The Discovery of a Massive SCUBA Core with both Inflow and Outflow Motions

Wu, Yuefang; Zhu, Meiping; Wei, Yuyang; Xu, D.; Zhang, Qizhou; Fiege, Jason D.

doi:10.1086/432614

Cited by 40 publications

(63 citation statements)

References 22 publications

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“…As a consequence of the selection criteria, MSX data (Egan et al 2003) are available for all of the 51 sources of the sample. We found IRAS data (Helou & Walker 1988) for 45 sources, Scuba data for 12 sources at 450 μm and for 16 at 850 μm (Williams et al 2004;Wu et al 2005;Thompson et al 2006), and Calthech Submillimeter Observatory (CSO) data for 4 sources at 350 μm (Hunter et al 2000;Motte et al 2003). For 8 sources, we found measurements at 1.2 mm carried out with the IRAM 30 m Radiotelescope (Altenhoff et al 1994;Beuther et al 2002) and SIMBA (Faúndez et al 2004).…”

Section: The Dust Contributionmentioning

confidence: 89%

7 mm continuum observations of ultra compact HII regions

Leto

Umana²,

Trigilio³

et al. 2009

A&A

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Aims. Ultra compact HII (UCHII) regions are indicators of high-mass star formation sites and are distributed mainly in the Galactic plane. They exhibit a broad band spectrum with significant emission between near-IR and radio wavelengths. We intend to investigate the possible contribution of the forthcoming ESA Planck mission to the science of UCHII regions by evaluating the possibility of detecting UCHIIs that are bright in the radio regime. Methods. We performed new 7 mm observations of a sample of UCHII regions. The observations were designed to acquire highfrequency radio spectra. For each source in our sample, the free-free radio spectrum has been modeled. Along with far-IR measurements, our spectra allow us to estimate the flux densities of the sources in the millimeter and sub-millimeter bands. We extrapolated and summed the ionized-gas (free-free radio emission) and dust (thermal emission) contributions in the afore mentioned wavelength ranges. The possibility of Planck detecting the selected sources can be assessed by comparing the estimated flux densities to the expected sensitivity in each Planck channel. To obtain a realistic estimation of the noise produced by the Galactic emission, the Planck sky model software package was used. Results. For each target source, from our new 7 mm data and other radio measurements from the literature, important physical parameters such as electron density and their spatial distribution, source geometry and emission measure were derived. We conclude that, in the case of the present sample, located close to the Galactic center, Planck will have a very low detection rate. In contrast, assuming that our sample is representative of the whole UCHII-region population, we derive a very high probability of detecting this kind of source with Planck if located instead close to the anticenter. From the analysis of the ionized-gas properties, we suggest that the selected sample could also be contaminated by other kinds of Galactic objects.

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Section: The Dust Contributionmentioning

confidence: 89%

7 mm continuum observations of ultra compact HII regions

Leto

Umana²,

Trigilio³

et al. 2009

A&A

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“…The dense core JCMT 18354−0649S was first detected in an ammonia survey of high-mass star-forming regions with the Max-Planck-Institut für Radioastronomie (MPIfR) 100 m telescope at Effelsberg (Wu et al 2006), and was later confirmed by the observation with the Submillimeter Common-User Bolometric Array (SCUBA) of the James Clerk Maxwell telescope (JCMT; Wu et al 2005). Another SCUBA core which harbors a UC H ii region, G35.4 NW, is located about 1 north of JCMT 18354−0649S.…”

Section: Introductionmentioning

confidence: 94%

“…Another SCUBA core which harbors a UC H ii region, G35.4 NW, is located about 1 north of JCMT 18354−0649S. The kinetic distance of the two SCUBA cores is 5.7 or 9.6 kpc (Wu et al 2005), and 5.7 kpc was adopted in this paper. Core JCMT 18354−0649S has no counterpart in the radio continuum.…”

Section: Introductionmentioning

confidence: 99%

Infall and Outflow Detections in a Massive Core JCMT 18354–0649s

Zhang

Ren

et al. 2011

ApJ

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We present a high-resolution study of a massive dense core JCMT 18354−0649S with the Submillimeter Array. The core is mapped with continuum emission at 1.3 mm and molecular lines including CH 3 OH (5 23 -4 13 ) and HCN (3-2). The dust core detected in the compact configuration has a mass of 47 M and a diameter of 2 (0.06 pc), which is further resolved into three condensations with a total mass of 42 M under higher spatial resolution. The HCN (3-2) line exhibits an asymmetric profile consistent with infall signature. The infall rate is estimated to be 2.0 × 10 −3 M yr −1 . The high-velocity HCN (3-2) line wings present an outflow with three lobes. Their total mass is 12 M and the total momentum is 121 M km s −1 . Analysis shows that the N-bearing molecules especially HCN can trace both inflow and outflow.

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“…(EGOs, Chen et al 2010), which are shocked regions, and -0.5 for the cluster-forming clump G24.4 (Wu et al 2005).…”

Section: The Skewness Parameter δVmentioning

confidence: 99%

Initial phases of massive star formation in high infrared extinction clouds

Rygl

Wyrowski

Schüller

et al. 2012

A&A

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Context. The onset of massive star formation is not well understood because of observational and theoretical difficulties. To find the dense and cold clumps where massive star formation can take place, we compiled a sample of high infrared extinction clouds. We observed the clumps in these high extinction clouds in the 1.2 mm continuum emission and ammonia with the goals of deriving the masses, densities, temperatures, and kinematic distances. Aims. We try to understand the star-formation stages of the high extinction clumps by studying their infall and outflow properties, the presence of a young stellar object (YSO), and the level of the CO depletion. Are the physical parameters, density, mass, temperature, and column density correlated with the star-forming properties? Does the cloud morphology, quantified through the column density contrast between the clump and the clouds, have an impact on the evolution of star formation occurring inside it? Methods. Star-formation properties, such as infall, outflow, CO depletion, and the presence of YSOs, were derived from a molecular line survey performed with the IRAM 30 m and the APEX 12 m telescopes. Results. We find that the HCO + (1-0) transition is the most sensitive for detecting infalling motions. SiO, an outflow tracer, was mostly detected toward sources with infall, indicating that infall is accompanied by collimated outflows. We calculated infall velocities from the line profiles and found them to be of the order of 0.3-7 km s −1 . The presence of YSOs within a clump depends mostly on the clump column density; no indication of YSOs were found below 4 × 10 22 cm −2 . Conclusions. Star formation is on the verge of beginning in clouds that have a low column density contrast; the infall is not yet present in the majority of the clumps. The first signs of ongoing star formation are broadly observed in clouds where the column density contrast between the clump and the cloud is higher than two; most clumps show infall and outflow. Finally, we find the most evolved clumps in clouds that have a column density contrast higher than three; in many clumps, the infall has already halted, and toward most clumps we found indications of YSOs. Hence, the cloud morphology, based on the column density contrast between the cloud and the clumps, seems to have a direct connection with the evolutionary stage of the objects forming inside.

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The Discovery of a Massive SCUBA Core with both Inflow and Outflow Motions

Cited by 40 publications

References 22 publications

7 mm continuum observations of ultra compact HII regions

7 mm continuum observations of ultra compact HII regions

Infall and Outflow Detections in a Massive Core JCMT 18354–0649s

Initial phases of massive star formation in high infrared extinction clouds

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