The structured environments of embedded star-forming cores

Linz, H.; Krause, O.; Beuther, H.; Henning, Th.; Klein, Randolf; Nielbock, M.; Stecklum, B.; Steinacker, J.; Stutz, Amelia M.

doi:10.1051/0004-6361/201014669

Cited by 20 publications

(34 citation statements)

References 17 publications

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“…The crosses in the bottom-left panel mark the positions of a double-component radio recombination line Hii region from Anderson et al (2011), the W43-MM1 position from Motte et al (2003) as well as the approximate center of the Wolf-Rayet/OB cluster (Blum et al 1999;Motte et al 2003). to search for and to study these initial conditions. Early work from the first data revealed already exciting results, e.g., we identified candidate high-mass starless cores (HMSCs) as well as weak 70 μm sources within IRDCs that may be the very first manifestation of high-mass star formation Henning et al 2010;Linz et al 2010). …”

Section: Introductionmentioning

confidence: 91%

The onset of high-mass star formation in the direct vicinity of the Galactic mini-starburst W43

Beuther

Tackenberg

Linz

et al. 2012

A&A

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Context. The earliest stages of high-mass star formation are still poorly characterized. Densities, temperatures and kinematics are crucial parameters for simulations of high-mass star formation. It is also unknown whether the initial conditions vary with environment. Aims. We want to investigate the youngest massive gas clumps in the environment of extremely active star formation. Methods. We selected the IRDC 18454 complex, directly associated with the W43 Galactic mini-starburst, and observed it in the continuum emission between 70 μm and 1.2 mm with Herschel, APEX and the 30 m telescope, and in spectral line emission of N 2 H + and 13 CO with the Nobeyama 45 m, the IRAM 30 m and the Plateau de Bute Interferometer. Results. The multi-wavelength continuum study allows us to identify clumps that are infrared dark even at 70 μm and hence the best candidates to be genuine high-mass starless gas clumps. The spectral energy distributions reveal elevated temperatures and luminosities compared to more quiescent environments. Furthermore, we identify a temperature gradient from the W43 mini-starburst toward the starless clumps. We discuss whether the radiation impact of the nearby mini-starburst changes the fragmentation properties of the gas clumps and by that maybe favors more high-mass star formation in such an environment. The spectral line data reveal two different velocity components of the gas at 100 and 50 km s −1 . While chance projection is a possibility to explain these components, the projected associations of the emission sources as well as the prominent location at the Galactic bar -spiral arm interface also allow the possibility that these two components may be spatially associated and even interacting. Conclusions. High-mass starless gas clumps can exist in the close environment of very active star formation without being destroyed. The impact of the active star formation sites may even allow for more high-mass stars to form in these 2nd generation gas clumps. This particular region near the Galactic bar -spiral arm interface has a broad distribution of gas velocities, and cloud interactions may be possible.

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Section: Introductionmentioning

confidence: 91%

The onset of high-mass star formation in the direct vicinity of the Galactic mini-starburst W43

Beuther

Tackenberg

Linz

et al. 2012

A&A

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“…These clumps are expected to contain high-mass protostellar objects that are still in the process of accretion, and that have not substantially heated the molecular environment (e.g., G11.11-0.12P1, Rosero et al 2014). We selected 10 CMC-IRs from Rathborne et al (2006) and 5 additional CMC-IRs were selected from other studies (Pillai et al 2006b;Beuther et al 2010;Linz et al 2010;Olmi et al 2010). 3.…”

Section: Sample Selectionmentioning

confidence: 99%

Weak and Compact Radio Emission in Early High-Mass Star-Forming Regions. I. Vla Observations

Rosero

Höfner

Claussen

et al. 2016

ApJS

141

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We present a high-sensitivity radio continuum survey at 6 and 1.3 cm using the Karl G. Jansky Very Large Array toward a sample of 58 high-mass star-forming regions. Our sample was chosen from dust clumps within infrared dark clouds with and without IR sources (CMC-IRs and CMCs, respectively), and hot molecular cores (HMCs), with no previous, or relatively weak radio continuum detection at the 1 mJy level. Due to the improvement in the continuum sensitivity of the Very Large Array, this survey achieved map rms levels of ∼3-10μJybeam −1 at subarcsecond angular resolution. We extracted 70 continuum sources associated with 1.2 mm dust clumps. Most sources are weak, compact, and prime candidates for high-mass protostars. Detection rates of radio sources associated with the millimeter dust clumps for CMCs, CMC-IRs, and HMCs are 6%, 53%, and 100%, respectively. This result is consistent with increasing high-mass star formation activity from CMCs to HMCs. The radio sources located within HMCs and CMC-IRs occur close to the dust clump centers, with a median offset from it of 12,000 au and 4000 au, respectively. We calculated 5-25 GHz spectral indices using power-law fits and obtained a median value of 0.5 (i.e., flux increasing with frequency), suggestive of thermal emission from ionized jets. In this paper we describe the sample, observations, and detections. The analysis and discussion will be presented in Paper II.

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“…A first detailed follow-up study of another source from this sample (B 68) was published by Nielbock et al (2012). Initial results on the high-mass cores observed in the framework of EPoS are published by Beuther et al (2010Beuther et al ( , 2012, Henning et al (2010), and Linz et al (2010). An overview on the high-mass part of EPoS is given in Ragan et al (2012).…”

Section: Introduction and Scientific Goalsmentioning

confidence: 99%

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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The structured environments of embedded star-forming cores

Cited by 20 publications

References 17 publications

The onset of high-mass star formation in the direct vicinity of the Galactic mini-starburst W43

The onset of high-mass star formation in the direct vicinity of the Galactic mini-starburst W43

Weak and Compact Radio Emission in Early High-Mass Star-Forming Regions. I. Vla Observations

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

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