Clumpy filaments of the Chamaeleon I cloud: C$\mathsf{^{18}}$O mapping with the SEST

Haikala, L. K.; Harju, J.; Mattila, K.; Toriseva, M.

doi:10.1051/0004-6361:200400057

Cited by 28 publications

(54 citation statements)

References 33 publications

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“…Two other faint, elongated, large-scale structures are present in fields Cha-Center and Cha-South, respectively. These filamentary structures were already noticed by Haikala et al (2005) in their C 18 O 1-0 map where they appear to be broader, certainly because their map is more sensitive to lower densities than our 870 μm dust emission map. These authors mentioned that the C 18 O filaments are oriented at roughly right angles to the magnetic field (see their Fig.…”

Section: Large Scale Structuressupporting

confidence: 64%

“…Assuming a dust mass opacity κ 870 = 0.01 cm 2 g −1 , this translates into a cloud mass of 61 M . It corresponds to 5.9% of the total mass traced by CO in Cha I (1030 M , Mizuno et al 2001), 7.7% of the mass traced by 13 CO (790 M , Mizuno et al 1999), and 27-32% of the mass traced by C 18 O (190-230 M , Mizuno et al 1999;Haikala et al 2005).…”

Section: Masses Traced With Laboca and 2massmentioning

confidence: 97%

“…The eastern part of Cha I was mapped with the Swedish ESO Submillimeter Telescope (SEST) in the C 18 O 1-0 line by Haikala et al (2005). The angular resolution is 45 but the map is highly undersampled since the observations were done with a step of 1 .…”

Section: Archival C 18 O 1-0 Observations With Sestmentioning

confidence: 99%

“…The extinction map derived from 2MASS is compared with the C 18 O 1-0 map obtained by Haikala et al (2005) with the SEST in Fig. 13a.…”

Section: Correlation Between C 18 O 1-0 Emission and A Vmentioning

confidence: 99%

“…It varies by more than one order of magnitude, being the lowest at the 870 μm peaks. If we assume that the dust temperature and the excitation temperature of C 18 O 1-0 are the same, the gas-to-dust mass ratio is uniform, and the line is optically thin (see Haikala et al 2005), then the ratio plotted in Fig. 14b should roughly trace the CO abundance.…”

Section: Comparison Of Continuum Emission With C 18 O 1-0 Emissionmentioning

confidence: 99%

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The end of star formation in Chamaeleon I?

Беллоче

Schüller

Parise

et al. 2011

A&A

144

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Context. Chamaeleon I is the most active region in terms of star formation in the Chamaeleon molecular cloud complex. Although it is one of the nearest low-mass star forming regions, its population of prestellar and protostellar cores is not known and a controversy exists concerning its history of star formation. Aims. Our goal is to search for prestellar and protostellar cores and characterize the earliest stages of star formation in this cloud. Methods. We used the bolometer array LABOCA at the APEX telescope to map the cloud in dust continuum emission at 870 μm with a high sensitivity. This deep, unbiased survey was performed based on an extinction map derived from 2MASS data. The 870 μm map is compared with the extinction map and C 18 O observations, and decomposed with a multiresolution algorithm. The extracted sources are analysed by carefully taking into account the spatial filtering inherent in the data reduction process. A search for associations with young stellar objects is performed using Spitzer data and the SIMBAD database. Results. Most of the detected 870 μm emission is distributed in five filaments. We identify 59 starless cores, one candidate first hydrostatic core, and 21 sources associated with more evolved young stellar objects. The estimated 90% completeness limit of our survey is 0.22 M for the starless cores. The latter are only found above a visual extinction threshold of 5 mag. They are less dense than those detected in other nearby molecular clouds by a factor of a few on average, maybe because of the better sensitivity of our survey. The core mass distribution is consistent with the IMF at the high-mass end but is overpopulated at the low-mass end. In addition, at most 17% of the cores have a mass larger than the critical Bonnor-Ebert mass. Both results suggest that a large fraction of the starless cores may not be prestellar in nature. Based on the census of prestellar cores, Class 0 protostars, and more evolved young stellar objects, we conclude that the star formation rate has decreased with time in this cloud. Conclusions. The low fraction of candidate prestellar cores among the population of starless cores, the small number of Class 0 protostars, the high global star formation efficiency, the decrease of the star formation rate with time, and the low mass per unit length of the detected filaments all suggest that we may be witnessing the end of the star formation process in Chamaeleon I.

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Section: Large Scale Structuressupporting

confidence: 64%

Section: Masses Traced With Laboca and 2massmentioning

confidence: 97%

Section: Archival C 18 O 1-0 Observations With Sestmentioning

confidence: 99%

“…The extinction map derived from 2MASS is compared with the C 18 O 1-0 map obtained by Haikala et al (2005) with the SEST in Fig. 13a.…”

Section: Correlation Between C 18 O 1-0 Emission and A Vmentioning

confidence: 99%

Section: Comparison Of Continuum Emission With C 18 O 1-0 Emissionmentioning

confidence: 99%

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The end of star formation in Chamaeleon I?

Беллоче

Schüller

Parise

et al. 2011

A&A

144

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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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The dynamical state of the first hydrostatic core candidate Chamaeleon-MMS1

Tsitali¹,

Беллоче²,

Commerçon³

et al. 2013

A&A

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Context. First hydrostatic cores represent a theoretically predicted intermediate evolutionary link between the prestellar and protostellar phases. Studying the observational characteristics of first core candidates is therefore vital for probing and understanding the earliest phases of star formation. Aims. We aim to determine the dynamical state of the first hydrostatic core candidate Chamaeleon-MMS1 (Cha-MMS1). Methods. We observed Cha-MMS1 in various molecular transitions with the APEX and Mopra telescopes. Continuum data retrieved from the Spitzer Heritage Archive were used to estimate the internal luminosity of the source. The molecular emission was modelled with a radiative transfer code to derive constraints on the kinematics of the envelope, which were then compared to the predictions of magneto-hydrodynamic simulations. Results. We derive an internal luminosity of 0.08 L −0.18 L for Cha-MMS1. An average velocity gradient of 3.1 ± 0.1 km s −1 pc −1 over ∼0.08 pc is found perpendicular to the filament in which Cha-MMS1 is embedded. The gradient is flatter in the outer parts and, surprisingly, also at the innermost ∼2000 AU to 4000 AU. The former features are consistent with solid-body rotation beyond 4000 AU and slower, differential rotation beyond 8000 AU, but the origin of the flatter gradient in the innermost parts is unclear. The classical infall signature is detected in HCO + 3−2 and CS 2−1. The radiative transfer modelling indicates a uniform infall velocity in the outer parts of the envelope. In the inner parts (at most 9000 AU), an infall velocity field scaling with r −0.5 is consistent with the data, but the shape of the profile is less well constrained and the velocity could also decrease toward the centre. The infall velocities are subsonic to transonic, 0.1 km s −1 −0.2 km s −1 at r ≥ 3300 AU, and subsonic to supersonic, 0.04 km s −1 −0.6 km s −1 at r ≤ 3300 AU. Both the internal luminosity of Cha-MMS1 and the infall velocity field in its envelope are consistent with predictions of MHD simulations for the first core phase. There is no evidence of any fast, large-scale outflow stemming from Cha-MMS1, but excess emission from the high-density tracers CS 5−4, CO 6−5, and CO 7−6 suggests the presence of higher velocity material at the inner core. Conclusions. Its internal luminosity excludes Cha-MMS1 being a prestellar core. The kinematical properties of its envelope are consistent with Cha-MMS1 being a first hydrostatic core candidate or a very young Class 0 protostar.

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Clumpy filaments of the Chamaeleon I cloud: C$\mathsf{^{18}}$O mapping with the SEST

Cited by 28 publications

References 33 publications

The end of star formation in Chamaeleon I?

The end of star formation in Chamaeleon I?

Herschelfar-IR observations of the Chamaeleon molecular cloud complex

The dynamical state of the first hydrostatic core candidate Chamaeleon-MMS1

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