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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 730221.0, MPI für Astronomie / Publikationen_mpia
The blue supergiant MN18 and its bipolar circumstellar nebula
Authors:Gvaramadze, V. V.; Kniazev, A. Y.; Bestenlehner, J. M.; Bodensteiner, J.; Langer, N.; Greiner, J.; Grebel, E. K.; Berdnikov, L. N.; Beletsky, Y.
Date of Publication (YYYY-MM-DD):2015
Title of Journal:Monthly Notices of the Royal Astronomical Society
Volume:454
Issue / Number:1
Start Page:219
End Page:237
Audience:Not Specified
Abstract / Description:We report the results of spectrophotometric observations of the massive star MN18 revealed via discovery of a bipolar nebula around it with the Spitzer Space Telescope. Using the optical spectrum obtained with the Southern African Large Telescope, we classify this star as B1 Ia. The evolved status of MN18 is supported by the detection of nitrogen overabundance in the nebula, which implies that it is composed of processed material ejected by the star. We analysed the spectrum of MN18 by using the code CMFGEN, obtaining a stellar effective temperature of ≈21 kK. The star is highly reddened, E(B - V) ≈ 2 mag. Adopting an absolute visual magnitude of MV = -6.8 ± 0.5 (typical of B1 supergiants), MN18 has a luminosity of log L/L ≈ 5.42 ± 0.30, a mass-loss rate of ≈(2.8-4.5) × 10- 7 M yr- 1, and resides at a distance of ≈5.6^{+1.5} _{-1.2} kpc. We discuss the origin of the nebula around MN18 and compare it with similar nebulae produced by other blue supergiants in the Galaxy (Sher 25, HD 168625, [SBW2007] 1) and the Large Magellanic Cloud (Sk-69°202). The nitrogen abundances in these nebulae imply that blue supergiants can produce them from the main-sequence stage up to the pre-supernova stage. We also present a K-band spectrum of the candidate luminous blue variable MN56 (encircled by a ring-like nebula) and report the discovery of an OB star at ≈17 arcsec from MN18. The possible membership of MN18 and the OB star of the star cluster Lynga 3 is discussed.
Free Keywords:circumstellar matter; stars: individual: [GKF2010] MN18; stars: individual: [GKF2010] MN56; stars: individual: [GKF2010] MN109; supergiants; stars: winds; outflows; open clusters and associations: individual: Lynga 3
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0035-8711 %R 10.1093/mnras/stv1995
URL:http://cdsads.u-strasbg.fr/abs/2015MNRAS.454..219G
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