Discovery of Four New Massive and Dense Cold Cores

Garay, Guido; Faundez, S.; Mardones, Diego; Bronfman, L.; Chini, R.; Nyman, L.-Å.

doi:10.1086/421437

Cited by 77 publications

(120 citation statements)

References 25 publications

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“…We assess their potential contamination of the sample of the youngest massive clumps by using sensitive radio-surveys such as COR-NISH (Hoare et al 2012;Purcell et al 2013) and Urquhart et al (2007) to search for ionising emission from stars in our sample of types later than B0.5. Since there is no homogeneous high angular-resolution radio dataset available covering the en- (Garay et al 2004) with a positional shift between the dust and the 24 µm point source in the MIPSGAL image, which also coincides with a UC-H II region from CORNISH marked by a blue cross.…”

Section: Tracers Of Embedded High-mass Starsmentioning

confidence: 99%

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The ATLASGAL survey: The sample of young massive cluster progenitors

Csengeri

Bontemps

Wyrowski

et al. 2017

A&A

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Context. The progenitors of high-mass stars and clusters are still challenging to recognise. Only unbiased surveys, sensitive to compact regions of high dust column density, can unambiguously reveal such a small population of particularly massive and cold clumps. Aims. Here we use the ATLASGAL survey to identify a sample of candidate progenitors of massive clusters in the inner Galaxy. Methods. We characterise a flux limited sample of compact sources selected from the ATLASGAL survey. Sensitive mid-infrared data at 21−24 µm from the WISE and MIPSGAL surveys were explored to search for embedded objects, and complementary spectroscopic data were used to investigate their stability and their star formation activity. Results. We identify an unbiased sample of infrared-quiet massive clumps in the Galaxy that potentially represent the earliest stages of massive cluster formation. An important fraction of this sample consists of sources that have not been studied in detail before. We first find that clumps hosting more evolved embedded objects and infrared-quiet clumps exhibit similar physical properties in terms of mass and size, suggesting that the sources are not only capable of forming high-mass stars, but likely also follow a single evolutionary track leading to the formation of massive clusters. The majority of the clumps are likely not in virial-equilibrium, suggesting collapse on the clump scale. Conclusions. We identify the precursors of the most massive clusters in the Galaxy within our completeness limit, and argue that these objects are undergoing large-scale collapse. This is in line with the low number of infrared-quiet massive clumps and earlier findings that star formation, in particular for high-mass objects is a fast, dynamic process. We propose a scenario in which massive clumps start to fragment and collapse before their final mass is accumulated indicating that strong self-gravity and global collapse is needed to build up rich clusters and the most massive stars.

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Section: Tracers Of Embedded High-mass Starsmentioning

confidence: 99%

“…Garay et al 2004;Thompson et al 2005). To look for neighbouring, more evolved objects with UC-H II regions in the close vicinity of the infrared-quiet sample, we used the CS (2-1) survey of IRAS sources (Bronfman et al 1996), which is complete towards IRAS selected UC-H II regions in the Galactic plane.…”

Section: Massive Cluster Progenitors In Isolation?mentioning

confidence: 99%

The ATLASGAL survey: The sample of young massive cluster progenitors

Csengeri

Bontemps

Wyrowski

et al. 2017

A&A

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“…Much effort has focused on follow-up studies of bright IR sources detected by the Infrared Astronomy Satellite (IRAS) and showing far-infrared (FIR) colors typical of ultra-compact H ii regions (Wood & Churchwell 1989), e.g., in high-density molecular tracers (Bronfman et al 1996;Molinari et al 1996), dust continuum emission , or maser emission (e.g., Palla et al 1993;Beuther et al 2002). While some studies have revealed a few massive cold cores in the neighborhood of the central compact H ii region (e.g., Garay et al 2004), they were mostly biased against the earliest, possibly coldest phases of massive star formation.…”

Section: Article Published By Edp Sciencesmentioning

confidence: 99%

ATLASGAL – The APEX telescope large area survey of the galaxy at 870 $\mathsf{\mu}$m

Schüller¹,

Menten²,

Contreras

et al. 2009

A&A

729

927

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Context. Thanks to its excellent 5100 m high site in Chajnantor, the Atacama Pathfinder Experiment (APEX) systematically explores the southern sky at submillimeter wavelengths, in both continuum and spectral line emission. Studying continuum emission from interstellar dust is essential to locating the highest density regions in the interstellar medium, and deriving their masses, column densities, density structures, and large-scale morphologies. In particular, the early stages of (massive) star formation remain poorly understood, mainly because only small samples of high-mass proto-stellar or young stellar objects have been studied in detail so far. Aims. Our goal is to produce a large-scale, systematic database of massive pre-and proto-stellar clumps in the Galaxy, to understand how and under what conditions star formation takes place. Only a systematic survey of the Galactic Plane can provide the statistical basis for unbiased studies. A well characterized sample of Galactic star-forming sites will deliver an evolutionary sequence and a mass function of high-mass, star-forming clumps. This systematic survey at submillimeter wavelengths also represents a preparatory work for Herschel and ALMA. Methods. The APEX telescope is ideally located to observe the inner Milky Way. The Large APEX Bolometer Camera (LABOCA) is a 295-element bolometer array observing at 870 μm, with a beam size of 19. 2. Taking advantage of its large field of view (11. 4) and excellent sensitivity, we started an unbiased survey of the entire Galactic Plane accessible to APEX, with a typical noise level of 50−70 mJy/beam: the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). Results. As a first step, we covered ∼95 deg 2 of the Galactic Plane. These data reveal ∼6000 compact sources brighter than 0.25 Jy, or 63 sources per square degree, as well as extended structures, many of them filamentary. About two thirds of the compact sources have no bright infrared counterpart, and some of them are likely to correspond to the precursors of (high-mass) proto-stars or protoclusters. Other compact sources harbor hot cores, compact H ii regions, or young embedded clusters, thus tracing more evolved stages after massive stars have formed. Assuming a typical distance of 5 kpc, most sources are clumps smaller than 1 pc with masses from a few 10 to a few 100 M . In this first introductory paper, we show preliminary results from these ongoing observations, and discuss the mid-and long-term perspectives of the survey.

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“…Infrared studies, however, cannot provide a complete census of the birth sites of massive stars, since there are massive condensations that are undetected at infrared wavelengths. For example, Garay et al (2004) found four clumps with masses between 4 × 10 2 and 2 × 10 3 M and densities of ∼2 × 10 5 cm −3 , without infrared emission, located close to clumps associated with MSFRs. They suggested that these cold ( 17 K), dense, and massive clumps will eventually form high mass stars.…”

Section: Massive-star Forming Regionsmentioning

confidence: 99%

Massive star formation in the GMC G345.5+1.0: spatial distribution of the dust emission

López¹,

Bronfman²,

Nyman³

et al. 2011

A&A

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Context. Massive condensations in giant molecular clouds (GMCs) are linked to the formation of high mass stars, which are the principal source of heavy elements and UV radiation, playing an important role in the evolution of galaxies. Aims. We attemp to make a complete census of massive-star formation within all of GMC G345.5+1.0. This cloud is located one degree above the Galactic plane and at 1.8 kpc from the Sun, thus there is little superposition of dust along the line-of-sight, minimizing confusion effects in identifying individual clumps. Methods. We observed the 1.2 mm continuum emission across the whole GMC using the Swedish-ESO Submillimetre Telescope (SEST) Imaging Bolometer Array (SIMBA) mounted on the SEST. Observations have a spatial resolution of 0.2 pc and cover 1.• 8 × 2.• 2 in the sky with a noise of 20 mJy beam −1 . Results. We identify 201 clumps with diameters between 0.2 and 0.6 pc, masses between 3.0 and 1.3 × 10 3 M , and densities between 5 × 10 3 and 4 × 10 5 cm −3 . The total mass of the clumps is 1.2 × 10 4 M , thus the efficiency in forming these clumps, estimated as the ratio of the total clump mass to the total GMC mass, is ∼0.02. The clump mass distribution for masses between 10 and 10 3 M is well-fitted by a power law dN/dM ∝ M −α , with a spectral mass index α of 1.7 ± 0.1. Given their mass distribution, clumps do not appear to be the direct progenitors of single stars. Comparing the 1.2 mm continuum emission with infrared images taken by the Midcourse Space Experiment (MSX) and by the Spitzer satellite, we find that at least ∼20% of the clumps are forming stars, and at most ∼80% are starless. Six massive-star forming regions (MSFRs) embedded in clumps and associated with IRAS point sources have mean densities of ∼10 5 cm −3 , luminosities >10 3 L , and spectral energy distributions that can be modeled with two dust components at different mean temperatures of 28 ± 5 and 200 ± 10 K.

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Discovery of Four New Massive and Dense Cold Cores

Cited by 77 publications

References 25 publications

The ATLASGAL survey: The sample of young massive cluster progenitors

The ATLASGAL survey: The sample of young massive cluster progenitors

ATLASGAL – The APEX telescope large area survey of the galaxy at 870 $\mathsf{\mu}$m

Massive star formation in the GMC G345.5+1.0: spatial distribution of the dust emission

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