Tracing early evolutionary stages of high-mass star formation with molecular lines

Marseille, M.; Tak, F. F. S. van der; Herpin, Fabrice; Jacq, T.

doi:10.1051/0004-6361/200913557

Cited by 36 publications

(47 citation statements)

References 54 publications

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“…The latter temperature is just below the sublimation temperature of the bulk of water (100 K), when PN is efficiently destroyed and partially converted to PO. Then, the gas abundance of water predicted by the model at this stage is still low, ∼10 −9 , which is in good agreement with the values of 5 × 10 −10 -4 × 10 −8 found toward several massive star-forming regions by Marseille et al (2010;see Figure 7(b)). …”

Section: Chemical Model: Constraining the Phosphorus Chemistrysupporting

confidence: 87%

The First Detections of the Key Prebiotic Molecule Po in Star-Forming Regions

Rivilla

Fontani

Beltrán

et al. 2016

ApJ

106

135

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Phosphorus is a crucial element in biochemistry, in particular the P−O bond, which is key in the formation of the backbone of deoxyribonucleic acid. So far, PO has only been detected toward the envelope of evolved stars, but never toward star-forming regions. We report the first detection of PO toward two massive star-forming regions, W51 e1/e2 and W3(OH), using data from the IRAM 30 m telescope. PN has also been detected toward the two regions. The abundance ratio PO/PN is 1.8 and 3 for W51 and W3(OH), respectively. Our chemical model indicates that the two molecules are chemically related and are formed via gas-phase ion-molecule and neutralneutral reactions during cold collapse. The molecules freeze out onto grains at the end of the collapse and desorb during the warm-up phase once the temperature reaches ∼35 K. Similar abundances of the two species are expected during a period of ∼5 × 10 4 yr at the early stages of the warm-up phase, when the temperature is in the range 35-90 K. The observed molecular abundances of 10 −10 are predicted by the model if a relatively high initial abundance of 5 × 10 −9 of depleted phosphorus is assumed.

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Section: Chemical Model: Constraining the Phosphorus Chemistrysupporting

confidence: 87%

The First Detections of the Key Prebiotic Molecule Po in Star-Forming Regions

Rivilla

Fontani

Beltrán

et al. 2016

ApJ

106

135

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“…To reproduce these lines, an abundance jump at 100 K is necessary but not for the remaining lines. The derived H 16 2 O abundance relative to H 2 is 1.4 × 10 −4 in the warm part of the envelope where T > 100 K, while it is 8.0 × 10 −8 in the outer parts where T < 100 K, in agreement with the values found by Marseille et al (2010a) from H 18 2 O observations. No deviation from the standard o/p ratio of 3 at high temperature (≥100 K) is found.…”

Section: Abundance Structuresupporting

confidence: 86%

The massive protostar W43-MM1 as seen byHerschel-HIFI water spectra: high turbulence and accretion luminosity

Herpin

Chavarría

Tak

et al. 2012

A&A

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Aims. We present Herschel-HIFI observations of 14 water lines in W43-MM1, a massive protostellar object in the luminous starcluster-forming region W43. We place our study in the more general context of high-mass star formation. The dynamics of these regions may be represented by either the monolithic collapse of a turbulent core, or competitive accretion. Water turns out to be a particularly good tracer of the structure and kinematics of the inner regions, allowing an improved description of the physical structure of the massive protostar W43-MM1 and an estimation of the amount of water around it. Methods. We analyze the gas dynamics from the line profiles using Herschel-HIFI observations acquired as part of the Water In Star-forming regions with Herschel project of 14 far-IR water lines (H 16 2 O, H 17 2 O, H 18 2 O), CS(11-10), and C 18 O(9-8) lines, using our modeling of the continuum spectral energy distribution. The spectral modeling tools allow us to estimate outflow, infall, and turbulent velocities and molecular abundances. We compare our results to previous studies of low-, intermediate-, and other high-mass objects. Results. As for lower-mass protostellar objects, the molecular line profiles are a mix of emission and absorption, and can be decomposed into "medium" (full width at half maximum FWHM 5-10 km s −1 ), and "broad" velocity components (FWHM 20-35 km s −1 ). The broad component is the outflow associated with protostars of all masses. Our modeling shows that the remainder of the water profiles can be well-fitted by an infalling and passively heated envelope, with highly supersonic turbulence varying from 2.2 km s −1 in the inner region to 3.5 km s −1 in the outer envelope. In addition, W43-MM1 has a high accretion rate of between 4.0 × 10 −4 and 4.0 × 10 −2 M yr −1 , as derived from the fast (0.4-2.9 km s −1 ) infall observed. We estimate a lower mass limit for gaseous water of 0.11 M and total water luminosity of 1.5 L (in the 14 lines presented here). The central hot core is detected with a water abundance of 1.4 × 10 −4 , while the water abundance for the outer envelope is 8 × 10 −8 . The latter value is higher than in other sources, and most likely related to the high turbulence and the micro-shocks created by its dissipation. Conclusions. Examining the water lines of various energies, we find that the turbulent velocity increases with the distance from the center. While not in clear disagreement with the competitive accretion scenario, this behavior is predicted by the turbulent core model. Moreover, the estimated accretion rate is high enough to overcome the expected radiation pressure.

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“…2 ), this water absorption is probably produced by a cold (T ∼ 10 K) foreground cloud on the line of sight. Other cases of absorption due to clouds along the line of sight toward similar sources are reported by Marseille et al (2010) and Wyrowski et al (2010).…”

Section: Results and Analysissupporting

confidence: 69%

Water in massive star-forming regions: HIFI observations of W3 IRS5

Chavarría

Herpin

Jacq

et al. 2010

A&A

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We present Herschel observations of the water molecule in the massive star-forming region W3 IRS5. lines show absorption from the cold material (T ∼ 10 K) in which the high-mass protostellar envelope is embedded. One-dimensional radiative transfer models are used to estimate water abundances and to further study the kinematics of the region. We show that the emission in the rare isotopologues comes directly from the inner parts of the envelope (T 100 K) where water ices in the dust mantles evaporate and the gas-phase abundance increases. The resulting jump in the water abundance (with a constant inner abundance of 10 −4 ) is needed to reproduce the o-H 17 2 O 1 10 -1 01 and p-H 18 2 O 1 11 -0 00 spectra in our models. We estimate water abundances of 10 −8 to 10 −9 in the outer parts of the envelope (T 100 K). The possibility of two protostellar objects contributing to the emission is discussed.

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Tracing early evolutionary stages of high-mass star formation with molecular lines

Cited by 36 publications

References 54 publications

The First Detections of the Key Prebiotic Molecule Po in Star-Forming Regions

The First Detections of the Key Prebiotic Molecule Po in Star-Forming Regions

The massive protostar W43-MM1 as seen byHerschel-HIFI water spectra: high turbulence and accretion luminosity

Water in massive star-forming regions: HIFI observations of W3 IRS5

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