<i>Herschel</i>SPIRE-FTS observations of RCW 120

Rodón, J. A.; Zavagno, A.; Baluteau, J. P.; Habart, E.; Koehler, Melanie; Bourlot, J. Le; Petit, Franck; Abergel, A.

doi:10.1051/0004-6361/201220449

Cited by 6 publications

(6 citation statements)

References 40 publications

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“…Line ratios of CO and CI lines are interesting since they are sensitive to the physical conditions of the emitting gas. In particular, they can be used to derive -at least comparatively -the density and temperature of different regions (e.g., Kramer et al 2004;Rodón et al 2015). Both neutral and ionised carbon can be formed in low density gas, as they have critical densities of only 5 − −30 × 10 2 cm −3 (Kaufman et al 1999), while for the lowest CO transition in our data (J = 4 − 3) the critical density is 100 times higher, 2.6 × 10 5 cm −3 .…”

Section: Physical Conditions Of the Gasmentioning

confidence: 99%

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Herschel observations of the circumstellar environments of the Herbig Be stars R Mon and PDS 27

Jiménez-Donaire

Meeus

Karska

et al. 2017

A&A

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Context. The circumstellar environment of Herbig Be stars in the far-infrared is poorly characterised, mainly because they are often embedded and rather distant. The analysis of far-infrared spectroscopy allows us to make a major step forward by covering multiple rotational lines of molecules, e.g. CO, that are useful probes of physical conditions of the gas. Aims. To characterise the gas and dust in the disc and environment of Herbig Be stars, and to compare the results with those of their lower-mass counterparts, the Herbig Ae stars. Methods. We report and analyse far-infrared observations of two Herbig Be stars, R Mon and PDS 27, obtained with Herschel's instruments PACS and SPIRE. We construct spectral energy distributions and derive the infrared excess. We extract line fluxes from the PACS and SPIRE spectra and construct rotational diagrams in order to estimate the excitation temperature of the gas. We derive CO, [O I] and [C I] luminosities to determine physical conditions of the gas, as well as the dominant cooling mechanism. Results. We confirm that the Herbig Be stars are surrounded by remnants from their parental clouds, with an IR excess that mainly originates in a disc. In R Mon we detect [O I], [C I], [C II], CO (26 transitions), water and OH, while in PDS 27 we only detect [C I] and CO (8 transitions). We attribute the absence of OH and water in PDS 27 to UV photo-dissociation and photo-evaporation. From the rotational diagrams, we find several components for CO: we derive T rot 949±90 K, 358±20 K & 77±12 K for R Mon, 96±12 K & 31±4 K for PDS 27 and 25±8 K & 27±6 K for their respective compact neighbours. The forsterite feature at 69 µm was not detected in either of the sources, probably due to the lack of (warm) crystalline dust in a flat disc. We find that cooling by molecules is dominant in the Herbig Be stars, while this is not the case in Herbig Ae stars where cooling by [O I] dominates. Moreover, we show that in the Herbig Be star R Mon, outflow shocks are the dominant gas heating mechanism, while in Herbig Ae stars this is stellar. Conclusions. The outflow of R Mon contributes to the observed line emission by heating the gas, both in the central spaxel/beam covering the disc and the immediate surroundings, as well as in those spaxels/beams covering the parabolic shell around it. PDS 27, a B2 star, has dispersed a large part of its gas content and/or destroyed molecules; this is likely given its intense UV field.

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Section: Physical Conditions Of the Gasmentioning

confidence: 99%

“…For R Mon, the beam C2 has a low signal-to-noise spectrum, where only [C I] (2-1) was detected. We calculate the following line ratios, following Rodón et al (2015), see Table 4:…”

Section: Physical Conditions Of the Gasmentioning

confidence: 99%

Herschel observations of the circumstellar environments of the Herbig Be stars R Mon and PDS 27

Jiménez-Donaire

Meeus

Karska

et al. 2017

A&A

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“…In this paper, we adopt the most recent distance estimate of 1.68 kpc. RCW 120 is the testbed for studying the interaction of H II region feedback with the ambient gas, dust, and triggered star formation (Zavagno et al 2007(Zavagno et al , 2010(Zavagno et al , 2020Deharveng et al 2009;Martins et al 2010;Anderson et al 2010Anderson et al , 2012Anderson et al , 2015Pavlyuchenkov et al 2013;Tremblin et al 2014b;Ochsendorf et al 2014;Torii et al 2015;Rodón et al 2015;Walch et al 2015;Mackey et al 2016;Akimkin et al 2017;Figueira et al 2017Figueira et al , 2018Figueira et al , 2020Marsh & Whitworth 2019;Rodríguez-González et al 2019;Kirsanova et al 2019Kirsanova et al , 2021Luisi et al 2021;Kabanovic et al 2022). These results greatly enrich our understandings of RCW 120, especially to the star formation on the boarder of RCW 120.…”

Section: Introductionmentioning

confidence: 95%

The Role of Magnetic Fields in Triggered Star Formation of RCW 120

Chen,

Sefako,

Yang

et al. 2022

Preprint

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We report on the near-IR polarimetric observations of RCW 120 with the 1.4 m IRSF telescope. The starlight polarization of the background stars reveal for the first time the magnetic field of RCW 120. The global magnetic field of RCW 120 is along the direction of 20 • , parallel to the galactic plane. The field strength on the plane of the sky is 100 ± 26 µG. The magnetic field around the eastern shell shows evidence of compression by the H II region. The external pressure (turbulent pressure + magnetic pressure) and the gas density of the ambient cloud are minimum along the direction where RCW 120 breaks out, which explains the observed elongation of RCW 120. The dynamical age of RCW 120, depending on the magnetic field strength, is ∼ 1.6 Myr for field strength of 100 µG, older than the hydrodynamic estimates. In direction perpendicular to the magnetic field, the density contrast of the western shell is greatly reduced by the strong magnetic field. The strong magnetic field in general reduces the efficiency of triggered star formation, in comparison with the hydrodynamic estimates. Triggered star formation via the "collect and collapse" mechanism could occur in the direction along the magnetic field. Core formation efficiency (CFE) is found to be higher in the southern and eastern shells of RCW 120 than in the infrared dark cloud receiving little influence from the H II region, suggesting increase in the CFE related to triggering from ionization feedback.

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“…As a simple example of the application of J plots to observational images, we take the 'tile' from the Hi-GAL survey shown in Figure 2, which contains the well known RCW 120 bubble centred near = 353.20 o , b = 0.30 o . This HII region has been described as 'the perfect bubble' (Deharveng et al 2009), and much work has been done studying the physical conditions in and around the bubble (Anderson et al 2010;Pavlyuchenkov, Kirsanova & Wiebe 2013;Rodón et al 2015), and the likelihood of triggered star formation in the swept up shell (Motte et al 2010;Walch et al 2015;Figueira et al 2017). We therefore use this well characterized bubble as a test case to see how it appears on the J plot.…”

Section: Bubbles In Observationsmentioning

confidence: 99%

J plots: a new method for characterizing structures in the interstellar medium

Jaffa

Whitworth

Clarke

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Large scale surveys have brought about a revolution in astronomy. To analyse the resulting wealth of data, we need automated tools to identify, classify, and quantify the important underlying structures. We present here a method for classifying and quantifying a pixelated structure, based on its principal moments of inertia. The method enables us to automatically detect, and objectively compare, centrally condensed cores, elongated filaments and hollow rings. We illustrate the method by applying it to (i) observations of surface-density from Hi-GAL, and (ii) simulations of filament growth in a turbulent medium. We limit the discussion here to 2D data; in a future paper we will extend the method to 3D data.

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HerschelSPIRE-FTS observations of RCW 120

Cited by 6 publications

References 40 publications

Herschel observations of the circumstellar environments of the Herbig Be stars R Mon and PDS 27

Herschel observations of the circumstellar environments of the Herbig Be stars R Mon and PDS 27

The Role of Magnetic Fields in Triggered Star Formation of RCW 120

J plots: a new method for characterizing structures in the interstellar medium

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