The JCMT Legacy Survey of the Gould Belt: a first look at Serpens with HARP
S. F. Graves, J. S. Richer, J. V. Buckle, A. Duarte-Cabral, G. A. Fuller, M. R. Hogerheijde, J. E. Owen, C. Brunt, H. M. Butner, B. Cavanagh, A. Chrysostomou, E… 展开作者
S. F. Graves, J. S. Richer, J. V. Buckle, A. Duarte-Cabral, G. A. Fuller, M. R. Hogerheijde, J. E. Owen, C. Brunt, H. M. Butner, B. Cavanagh, A. Chrysostomou, E. I. Curtis, C. J. Davis, M. Etxaluze, J. Di Francesco, P. Friberg, R. K. Friesen, J. S. Greaves, J. Hatchell, D. Johnstone, B. Matthews, H. Matthews, C. D. Matzner, D. Nutter, J. M. C. Rawlings, J. F. Roberts, S. Sadavoy, R. J. Simpson, N. F. H. Tothill, Y. G. Tsamis, S. Viti, D. Ward-Thompson, G. J. White, J. G. A. Wouterloot, J. Yates
JCMT上的Gould Belt Legacy Survey（GBS）观测到巨蛇座分子云中12 CO J=3- 2发射的260平方角分区域，以及13 CO和C18 O发射的190平方角分子集。我们研究了非流出气体的全局速度结构，并计算了激发温度和不透明度。大规模的质量和能量的区域进行评估，特别考虑到高速气体。我们发现这个云的质量是203个太阳质量，并且受到引力束缚，流出气体的动能大约是云湍流动能的70%。我们确定了该地区一些亚毫米级0/I类源的紧凑流出
英文摘要：
The Gould Belt Legacy Survey (GBS) on the JCMT has observed a region of 260 square arcminutes in 12CO J=3--2 emission, and a 190 square arcminute subset of this in 13CO and C18O towards the Serpens molecular cloud. We examine the global velocity structure of the non-outflowing gas, and calculate excitation temperatures and opacities. The large scale mass and energetics of the region are evaluated, with special consideration for high velocity gas. We find the cloud to have a mass of 203 solar masses, and to be gravitationally bound, and that the kinetic energy of the outflowing gas is approximately seventy percent of the turbulent kinetic energy of the cloud. We identify compact outflows towards some of the submillimetre Class 0/I sources in the region
Radiative feedback can influence subsequent star formation. We quantify the heating from OB stars in the local star-forming regions in the JCMT Gould Belt survey. Dust temperatures are calculated from 450/850 micron flux ratios from SCUBA-2 observations at the JCMT assuming a fixed dust opacity spectral index $β=1.8$. Mean dust temperatures are calculated for each submillimetre clump along with projected distances from the main OB star in the region. Temperature vs. distance is fit with a simple model of dust heating by the OB star radiation plus the interstellar radiation field and dust cooli…
The JCMT Transient Survey: Identifying Submillimetre Continuum Variability over Several Year Timescales Using Archival JCMT Gould Belt Survey Observations
We present a subset of the James Clerk Maxwell Telescope Gould Belt Survey's "first-look" results of the southern extent of the Orion A molecular cloud. Employing a two-step structure identification process, we constructed individual catalogues for large-scale regions of significant emission labeled as "islands" and smaller-scale subregions called "fragments" using the 850 $μ$m continuum maps obtained using the Submillimetre Common-User Bolometer Array 2 (SCUBA-2). We highlight the relationship between the concentration and Jeans stability for regions of significant emission and present the re…
The Herschel Gould Belt survey mapped the nearby (d < 500 pc) star-forming regions to understand better how the prestellar phase influences the star formation process. Here we report a complete census of dense cores in a 15 deg2 area of the Serpens star-forming region located between d=420 pc and 484 pc. The PACS and SPIRE cameras imaged this cloud from 70micron to 500micron. With the multi-wavelength source extraction algorithm getsources, we extract 833 sources, of which 709 are starless cores and 124 are candidate proto-stellar cores. We obtain temperatures and masses for all the sample, cl…
The JCMT Gould Belt Survey: First results from the Corona Australis molecular cloud and evidence of variable dust emissivity indices in the Coronet region
The JCMT Gould Belt Survey was one of the first Legacy Surveys with the James Clerk Maxwell Telescope in Hawaii, mapping 47 square degrees of nearby (< 500 pc) molecular clouds in both dust continuum emission at 850 $μ$m and 450 $μ$m, as well as a more-limited area in lines of various CO isotopologues. While molecular clouds and the material that forms stars have structures on many size scales, their larger-scale structures are difficult to observe reliably in the submillimetre regime using ground-based facilities. In this paper, we quantify the extent to which three subsequent data-reduction …
We present 850 and 450 micron observations of the dense regions within the Auriga-California molecular cloud using SCUBA-2 as part of the JCMT Gould Belt Legacy Survey to identify candidate protostellar objects, measure the masses of their circumstellar material (disk and envelope), and compare the star formation to that in the Orion A molecular cloud. We identify 59 candidate protostars based on the presence of compact submillimeter emission, complementing these observations with existing Herschel/SPIRE maps. Of our candidate protostars, 24 are associated with young stellar objects (YSOs) in …
The JCMT Gould Belt Survey: First results from the SCUBA-2 observations of the Ophiuchus molecular cloud and a virial analysis of its prestellar core population
在本文中，我们提出了第一次观测的蛇夫座分子云的詹姆斯克拉克麦克斯韦望远镜（JCMT）古尔德带调查（GBS）的一部分，与SCUBA-2仪器。我们展示了将这些数据与以前的HARP CO，Herschel和IRAM N $_{2}$ H $^{+}$观测相结合的方法，以准确地量化蛇夫座SCUBA-2源的特性。我们制作了一份SCUBA-2发现的所有来源的目录。我们把它们分成原恒星和无恒星的核心。我们列出了所有的无星核心，并进行了全面的维里分析，包括外部压力。这是第一次将外部压力包括在这一详细程度中。我们发现我们的大多数核心要么是束缚的，要么是男性化的。引力能和外压的平均值在数量级上是相似的，但各区域之间有一些差异。我们发现，在OPH A区域的核心是重力约束的星前核心，而在OPH C和E区域的核心是压力限制。我们确定，N $_{2}$ H $^{+}$是一个很好的示踪剂的结合材料的星前核心，虽然我们发现了一些证据N $_{2}$ H $^{+}$冻结在非常高的核心密度。我们发现，非热线宽之间的跟踪由C $^{18}$ O和跟踪由N $_{2}$ H $^{+}$，表明在较高的密度湍流耗散的气体大幅减少。我们发现，临界Bonnor-Ebert稳定性准则是不是一个很好的指标，我们的核心的有界性。我们探测到前褐矮星候选者Oph B-11，并发现与以前的工作一致的通量密度和质量。我们讨论的核心的性质…
This white paper gives a brief summary of Galactic continuum surveys with the next generation 850 micron camera at the James Clerk Maxwell Telescope (JCMT) in the next decade. This new camera will have mapping speeds at least 10-20 times faster than the present SCUBA-2 camera, and will enable deep (<10 mJy/beam) and extensive continuum surveys such as a wider (-5 deg.<l<240 deg., |b|<2-5 deg.) Galactic Plane survey, a larger Gould Belt survey, and a follow-up survey of all Planck compact objects visible from the northern hemisphere. These surveys will provide a complete census of molecular clo…
Protostars likely accrete material at a highly time variable rate, however, measurements of accretion variability from the youngest protostars are rare, as they are still deeply embedded within their envelopes. Sub-mm/mm observations can trace the thermal response of dust in the envelope to accretion luminosity changes, allowing variations in the accretion rate to be quantified. In this paper, we present contemporaneous sub-mm/mm light curves of variable protostars in Serpens Main, as observed by the ALMA ACA, SMA, and JCMT. The most recent outburst of EC 53 (V371 Ser), an $\sim 18$ month peri…
Short-duration flares at millimeter wavelengths provide unique insights into the strongest magnetic reconnection events in stellar coronae, and combine with longer-term variability to introduce complications to next-generation cosmology surveys. We analyze 5.5 years of JCMT Transient Survey 850 micron submillimeter monitoring observations toward eight Gould Belt star-forming regions to search for evidence of transient events or long-duration variability from faint sources. The eight regions (30 arcmin diameter fields), including ~1200 infrared-selected YSOs, have been observed on average 47 ti…
We present 850 $μ$m polarimetric observations toward the Serpens Main molecular cloud obtained using the POL-2 polarimeter on the James Clerk Maxwell Telescope (JCMT) as part of the B-fields In STar-forming Region Observations (BISTRO) survey. These observations probe the magnetic field morphology of the Serpens Main molecular cloud on about 6000 au scales, which consists of cores and six filaments with different physical properties such as density and star formation activity. Using the histogram of relative orientation (HRO) technique, we find that magnetic fields are parallel to filaments in…
