The ratio of<i>N</i>(C$\mathsf{^{18}}$O) and<i>A</i>$\mathsf{_{V}}$ in Chamaeleon I and III-B

Kainulainen, J.; Lehtinen, K.; Harju, J.

doi:10.1051/0004-6361:20053593

Cited by 32 publications

(45 citation statements)

References 57 publications

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“…6 and the online material for a color version. We note that our extinction value is in between the A V of 7.9 mag measured in a slope in the A V map from Kainulainen et al (2006) and the first ever measured value of 3.55 mag by Neuhäuser & Comerón (1998). Given the quality of our fit, we find here further evidence for the physical binarity of Cha Hα 2 being a double of almost identical mid-to late-M-type objects.…”

Section: Spectroscopysupporting

confidence: 74%

Confirmation of the binary status of Chamaeleon Hα 2 – a very young low-mass binary in Chamaeleon

Schmidt

Neuhäuser

Vogt

et al. 2008

A&A

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Context. Neuhäuser & Comerón (1998, Science, 282, 83; 1999, A&A, 350, 612) presented direct imaging evidence, as well as first spectra, of several young stellar and sub-stellar M6-to M8-type objects in the Cha I dark cloud. One of these objects is Cha Hα 2, classified as brown dwarf candidate in several publications and suggested as possible binary in Neuhäuser et al. (2002, A&A, 384, 999 After confirmation of common proper motion, we deduce physical parameters of the objects by spectroscopy, like temperature and mass. Results. We find Cha Hα 2 to be a very close binary of ∼0.16 arcsec separation, having a flux ratio of ∼0.91, thus having almost equal brightness and indistinguishable spectral types within the errors. We show that the two tentative components of Cha Hα 2 form a common proper motion pair, and that neither component is a non-moving background object. We even find evidence for orbital motion. A combined spectrum of both stars spanning optical and near-infrared parts of the spectral energy distribution yields a temperature of 3000 ± 100 K, corresponding to a spectral type of M6 ± 1 and a surface gravity of log g = 4.0 +0.75 −0.5 , both from a comparison with GAIA model atmospheres. Furthermore, we obtained an optical extinction of A V 4.3 mag from this comparison. Conclusions. We derive masses of ∼0.110 M (≥0.070 M ) and ∼0.124 M (≥0.077 M ) for the two components of Cha Hα 2, i.e., probably low-mass stars, but one component could possibly be a brown dwarf.

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Section: Spectroscopysupporting

confidence: 74%

Confirmation of the binary status of Chamaeleon Hα 2 – a very young low-mass binary in Chamaeleon

Schmidt

Neuhäuser

Vogt

et al. 2008

A&A

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“…Our map looks very similar to the extinction map of Kainulainen et al (2006) in terms of structure and sensitivity. Their map was also based on 2MASS data and a similar method was used to compute the extinction.…”

Section: Extinction Map From 2masssupporting

confidence: 71%

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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“…In their study of the Chamaeleon complex, Hayakawa et al (2001) found evidence of variations of 13 CO versus A V from cloud to cloud, which they attributed to chemical fractionation increasing the 13 CO abundance in regions with 2 mag < A V < 4 mag. Although their result was not confirmed by Kainulainen et al (2006), CO abundance variations may exist and may complicate the statistical analysis of CO maps. As Padoan et al (2004) assumed a constant 13 CO abundance in their models, it is possible that the 13 CO power spectra that they derive are affected by variations in the 13 CO abundance.…”

Section: Discussionmentioning

confidence: 92%

Can We Trust the Dust? Evidence of Dust Segregation in Molecular Clouds

Padoan

Cambrésy

Juvela

et al. 2006

ApJ

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Maps of estimated dust column density in molecular clouds are usually assumed to reliably trace the total gas column density structure. In this work we present results showing a clear discrepancy between the dust and the gas distribution in the Taurus molecular cloud complex. We compute the power spectrum of a 2MASS extinction map of the Taurus region and find that it is much shallower than the power spectrum of a 13 CO map of the same region that was previously analyzed. This discrepancy could be explained as the effect of grain growth on the grain extinction efficiency. However, this would require a wide range of maximum grain sizes, which is ruled out based on constraints from the extinction curve and the available grain models. We show that major effects due to CO formation and depletion are also ruled out. Our result may therefore suggest the existence of intrinsic spatial fluctuations of the dustto-gas ratio, with amplitude increasing toward smaller scales. Preliminary results of numerical simulations of trajectories of inertial particles in turbulent flows illustrate how the process of clustering of dust grains by the cloud turbulence may lead to observable effects. However, these results cannot be directly applied to large-scale supersonic and magnetized turbulence at present.

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The ratio ofN(C$\mathsf{^{18}}$O) andA$\mathsf{_{V}}$ in Chamaeleon I and III-B

Cited by 32 publications

References 57 publications

Confirmation of the binary status of Chamaeleon Hα 2 – a very young low-mass binary in Chamaeleon

Confirmation of the binary status of Chamaeleon Hα 2 – a very young low-mass binary in Chamaeleon

The end of star formation in Chamaeleon I?

Can We Trust the Dust? Evidence of Dust Segregation in Molecular Clouds

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