The<i>Herschel</i>Gould Belt Survey in Chamaeleon II

Spezzi, L.; Cox, Nicholas; Prusti, T.; Merın, Bruno; Ribas, Álvaro; Oliveira, Catarina Alves de; Winston, E.; Kóspál, Á.; Royer, P.; Vavrek, R.; André, Ph.; Pilbratt, G. L.; Testi, L.; Bressert, E.; Ricci, Luca; Men’shchikov, A.; Könyves, V.

doi:10.1051/0004-6361/201321444

Cited by 25 publications

(46 citation statements)

References 89 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, the detection bias can also affect the correlation since most other samples have worse sensitivity to disk mass compared to TWA sources because they are located at larger distances and observed with shorter exposure times. For example, the data points taken from Spezzi et al (2013) and Olofsson et al (2013) are based on the Herschel Gould Belt survey (André et al 2010) that is not sensitive enough to detect very faint disks as compared to dedicated projects like our program and the one in Harvey et al (2012a). The ambiguity of non-detections by current PACS observations may cause additional spread in F 70 and in turn weaken the M disk ∼ M relation.…”

Section: Dependence On the Stellar Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

Herschel/PACS view of disks around low-mass stars and brown dwarfs in the TW Hydrae association

Liu

Herczeg

Gong

et al. 2014

A&A

View full text Add to dashboard Cite

We conducted Herschel/PACS observations of five very low-mass stars or brown dwarfs located in the TW Hya association with the goal of characterizing the properties of disks in the low stellar mass regime. We detected all five targets at 70 μm and 100 μm and three targets at 160 μm. Our observations, combined with previous photometry from 2MASS, WISE, and SCUBA-2, enabled us to construct spectral energy distributions (SEDs) with extended wavelength coverage. Using sophisticated radiative transfer models, we analyzed the observed SEDs of the five detected objects with a hybrid fitting strategy that combines the model grids and the simulated annealing algorithm and evaluated the constraints on the disk properties via the Bayesian inference method. The modeling suggests that disks around low-mass stars and brown dwarfs are generally flatter than their higher mass counterparts, but the range of disk mass extends to well below the value found in T Tauri stars, and the disk scale heights are comparable in both groups. The inferred disk properties (i.e., disk mass, flaring, and scale height) in the low stellar mass regime are consistent with previous findings from large samples of brown dwarfs and very low-mass stars. We discuss the dependence of disk properties on their host stellar parameters and find a significant correlation between the Herschel far-IR fluxes and the stellar effective temperatures, probably indicating that the scaling between the stellar and disk masses (i.e., M disk ∝ M ) observed mainly in low-mass stars may extend down to the brown dwarf regime.

show abstract

Section: Dependence On the Stellar Propertiesmentioning

confidence: 99%

“…In Fig. 3, we show the results from our program and from the literature (Harvey et al 2012a,b;Olofsson et al 2013;Spezzi et al 2013;Alves de Oliveira et al 2013;Riviere-Marichalar et al 2013). All fluxes are scaled assuming a distance of 100 pc.…”

Section: Dependence On the Stellar Propertiesmentioning

confidence: 99%

Herschel/PACS view of disks around low-mass stars and brown dwarfs in the TW Hydrae association

Liu

Herczeg

Gong

et al. 2014

A&A

View full text Add to dashboard Cite

show abstract

“…In another recent study using Herschel observations, Spezzi et al (2013) have used a different radiative transfer code to study the disk properties of low-mass stars in the ∼2 Myr old Chamaeleon II cluster. Although their sample does not reach into the substellar regime, a few of their targets have spectral types corresponding to low masses of ∼0.3 M .…”

Section: Comparison To Other Disk Studiesmentioning

confidence: 99%

Herschelsurvey of brown dwarf disks inρOphiuchi

Oliveira

Ábrahám

Márton

et al. 2013

A&A

Self Cite

View full text Add to dashboard Cite

Context. Young brown dwarfs are known to possess circumstellar disks, a characteristic that is fundamental to the understanding of their formation process, and raises the possibility that these objects harbour planets. Aims. We want to characterise the far-IR emission of disks around the young brown dwarf population of the ρ Ophiuchi cluster in LDN 1688. Methods. Recent observations of the ρ Ophiuchi cluster with the Herschel Space Observatory allow us to probe the spectral energy distribution (SED) of the brown dwarf population in the far-IR, where the disk emission peaks. We performed aperture photometry at 70, 100, and 160 µm, and constructed SEDs for all previously known brown dwarfs detected. These were complemented with ancillary photometry at shorter wavelengths. We compared the observed SEDs to a grid of synthetic disks produced with the radiative transfer code MCFOST, and used the relative figure of merit estimated from the Bayesian inference of each disk parameter to analyse the structural properties. Results. We detected 12 Class II brown dwarfs with Herschel, which corresponds to one-third of all currently known brown dwarf members of ρ Ophiuchi. We did not detect any of the known Class III brown dwarfs. Comparison to models reveals that the disks are best described by an inner radius between 0.01 and 0.07 AU, and a flared disk geometry with a flaring index between 1.05 and 1.2. Furthermore, we can exclude values of the disk scale-height lower than 10 AU (measured at a fiducial radius of 100 AU). We combined the Herschel data with recent ALMA observations of the brown dwarf GY92 204 (ISO−Oph 102), and by comparing its SED to the same grid of disk models, we derived an inner disk radius of 0.035 AU, a scale height of 15 AU with a flaring index of β ∼ 1.15, an exponent for dust settling of −1.5, and a disk mass of 0.001 M . This corresponds to a disk-to-central object mass ratio of ∼1%. Conclusions. The structural parameters constrained by the extended SED coverage (inner radius and flaring index) show a narrow distribution for the young brown dwarfs detected in ρ Ophiuchi, suggesting that these objects share the same disk evolution and, perhaps, formation.

show abstract

“…IRAS 12500-7658 has been catalogued as a Class I object of spectral type close to K5 (Spezzi et al 2013). In this work, we detect compact submillimetre emission that is associated with this IRAS source and that is very close to a southern and extended starless core of 10 4 AU size (see Figs.…”

Section: Previously Known Ysos In the Regionmentioning

confidence: 60%

“…This source has been extensively studied by Spezzi et al (2013), and provides an estimation of the most probable parameters of the disk surrounding DK Cha. Spezzi et al (2013) model the SED of this source from the optical to millimetre wavelengths (using Herschel data), while the flux at 870 µm, which is expected from their set of bestfitting models, agrees very well with our measurements given in Table 2.…”

Section: Previously Known Ysos In the Regionmentioning

confidence: 99%

A submillimetre search for pre- and proto-brown dwarfs in Chamaeleon II

Gregorio-Monsalvo

Barrado

Bouy

et al. 2016

A&A

Self Cite

View full text Add to dashboard Cite

Context. The Chamaeleon II molecular cloud is an active star-forming region that offers an excellent opportunity to study the formation of brown dwarfs in the southern hemisphere. Aims. Our aims are to identify a population of pre-and proto-brown dwarfs (5σ mass limit threshold of ∼0.015 M ) and provide information on the formation mechanisms of substellar objects. Methods. We performed high sensitivity observations at 870 µm using the LABOCA bolometer at the APEX telescope towards an active star-forming region in Chamaeleon II. The data are complemented by an extensive multiwavelength catalogue of sources, which covers the optical to the far-infrared, to study the nature of the LABOCA detections. Results. We detect 15 cores at 870 µm, and 11 of them show masses in the substellar regime. The most intense objects in the surveyed field correspond to the submillimetre counterparts of the well-known young stellar objects DK Cha and IRAS 12500-7658. We identify a possible proto-brown dwarf candidate (ChaII-APEX-L) with IRAC emission at 3.6 and 4.5 µm. Conclusions. Our analysis indicates that most of the spatially resolved cores are transient, and that the point-like starless cores in the substellar regime (with masses between 0.016 M and 0.066 M ) could be pre-brown dwarfs cores that are gravitationally unstable if they have radii less than 220 AU to 907 AU (1.2 to 5 at 178 pc), respectively, for different masses. ALMA observations will be key to revealing the energetic state of these pre-brown dwarfs candidates.

show abstract

TheHerschelGould Belt Survey in Chamaeleon II

Cited by 25 publications

References 89 publications

Herschel/PACS view of disks around low-mass stars and brown dwarfs in the TW Hydrae association

Herschel/PACS view of disks around low-mass stars and brown dwarfs in the TW Hydrae association

Herschelsurvey of brown dwarf disks inρOphiuchi

A submillimetre search for pre- and proto-brown dwarfs in Chamaeleon II

Contact Info

Product

Resources

About