Detection of 6 K gas in Ophiuchus D

Harju, J.; Juvela, M.; Schlemmer, S.; Haikala, L. K.; Lehtinen, K.; Mattila, K.

doi:10.1051/0004-6361:20079259

Cited by 62 publications

(87 citation statements)

References 29 publications

(56 reference statements)

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“…R CrA itself is a Herbig Be star (spectral class B5-B8; Gray et al 2006;Bibo et al 1992) with a mass of 3.0 M (Bibo et al 1992) and a luminosity between 100 and 166 L (the lower value is a lower limit from SED estimates with incomplete data in the UV range; Bibo et al 1992). Several dense molecular cloud cores with masses between 2 and 50 M were found near the Herbig Be star R CrA in C 18 O SEST observations by Harju et al (1993). The IRS7 region is located with its centre between the Herbig Be star R CrA and the T Tauri star T CrA (Taylor & Storey 1984), ∼30 (≈4000 AU) from each of these stars, and harbours a handful of Class 0/I YSOs.…”

Section: Introductionmentioning

confidence: 94%

Strong irradiation of protostellar cores in Corona Australis

Lindberg

Jørgensen

2012

A&A

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Context. The importance of the physical environment in the evolution of newly formed low-mass stars remains an open question. In particular, radiation from nearby more massive stars may affect both the physical and chemical structure of these kinds of young stars. Aims. We constrain the physical characteristics of a group of embedded low-mass protostars in Corona Australis in the vicinity of the young luminous Herbig Be star R CrA. Methods. Millimetre wavelength maps of molecular line and continuum emission towards the low-mass star forming region IRS7 near R CrA from the Submillimeter Array (SMA) and Atacama Pathfinder Experiment (APEX) are presented. The maps show the distribution of 18 lines from 7 species (H 2 CO, CH 3 OH, HC 3 N, c-C 3 H 2 , HCN, CN and SiO) on scales from 3 to 60 (400-8000 AU). Using a set of H 2 CO lines, we estimate the temperatures and column densities in the region using both LTE and non-LTE methods. The results are compared with 1-D radiative transfer modelling of the protostellar cores. These models constrain which properties of the central source, protostellar envelope, and surrounding radiation field can give rise to the observed line and continuum emission. Results. Most of the H 2 CO emission from the regions emerges from two elongated (∼6000 AU long) narrow (<1500 AU) ridges dominating the emission picked up in both interferometric and single-dish measurements. The temperatures inferred from the H 2 CO lines are no less than ∼30 K and more likely 50-60 K, and the line emission peaks are offset by ∼2500 AU from the location of the embedded protostars. These temperatures can not be explained by the heating from the young stellar objects (YSOs) themselves. Irradiation by the nearby Herbig Be star R CrA could, however, explain these high temperatures. The elevated temperatures can in turn impact the physical and chemical characteristics of protostars, in particular, lead to enhanced abundances of typical tracers of photon dominated regions (PDRs) such as seen in single-dish line surveys of embedded protostars in the region.

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Section: Introductionmentioning

confidence: 94%

Strong irradiation of protostellar cores in Corona Australis

Lindberg

Jørgensen

2012

A&A

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“…The real dust temperature inside the clumps cannot be directly measured and could be estimated only by modelling. From earlier theoretical studies, it is clear that in many cases the central temperature of the dense cores goes below 10 K (e.g., Evans et al 2001;Harju et al 2008). In particular, in LDN 183, our field G6.03+36.73, Pagani et al (2004) reported dust temperatures down to ∼7 K. In the dense and cold environment the dust grains are expected to undergo coagulation that can lead to increased opacity at submillimetre wavelengths (Ossenkopf 1993;Stepnik et al 2003;Ysard et al 2012;Köhler & et al 2012).…”

Section: Fig 11mentioning

confidence: 99%

Galactic cold cores

Juvela

Ristorcelli

Pagani

et al. 2012

A&A

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Context. In the project galactic cold cores we are carrying out Herschel photometric observations of cold regions of the interstellar clouds as previously identified with the Planck satellite. The aim of the project is to derive the physical properties of the population of cold clumps and to study its connection to ongoing and future star formation. Aims. We examine the cloud structure around the Planck detections in 71 fields observed with the Herschel SPIRE instrument by the summer of 2011. We wish to determine the general physical characteristics of the fields and to examine the morphology of the clouds where the cold high column density clumps are found. Methods. Using the Herschel SPIRE data, we derive colour temperature and column density maps of the fields. Together with ancillary data, we examine the infrared spectral energy distributions of the main clumps. The clouds are categorised according to their large scale morphology. With the help of recently released WISE satellite data, we look for signs of enhanced mid-infrared scattering ("coreshine"), an indication of growth of the dust grains, and have a first look at the star formation activity associated with the cold clumps. Results. The mapped clouds have distances ranging from ∼100 pc to several kiloparsecs and cover a range of sizes and masses from cores of less than 10 M to clouds with masses in excess of 10 000 M . Most fields contain some filamentary structures and in about half of the cases a filament or a few filaments dominate the morphology. In one case out of ten, the clouds show a cometary shape or have sharp boundaries indicative of compression by an external force. The width of the filaments is typically ∼0.2-0.3 pc. However, there is significant variation from 0.1 pc to 1 pc and the estimates are sensitive to the methods used and the very definition of a filament. Enhanced mid-infrared scattering, coreshine, was detected in four clouds with six additional tentative detections. The cloud LDN 183 is included in our sample and remains the best example of this phenomenon. About half of the fields are associated with active star formation as indicated by the presence of mid-infrared point sources. The mid-infrared sources often coincide with structures whose sub-millimetre spectra are still dominated by the cold dust.

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“…10). The region has been studied by Harju et al (1993) in CO emission and with Spitzer by Peterson et al (2011), and it is reviewed in Neuhäuser & Forbrich (2008). The central object is the R Corona Australis dark cloud (R CrA), which has a tail extending to the bottom-left of the maps consisting of the reflection nebula NGC 6729.…”

Section: Diffuse Ame Regionsmentioning

confidence: 99%

Planck2015 results

Ade

Aghanim

Alves

et al. 2016

A&A

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162

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We discuss the Galactic foreground emission between 20 and 100 GHz based on observations by Planck and WMAP. The total intensity in this part of the spectrum is dominated by free-free and spinning dust emission, whereas the polarized intensity is dominated by synchrotron emission. The Commander component-separation tool has been used to separate the various astrophysical processes in total intensity. Comparison with radio recombination line templates verifies the recovery of the free-free emission along the Galactic plane. Comparison of the high-latitude Hα emission with our free-free map shows residuals that correlate with dust optical depth, consistent with a fraction (≈30%) of Hα having been scattered by high-latitude dust. We highlight a number of diffuse spinning dust morphological features at high latitude. There is substantial spatial variation in the spinning dust spectrum, with the emission peak (in I ν ) ranging from below 20 GHz to more than 50 GHz. There is a strong tendency for the spinning dust component near many prominent H ii regions to have a higher peak frequency, suggesting that this increase in peak frequency is associated with dust in the photo-dissociation regions around the nebulae. The emissivity of spinning dust in these diffuse regions is of the same order as previous detections in the literature. Over the entire sky, the Commander solution finds more anomalous microwave emission (AME) than the WMAP component maps, at the expense of synchrotron and free-free emission. This can be explained by the difficulty in separating multiple broadband components with a limited number of frequency maps. Future surveys, particularly at 5-20 GHz, will greatly improve the separation by constraining the synchrotron spectrum. We combine Planck and WMAP data to make the highest signal-to-noise ratio maps yet of the intensity of the all-sky polarized synchrotron emission at frequencies above a few GHz. Most of the high-latitude polarized emission is associated with distinct large-scale loops and spurs, and we re-discuss their structure. We argue that nearly all the emission at 40 • > l > −90 • is part of the Loop I structure, and show that the emission extends much further in to the southern Galactic hemisphere than previously recognised, giving Loop I an ovoid rather than circular outline. However, it does not continue as far as the "Fermi bubble/microwave haze", making it less probable that these are part of the same structure. We identify a number of new faint features in the polarized sky, including a dearth of polarized synchrotron emission directly correlated with a narrow, roughly 20 • long filament seen in Hα at high Galactic latitude. Finally, we look for evidence of polarized AME, however many AME regions are significantly contaminated by polarized synchrotron emission, and we find a 2σ upper limit of 1.6% in the Perseus region.

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Detection of 6 K gas in Ophiuchus D

Cited by 62 publications

References 29 publications

Strong irradiation of protostellar cores in Corona Australis

Strong irradiation of protostellar cores in Corona Australis

Galactic cold cores

Planck2015 results

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