THE<i>SPITZER</i>c2d SURVEY OF NEARBY DENSE CORES. V. DISCOVERY OF A VeLLO IN THE “STARLESS” DENSE CORE L328

Lee, Chang Won; Bourke, Tyler L.; Myers, Philip C.; Dunham, Mike; Evans, Neal J.; Lee, Youngung; Huard, Tracy L.; Wu, Jingwen; Gutermuth, Robert; Kim, Mi-Ryang; Kang, Hyun Woo

doi:10.1088/0004-637x/693/2/1290

Cited by 51 publications

(69 citation statements)

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“…Later, several authors assigned a distance of 200 pc assuming that the clouds, L328 and L323, are located in-between the Ophiuchus cloud and the Aquila Rift (e.g., Lee et al 2009). Using photometry on the Vilnius system, Straižys et al (2003) estimated a distance of 225 ± 55 pc to the front edge of the Aquila Rift with a possible depth of 80 pc to the cloud complex.…”

Section: L328mentioning

confidence: 99%

Distances to dense cores that contain very low luminosity objects

Maheswar

Lee

Dib

2011

A&A

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Aims. We estimate the distances to dense molecular cores that harbour very low luminosity objects (VeLLOs) detected by the Spitzer Space Telescope and attempt to confirm their VeLLO nature. Methods. The cloud distances are estimated using a near-IR photometric method. We use a technique that performs a spectral classification of stars lying towards the fields containing the clouds as either main-sequence stars or giants. In this technique, the observed (J − H) and (H − K s ) colours are dereddened simultaneously using trial values of A V and a normal interstellar extinction law. The best fit of the dereddened colours to the intrinsic colours giving a minimum value of χ 2 then yields the corresponding spectral type and A V for the star. The main-sequence stars, thus classified, are then utilized in an A V versus distance plot to bracket the cloud distances. The typical error in the estimation of distances to the clouds are found to be ∼18%. Results. We estimate distances to seven cloud cores, IRAM 04191, L1521F, BHR 111, L328, L673-7, L1014, and L1148 using the above method. These clouds contain VeLLO candidates. The estimated distances to the cores are found to be 127 ± 25 pc (IRAM 04191), 136 ± 36 pc (L1521F), 355 ± 65 pc (BHR 111), 217 ± 30 pc (L328), 240 ± 45 pc (L673-7), 258 ± 50 pc (L1014), and 301 ± 55 pc (L1148). We re-evaluated the internal luminosities of the VeLLOs discovered in these seven clouds using the distances estimated from this work. Except for L1014−IRS (L int = 0.15 L ), all other VeLLO candidates are found to be consistent with the definition of a VeLLO (L int ≤ 0.1 L ). In addition to the cores that harbour VeLLO candidates, we also obtained distances to the clouds L323, L675, L676, CB 188, L1122, L1152, L1155, L1157, and L1158, which are located in the directions of the above seven cores. Towards L1521F and L1148, we found evidence of multiple dust layers.

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Section: L328mentioning

confidence: 99%

Distances to dense cores that contain very low luminosity objects

Maheswar

Lee

Dib

2011

A&A

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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: 97%

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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“…Only a handful of VeLLOs has been studied in detail (for instance, André et al 1999;Young et al 2004;Kauffmann et al 2005Kauffmann et al , 2008Lee et al 2009), the least luminous having a bolometric luminosity of ∼0.1 L (Lee et al 2009). Therefore, we Article published by EDP Sciences developed a strategy to search systematically for proto brown dwarfs (Morales-Calderón et al 2009, in prep.…”

Section: Introductionmentioning

confidence: 99%

A proto brown dwarf candidate in Taurus

Barrado¹,

Morales-Calderón

Palau³

et al. 2009

A&A

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Aims. We search for brown dwarfs at the Class 0/I evolutionary stage, or proto brown dwarfs.Methods. We present a multi wavelength study, ranging from optical at 0.8 μm to radio wavelengths at 6 cm, of a cool, very faint, and red multiple object, SSTB213 J041757, detected by Spitzer toward the Barnard 213 dark cloud, in Taurus.Results. The SED of SSTB213 J041757 displays a clear excess at long wavelengths resembling that of a Class I object. The mid-IR source has two possible counterparts, A and B, in the near-IR and optical images, and the 350 μm observations detect clear extended emission, presumably from an envelope around the two sources. The position of A & B in the (Ic − J) versus (J − [3.6]) colour-colour diagram is consistent with them being Galactic sources and not extragalactic contaminants. A proper-motion study confirms this result for A, while it is inconclusive for B. The temperature and mass of the two possible central objects, according to COND evolutionary models, range between 1550−1750 K and 3−4 M Jupiter , and 950−1300 K and 1−2 M Jupiter , for A and B, respectively. The integrated SED provides bolometric temperatures and luminosities of 280 K and 0.0034 L , assuming that the emission at wavelengths >5 μm is associated with component A, and 150 K and 0.0033 L , assuming that the emission at wavelengths >5 μm is associated with component B, which would imply the SSTB213 J041757 object has a luminosity well below the luminosity of other very low luminosity objects discovered up to date. Conclusions. With these characteristics, SSTB213 J041757 seems to be a promising, and perhaps double, proto brown dwarf candidate.

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THESPITZERc2d SURVEY OF NEARBY DENSE CORES. V. DISCOVERY OF A VeLLO IN THE “STARLESS” DENSE CORE L328

Cited by 51 publications

References 53 publications

Distances to dense cores that contain very low luminosity objects

Distances to dense cores that contain very low luminosity objects

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

A proto brown dwarf candidate in Taurus

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