Gas Kinematics of the Massive Protocluster G286.21+0.17 Revealed by ALMA

Cheng, Yu; Tan, Jonathan C.; Liu, Mengyao; Lim, Wanggi; Andersen, M.

doi:10.3847/1538-4357/ab879f

Cited by 10 publications

(10 citation statements)

References 65 publications

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“…For the second method with deconvolved sizes that focus on the larger cores, we obtain a median value of 1.45, with 2 out of the 7 cores exceeding the critical value of α vir,cr = 2.5. For comparison, the virial parameters of the cores appear to be similar to those of the 76 cores in G286, which have a median value of 1.22 (Cheng et al 2020). Thus we see that most cores have a virial parameter that is consistent with a value expected in virial equilibrium.…”

Section: Virial State Of Coresmentioning

confidence: 83%

“…Following the procedures in Cheng et al (2020), we calculate the virial parameters separately using each tracer, i.e., N 2 H + , N 2 D + , DCO + and DCN. The intrin-sic velocity dispersion σ c is derived from the observed dispersion σ obs following the Equation…”

Section: Virial State Of Coresmentioning

confidence: 99%

“…We compare the CR1 clump with another well studied region, G286.21+0.17 (G286), which is a protocluster at a distance of 2.5 kpc (Cheng et al 2018). G286 has a total Herschel-estimated mass of around 2900 M in a 2.6'×1.7' elliptical aperture (Cheng et al 2020), leading to an average column density, N H , of ∼ 4 × 10 22 cm −2 , similar to the Vela C CR1 clump (∼ 5 × 10 22 cm −2 ). For the compact gas mass we adopt two methods.…”

Section: The Bridging Filament Connecting Cores Cr1c1 and Cr1c2mentioning

confidence: 99%

“…Our band 6 spectral set-up and analysis methods are similar to our previous studies of the G286 protocluster (Cheng et al 2020) and Infrared Dark Clouds (IRDCs) (e.g., Tan et al 2013;Kong et al 2017), which have a goal of studying cores via their mm dust continuum emission and via emission lines from dense gas tracers, especially N 2 D + (3-2). The band 7 spectral set-up is designed to obtain a sub-mm dust continuum measurement, as well as observation of N 2 H + (3-2) that allows an accurate estimate of the level of deuteration of N 2 H + , which is expected to be boosted in cold, dense conditions and thus may be a useful evolutionary indicator of prestellar and early stage protostellar cores.…”

Section: Introductionmentioning

confidence: 99%

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Star Formation in a Strongly Magnetized Cloud

Cheng

Tan

Caselli

et al. 2021

ApJ

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We study star formation in the Center Ridge 1 (CR1) clump in the Vela C giant molecular cloud, selected as a high column density region that shows the lowest level of dust continuum polarization angle dispersion, likely indicating that the magnetic field is relatively strong. We observe the source with the ALMA 7m-array at 1.05 mm and 1.3 mm wavelengths, which enable measurements of dust temperature, core mass and astrochemical deuteration. A relatively modest number of eleven dense cores are identified via their dust continuum emission, with masses spanning from 0.17 to 6.7 M . Overall CR1 has a relatively low compact dense gas fraction compared with other typical clouds with similar column densities, which may be a result of the strong magnetic field and/or the very early evolutionary stage of this region. The deuteration ratios, D frac , of the cores, measured with N 2 H + (3-2) and N 2 D + (3-2) lines, span from 0.011 to 0.85, with the latter being one of the highest values yet detected. The level of deuteration appears to decrease with evolution from prestellar to protostellar phase. A linear filament, running approximately parallel with the large scale magnetic field orientation, is seen connecting the two most massive cores, each having CO bipolar outflows aligned orthogonally to the filament. The filament contains the most deuterated core, likely to be prestellar and located midway between the protostars. The observations permit measurement of the full deuteration structure of the filament along its length, which we present. We also discuss the kinematics and dynamics of this structure, as well as of the dense core population.

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Section: Virial State Of Coresmentioning

confidence: 83%

Section: Virial State Of Coresmentioning

confidence: 99%

Section: The Bridging Filament Connecting Cores Cr1c1 and Cr1c2mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Star Formation in a Strongly Magnetized Cloud

Cheng

Tan

Caselli

et al. 2021

ApJ

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“…Cheng et al (2018) present the 1.3 mm ALMA continuum observation of G286 and an analysis of the core mass function (CMF) in this region. Subsequently, Cheng et al (2020a) (hereafter C20) present a follow-up study of multiple spectral lines from the same ALMA observations to investigate the gas kinematics and dynamics of G286 from clump to core scales. In this paper, we use new ALMA data from the ATOMS survey (see Sec.…”

Section: Introductionmentioning

confidence: 99%

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions–VI. On the formation of the ‘L’ type filament in G286.21+0.17

Zhou

Liu

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Filaments play an important role in star formation, but the formation process of filaments themselves is still unclear. The high-mass star forming clump G286.21+0.17 (G286 for short) that contains an “L” type filament was thought to undergo global collapse. Our high resolution ALMA band 3 observations resolve the gas kinematics of G286 and reveal two sub-clumps with very different velocities inside it. We find that the “blue profile” (an indicator of gas infall) of HCO+ lines in single dish observations of G286 is actually caused by gas emission from the two sub-clumps rather than gas infall. We advise great caution in interpreting gas kinematics (e.g. infall) from line profiles toward distant massive clumps in single dish observations. Energetic outflows are identified in G286 but the outflows are not strong enough to drive expansion of the two sub-clumps. The two parts of the “L” type filament (“NW-SE” and “NE-SW” filaments) show prominent velocity gradients perpendicular to their major axes, indicating that they are likely formed due to large-scale compression flows. We argue that the large-scale compression flows could be induced by the expansion of nearby giant H ii regions. The “NW-SE” and “NE-SW” filaments seem to be in collision, and a large amount of gas has been accumulated in the junction region where the most massive core G286c1 forms.

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Alma-Imf

Cunningham¹,

Ginsburg²,

Galván-Madrid³

et al. 2023

A&A

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ALMA-IMF is an Atacama Large Millimeter/submillimeter Array (ALMA) Large Program designed to measure the core mass function (CMF) of 15 protoclusters chosen to span their early evolutionary stages. It further aims to understand their kinematics, chemistry, and the impact of gas inflow, accretion, and dynamics on the CMF. We present here the first release of the ALMA-IMF line data cubes (DR1), produced from the combination of two ALMA 12 m-array configurations. The data include 12 spectral windows, with eight at 1.3 mm and four at 3 mm. The broad spectral coverage of ALMA-IMF (∼6.7 GHz bandwidth coverage per field) hosts a wealth of simple atomic, molecular, ionised, and complex organic molecular lines. We describe the line cube calibration done by ALMA and the subsequent calibration and imaging we performed. We discuss our choice of calibration parameters and optimisation of the cleaning parameters, and we demonstrate the utility and necessity of additional processing compared to the ALMA archive pipeline. As a demonstration of the scientific potential of these data, we present a first analysis of the DCN (3–2) line. We find that DCN (3–2) traces a diversity of morphologies and complex velocity structures, which tend to be more filamentary and widespread in evolved regions and are more compact in the young and intermediate-stage protoclusters. Furthermore, we used the DCN (3–2) emission as a tracer of the gas associated with 595 continuum cores across the 15 protoclusters, providing the first estimates of the core systemic velocities and linewidths within the sample. We find that DCN (3–2) is detected towards a higher percentage of cores in evolved regions than the young and intermediate-stage protoclusters and is likely a more complete tracer of the core population in more evolved protoclusters. The full ALMA 12m-array cubes for the ALMA-IMF Large Program are provided with this DR1 release.

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Gas Kinematics of the Massive Protocluster G286.21+0.17 Revealed by ALMA

Cited by 10 publications

References 65 publications

Star Formation in a Strongly Magnetized Cloud

Star Formation in a Strongly Magnetized Cloud

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions–VI. On the formation of the ‘L’ type filament in G286.21+0.17

Alma-Imf

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