A proto brown dwarf candidate in Taurus

Barrado, D.; Morales-Calderón, M.; Palau, Aina; Bayo, A.; Gregorio-Monsalvo, I. de; Eiroa, C.; Huélamo, N.; Bouy, H.; Morata, Ó.; Schmidtobreick, L.

doi:10.1051/0004-6361/200912276

Cited by 26 publications

(99 citation statements)

References 43 publications

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“…Palau et al (2012) or André et al (2012). Up to now, several objects have been identified as VeLLOs whose properties are consistent with proto-BDs (see e.g., Young et al 2004;Bourke et al 2006;Lee et al 2009;Barrado et al 2009;Palau et al 2012Palau et al , 2014Morata et al 2015). However, the samples of proto-BD candidates are still very small.…”

Section: Introductionmentioning

confidence: 96%

A search for pre- and proto-brown dwarfs in the dark cloud Barnard 30 with ALMA

Huélamo

Gregorio-Monsalvo

Palau

et al. 2016

A&A

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Context. The origin of brown dwarfs is still under debate. While some models predict a star-like formation scenario, others invoke a substellar mass embryo ejection, a stellar disk fragmentation, or the photo-evaporation of an external core due to the presence of massive stars. Aims. The aim of our work is to characterize the youngest and lowest mass population of the dark cloud Barnard 30, a region within the Lambda Orionis star-forming region. In particular, we aim to identify proto-brown dwarfs and study the mechanism of their formation. Methods. We obtained ALMA continuum observations at 880 µm of 30 sub-mm cores previously identified with APEX/LABOCA at 870 µm. We have complemented part of the ALMA data with sub-mm APEX/SABOCA observations at 350 µm, and with multiwavelength ancillary observations from the optical to the far-infrared (e.g., Spitzer, CAHA/O2000, WISE, INT/WFC). Results. We report the detection of five (out of 30) spatially unresolved sources with ALMA, with estimated masses between 0.9 and 67 M Jup . From these five sources, only two show gas emission. The analysis of multi-wavelength photometry from these two objects, namely B30-LB14 and B30-LB19, is consistent with one Class II-and one Class I low-mass stellar object, respectively. The gas emission is consistent with a rotating disk in the case of B30-LB14, and with an oblate rotating envelope with infall signatures in the case of LB19. The remaining three ALMA detections do not have infrared counterparts and can be classified as either deeply embedded objects or as starless cores if B30 members. In the former case, two of them (LB08 and LB31) show internal luminosity upper limits consistent with Very Low Luminosity objects, while we do not have enough information for LB10. In the starless core scenario, and taking into account the estimated masses from ALMA and the APEX/LABOCA cores, we estimate final masses for the central objects in the substellar domain, so they could be classified as pre-BD core candidates. According to the turbulent fragmentation scenario, the three ALMA pre-BD core candidates should be gravitationally stable based on APEX/LABOCA data. However, this result is not consistent with the presence of compact sources inside the cores, indicative of on-going collapse. As an alternative scenario we propose that these cores could be the result of on-going gravitational contraction. Indeed, we have verified that their estimated masses are consistent with the ones expected within an ALMA beam for a r −2 density profile, which is typical for a collapsing core. Conclusions. ALMA observations have allowed us to detect very low-mass compact sources within three APEX/LABOCA cores. Future observations will help us to unveil their true nature.

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Section: Introductionmentioning

confidence: 96%

A search for pre- and proto-brown dwarfs in the dark cloud Barnard 30 with ALMA

Huélamo

Gregorio-Monsalvo

Palau

et al. 2016

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“…We have used their criteria and verified that a small number of our possible counterparts fall in the regions where extra-galactic sources are located. We note that young substellar objects could be located in the same areas in the CCD and CMD (see the case of an excellent proto-brown dwarf in Taurus Barrado et al 2009;Palau et al 2012). We have classified these objects as possible extra-galactic, and added the tag G to the membership criteria listed in Table 7.…”

Section: Classification Of the Laboca Submm Sources And The Counterpartsmentioning

confidence: 99%

Early phases in the stellar and substellar formation and evolution

Barrado¹,

Gregorio-Monsalvo²,

Huélamo³

et al. 2018

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Aims. The early evolutionary stage of brown dwarfs are not very well characterized, specially during the embedded phase. Our goal is to gain insight into the dominant formation mechanism of very low-mass objects and brown dwarfs. Methods. We have conducted deep observations at 870 µm obtained with the LABOCA bolometer at the APEX telescope in order to identify young submillimeter sources in the Barnard 30 dark cloud. We have complemented these data with multi-wavelength observations from the optical to the far-IR and compiled complete spectral energy distributions (SEDs) in order to identify the counterparts, characterize the sources and to assess their membership to the association and stellar or substellar status based on the available photometric information. Results. We have identified 34 submillimeter sources and a substantial number of possible and probable Barnard 30 members within each individual APEX/LABOCA beam. They can be classified in three distinct groups. First, 15 out of these 34 have a clear optical or IR counterpart to the submm peak and nine of them are potential proto-BDs candidates. Moreover, a substantial number of them could be multiple systems. A second group of 13 sources comprises candidate members with significant infrared excesses located away from the central submm emission. All of them include brown dwarf candidates, some displaying IR excess, but their association with submm emission is unclear. In addition, we have found six starless cores and, based on the total dust mass estimate, three might be pre-substellar (or pre-BDs) cores. Finally, the complete characterization of our APEX/LABOCA sources, focusing on those detected at 24 and/or 70 µm, indicates that in our sample of 34 submm sources there are, at least: two WTTs, four CTTs, five young stellar objects (YSOs), eight proto-BD candidates (with another three dubious cases), and one Very Low Luminosity objects (VeLLO). Conclusions. Our findings provide additional evidence concerning the brown dwarf formation mechanism, which seems to be a downsized version of the stellar formation.

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“…5 (left), strongly suggests that the infrared and submillimetre sources are spatially associated. To further explore the possible nature of core L, we compared its SED (we list its photometry in Table 3) to the known SEDs of previously reported Class I (J041757B, Barrado et al 2009;Palau et al 2012) and Class 0 (Lee et al 2013;Palau et al 2014) proto-BD candidates, and the result is shown in Fig. 5 (right).…”

Section: A Possible Candidate For Proto-bdmentioning

confidence: 99%

“…Greaves et al 2003), and the study of individual objects using previous information at other wavelengths (e.g. Barrado et al 2009;André et al 2012;Palau et al 2012Palau et al , 2014Lee et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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

Gregorio-Monsalvo

Barrado

Bouy

et al. 2016

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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.

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A proto brown dwarf candidate in Taurus

Cited by 26 publications

References 43 publications

A search for pre- and proto-brown dwarfs in the dark cloud Barnard 30 with ALMA

A search for pre- and proto-brown dwarfs in the dark cloud Barnard 30 with ALMA

Early phases in the stellar and substellar formation and evolution

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

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