Search for LBVs in the Local Volume galaxies: study of four stars in NGC 4449

Abstract

We continue to search for LBV stars in galaxies outside the Local Group. In this work, we have investigated four luminous stars in NGC 4449. Multiple spectral observations carried out for J122810.94+440540.6, J122811.70+440550.9, and J122809.72+440514.8 revealed the emission features in their spectra that are characteristic of LBVs. Photometry showed noticeable brightness changes of J122809.72+440514.8 ($\Delta I=0.69\pm 0.13^m$) and J122817.83+440630.8 ($\Delta R=2.15\pm 0.13^m$), while the variability of J122810.94+440540.6 and J122811.70+440550.9 does not exceed $0.3^m$ regardless of the filter. We have obtained estimates of the interstellar reddening, photosphere temperatures, and bolometric luminosities $\log ({\text{L}}_{\text{Bol}}/{\text{L}}_{\odot })\approx 5.24-6.42$. Using the CMFGEN code, we have modelled the spectrum of the cold state of J122809.72+440514.8 ($T_{\text{eff}}=9300$K) and have obtained possible value of the mass loss rate $\dot{M}=5.2\times 10^{-3}{M}_{\odot }y{r}^{-1}$. Based on the observational properties, J122809.72+440514.8 and J122817.83+440630.8 were classified as LBVs, while the other two stars were classified as LBV candidates or B[e]-supergiants candidates

References in corpus (10)

• 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 and Variable Stars in M31 and M33. II. Luminous Blue Variables, Candidate LBVs, Fe II Emission Line Stars, and Other Supergiants
• Luminous and Variable Stars in M31 and M33. IV. Luminous Blue Variables, Candidate LBVs, and the B[e] Supergiants; How to Tell Them Apart
• PNe and H II regions in the starburst irregular galaxy NGC 4449 from LBT MODS data
• Extremely metal-poor galaxy DDO 68: the LBV, H-alpha shells and the most luminous stars
• New Luminous Blue Variable Candidates in NGC 4736
• New luminous blue variable candidates in the NGC 247 galaxy
• Luminous Blue Variable candidates in M31
• Modeling spectra of MN112

Cited by in corpus (1)

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