STATCONT: A statistical continuum level determination method for line-rich sources

Sánchez-Monge, Á.; Schilke, P.; Ginsburg, Adam; Cesaroni, R.; Schmiedeke, A.

doi:10.1051/0004-6361/201730425

Cited by 68 publications

(39 citation statements)

References 71 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An overview of the CH 3 CN transitions analyzed in this paper is given in Table 1. Sánchez-Monge et al 2018) at the frequencies of the spectral windows that cover the three CH 3 CN ground state transitions: 220 GHz (left), 239 GHz (center), and 257 GHz (right). The black contour shows the 10% level of the continuum emission peak.…”

Section: Observational Resultsmentioning

confidence: 99%

The physical and chemical structure of Sagittarius B2

Pols

Schwörer

Schilke

et al. 2018

A&A

Self Cite

View full text Add to dashboard Cite

Context. We model the emission of methyl cyanide (CH3CN) lines towards the massive hot molecular core Sgr B2(M). Aims. We aim to reconstruct the CH3CN abundance field, and investigate the gas temperature distribution as well as the velocity field. Methods. Sgr B2(M) was observed with the Atacama Large Millimeter/submillimeter Array (ALMA) in a spectral line survey from 211 to 275 GHz. This frequency range includes several transitions of CH3CN (including isotopologues and vibrationally excited states). We employed the three-dimensional radiative transfer toolbox Pandora in order to retrieve the velocity and abundance field by modeling different CH3CN lines. For this purpose, we based our model on the results of a previous study that determined the physical structure of Sgr B2(M), i.e., the distribution of dust dense cores, ionized regions, and heating sources. Results. The morphology of the CH3CN emission can be reproduced by a molecular density field that consists of a superposition of cores with modified Plummer-like density profiles. The averaged relative abundance of CH3CN with respect to H2 ranges from 4 × 10−11 to 2 × 10−8 in the northern part of Sgr B2(M) and from 2 × 10−10 to 5 × 10−7 in the southern part. In general, we find that the relative abundance of CH3CN is lower at the center of the very dense, hot cores, causing the general morphology of the CH3CN emission to be shifted with respect to the dust continuum emission. The dust temperature calculated by the radiative transfer simulation based on the available luminosity reaches values up to 900 K. However, in some regions vibrationally excited transitions of CH3CN are underestimated by the model, indicating that the predicted gas temperature, which is assumed to be equal to the dust temperature, is partly underestimated. The determination of the velocity component along the line of sight reveals that a velocity gradient from the north to the south exists in Sgr B2(M).

show abstract

Section: Observational Resultsmentioning

confidence: 99%

The physical and chemical structure of Sagittarius B2

Pols

Schwörer

Schilke

et al. 2018

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…One possible drawback of the AsLS method is that once the baseline is removed a portion of the emission could go below zero. In the future we plan to use STATCONT to prevent this (Sánchez-Monge et al 2018). Figure A.2 shows the generated filaments width equal widths (Case 1; top left), and unequal widths (Case 2; top right).…”

Section: A1 Baseline Subtractionmentioning

confidence: 99%

The CARMA-NRO Orion Survey

Suri

Sánchez-Monge

Schilke

et al. 2019

A&A

View full text Add to dashboard Cite

Context. We present an initial overview of the filamentary structure in the Orion A molecular cloud utilizing a high angular and velocity resolution C18O(1–0) emission map that was recently produced as part of the CARMA-NRO Orion Survey. Aims. The main goal of this study is to build a credible method to study varying widths of filaments which has previously been linked to star formation in molecular clouds. Due to the diverse star forming activities taking place throughout its ~20 pc length, together with its proximity of 388 pc, the Orion A molecular cloud provides an excellent laboratory for such an experiment to be carried out with high resolution and high sensitivity. Methods. Using the widely-known structure identification algorithm, DisPerSE, on a three-dimensional (PPV) C18O cube, we identify 625 relatively short (the longest being 1.74 pc) filaments over the entire cloud. We studied the distribution of filament widths using FilChaP, a python package that we have developed and made publicly available. Results. We find that the filaments identified in a two square-degree PPV cube do not overlap spatially, except for the complex OMC-4 region that shows distinct velocity components along the line of sight. The filament widths vary between 0.02 and 0.3 pc depending on the amount of substructure that a filament possesses. The more substructure a filament has, the larger is its width. We also find that despite this variation, the filament width shows no anticorrelation with the central column density which is in agreement with previous Herschel observations.

show abstract

“…For the ACA data 11 antennas were available and the array had baselines ranging from 8.9 to 45.0 m. The total time on source was about three minutes for the ACA. Because of this disproportionately short on-source 3 The STATCONT package by Sánchez-Monge et al (2018) was used for continuum subtraction in the other targets of Cesaroni et al (2017) which have very few line-free channels. Comparisons were made for G17.64 using STATCONT which did produce comparable products although continuum subtraction in the image plane does not allow for self-calibration after the analysis.…”

Section: Observationsmentioning

confidence: 99%

Chasing discs around O-type (proto)stars

Maud

Cesaroni

Kumar

et al. 2018

A&A

Self Cite

View full text Add to dashboard Cite

We present high angular resolution (∼0.2 ) continuum and molecular emission line Atacama Large Millimeter/sub-millimeter Array (ALMA) observations of G17.64+0.16 in Band 6 (220−230 GHz) taken as part of a campaign in search of circumstellar discs around (proto)-O-stars. At a resolution of ∼400 au the main continuum core is essentially unresolved and isolated from other strong and compact emission peaks. We detect SiO (5-4) emission that is marginally resolved and elongated in a direction perpendicular to the large-scale outflow seen in the 13 CO (2−1) line using the main ALMA array in conjunction with the Atacama Compact Array (ACA). Morphologically, the SiO appears to represent a disc-like structure. Using parametric models we show that the position-velocity profile of the SiO is consistent with the Keplerian rotation of a disc around an object between 10 and 30 M in mass, only if there is also radial expansion from a separate structure. The radial motion component can be interpreted as a disc wind from the disc surface. Models with a central stellar object mass between 20 and 30 M are the most consistent with the stellar luminosity (1 × 10 5 L ) and indicative of an O-type star. The H30α millimetre recombination line (231.9 GHz) is also detected, but spatially unresolved, and is indicative of a very compact, hot, ionised region co-spatial with the dust continuum core. The broad line-width of the H30α emission (full-width-half-maximum = 81.9 km s −1 ) is not dominated by pressure-broadening but is consistent with underlying bulk motions. These velocities match those required for shocks to release silicon from dust grains into the gas phase. CH 3 CN and CH 3 OH thermal emission also shows two arc shaped plumes that curve away from the disc plane. Their coincidence with OH maser emission suggests that they could trace the inner working surfaces of a wide-angle wind driven by G17.64 which impacts the diffuse remnant natal cloud before being redirected into the large-scale outflow direction. Accounting for all observables, we suggest that G17.64 is consistent with a O-type young stellar object in the final stages of protostellar assembly, driving a wind, but that has not yet developed into a compact HII region. The existance and detection of the disc in G17.64 is likely related to its isolated and possibly more evolved nature, traits which may underpin discs in similar sources.The reduced datacubes are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via

show abstract

STATCONT: A statistical continuum level determination method for line-rich sources

Cited by 68 publications

References 71 publications

The physical and chemical structure of Sagittarius B2

The physical and chemical structure of Sagittarius B2

The CARMA-NRO Orion Survey

Chasing discs around O-type (proto)stars

Contact Info

Product

Resources

About