• Multiplicity of Galactic Luminous Blue Variable stars
• The isolation of Luminous Blue Variables: On subdividing the sample
• Extremely metal-poor galaxy DDO 68: the LBV, H-alpha shells and the most luminous stars
• Spectroscopic and photometric oscillatory envelope variability during the S Doradus outburst of the Luminous Blue Variable R71
• New Luminous Blue Variable Candidates in NGC 4736
• Candidate LBV stars in galaxy NGC 7793 found via HST photometry + MUSE spectroscopy
• The Blue Supergiant Progenitor of the Supernova Imposter AT~2019krl
• The Nearby and Extremely Metal-Poor Galaxy CGCG 269-049
• New luminous blue variable candidates in the NGC 247 galaxy
• The contribution by luminous blue variable stars to the dust content of the Magellanic Clouds
• Search for LBVs in the Local Volume galaxies: study of four stars in NGC 4449
• LBV phenomenon and binarity: The environment of HR Car

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