The evolution of the spectral energy distribution in massive young stellar objects

Molinari, S.; Pezzuto, S.; Cesaroni, R.; Brand, J.; Faustini, F.; Testi, L.

doi:10.1051/0004-6361:20078661

Cited by 244 publications

(527 citation statements)

References 50 publications

(84 reference statements)

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“…We show the empirical loci derived by Molinari et al (2008) and Saraceno et al (1996). To mirror the familiar "Class 0/I/II" distinction in low-mass star formation, Molinari et al (2008) from Saraceno et al (1996) and Molinari's high-mass equivalent "IR-P" source locus is plotted in the solid magenta line.…”

Section: Evolutionary Diagnosticsmentioning

confidence: 67%

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APEX/SABOCA observations of small-scale structure of infrared-dark clouds

Ragan

Henning

Beuther

2013

A&A

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Infrared-dark clouds (IRDCs) harbor the early phases of cluster and high-mass star formation and are comprised of cold (∼20 K), dense (n > 10 4 cm −3 ) gas. The spectral energy distribution (SED) of IRDCs is dominated by the far-infrared and millimeter wavelength regime, and our initial Herschel study examined IRDCs at the peak of the SED with high angular resolution. Here we present a follow-up study using the SABOCA instrument on APEX which delivers 7.8 angular resolution at 350 µm, matching the resolution we achieved with Herschel/PACS, and allowing us to characterize substructure on ∼0.1 pc scales. Our sample of 11 nearby IRDCs are a mix of filamentary and clumpy morphologies, and the filamentary clouds show significant hierarchical structure, while the clumpy IRDCs exhibit little hierarchical structure. All IRDCs, regardless of morphology, have about 14% of their total mass in small scale core-like structures which roughly follow a trend of constant volume density over all size scales. Out of the 89 protostellar cores we identified in this sample with Herschel, we recover 40 of the brightest and re-fit their SEDs and find their properties agree fairly well with our previous estimates ( T ∼ 19 K). We detect a new population of "cold cores" which have no 70 µm counterpart, but are 100 and 160 µm-bright, with colder temperatures ( T ∼ 16 K). This latter population, along with SABOCA-only detections, are predominantly low-mass objects, but their evolutionary diagnostics are consistent with the earliest starless or prestellar phase of cores in IRDCs.Key words. catalogs -stars: formation -ISM: structure -submillimeter: ISM Background and motivationDespite the importance of high-mass stars to the energy budget of galaxies, their formation remains a major open question in astronomy (Zinnecker & Yorke 2007). A major hindrance to progress is the inherent difficulty in obtaining well-defined initial conditions observationally. Because high-mass stars are rare, they are on average at large distances, thus angular resolution is of paramount importance. With the advent of Spitzer Space Telescope and Herschel Space Observatory (Pilbratt et al. 2010), coupled with extensive ground-based survey efforts, we now can approach this observational task statistically.Ever since their discovery in absorption in mid-infrared Galactic plane surveys, ISO data (Perault et al. 1996) and MSX observations (Egan et al. 1998), infrared-dark clouds (IRDCs) have been subject to intense study because they are the cold (T < 20 K), dense (n > 10 4 cm −3 ) environments believed to be required for the formation of high-mass stars and clusters (cf. Rathborne et al. 2006;Ragan et al. 2009;Battersby et al. 2010). They are located throughout the Galactic plane, concentrated within the spiral arms (Jackson et al. 2008). The formation of IRDCs, their kinematic structure and population of Based on observations carried out with the Atacama Pathfinder Experiment (APEX). APEX is a collaboration between Max Planck Institut für Radioastronomie (MPIf...

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Section: Evolutionary Diagnosticsmentioning

confidence: 67%

“…For example, various evolutionary tracks have been proposed (e.g. Saraceno et al 1996;Molinari et al 2008;André et al 2008) which directly connect an initial phase among the SABOCA leaves to the PACS cores a few 10 5 yr later (see Fig. 14).…”

Section: Starless and Protostellar Cores In Irdcsmentioning

confidence: 99%

APEX/SABOCA observations of small-scale structure of infrared-dark clouds

Ragan

Henning

Beuther

2013

A&A

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“…the ratio of their infrared luminosity (LIR) to mass (cf. Molinari et al 2008;Urquhart et al 2013), and has some dependence on the average clump mass, since the highest-mass clumps have an undetectably short infrared-dark lifetime (Motte et al 2007;Urquhart et al 2014b). The mean SFF is therefore set by the relative timescale of the IR-bright protostellar stage to that of the pre-stellar stage, multiplied by the average fraction of productive dense cores.…”

Section: What Does the Star-forming Fraction (Sff) Mean?mentioning

confidence: 99%

The prevalence of star formation as a function of Galactocentric radius

Ragan

Moore

Eden

et al. 2016

Mon. Not. R. Astron. Soc.

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We present large-scale trends in the distribution of star-forming objects revealed by the Hi-GAL survey. As a simple metric probing the prevalence of star formation in Hi-GAL sources, we define the fraction of the total number of Hi-GAL sources with a 70 µm counterpart as the "star-forming fraction" or SFF. The mean SFF in the inner galactic disc (3.1 kpc < R GC < 8.6 kpc) is 25%. Despite an apparent pile-up of source numbers at radii associated with spiral arms, the SFF shows no significant deviations at these radii, indicating that the arms do not affect the star-forming productivity of dense clumps either via physical triggering processes or through the statistical effects of larger source samples associated with the arms. Within this range of Galactocentric radii, we find that the SFF declines with R GC at a rate of −0.026±0.002 per kiloparsec, despite the dense gas mass fraction having been observed to be constant in the inner Galaxy. This suggests that the SFF may be weakly dependent on one or more largescale physical properties of the Galaxy, such as metallicity, radiation field, pressure or shear, such that the dense sub-structures of molecular clouds acquire some internal properties inherited from their environment.

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“…L bol/mmb /M clump is therefore expected to increase as the embedded source evolves towards the main sequence. This model has been reasonably successful in tracing the evolution of massive protostars (e.g., Molinari et al 2008;Giannetti et al 2013;Urquhart et al 2014c).…”

Section: Evidence For An Evolutionary Sequencementioning

confidence: 99%

The almost ubiquitous association of 6.7-GHz methanol masers with dust★

Urquhart

Moore

Menten

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We report the results of 870-µmcontinuum observations, using the Large APEX Bolometer Camera (LABOCA), towards 77 class-II, 6.7-GHz methanol masers identified by the Methanol Multibeam (MMB) survey to map the thermal emission from cool dust towards these objects. These data complement a study of 630 methanol masers associated with compact dense clumps identified from the ATLASGAL survey. Compact dust emission is detected towards 70 sources, which implies a dust-association rate of 99 per cent for the full MMB catalogue. Evaluation of the derived dust and maser properties leads us to conclude that the combined sample represents a single population tracing the same phenomenon. We find median clump masses of a few 10 3 M ⊙ and that all but a handful of sources satisfy the mass-size criterion required for massive star formation. This study provides the strongest evidence of the almost ubiquitous association of methanol masers with massive, star-forming clumps. The fraction of methanol-maser associated clumps is a factor of ∼2 lower in the outer Galaxy than the inner Galaxy, possibly a result of the lower metallicity environment of the former. We find no difference in the clump-mass and maser-luminosity distributions of the inner and outer Galaxy. The maser-pumping and clump-formation mechanisms are therefore likely to be relatively invariant to Galactic location. Finally, we use the ratio of maser luminosity and clump mass to investigate the hypothesis that the maser luminosity is a good indicator of the evolutionary stage of the embedded source, however, we find no evidence to support this.

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The evolution of the spectral energy distribution in massive young stellar objects

Cited by 244 publications

References 50 publications

APEX/SABOCA observations of small-scale structure of infrared-dark clouds

APEX/SABOCA observations of small-scale structure of infrared-dark clouds

The prevalence of star formation as a function of Galactocentric radius

The almost ubiquitous association of 6.7-GHz methanol masers with dust★

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