Two New LBV Candidates in the M 33 Galaxy
Abstract
We present two new luminous blue variable (LBV) candidate stars discovered in M 33. We identified these stars (Valeev et al. 2010a, b) as massive star candidates at the final stages of evolution. The candidates were selected from the Massey et al. (2006) catalog based on the following criteria: emission in Hα, V<18.5m and 0.35m < (B-V) < 1.2m (presumably reddened early stars). Based on our spectroscopy of the stars, we estimated their main parameters. Object N 45901 has a bolometric luminosity log(L/L_{sun}) = 6.0 - 6.2 with the value of interstellar extinction A_V = 2.3 ± 0.1. The temperature of the star's photosphere is T_star ∼ 13000 - 15000 K, its probable mass is M ∼ 60-80 M_{sun}. The infrared excess in N
45901 corresponds to the emission of warm dust with a temperature T_{{warm}} ∼ 1000 K. the bolometric luminosity of the second object, N 125093, is log(L/L_{sun}) = 6.3 - 6.6, the value of interstellar extinction is A_V = 2.75 ± 0.15. Its photosphere's temperature is T_star ∼ 13000 - 16000 K, the initial mass is M∼ 90-120 M_{sun}. The infrared excess in N 125093 amounts to 5-6 % of the bolometric luminosity. Its spectral energy distribution reveals two thermal components with temperatures T_{warm} ∼ 1000 K and T_{cold} ∼ 480 K. The CaII] λ λ 7291, 7323 lines, observed in LBV-like stars Var A and N 93351 in M 33, are also present in the spectrum of N 125093. The high bolometric luminosities of these stars and broad Hα, emissions allow classifying the studied objects as LBV candidates.- Publication:
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Bulletin de la Societe Royale des Sciences de Liege
- Pub Date:
- January 2011
- Bibcode:
- 2011BSRSL..80..425S