The fidelity of the core mass functions derived  from dust column density data

Kainulainen, J.; Lada, Charles J.; Rathborne, Jill

doi:10.1051/0004-6361/200810987

Cited by 40 publications

(69 citation statements)

References 29 publications

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“…This arises due to a combination of geometrical effects during core collapse, and varying amounts of subsequent accretion from the surrounding environment which adds significant dispersion to the relation between the core mass and the final stellar mass. This is not very surprising given that the cores in a clustered region are somewhat artificial in that they do not have distinct boundaries but are instead the high-density peaks of a larger mass distribution (Smith et al 2008, Kainulainen et al 2009.…”

Section: Monolithic Massive Star Formationmentioning

confidence: 97%

The Formation of Massive Stars

Bonnell¹,

Smith

2010

Proc. IAU

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Abstract. There has been considerable progress in our understanding of how massive stars form but still much confusion as to why they form. Recent work from several sources has shown that the formation of massive stars through disc accretion, possibly aided by gravitational and Rayleigh-Taylor instabilities is a viable mechanism. Stellar mergers, on the other hand, are unlikely to occur in any but the most massive clusters and hence should not be a primary avenue for massive star formation. In contrast to this success, we are still uncertain as to how the mass that forms a massive star is accumulated. there are two possible mechanisms including the collapse of massive prestellar cores and competitive accretion in clusters. At present, there are theoretical and observational question marks as to the existence of high-mass prestellar cores. theoretically, such objects should fragment before they can attain a relaxed, centrally condensed and high-mass state necessary to form massive stars. Numerical simulations including cluster formation, feedback and magnetic fields have not found such objects but instead point to the continued accretion in a cluster potential as the primary mechanism to form high-mass stars. Feedback and magnetic fields act to slow the star formation process and will reduce the efficiencies from a purely dynamical collapse but otherwise appear to not significantly alter the process.

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Section: Monolithic Massive Star Formationmentioning

confidence: 97%

The Formation of Massive Stars

Bonnell¹,

Smith

2010

Proc. IAU

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“…Generally, identifying "cores" from column density maps is an ill-defined problem, because there is no common standard for what exactly constitutes "a core" (see discussion in, e.g., di Francesco et al 2007;Bergin & Tafalla 2007;André et al 2014). Consequently, different approaches undoubtedly result in somewhat different results (e.g., Smith et al 2008;Kainulainen et al 2009;Beaumont et al 2013). Here, our emphasis is in taking the advantage of the high resolution of the ALMA data, and hence, in identifying structures that are centrally concentrated at scales a few times the beamsize (i.e., 3 000-4 000 AU).…”

Section: Identification Of Dense Coresmentioning

confidence: 99%

Resolving the fragmentation of high line-mass filaments with ALMA: the integral shaped filament in Orion A

Kainulainen

Stutz

Stanke³

et al. 2017

A&A

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112

151

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We study the fragmentation of the nearest high line-mass filament, the integral shaped filament (ISF, line-mass ∼ 400 M ⊙ pc −1 ) in the Orion A molecular cloud. We have observed a 1.6 pc long section of the ISF with the Atacama Large Millimetre/submillimeter Array (ALMA) at 3 mm continuum emission, at a resolution of ∼3 ′′ (1 200 AU). We identify from the region 43 dense cores with masses about a solar mass. 60% of the ALMA cores are protostellar and 40% are starless. The nearest neighbour separations of the cores do not show a preferred fragmentation scale; the frequency of short separations increases down to 1 200 AU. We apply a twopoint correlation analysis on the dense core separations and show that the ALMA cores are significantly grouped at separations below ∼17 000 AU and strongly grouped below ∼6 000 AU. The protostellar and starless cores are grouped differently: only the starless cores group strongly below ∼6 000 AU. In addition, the spatial distribution of the cores indicates periodic grouping of the cores into groups of ∼30 000 AU in size, separated by ∼50 000 AU. The groups coincide with dust column density peaks detected by Herschel. These results show hierarchical, two-mode fragmentation in which the maternal filament periodically fragments into groups of dense cores. Critically, our results indicate that the fragmentation models for lower line-mass filaments (∼ 16 M ⊙ pc −1 ) fail to capture the observed properties of the ISF. We also find that the protostars identified with Spitzer and Herschel in the ISF are grouped at separations below ∼17 000 AU. In contrast, young stars with disks do not show significant grouping. This suggests that the grouping of dense cores is partially retained over the protostar lifetime, but not over the lifetime of stars with disks. This is in agreement with a scenario where protostars are ejected from the maternal filament by the slingshot mechanism, a model recently proposed for the ISF by Stutz & Gould. The separation distributions of the dense cores and protostars may also provide an evolutionary tracer of filament fragmentation.

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“…To test the robustness of the chosen thresholds, we compared the integrated clump fluxes of our clump extraction to classical 3σ spaced thresholds as proposed in Kainulainen et al (2009). The two right columns of Fig.…”

Section: Clump Extractionmentioning

confidence: 99%

Search for starless clumps in the ATLASGAL survey

Tackenberg

Beuther

Henning

et al. 2012

A&A

100

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Context. Understanding massive star formation requires comprehensive knowledge about the initial conditions of this process. The cradles of massive stars are believed to be located in dense and massive molecular clumps. Aims. In this study, we present an unbiased sample of the earliest stages of massive star formation across 20 deg 2 of the sky. Methods. Within the region 10 • < l < 20 • and |b| < 1 • , we search the ATLASGAL survey at 870 μm for dense gas condensations. These clumps are carefully examined for indications of ongoing star formation using YSOs from the GLIMPSE source catalog as well as sources in the 24 μm MIPSGAL images, to search for starless clumps. We calculate the column densities as well as the kinematic distances and masses for sources where the v lsr is known from spectroscopic observations. Results. Within the given region, we identify 210 starless clumps with peak column densities >1 × 10 23 cm −2 . In particular, we identify potential starless clumps on the other side of the Galaxy. The sizes of the clumps range between 0.1 pc and 3 pc with masses between a few tens of M up to several ten thousands of M . Most of them may form massive stars, but in the 20 deg 2 area we only find 14 regions massive enough to form stars more massive than 20 M and 3 regions with the potential to form stars more massive than 40 M . The slope of the high-mass tail of the clump mass function for clumps on the near side of the Galaxy is α = 2.2 and, therefore, Salpeter-like. We estimate the lifetime of the most massive starless clumps to be (6 ± 5) × 10 4 yr. Conclusions. The sample offers a uniform selection of starless clumps. In the large area surveyed, we only find a few potential precursors of stars in the excess of 40 M . It appears that the lifetime of these clumps is somewhat shorter than their free-fall times, although both values agree within the errors. In addition, these are ideal objects for detailed studies and follow-up observations.

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The fidelity of the core mass functions derived from dust column density data

Cited by 40 publications

References 29 publications

The Formation of Massive Stars

The Formation of Massive Stars

Resolving the fragmentation of high line-mass filaments with ALMA: the integral shaped filament in Orion A

Search for starless clumps in the ATLASGAL survey

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