Galactic cold cores:<i>Herschel</i>study of first<i>Planck</i>detections

Juvela, M.; Ristorcelli, I.; Montier, L.; Marshall, D. J.; Pelkonen, Veli-Matti; Malinen, J.; Ysard, N.; Tóth, L. V.; Harju, J.; Bernard, J.-P.; Schneider, N.; Verebélyi, Erika; Anderson, L. D.; André, P.; Giard, M.; Krause, O.; Lehtinen, K.; Macías-Pérez, J. F.; Martín, P. G.; McGehee, P.; Meny, C.; Motte, F.; Pagani, L.; Paladini, R.; Reach, W. T.; Valenziano, L.; Ward-Thompson, Derek; Zavagno, A.

doi:10.1051/0004-6361/201014619

Cited by 69 publications

(91 citation statements)

References 24 publications

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“…The source extraction (Montillaud et al, in prep. ) was made as part of the effort to catalogue the cold clumps detected in the fields observed in the Galactic Cold Cores project (Juvela et al 2010). The method proceeds in several steps, first extracting sources independently in each band, then combining all the data.…”

Section: Source Extractionmentioning

confidence: 99%

“…L1642 was recently observed as part of the Herschel open time key programme Galactic Cold Cores (Juvela et al 2010) with unprecedented spatial resolution and sensitivity at 100, 160, 250, 350 and 500 μm. Juvela et al (2012) presented these observations and studied the properties of the cloud on large-scale images, without separating the distinct objects.…”

Section: Introductionmentioning

confidence: 99%

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Multiwavelength study of the high-latitude cloud L1642: chain of star formation

Malinen

Juvela

Zahorecz

et al. 2014

A&A

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Context. L1642 is one of the two high galactic latitude (|b| > 30 • ) clouds confirmed to have active star formation. Aims. We examine the properties of this cloud, especially the large-scale structure, dust properties, and compact sources at different stages of star formation.Methods. We present high-resolution far-infrared and submillimetre observations with the Herschel and AKARI satellites and millimetre observations with the AzTEC/ASTE telescope, which we combined with archive data from near-and mid-infrared (2MASS, WISE) to millimetre wavelength observations (Planck).Results. The Herschel observations, combined with other data, show a sequence of objects from a cold clump to young stellar objects (YSOs) at different evolutionary stages. Source B-3 (2MASS J04351455-1414468) appears to be a YSO forming inside the L1642 cloud, instead of a foreground brown dwarf, as previously classified. Herschel data reveal striation in the diffuse dust emission around the cloud L1642. The western region shows striation towards the NE and has a steeper column density gradient on its southern side. The densest central region has a bow-shock like structure showing compression from the west and has a filamentary tail extending towards the east. The differences suggest that these may be spatially distinct structures, aligned only in projection. We derive values of the dust emission cross-section per H nucleon of σ e (250 μm) = 0.5−1.5 × 10 −25 cm 2 /H for different regions of the cloud. Modified black-body fits to the spectral energy distribution of Herschel and Planck data give emissivity spectral index β values 1.8-2.0 for the different regions. The compact sources have lower β values and show an anticorrelation between T and β. Conclusions. Markov chain Monte Carlo calculations demonstrate the strong anticorrelation between β and T errors and the importance of millimetre wavelength Planck data in constraining the estimates. L1642 reveals a more complex structure and sequence of star formation than previously known.

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Section: Source Extractionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multiwavelength study of the high-latitude cloud L1642: chain of star formation

Malinen

Juvela

Zahorecz

et al. 2014

A&A

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“…Within the Herschel open time key programme Galactic cold cores (Juvela et al 2010), we have mapped selected Planck C3PO objects with the Herschel PACS 1 and SPIRE 2 instruments (100−500 µm, Poglitsch et al 2010;Griffin et al 2010). Thanks to its higher spatial resolution, Herschel (Pilbratt et al 2010) makes it possible to examine the structure of the sources which gave rise to the Planck detections, often resolving the individual cores.…”

Section: Introductionmentioning

confidence: 99%

Galactic cold cores

Montillaud

Juvela

Rivera-Ingraham

et al. 2015

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160

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Context. For the project Galactic cold cores, Herschel photometric observations were carried out as a follow-up of cold regions of interstellar clouds previously identified with the Planck satellite. The aim of the project is to derive the physical properties of the population of cold sources and to study its connection to ongoing and future star formation. Aims. We build a catalogue of cold sources within the clouds in 116 fields observed with the Herschel PACS and SPIRE instruments. We wish to determine the general physical characteristics of the cold sources and to examine the correlations with their host cloud properties. Methods. From Herschel data, we computed colour temperature and column density maps of the fields. We estimated the distance to the target clouds and provide both uncertainties and reliability flags for the distances. The getsources multiwavelength source extraction algorithm was employed to build a catalogue of several thousand cold sources. Mid-infrared data were used, along with colour and position criteria, to separate starless and protostellar sources. We also propose another classification method based on submillimetre temperature profiles. We analysed the statistical distributions of the physical properties of the source samples. Results. We provide a catalogue of ∼4000 cold sources within or near star forming clouds, most of which are located either in nearby molecular complexes ( 1 kpc) or in star forming regions of the nearby galactic arms (∼2 kpc). About 70% of the sources have a size compatible with an individual core, and 35% of those sources are likely to be gravitationally bound. Significant statistical differences in physical properties are found between starless and protostellar sources, in column density versus dust temperature, mass versus size, and mass versus dust temperature diagrams. The core mass functions are very similar to those previously reported for other regions. On statistical grounds we find that gravitationally bound sources have higher background column densities (median N bg (H 2 ) ∼ 5 × 10 21 cm −2 ) than unbound sources (median N bg (H 2 ) ∼ 3 × 10 21 cm −2 ). These values of N bg (H 2 ) are higher for higher dust temperatures of the external layers of the parent cloud. However, only in a few cases do we find clear N bg (H 2 ) thresholds for the presence of cores. The dust temperatures of cloud external layers show clear variations with galactic location, as may the source temperatures. Conclusions. Our data support a more complex view of star formation than in the simple idea of a column density threshold. They show a clear influence of the surrounding UV-visible radiation on how cores distribute in their host clouds with possible variations on the Galactic scale.

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“…Large variations exist from one dust model to another, depending on the dust properties considered: composition (with or without ice mantles); structure (compact or fluffy aggregates); as well as size (see reviews from Beckwith et al 1990;Henning et al 1995). Dust models and observations show that κ ν values may vary by factors of 3-4 (or higher) from diffuse to dense and cold regions (Ossenkopf & Henning 1994;Kruegel & Siebenmorgen 1994;Stepnik et al 2003;Juvela et al 2010).…”

Section: Column Densitiesmentioning

confidence: 99%

“…In Juvela et al (2010Juvela et al ( , 2011 and our companion Paper II, we have conducted a preliminary analysis using Herschel observations of a sample of ten cold clumps detected with Planck. These sources have been selected to sample different environments, from high latitude cirrus to nearby and remote molecular complexes.…”

Section: A Broad Range Of Physical Propertiesmentioning

confidence: 99%

Planckearly results. XXIII. The first all-sky survey of Galactic cold clumps

Ade¹,

Aghanim²,

Arnaud³

et al. 2011

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154

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We present the statistical properties of the Cold Clump Catalogue of Planck Objects (C3PO), the first all-sky catalogue of cold objects, in terms of their spatial distribution, dust temperature, distance, mass, and morphology. We have combined Planck and IRAS data to extract 10 342 cold sources that stand out against a warmer environment. The sources are distributed over the whole sky, including in the Galactic plane, despite the confusion, and up to high latitudes (>30 • ). We find a strong spatial correlation of these sources with ancillary data tracing Galactic molecular structures and infrared dark clouds where the latter have been catalogued. These cold clumps are not isolated but clustered in groups. Dust temperature and emissivity spectral index values are derived from their spectral energy distributions using both Planck and IRAS data. The temperatures range from 7 K to 19 K, with a distribution peaking around 13 K. The data are inconsistent with a constant value of the associated spectral index β over the whole temperature range: β varies from 1.4 to 2.8, with a mean value around 2.1. Distances are obtained for approximately one third of the objects. Most of the detections lie within 2 kpc of the Sun, but more distant sources are also detected, out to 7 kpc. The mass estimates inferred from dust emission range from 0.4 M to 2.4 × 10 5 M . Their physical properties show that these cold sources trace a broad range of objects, from low-mass dense cores to giant molecular clouds, hence the "cold clump" terminology. This first statistical analysis of the C3PO reveals at least two colder populations of special interest with temperatures in the range 7 to 12 K: cores that mostly lie close to the Sun; and massive cold clumps located in the inner Galaxy. We also describe the statistics of the early cold core (ECC) sample that is a subset of the C3PO, containing only the 915 most reliable detections. The ECC is delivered as a part of the Planck Early Release Compact Source Catalogue (ERCSC).

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Galactic cold cores:Herschelstudy of firstPlanckdetections

Cited by 69 publications

References 24 publications

Multiwavelength study of the high-latitude cloud L1642: chain of star formation

Multiwavelength study of the high-latitude cloud L1642: chain of star formation

Galactic cold cores

Planckearly results. XXIII. The first all-sky survey of Galactic cold clumps

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