Spitzer-IRAC GLIMPSE of high mass protostellar objectsII. SED modelling of a bona fide sample

J. M. C. Grave; M. S. N. Kumar

摘要

Context. In a previous work (Paper 1, Kumar Grave, 2007, AA, 472, 155) a sample of 380 HMPO targets was studied using theGLIMPSE point source catalog and images. A colour—magnitude analysis of the point sources resulted in the identification of infraredcounterparts (IRC) of the (sub)mm cores of HMPO candidates which were considered bona fide targets.Aims. We aim to estimate and analyse the physical properties of the infrared counterparts of HMPOs by comparing their spectralenergy distributions (SED) with those predicted by radiative transfer accretion models of YSOs.Methods. The SED of 68 IRCs are extended beyond the GLIMPSE photometry to the possible limits, from the near-infrared to themillimetre wavelengths, by using the 2MASS, GLIMPSE version 2.0 catalogs, MSX, IRAS and some single dish (and interferometric)(sub)mm data. An online SED fitting tool that uses 2D radiative transfer accretion models of YSOs is employed to fit the observedSED to obtain various physical parameters.Results. The SED of IRCs were fitted by models of massive protostars with a range of masses between 5-42 Mo and ages between 103and 106 years. The median mass and age are 10 Me and 104 yrs. The observed data favours protostars of low effective temperatures(4000-1000 K) with correspondingly large effective photospheres (2-200 Re) for the observed luminosities. The envelopes are largewith a mean size of —0.2-0.3 pc and show a distribution that is very similar to the distribution of the sizes of 8 pm nebulae discussedin Paper I. The estimated envelope accretion rates are high with a mean value of 10-3 Mo/yr and show a power law dependence onmass with an exponent of 2, suggesting spherical accretion at those scales. Disks are found to exist in most of the sources with a meanmass of 10-1 4±0.7 mc)Conclusions. The observed infrared-millimetre SED of the infrared counterparts of HMPOs are successfully explained with an YSOaccretion model. The modelled sources mostly represent proto-B stars although some of them could become 0 stars in the future.We demonstrate that many of these results may represent a realistic picture of massive star formation, despite some of the discrepantresults which may be an effect of the assumptions within the models.

Spitzer-IRAC GLIMPSE of high mass protostellar objectsII. SED modelling of a bona fide sample

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