The dusty environment of HD 97300 as seen by<i>Herschel</i>and<i>Spitzer</i>

Kóspál, Á.; Prusti, T.; Cox, Nicholas; Pilbratt, G. L.; André, Ph.; Oliveira, Catarina Alves de; Winston, E.; Merın, Bruno; Ribas, Álvaro; Royer, P.; Vavrek, R.; Waelkens, Christoffel

doi:10.1051/0004-6361/201218823

Cited by 6 publications

(8 citation statements)

References 28 publications

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“…2 in Haikala et al 2005) shows that the structures seen in the column density map consist of overlapping filaments that are coherent in velocity, and individual clumps. The only hot spot in all regions is the dust ring around HD 97300 located in Cha I, with T ∼ 25 K (Kóspál et al 2012). Cha II has a more fragmented appearance (best seen in Fig.…”

Section: Column Density and Temperature Mapsmentioning

confidence: 93%

Herschelview of the large-scale structure in the Chamaeleon dark clouds

Oliveira¹,

Schneider²,

Merın³

et al. 2014

A&A

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Context. The Chamaeleon molecular cloud complex is one of the nearest star-forming sites and encompasses three molecular clouds (Cha I, II, and III) that have a different star-formation history, from quiescent (Cha III) to actively forming stars (Cha II), and one that reaches the end of star-formation (Cha I). Aims. We aim at characterising the large-scale structure of the three sub-regions of the Chamaeleon molecular cloud complex by analysing new far-infrared images taken with the Herschel Space Observatory. Methods. We derived column density and temperature maps using PACS and SPIRE observations from the Herschel Gould Belt Survey and applied several tools, such as filament tracing, power-spectra, Δ-variance, and probability distribution functions (PDFs) of the column density, to derive the physical properties. Results. The column density maps reveal a different morphological appearance for each of the three clouds, with a ridge-like structure for Cha I, a clump-dominated regime for Cha II, and an intricate filamentary network for Cha III. The filament width is measured to be about 0.12 ± 0.04 pc in the three clouds, and the filaments are found to be gravitationally unstable in Cha I and II, but mostly subcritical in Cha III. Faint filaments (striations) are prominent in Cha I and are mostly aligned with the large-scale magnetic field. The PDFs of all regions show a lognormal distribution at low column densities. For higher densities, the PDF of Cha I shows a turnover indicative of an extended higher density component and culminates in a power-law tail. Cha II shows a power-law tail with a slope characteristic of gravity. The PDF of Cha III can be best fit by a single lognormal. Conclusions. The turbulence properties of the three regions are found to be similar, pointing towards a scenario where the clouds are impacted by large-scale processes. The magnetic field might possibly play an important role for the star formation efficiency in the Chamaeleon clouds if it can be proven that it can effectively channel material onto Cha I, and possibly Cha II, but this is probably less efficient on the quiescent Cha III cloud.

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Section: Column Density and Temperature Mapsmentioning

confidence: 93%

Herschelview of the large-scale structure in the Chamaeleon dark clouds

Oliveira¹,

Schneider²,

Merın³

et al. 2014

A&A

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“…When compared to the Herschel detections, we find 51 sources in common between the two catalogues, with an additional fourteen possible matches where the offset is greater than 25 . Of the fifty-one common detections, all 21 of the Belloche detections associated with known YSOs are also detected with Herschel, two are associated with the ring of nebular emission surrounding HD 97300 (Kóspál et al 2012) and the remaining twenty-eight are associated with candidate prestellar cores which lack near or mid-IR detections. We likely do not find counterparts for the other twenty-nine 870 μm detections due to different source extraction algorithms, the difference in the resolution between the catalogues, and the requirements for greater than 7-σ detections in the Herschel catalogue.…”

Section: Cross Correlation With Other Cataloguesmentioning

confidence: 99%

“…Having compared the Herschel catalogue to those at all other available wavelengths, we match 86 of the 397 Herschel detections to known sources. This includes 49 YSOs, two outflow features, two emission features near HD 97300, discussed in detail in Kóspál et al (2012), 28 candidate prestellar/starless cores (Belloche et al 2011), and five CO clumps (Haikala et al 2005). Table 1 presents the identifications, evolutionary classification, the Herschel fluxes, and the spectral types for the identified YSOs in Cha I.…”

Section: Herschel Catalogue Of Known Objectsmentioning

confidence: 99%

Herschelfar-IR observations of the Chamaeleon molecular cloud complex

Winston

Cox

Prusti

et al. 2012

A&A

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Context. The Herschel Gould Belt survey of nearby star forming regions is providing great insights into the early stages of the formation and the evolution of stars and their circumstellar disks. The Chamaeleon I dark cloud is an elongated region of dense dust and gas where star formation is ongoing in two centres, a northern region centred on Ced 112 and a southern cluster subdivided into the two regions Ced 110 and 111. Aims. In this initial study we present Herschel data of previously identified young stellar objects (YSOs) in the cluster, focusing on the spatial distribution of the YSOs and the determination of the relative colours of the protostars and the disk-bearing stars in Chamaeleon I. Methods. Chamaeleon I has been observed as part of the Herschel Gould Belt Survey, using the PACS and SPIRE parallel mode imaging at 70, 160, 250, 350, and 500 μm. Source extraction was performed using the getsources software. Results. We have detected 397 sources over the five available PACS and SPIRE bands, and through comparison with previously identified objects in the cluster we have identified 49 YSOs, 4 bright nebular emission features, five CO clumps, and twenty-eight candidate prestellar or starless cores in the Herschel sample. The remaining sample consists of candidate prestellar cores, condensations within the cloud, or background galaxies. The Herschel detected YSOs are highly clustered and mainly associated with the three known Cederblad groups. The observations clearly show that the young stars are forming coincident with the denser regions of cold dust and gas, visible at longer Herschel wavelengths. Those YSOs detected with Herschel were found to have an IRAC m 3.6 μm < 10. No difference was found in the Herschel colours between the class I and class II young stars, however the class I sources were brighter than the class II at most Herschel wavelengths. One class III star and three transition disks are detected.

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“…In other cases, the source of PAH emission is an even more extended envelope (e.g. HD 97300, Siebenmorgen et al 1998;Kóspál et al 2012), or might be coming from the surrounding cloud material (e.g. IRAS 03260+3111 and MWC 865, Sloan et al 1999;Boersma et al 2009).…”

Section: Pah Dominated Objectsmentioning

confidence: 99%

Mid-Infrared Spectral Variability Atlas of Young Stellar Objects

Kóspál

Ábrahám

Acosta–Pulido

et al. 2012

ApJS

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Optical and near-infrared variability is a well-known property of young stellar objects. However, a growing number of recent studies claim that a considerable fraction of them also exhibit mid-infrared flux changes. With the aim of studying -2and interpreting variability on a decadal timescale, here we present a mid-infrared spectral atlas containing observations of 68 low-and intermediate mass young stellar objects. The atlas consists of 2.5-11.6 µm low-resolution spectra obtained with the ISOPHOT-S instrument on-board the Infrared Space Observatory (ISO) between 1996 and 1998, as well as 5.2-14.5 µm low-resolution spectra obtained with the IRS instrument on-board the Spitzer Space Telescope between 2004 and 2007. The observations were retrieved from the ISO and Spitzer archives and were post-processed interactively by our own routines. For those 47 objects where multi-epoch spectra were available, we analyze mid-infrared spectral variability on annual and/or decadal timescales. We identify 37 variable candidate sources. Many stars show wavelength-independent flux changes, possibly due to variable accretion rate. In several systems, all exhibiting 10 µm silicate emission, the variability of the 6−8 µm continuum and the silicate feature exhibit different amplitudes. A possible explanation is variable shadowing of the silicate emitting region by an inner disk structure of changing height or extra silicate emission from dust clouds in the disk atmosphere. Our results suggest that mid-infrared variability, in particular the wavelength-dependent changes, are more ubiquitous than was known before. Interpreting this variability is a new possibility to explore the structure of the disk and its dynamical processes.The Infrared Spectrograph (IRS) on-board the Spitzer Space Telescope had two low resolution and two high resolution modules, covering the 5.2-38 µm wavelength range. Since our aim is to look for mid-IR variability, here we utilize the Short-Low channel that covers the 5.2-14.5 µm wavelength range, thus has the largest wavelength overlap with ISOPHOT-S. The Short-Low channel has a spectral resolution of R ≈ 60-127, comparable to that of ISOPHOT-S. The width and length of the IRS Short-Low slit is 3. ′′ 6 and 57 ′′ , respectively. According to the IRS instrument handbook (Version 4.0), the uncertainty of the absolute flux calibration is 5-10%, while the repeatability is 2-5%.We downloaded basic calibrated data (BCD) files from the Spitzer archive, processed with the pipeline version 18.18.0. Measurements were taken either in staring mode (two nod positions), or in spectral mapping mode (small 2×3 maps). In the latter case, we used the central 2 positions, and considered them as normal staring measurements. We first subtracted the two nod positions from each other. Then we used the Spitzer IRS Custom Extraction software (SPICE) to extract the positive signal from the two-dimensional dispersed images. We extracted the spectra from a wavelength-dependent, tapered aperture around the target, and we averaged the two s...

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The dusty environment of HD 97300 as seen byHerschelandSpitzer

Cited by 6 publications

References 28 publications

Herschelview of the large-scale structure in the Chamaeleon dark clouds

Herschelview of the large-scale structure in the Chamaeleon dark clouds

Herschelfar-IR observations of the Chamaeleon molecular cloud complex

Mid-Infrared Spectral Variability Atlas of Young Stellar Objects

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