Evidence of a SiO collimated outflow from a massive YSO in IRAS 17233–3606

Leurini, S.; Codella, C.; Gusdorf, A.; Zapata, Luis A.; Gómez-Ruiz, Arturo I.; Testi, L.; Pillai, T.

doi:10.1051/0004-6361/201118154

Cited by 36 publications

(33 citation statements)

References 47 publications

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“…Unfortunately, this shock modelling cannot be used for evolutionary trend studies because the shocks are stationary. However, dense shocks can account for the observations of SiO in massive star-forming regions, as was also reported by Leurini et al (2013).…”

Section: Discussionsupporting

confidence: 71%

SiO excitation from dense shocks in the earliest stages of massive star formation

Leurini

Codella

López-Sepulcre

et al. 2014

A&A

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Molecular outflows are a direct consequence of accretion, and therefore they represent one of the best tracers of accretion processes in the still poorly understood early phases of high-mass star formation. Previous studies suggested that the SiO abundance decreases with the evolution of a massive young stellar object probably because of a decay of jet activity, as witnessed in low-mass star-forming regions. We investigate the SiO excitation conditions and its abundance in outflows from a sample of massive young stellar objects through observations of the SiO(8−7) and CO(4−3) lines with the APEX telescope. Through a non-local thermodynamic equilibrium analysis, we find that the excitation conditions of SiO increase with the velocity of the emitting gas. We also compute the SiO abundance through the SiO and CO integrated intensities at high velocities. For the sources in our sample we find no significant variation of the SiO abundance with evolution for a bolometric luminosity-to-mass ratio of between 4 and 50 L /M . We also find a weak increase of the SiO(8−7) luminosity with the bolometric luminosity-to-mass ratio. We speculate that this might be explained with an increase of density in the gas traced by SiO. We find that the densities constrained by the SiO observations require the use of shock models that include grain-grain processing. For the first time, such models are compared and found to be compatible with SiO observations. A pre-shock density of 10 5 cm −3 is globally inferred from these comparisons. Shocks with a velocity higher than 25 km s −1 are invoked for the objects in our sample where the SiO is observed with a corresponding velocity dispersion. Our comparison of shock models with observations suggests that sputtering of silicon-bearing material (corresponding to less than 10% of the total silicon abundance) from the grain mantles is occurring.

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Section: Discussionsupporting

confidence: 71%

SiO excitation from dense shocks in the earliest stages of massive star formation

Leurini

Codella

López-Sepulcre

et al. 2014

A&A

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“…9, we show the ratio of the (5-4/2-1) lines. We find that the line ratio is larger in the high-velocity wings compared to the low-velocity Gaussian component, suggesting a change in the excitation conditions for the low-versus the high-velocity components, and, A149, page 11 of 50 A&A 586, A149 (2016) therefore, a different origin for the low-and high-velocity component, as also noted by Nisini et al (2007), Leurini et al (2013). This trend is, however, less clear for the intermediate velocities, in particular towards the infrared-quiet sample.…”

Section: Averaged Line Profilessupporting

confidence: 69%

ATLASGAL-selected massive clumps in the inner Galaxy

Csengeri

Leurini

Wyrowski

et al. 2016

A&A

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144

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Context. The processes leading to the birth of high-mass stars are poorly understood. The key first step to reveal their formation processes is characterising the clumps and cores from which they form. Aims. We define a representative sample of massive clumps in different evolutionary stages selected from the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL), from which we aim to establish a census of molecular tracers of their evolution. As a first step, we study the shock tracer, SiO, mainly associated with shocks from jets probing accretion processes. In low-mass young stellar objects (YSOs), outflow and jet activity decreases with time during the star formation processes. Recently, a similar scenario was suggested for massive clumps based on SiO observations. Here we analyse observations of the SiO (2−1) and (5−4) lines in a statistically significant sample to constrain the change of SiO abundance and the excitation conditions as a function of evolutionary stage of massive star-forming clumps. Methods. We performed an unbiased spectral line survey covering the 3-mm atmospheric window between 84−117 GHz with the IRAM 30 m telescope of a sample of 430 sources of the ATLASGAL survey, covering various evolutionary stages of massive clumps. A smaller sample of 128 clumps has been observed in the SiO (5−4) transition with the APEX telescope to complement the (2−1) line and probe the excitation conditions of the emitting gas. We derived detection rates to assess the star formation activity of the sample, and we estimated the column density and abundance using both an LTE approximation and non-LTE calculations for a smaller subsample, where both transitions have been observed. Results. We characterise the physical properties of the selected sources, which greatly supersedes the largest samples studied so far, and show that they are representative of different evolutionary stages. We report a high detection rate of >75% of the SiO (2−1) line and a >90% detection rate from the dedicated follow-ups in the (5−4) transition. Up to 25% of the infrared-quiet clumps exhibit high-velocity line wings, suggesting that molecular tracers are more efficient tools to determine the level of star formation activity than infrared colour criteria. We also find infrared-quiet clumps that exhibit only a low-velocity component (FWHM ∼ 5−6 km s −1 ) SiO emission in the (2−1) line. In the current picture, where this is attributed to low-velocity shocks from cloud-cloud collisions, this can be used to pinpoint the youngest, thus, likely prestellar massive structures. Using the optically thin isotopologue ( 29 SiO), we estimate that the (2−1) line is optically thin towards most of the sample. Furthermore, based on the line ratio of the (5−4) to the (2−1) line, our study reveals a trend of changing excitation conditions that lead to brighter emission in the (5−4) line towards more evolved sources. Our models show that a proper treatment of non-LTE effects and beam dilution is necessary to constrain trends in the SiO column den...

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“…These fundamental studies are, however, mostly limited to the analysis of the secondary outflow at relatively low spatial resolution, whereas there are just a few interferometric studies of single sources that allow us to trace the molecular outflow and the driving source at (sub)arcsecond resolution (see e.g. Beuther et al 2004;Leurini et al 2013;Sanna et al 2014;Tan et al 2014).…”

Section: Introductionmentioning

confidence: 99%

A near-infrared spectroscopic survey of massive jets towards extended green objects

Garatti

Stecklum

Linz

et al. 2014

A&A

111

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Context. Protostellar jets and outflows are the main outcome of the star formation process, and their analysis can provide us with major clues about the ejection and accretion history of young stellar objects (YSOs). Aims. We aim at deriving the main physical properties of massive jets from near-infrared (NIR) observations, comparing them to those of a large sample of jets from low-mass YSOs, and relating them to the main features of their driving sources. Methods. We present a NIR imaging (H 2 and K s ) and low-resolution spectroscopic (0.95−2.50 μm) survey of 18 massive jets towards GLIMPSE extended green objects (EGOs), driven by intermediate-and high-mass YSOs, which have bolometric luminosities (L bol ) between 4 × 10 2 and 1.3 × 10 5 L . Results. As in low-mass jets, H 2 is the primary NIR coolant, detected in all the analysed flows, whereas the most important ionic tracer is [Fe ii], detected in half of the sampled jets. Our analysis indicates that the emission lines originate from shocks at high temperatures and densities. No fluorescent emission is detected along the flows, regardless of the source bolometric luminosity. On average, the physical parameters of these massive jets (i.e. visual extinction, temperature, column density, mass, and luminosity) have higher values than those measured in their low-mass counterparts. The morphology of the H 2 flows is varied, mostly depending on the complex, dynamic, and inhomogeneous environment in which these massive jets form and propagate. All flows and jets in our sample are collimated, showing large precession angles. Additionally, the presence of both knots and jets suggests that the ejection process is continuous with burst episodes, as in low-mass YSOs. We compare the flow H 2 luminosity with the source bolometric luminosity confirming the tight correlation between these two quantities. Five sources, however, display a lower L H 2 /L bol efficiency, which might be related to YSO evolution. Most important, the inferred L H 2 vs. L bol relationship agrees well with the correlation between the momentum flux of the CO outflows and the bolometric luminosities of high-mass YSOs indicating that outflows from high-mass YSOs are momentum driven, as are their low-mass counterparts. We also derive a less stringent correlation between the inferred mass of the H 2 flows and L bol of the YSOs, indicating that the mass of the flow depends on the driving source mass. Conclusions. By comparing the physical properties of jets in the NIR, a continuity from low-to high-mass jets is identified. Massive jets appear as a scaled-up version of their low-mass counterparts in terms of their physical parameters and origin. Nevertheless, there are consistent differences such as a more variegated morphology and, on average, stronger shock conditions, which are likely due to the different environment in which high-mass stars form.

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Evidence of a SiO collimated outflow from a massive YSO in IRAS 17233–3606

Cited by 36 publications

References 47 publications

SiO excitation from dense shocks in the earliest stages of massive star formation

SiO excitation from dense shocks in the earliest stages of massive star formation

ATLASGAL-selected massive clumps in the inner Galaxy

A near-infrared spectroscopic survey of massive jets towards extended green objects

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