Query : 2006A&A...447..221B

2006A&A...447..221B - Astronomy and Astrophysics, volume 447, 221-233 (2006/2-3)

Search for massive protostar candidates in the southern hemisphere. II. Dust continuum emission.


Abstract (from CDS):

In an ongoing effort to identify and study high-mass protostellar candidates we have observed in various tracers a sample of 235 sources selected from the IRAS Point Source Catalog, mostly with δ←30°, with the SEST antenna at millimeter wavelengths. The sample contains 142 Low sources and 93 High, which are believed to be in different evolutionary stages. Both sub-samples have been studied in detail by comparing their physical properties and morphologies. Massive dust clumps have been detected in all but 8 regions, with usually more than one clump per region. The dust emission shows a variety of complex morphologies, sometimes with multiple clumps forming filaments or clusters. The mean clump has a linear size of ∼0.5pc, a mass of ∼320M for a dust temperature Td=30K, an H2 density of 9.5x105cm–3, and a surface density of 0.4g/cm2. The median values are 0.4pc, 102M, 4x104cm–3, and 0.14g/cm2, respectively. The mean value of the luminosity-to-mass ratio, L/M≃99L/M, suggests that the sources are in a young, pre-ultracompact HII phase. We have compared the millimeter continuum maps with images of the mid-IR MSX emission, and have discovered 95 massive millimeter clumps non-MSX emitters, either diffuse or point-like, that are potential prestellar or precluster cores. The physical properties of these clumps are similar to those of the others, apart from the mass that is ∼3 times lower than for clumps with MSX counterpart. Such a difference could be due to the potential prestellar clumps having a lower dust temperature. The mass spectrum of the clumps with masses above M∼100M is best fitted with a power-law dN/dM∝M–α with α=2.1, consistent with the Salpeter (1955ApJ...121..161S) stellar IMF, with α=2.35. On the other hand, the mass function of clumps with masses 10M≲M ≲120M is better fitted with a power law of slope α=1.5, more consistent with the mass function of molecular clouds derived from gas observations.

Abstract Copyright:

Journal keyword(s): stars: circumstellar matter - stars: formation - ISM: clouds - radio continuum: ISM - infrared: ISM

VizieR on-line data: <Available at CDS (J/A+A/447/221): table1.dat table2.dat>

Nomenclature: Table 2: [BBC2006] IRAS HHMMm+DDMM Clump NN N=763.

Status at CDS : All or part of tables of objects could be ingested in SIMBAD with priority 2.

Simbad objects: 7

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Number of rows : 7
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 [BBC2006] IRAS 17149-3916 Clump 2 cor 17 18 19.1 -39 18 54           ~ 3 0
2 [BBC2006] IRAS 17149-3916 Clump 3 cor 17 18 22.5 -39 18 38           ~ 3 0
3 [BBC2006] IRAS 17149-3916 Clump 1 cor 17 18 23.9 -39 19 18           ~ 3 0
4 M 8 HII 18 03 37 -24 23.2           ~ 598 1
5 NAME M 8E IR Y*O 18 04 53.9 -24 26 41           ~ 86 0
6 MSX6C G059.7831+00.0648 Y*O 19 43 11.2464 +23 44 03.270           ~ 135 0
7 IRAS 19410+2336 SFR 19 43 11.5 +23 44 06           ~ 150 0

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