Sequential star formation in IRAS 06084-0611 (GGD 12-15): From intermediate-mass to high-mass stars

Abstract

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. 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. 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. Results. Two very young and reddened massive stars have been detected by SINFONI: a massive Young Stellar Object (YSO) con- sistent 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 \sim1.5-2.5 M\odot. For these stars we derive a median cluster age of \sim4 Myr. 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 \sim0.5 pc and \sim1.25 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.

14 pages, 10 figures, 2 tables. Astronomy and Astrophysics

References in corpus (7)

• A Spitzer Survey of Young Stellar Clusters within One Kiloparsec of the Sun: Cluster Core Extraction and Basic Structural Analysis
• Dynamical mass segregation on a very short timescale
• VLT K-band spectroscopy of massive young stellar objects in (ultra-)compact HII regions
• Different Evolutionary Stages in the Massive Star Forming Region S255 Complex
• The Complete Initial Mass Function Down to the Sub-Solar Regime in the Large Magellanic Cloud with Hubble Space Telescope ACS Observations
• Probing discs around massive young stellar objects with CO first overtone emission
• Massive molecular outflows associated with UCHII/HII regions

Cited by in corpus (12)

• Stars with Photometrically Young Gaia Luminosities Around the Solar System (SPYGLASS) I: Mapping Young Stellar Structures and their Star Formation Histories
• Polycyclic Aromatic Hydrocarbon in Protoplanetary Disks around Herbig Ae/Be and T Tauri Stars
• RCW36: characterizing the outcome of massive star formation
• Early science with the Large Millimetre Telescope: An LMT/AzTEC 1.1 mm Survey of Dense Cores in the Monoceros R2 Giant Molecular Cloud
• A Statistical Study of Massive Cluster-Forming Clumps
• YSOVAR: Mid-infrared Variability Among YSOs in the Star Formation Region GGD 12-15
• The young stellar content of the giant HII regions M8, G333.6-0.2, and NGC6357 with VLT/KMOS
• Which young clusters/associations are we missing today?
• Externally irradiated young stars in NGC 3603. A JWST NIRSpec catalogue of pre-main-sequence stars in a massive star formation region
• Cluster Formation in GGD12-15: Infall Motion with Rotation of the Natal Clump
• On the evolution of irradiated turbulent clouds: A comparative study between modes of triggered star-formation
• S2D2: Small-scale Significant substructure DBSCAN Detection II. Tracing episodes and gradients of star formation activity