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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 606333.0, MPI für Astronomie / Publikationen_mpia
Sequential star formation in IRAS 06084-0611 (GGD 12-15). From intermediate-mass to high-mass stars
Authors:Maaskant, K. M.; Bik, A.; Waters, L. B. F. M.; Kaper, L.; Henning, T.; Puga, E.; Horrobin, M.; Kainulainen, J.
Date of Publication (YYYY-MM-DD):2011
Journal Abbrev.:Astronomy and Astrophysics
Audience:Not Specified
Abstract / Description:Context. The formation and early evolution of high- and intermediate-mass stars towards the main sequence involves the interplay of stars in a clustered and highly complex environment. To obtain a full census of this interaction, the Formation and Early evolution of Massive Stars (FEMS) collaboration studies a well-selected sample of 10 high-mass star-forming regions. <BR /> Aims: In this study we examine the stellar content of the high-mass star-forming region centered on IRAS 06084-0611 in the Monoceros R2 cloud. <BR /> Methods: Using the near-infrared H- and K-band spectra from the VLT/SINFONI instrument on the ESO Very Large Telescope (VLT) and photometric near-infrared NTT/SOFI, 2MASS and Spitzer/IRAC data, we were able to determine the spectral types for the most luminous stars in the cluster. <BR /> Results: Two very young and reddened massive stars have been detected by SINFONI: a massive young stellar object (YSO) consistent with an early-B spectral type and a Herbig Be star. Furthermore, stars of spectral type G and K are detected while still in the Pre-Main Sequence (PMS) phase. We derive additional properties such as temperatures, extinctions, radii and masses. We present a Hertzsprung-Russell diagram and find most objects having intermediate masses between ~1.5-2.5 M&sun;. For these stars we derive a median cluster age of ~4 Myr. <BR /> Conclusions: Using Spitzer/IRAC data we confirm earlier studies that the younger class 0/I objects are centrally located while the class II objects are spread out over a larger area, with rough scale size radii of ~0.5 pc and ~1.25 pc respectively. Moreover, the presence of a massive YSO, an ultracompact H ii region and highly reddened objects in the center of the cluster suggest a much younger age of <1 Myr. A possible scenario for this observation would be sequential star formation along the line of sight; from a cluster of intermediate-mass to high-mass stars. Based on observations collected at the European Southern Observatory at Paranal, Chile (ESO program 078.C-0780).SINFONI spectra are available in electronic form upon request: kmaaskan@science.uva.nl
Free Keywords:infrared: stars; stars: early-type; stars: formation; stars: pre-main sequence; circumstellar matter
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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