G048.66–0.29: Physical State of an Isolated Site of Massive Star Formation

Pitann, J.; Linz, H.; Ragan, S. E.; Stutz, Amelia M.; Beuther, H.; Henning, Thomas; Krause, O.; Launhardt, R.; Schmiedeke, A.; Schüller, F.; Tackenberg, J.; Vasyunina, Tatiana

doi:10.1088/0004-637x/766/2/68

Cited by 17 publications

(20 citation statements)

References 109 publications

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“…The observed nonisothermality of dense clouds, derived from Herschel data, was already reported by other authors (e.g., Stutz et al 2010;Peretto et al 2010;Battersby et al 2011;Wilcock et al 2012;Pitann et al 2013). While the Stutz et al (2010) paper was the pilot study for the globule survey presented here, Peretto et al (2010), Battersby et al (2011), Wilcock et al (2012, and Pitann et al (2013) found that the LoS-averaged dust temperatures in IRDCs also systematically drop toward the highest column densities.…”

Section: Comparison With Earlier Observations and Models Of Dense Coressupporting

confidence: 85%

“…While the Stutz et al (2010) paper was the pilot study for the globule survey presented here, Peretto et al (2010), Battersby et al (2011), Wilcock et al (2012, and Pitann et al (2013) found that the LoS-averaged dust temperatures in IRDCs also systematically drop toward the highest column densities. Wilcock et al (2012, Fig.…”

Section: Comparison With Earlier Observations and Models Of Dense Coresmentioning

confidence: 83%

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The Earliest Phases of Star Formation (EPoS): aHerschelkey project

Launhardt

Stutz

Schmiedeke

et al. 2013

A&A

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247

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Context. The temperature and density structure of molecular cloud cores are the most important physical quantities that determine the course of the protostellar collapse and the properties of the stars they form. Nevertheless, density profiles often rely either on the simplifying assumption of isothermality or on observationally poorly constrained model temperature profiles. The instruments of the Herschel satellite provide us for the first time with both the spectral coverage and the spatial resolution that is needed to directly measure the dust temperature structure of nearby molecular cloud cores. Aims. With the aim of better constraining the initial physical conditions in molecular cloud cores at the onset of protostellar collapse, in particular of measuring their temperature structure, we initiated the guaranteed time key project (GTKP) "The Earliest Phases of Star Formation" (EPoS) with the Herschel satellite. This paper gives an overview of the low-mass sources in the EPoS project, the Herschel and complementary ground-based observations, our analysis method, and the initial results of the survey. Methods. We study the thermal dust emission of 12 previously well-characterized, isolated, nearby globules using FIR and submm continuum maps at up to eight wavelengths between 100 μm and 1.2 mm. Our sample contains both globules with starless cores and embedded protostars at different early evolutionary stages. The dust emission maps are used to extract spatially resolved SEDs, which are then fit independently with modified blackbody curves to obtain line-of-sight-averaged dust temperature and column density maps. Results. We find that the thermal structure of all globules (mean mass 7 M ) is dominated by external heating from the interstellar radiation field and moderate shielding by thin extended halos. All globules have warm outer envelopes (14-20 K) and colder dense interiors (8-12 K) with column densities of a few 10 22 cm −2 . The protostars embedded in some of the globules raise the local temperature of the dense cores only within radii out to about 5000 AU, but do not significantly affect the overall thermal balance of the globules. Five out of the six starless cores in the sample are gravitationally bound and approximately thermally stabilized. The starless core in CB 244 is found to be supercritical and is speculated to be on the verge of collapse. For the first time, we can now also include externally heated starless cores in the L smm /L bol vs. T bol diagram and find that T bol < 25 K seems to be a robust criterion to distinguish starless from protostellar cores, including those that only have an embedded very low-luminosity object.

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Section: Comparison With Earlier Observations and Models Of Dense Coressupporting

confidence: 85%

Section: Comparison With Earlier Observations and Models Of Dense Coresmentioning

confidence: 83%

The Earliest Phases of Star Formation (EPoS): aHerschelkey project

Launhardt

Stutz

Schmiedeke

et al. 2013

A&A

Self Cite

150

247

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“…This is done pixel wise using the following expression (Ward-Thompson & Robson 1990;Faimali et al 2012;Pitann et al 2013;Mallick et al 2015),…”

Section: Temperature and Column Density Distributionmentioning

confidence: 99%

Radio and infrared study of the star-forming region IRAS 20286+4105

Ramachandran

Das

Tej

et al. 2016

Mon. Not. R. Astron. Soc.

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A multi-wavelength investigation of the star forming complex IRAS 20286+4105, located in the Cygnus-X region, is presented here. Near-infrared K-band data is used to revisit the cluster / stellar group identified in previous studies. The radio continuum observations, at 610 and 1280 MHz show the presence of a HII region possibly powered by a star of spectral type B0 -B0.5. The cometary morphology of the ionized region is explained by invoking the bow-shock model where the likely association with a nearby supernova remnant is also explored. A compact radio knot with non-thermal spectral index is detected towards the centre of the cloud. Mid-infrared data from the Spitzer Legacy Survey of the Cygnus-X region show the presence of six Class I YSOs inside the cloud. Thermal dust emission in this complex is modelled using Herschel far-infrared data to generate dust temperature and column density maps. Herschel images also show the presence of two clumps in this region, the masses of which are estimated to be ∼ 175 M and 30 M . The mass-radius relation and the surface density of the clumps do not qualify them as massive star forming sites. An overall picture of a runaway star ionizing the cloud and a triggered population of intermediate-mass, Class I sources located toward the cloud centre emerges from this multiwavelength study. Variation in the dust emissivity spectral index is shown to exist in this region and is seen to have an inverse relation with the dust temperature.

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“…The Herschel key programme EPoS (Earliest Phases of Star formation, PI: O. Krause) is dedicated to observations of both high-mass star-forming regions (e.g., Beuther et al 2010Beuther et al , 2013Henning et al 2010;Linz et al 2010;Ragan et al 2012;Pitann et al 2013;Kainulainen et al 2013) and isolated low-mass pre-and protostellar cores (e.g., Stutz et al 2010;Nielbock et al 2012;Launhardt et al 2013;Lippok et al 2013). The focus for the low-mass part of the project is mainly on deriving the density and dust temperature structure in the early phases of protostellar evolution and on determining the initial conditions of protostellar collapse.…”

Section: Introductionmentioning

confidence: 99%

The Earliest Phases of Star formation (EPoS)

Schmalzl

Launhardt

Stutz

et al. 2014

A&A

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Context. The initial conditions for the gravitational collapse of molecular cloud cores and the subsequent birth of stars are still not well constrained. The characteristic cold temperatures (∼10 K) in such regions require observations at sub-millimetre and longer wavelengths. The Herschel Space Observatory and complementary ground-based observations presented in this paper have the unprecedented potential to reveal the structure and kinematics of a prototypical core region at the onset of stellar birth. Aims. This paper aims to determine the density, temperature, and velocity structure of the star-forming Bok globule CB 17. This isolated region is known to host (at least) two sources at different evolutionary stages: a dense core, SMM1, and a Class I protostar, IRS. Methods. We modeled the cold dust emission maps from 100 μm to 1.2 mm with both a modified blackbody technique to determine the optical depth-weighted line-of-sight temperature and column density and a ray-tracing technique to determine the core temperature and volume density structure. Furthermore, we analysed the kinematics of CB17 using the high-density gas tracer N 2 H + . Results. From the ray-tracing analysis, we find a temperature in the centre of SMM1 of T 0 = 10.6 K, a flat density profile with radius 9.5 × 10 3 au, and a central volume density of n H,0 = 2.3 × 10 5 cm −3 . The velocity structure of the N 2 H + observations reveal global rotation with a velocity gradient of 4.3 km s −1 pc −1 . Superposed on this rotation signature we find a more complex velocity field, which may be indicative of differential motions within the dense core. Conclusions. SMM is a core in an early evolutionary stage at the verge of being bound, but the question of whether it is a starless or a protostellar core remains unanswered.

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G048.66–0.29: Physical State of an Isolated Site of Massive Star Formation

Cited by 17 publications

References 109 publications

The Earliest Phases of Star Formation (EPoS): aHerschelkey project

The Earliest Phases of Star Formation (EPoS): aHerschelkey project

Radio and infrared study of the star-forming region IRAS 20286+4105

The Earliest Phases of Star formation (EPoS)

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