Infrared dark clouds (IRDCs) likely represent very early stages of high-mass star/star cluster formation. In this study, we aim to determine the physical properties and spatial distribution of dense clumps in the IRDC MSXDC G304.74+01.32 (G304.74), and bring these characteristics into relation to theories concerning the origin of IRDCs and their fragmentation into clumps and star-forming cores. G304.74 was mapped in the 870 $μ$m dust continuum with the LABOCA bolometer on APEX. Archival MSX and IRAS infrared data were used to study the nature and properties of the submillimetre clumps within the cloud. There are 8 clumps within G304.74 which are not associated with mid-infrared (MIR) emission. Some of them are candidates for being/harbouring high-mass starless cores (HMSCs). We compared the clump masses and their spatial distribution in G304.74 with those in several other recently studied IRDCs. There is a high likelihood that the clump mass distributions in G304.74 and in several other IRDCs represent the samples of the same parent distribution. In most cases the spatial distributions of clumps in IRDCs do not deviate significantly from random distributions. This is consistent with the idea that the origin of IRDCs, and their further sub-fragmentation down to scales of clumps is caused by supersonic turbulence in accordance with results from giant molecular clouds.
We present a parsec-scale molecular hydrogen (H$_2$ 1-0 S(1) at 2.12~\micron) outflow discovered from the UKIRT Widefield Infrared Survey for H$_2$. The outflow is located in the infrared dark cloud core MSXDC G053.11+00.05 MM1 at 1.7 kpc and likely associated with two young stellar objects (YSOs) at the center. The overall morphology of the outflow is bipolar along the NE-SW direction with a brighter lobe to the southwest, but the detailed structure consists of several flows and knots. With the total length of $\sim$1 pc, the outflow luminosity is fairly high with $L_{\rm H_{2}} > 6~L_{\sun}$…
The Seahorse Nebula: New views of the filamentary infrared dark cloud G304.74+01.32 from SABOCA, Herschel, and WISE
我们用SABOCA测辐射热计对350 $μ$ m的红外暗云（IRDC）G304.74+01.32进行了测图。新的SABOCA数据的分辨率比我们以前的LABOCA 870 $μ$ m云图高2.2倍。我们还使用了G304.74的Herschel远红外和亚毫米以及WISE IR数据。SABOCA数据表明，G304.74是一个致密的晶体结构，平均宽度只有$0.18\pm0.05$ pc。发现断裂成SABOCA核心的LABOCA团块的百分比为$36\%\pm16\%$。WISE的数据表明，SABOCA核心的$65\%\pm18\%$拥有年轻的恒星天体（YSO）。通过比较Herschel/SPIRE通量密度得到的尘埃团的平均温度为$15.0 \pm 0.8$ K。LABOCA团块的平均质量、光束平均H $_2$柱密度和H $_2$数密度估计为$55\pm10$ M $_{\odot}$、$(2.0\pm0.2)\times10^{22}$ cm $^{-2}$和$(3.1\pm0.2)\times10^4$ cm $^{-3}$。SABOCA核心的相应值为$29\pm3$ M $_{\odot}$、$(2.9\pm0.3)\times10^{22}$ cm $^{-2}$和$(7.9\pm1.2)\times10^4$ cm $^{-3}$。G304.74灯丝估计为热超临界的$\gtrsim3…
The early evolutionary stage of brown dwarfs are not very well characterized, specially during the embedded phase. To gain insight into the dominant formation mechanism of very low-mass objects and brown dwarfs, we conducted deep observations at 870$μ$m with the LABOCA bolometer at the APEX telescope. Our goal was to identify young sub-mm sources in the Barnard 30 dark cloud. We complemented these data with multi-wavelength observations from the optical to the far-IR and. As a result, we have identified 34 submm sources and a substantial number of possible and probable Barnard 30 members withi…
We used data from WISE, IRAS, and Herschel in conjuction with our previous observations with SABOCA and LABOCA, and constructed the far-IR to submillimetre spectral energy distributions (SEDs) of dense cores in the filamentary Seahorse infrared dark cloud (IRDC) G304.74+01.32. For the 12 analysed cores, which include two IR dark cores (no WISE counterpart), nine IR bright cores, and one HII region, the mean dust temperature of the cold (warm) component, the mass, luminosity, H$_2$ number density, and surface density were derived to be $13.3\pm1.4$ K ($47.0\pm5.0$ K), $113\pm29$ M$_{\odot}$, $1…
In this work we present ALMA continuum observations at 880 $μ$m of 30 sub-mm cores previously identified with APEX/LABOCA at 870$μ$m in the Barnard 30 cloud. The main goal is to characterize the youngest and lowest mass population in the cloud. As a result, we report the detection of five (out of 30) spatially unresolved sources with ALMA, with estimated masses between 0.9 and 67 M$_{\rm Jup}$. 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 lo…
We imaged the infrared dark clouds (IRDCs) G1.75-0.08 and G11.36+0.80 at 350 $μ$m and 450 $μ$m using the ArTéMiS bolometer. These data were used in conjunction with our previous 870 $μ$m observations with the Large APEX BOlometer CAmera (LABOCA). The clumps in G11.36+0.80 were also observed in the N$_2$H$^+(1-0)$ transition with the IRAM 30-metre telescope. G1.75-0.08 was found to be composed of two cold ($\sim14.5$ K), massive (several $\sim10^3$ M$_{\odot}$) clumps that are projectively separated by $\sim3.7$ pc. Both clumps are 70 $μ$m dark, but they do not appear to be bounded by self-grav…
