Initial highlights of the HOBYS key program, the<i>Herschel</i>imaging survey of OB young stellar objects

Motte, F.; Zavagno, A.; Bontemps, Sylvain; Schneider, N.; Hennemann, M.; Francesco, James Di; André, Ph.; Saraceno, P.; Griffin, Matthew Joseph; Marston, A. P.; Ward-Thompson, Derek; White, G. J.; Minier, V.; Men’shchikov, A.; Hill, T.; Abergel, A.; Anderson, L. D.; Aussel, H.; Balog, Z.; Baluteau, J. P.; Bernard, J.-P.; Cox, P.; Csengeri, T.; Deharveng, L.; Didelon, P.; Giorgio, A. M. Di; Hargrave, Peter Charles; Huang, M.; Kirk, J. M.; Leeks, S. J.; Li, J. Z.; Martín, P. G.; Molinari, S.; Nguyen-Luong, Q.; Olofsson, G.; Persi, P.; Peretto, N.; Pezzuto, S.; Roussel, Hervé; Russeil, D.; Sadavoy, Sarah; Sauvage, M.; Sibthorpe, B.; Spinoglio, L.; Testi, L.; Teyssier, D.; Vavrek, R.; Wilson, C. D.; Woodcraft, A.

doi:10.1051/0004-6361/201014690

Cited by 192 publications

(86 citation statements)

References 27 publications

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“…Within the far infrared regime, each methanol maser host clump is taken to emit thermally at the dust temperature as a single temperature modified blackbody, or greybody. This approximation describes the emission well for wavelengths ≥160 µm, but the 70 µm flux is found to trace the warm embedded protostellar component and not the emission from the envelope (Motte et al 2010;Dunham et al 2008). Additionally, the emission at 70 µm is not necessarily optically thin and cannot be reliably fitted without also modelling optical depth effects.…”

Section: Sed Fittingmentioning

confidence: 98%

“…The sample of masers studied further in this work is selected based on the visibility of compact emission over several Hi-GAL wavelengths. Since Class II methanol masers are pumped by radiation at ∼70 µm (Sobolev et al 2005), their host clumps are expected to be 'protostellar' in nature, visible as both compact emission from the cool dust envelope at wavelengths ≥160 µm and at 70 µm from a warmer inner component (Motte et al 2010). In order to fit to the spectral energy distribution (SED) of the dust envelope of a protostellar clump, a detection in at least 3 wavelengths ≥160 µm is required, as the emission at 70 µm is neither optically thin nor tracing the same cold material.…”

Section: Multi-wavelength Sample Selectionmentioning

confidence: 99%

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The evolutionary status of protostellar clumps hosting class II methanol masers

Jones

Fuller

Breen

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The Methanol MultiBeam survey (MMB) provides the most complete sample of Galactic massive young stellar objects (MYSOs) hosting 6.7 GHz class II methanol masers. We characterise the properties of these maser sources using dust emission detected by the Herschel Infrared Galactic Plane Survey (Hi-GAL) to assess their evolutionary state. Associating 731 (73%) of MMB sources with compact emission at four Hi-GAL wavelengths, we derive clump properties and define the requirements of a MYSO to host a 6.7 GHz maser. The median far-infrared (FIR) mass and luminosity are 630 M and 2500 L for sources on the near side of Galactic centre and 3200 M and 10000 L for more distant sources. The median luminosity-to-mass ratio is similar for both at ∼4.2 L / M . We identify an apparent minimum 70 µm luminosity required to sustain a methanol maser of a given luminosity (with L 70 ∝ L 6.7 0.6 ). The maser host clumps have higher mass and higher FIR luminosities than the general Galactic population of protostellar MYSOs. Using principal component analysis, we find 896 protostellar clumps satisfy the requirements to host a methanol maser but lack a detection in the MMB. Finding a 70 µm flux density deficiency in these objects, we favour the scenario in which these objects are evolved beyond the age where a luminous 6.7 GHz maser can be sustained. Finally, segregation by association with secondary maser species identifies evolutionary differences within the population of 6.7GHz sources.

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Section: Sed Fittingmentioning

confidence: 98%

Section: Multi-wavelength Sample Selectionmentioning

confidence: 99%

The evolutionary status of protostellar clumps hosting class II methanol masers

Jones

Fuller

Breen

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…From the C 18 O J = 1-0 observations, we estimate the C 18 O column density for all available sources and each position, following Mangum & Shirley (2015) and Schneider et al (2016). For the rotational excitation temperature, we used values based on the dust temperatures from the Herschel Gould Belt (André et al 2010) and HOBYS (Motte et al 2010) imaging key programs and published in Stutz & Kainulainen (2015) for M43, Rayner et al (2017) for Mon R2, and Schneider, N., priv. comm., for M17 SW.…”

Section: Co Molecular Emissionmentioning

confidence: 99%

[C II] 158 μm self-absorption and optical depth effects

Guevara

Stützki

Ossenkopf-Okada

et al. 2020

A&A

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Context. The [C ii] 158 µm far-infrared (FIR) fine-structure line is one of the most important cooling lines of the star-forming interstellar medium (ISM). It is used as a tracer of star formation efficiency in external galaxies and to study feedback effects in parental clouds. High spectral resolution observations have shown complex structures in the line profiles of the [C ii] emission. Aims. Our aim is to determine whether the complex profiles observed in [ 12 C ii] are due to individual velocity components along the line-of-sight or to self-absorption based on a comparison of the [ 12 C ii] and isotopic [ 13 C ii] line profiles. Methods. Deep integrations with the SOFIA/upGREAT 7-pixel array receiver in the sources of M43, Horsehead PDR, Monoceros R2, and M17 SW allow for the detection of optically thin [ 13 C ii] emission lines, along with the [ 12 C ii] emission lines, with a high signalto-noise ratio (S/N). We first derived the [ 12 C ii] optical depth and the [C ii] column density from a single component model. However, the complex line profiles observed require a double layer model with an emitting background and an absorbing foreground. A multicomponent velocity fit allows us to derive the physical conditions of the [C ii] gas: column density and excitation temperature. Results. We find moderate to high [ 12 C ii] optical depths in all four sources and self-absorption of [ 12 C ii] in Mon R2 and M17 SW. The high column density of the warm background emission corresponds to an equivalent A v of up to 41 mag. The foreground absorption requires substantial column densities of cold and dense [C ii] gas, with an equivalent A v ranging up to about 13 mag. Conclusions. The column density of the warm background material requires multiple photon-dominated region (PDR) surfaces stacked along the line of sight and in velocity. The substantial column density of dense and cold foreground [C ii] gas detected in absorption cannot be explained with any known scenario and we can only speculate on its origins. Key words. ISM:clouds -ISM:individual objects: M43 -ISM:individual objects: M17 -photon-dominated region (PDR) -ISM:individual objects: Horsehead -ISM:individual objects: MonR2 1 At that time, the spectroscopic data were less accurate and the wavelength of the transition was assumed to fall at 157 µm instead of 158 µm.Article number, page 1 of 40 A&A proofs: manuscript no. 34380corr_2 mentum change F=2→1, F=1→0, and F=1→1. The frequencies of the fine structure transitions of both isotopes were determined by Cooksy et al. (1986). The astronomical observations are fully consistent with these frequencies, as was discussed by Ossenkopf et al. (2013), who also noted that the relative strengths of the [ 13 C ii] hyperfine satellites (s F→F , see Table 1) given by Cooksy et al. (1986) are incorrect. We summarize all the relevant [ 12 C ii] and [ 13 C ii] spectroscopic parameters in Table 1, including the velocity offsets of the [ 13 C ii] hyperfine components relative to [ 12 C ii]. The frequency separation of the hyperfi...

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“…The deuterium fractionation is plotted against the current dust temperature of their surrounding cloud as measured by the Planck observatory for NGC 7129 FIRS2 and by the PACS and SPIRE instruments onboard the Herschel Space Observatory for other sources. The Ophiuchus, Perseus, and Orion molecular clouds have been observed with the Gould Belt Survey key program (André et al 2010), the Sgr B2 region has been observed by Etxaluze et al (2013) as part of the Hi-GAL key program (Molinari et al 2010), whilst the NGC6334 massive complex has been observed with the HOBYS key program (Motte et al 2010;Russeil et al 2013;Tige et al 2017). To estimate the dust temperature, we extract 10 arcmin maps surrounding the selected sources.…”

Section: Deuteration From Low-to High-mass Protostarsmentioning

confidence: 99%

Interferometric observations of warm deuterated methanol in the inner regions of low-mass protostars

Taquet

Bianchi

Codella

et al. 2019

A&A

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Methanol is a key species in astrochemistry since it is the most abundant organic molecule in the interstellar medium and is thought to be the mother molecule of many complex organic species. Estimating the deuteration of methanol around young protostars is of crucial importance because it highly depends on its formation mechanisms and the physical conditions during its moment of formation. We analyse several dozens of transitions from deuterated methanol isotopologues coming from various existing observational datasets obtained with the IRAM-PdBI and ALMA submm interferometers to estimate the methanol deuteration surrounding three low-mass protostars on Solar System scales. A population diagram analysis allows us to derive a [CH2DOH]/[CH3OH] abundance ratio of 3 − 6 % and a [CH3OD]/[CH3OH] ratio of 0.4 − 1.6 % in the warm inner (≤ 100 − 200 AU) protostellar regions. These values are typically ten times lower than those derived with previous single-dish observations towards these sources but they are one to two orders of magnitude higher than the methanol deuteration measured in massive hot cores. Dust temperature maps obtained from Herschel and Planck observations show that massive hot cores are located in warmer molecular clouds than low-mass sources, with temperature differences of ∼10 K. The comparison of our measured values with the predictions of the gas-grain astrochemical model GRAINOBLE shows that such a temperature difference is sufficient to explain the different deuteration observed in low-to high-mass sources. This suggests that the physical conditions of the molecular cloud at the origin of the protostars mostly govern the present observed deuteration of methanol and, therefore, of more complex organic molecules. Finally, the methanol deuteration measured towards young solar-type protostars on Solar System scales seems to be higher by a factor of ∼ 5 than the upper limit in methanol deuteration estimated in comet Hale-Bopp. If this result is confirmed by subsequent observations of other comets, this would imply that an important reprocessing of the organic material likely occurred in the solar nebula during the formation of the Solar System.

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Initial highlights of the HOBYS key program, theHerschelimaging survey of OB young stellar objects

Cited by 192 publications

References 27 publications

The evolutionary status of protostellar clumps hosting class II methanol masers

The evolutionary status of protostellar clumps hosting class II methanol masers

[C II] 158 μm self-absorption and optical depth effects

Interferometric observations of warm deuterated methanol in the inner regions of low-mass protostars

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Initial highlights of the HOBYS key program, theHerschelimaging survey of OB young stellar objects

Cited by 192 publications

References 27 publications

The evolutionary status of protostellar clumps hosting class II methanol masers

The evolutionary status of protostellar clumps hosting class II methanol masers

[C II] 158 μm self-absorption and optical depth effects

Interferometric observations of warm deuterated methanol in the inner regions of low-mass protostars

Contact Info

Product

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[C II] 158 μm self-absorption and optical depth effects