Molecular Outflows around High-Mass Young Stellar Objects

Xu, Ye; Shen, Zhi-Qiang; Yang, Ji; Zheng, Xingwu; Miyazaki, Akira; Sunada, Kazuyoshi; J., H.; Li, J. J.; Sun, Jin; Pei, Chunchuan

doi:10.1086/504466

Cited by 26 publications

(31 citation statements)

References 52 publications

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“…Small scale outflow found toward IRS 1: The parameters of the IRS 1 outflow are similar to the mean values of low-mass outflows (Wu et al 2004), and are about 2 orders of magnitude smaller than the parameters derived from surveys of high-mass outflows (Beuther et al 2002b;Wu et al 2005;Zhang et al 2005;Xu et al 2006). However, given that the surveys of high-mass molecular outflows are based on single-dish observations, picking up large-scale structure and considering thus larger areas of outflow emission, we compared the parameters of the IRS 1 outflow with other high-mass outflows observed with interferometers, listed in Table 4.…”

Section: The Young High-velocity Bipolar Outflow Toward Irsmentioning

confidence: 57%

Unveiling the nature and interaction of the intermediate/high-mass YSOs in IRAS 20343+4129

Palau

Estalella

et al. 2007

A&A

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Context. IRAS 20343+4129 was suggested to harbor one of the most massive and embedded stars in the Cygnus OB2 association, IRS 1, which seemed to be associated with a north-south molecular outflow. However, the dust emission peaks do not coincide with the position of IRS 1, but lie on either side of another massive Young Stellar Object (YSO), IRS 3, which is associated with centimeter emission. Aims. The goal of this work is to elucidate the nature of IRS 1 and IRS 3, and study their interactions with the surrounding medium. Methods. The Submillimeter Array (SMA) was used to observe with high angular resolution the 1.3 mm continuum and CO (2-1) emission of the region, and we compared this millimeter emission with the infrared emission from 2MASS. Results. Faint millimeter dust continuum emission was detected toward IRS 1, and we derived an associated gas mass of ∼0.8 M . The IRS 1 Spectral Energy Distribution (SED) agrees with IRS 1 being an intermediate-mass Class I source of about 1000 L , whose circumstellar material is producing the observed large infrared excess. We have discovered a high-velocity CO (2-1) bipolar outflow in the east-west direction, which is clearly associated with IRS 1. Its outflow parameters are similar to those of intermediate-mass YSOs. Associated with the blue large-scale CO (2-1) outflow lobe, detected with single-dish observations, we only found two elongated lowvelocity structures on either side of IRS 3. The large-scale outflow lobe is almost completely resolved out by the SMA. Our detected low-velocity CO structures are coincident with elongated H 2 emission features. The strongest millimeter continuum condensations in the region are found on either side of IRS 3, where the infrared emission is extremely weak. The CO and H 2 elongated structures follow the border of the millimeter continuum emission that is facing IRS 3. All these results suggest that the dust is associated with the walls of an expanding cavity driven by IRS 3, estimated to be a B2 star from both the centimeter and the infrared continuum emission. Conclusions. IRS 1 seems to be an intermediate-mass Class I YSO driving a molecular outflow in the east-west direction, while IRS 3 is most likely a more evolved intermediate/high-mass star that is driving a cavity and accumulating dust in its walls. Within and beyond the expanding cavity, the millimeter continuum sources can be sites of future low-mass star formation.

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Section: The Young High-velocity Bipolar Outflow Toward Irsmentioning

confidence: 57%

Unveiling the nature and interaction of the intermediate/high-mass YSOs in IRAS 20343+4129

Palau

Estalella

et al. 2007

A&A

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“…One of the primary questions is that we do not yet have the resolving power to detect the accretion disk (with a scale of a few 1000 AU) directly with current instruments, and thus cannot answer where accretion occurs, in an isolated core (monolithic collapse) or in a protocluster environment (competitive accretion). In recent years, a lot of observational evidence showing collimated and energetic outflows in MSFRs (e.g., Beuther et al 2002;Xu et al 2006) indirectly infer the existence of an accretion disk under the assumption that the high-mass accretion disk drives these outflows via magnetocentrifugal acceleration. However, these outflow evidences still do not show whether accretion is from an isolated protostar or from a protocluster, as both monolithic collapse and competitive accretion will be accompanied by large-scale outflow.…”

Section: No 1 2010 Infall Evidence In Egos I 151mentioning

confidence: 99%

A SEARCH FOR INFALL EVIDENCE IN EGOs. I. THE NORTHERN SAMPLE

Chen

Shen

et al. 2010

ApJ

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We report the first systematic survey of molecular lines (including HCO + (1-0) and 12 CO, 13 CO, C 18 O (1-0) lines at the 3 mm band) toward a new sample of 88 massive young stellar object (MYSO) candidates associated with ongoing outflows (known as extended green objects or EGOs) identified from the Spitzer GLIMPSE survey in the northern hemisphere with the Purple Mountain Observatory 13.7 m radio telescope. By analyzing the asymmetries of the optically thick line HCO + for 69 of 72 EGOs with HCO + detection, we found 29 sources with "blue asymmetric profiles" and 19 sources with "red asymmetric profiles." This results in a blue excess of 0.14, seen as a signature of collapsing cores in the observed EGO sample. We found that the sources not associated with infrared dark clouds (IRDCs) show a higher blue excess (0.41) than those associated with IRDCs (−0.08), and "possible" outflow candidates show a higher blue excess (0.29) than "likely" outflow candidates (0.05). A higher blue excess (0.19) and a lower blue excess (0.07) were also measured in ultracompact H ii regions and 6.7 GHz class II methanol maser sources, respectively. These suggest that the relatively small blue excess (0.14) in our full sample is due to the fact that the observed EGOs are mostly dominated by outflows and at an earlier evolutionary phase associated with IRDCs and 6.7 GHz methanol masers. The physical properties of clouds surrounding EGOs derived from CO lines are similar to those of massive clumps wherein the massive star-forming cores associated with EGOs possibly embedded. The infall velocities and mass infall rates derived for 20 infall candidates are also consistent with the typical values found in MYSOs. Thus, our observations further support the speculation of Cyganowski et al. that EGOs trace a population with ongoing outflow activity and at the active rapid accretion stage of massive protostellar evolution from a statistical view, although there may be limitations due to a single-pointing survey with a large beam.

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“…The excitation temperature, T ex was assumed to be 30 K here for high-mass sources (Shepherd & Churchwell 1996a;Beuther et al 2002;Wu et al 2004;Xu et al 2006;Wu et al 2010). …”

Section: B Calculation Of Outflow Parametersmentioning

confidence: 99%

“…As the first CO outflow was discovered in Orion KL by Kwan & Scoville (1976), accumulated observations of high mass star formation regions show outflows are also common in massive star formation regions (e.g. Snell et al 1990;Shepherd & Churchwell 1996a;Ridge & Moore 2001;Beuther et al 2002;Wu et al 2004;Xu et al 2006;Arce et al 2007;de Villiers et al 2014;Maud et al 2015), indicating a similar driven mechanism. Despite the similarity, whether there are differences between low and high mass star formation region outflows (Beuther et al 2002;Wu et al 2004;Zinnecker & Yorke 2007) remain under debate.…”

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confidence: 95%

AMMONIA AND CO OUTFLOW AROUND 6.7 GHz METHANOL MASERS

Li¹,

Xu²,

Wu³

et al. 2016

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Single point observations are presented in NH 3 (1,1) and (2,2) inversion transitions using the Effelsberg 100 m telescope for a sample of 100 6.7 GHz methanol masers and mapping observations in the 12 CO and 13 CO (1 − 0) transitions using the PMO Delingha 13.7 m telescope for 82 sample sources with detected ammonia. A further 62 sources were selected for either 12 CO or 13 CO line outflow identification, producing 45 outflow candidates, 29 using 12 CO and 16 using 13 CO data. Twenty-two of the outflow candidates were newly identified, and 23 had trigonometric parallax distances. Physical properties were derived from ammonia lines and CO outflow parameters calculated. Histograms and statistical correlations for ammonia, CO outflow parameters, and 6.7 GHz methanol maser luminosities are also presented. No significant correlation was found between ammonia and maser luminosity. However, weak correlations were found between outflow properties and maser luminosities, which may indicate that outflows are physically associated with 6.7 GHz masers.

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Molecular Outflows around High-Mass Young Stellar Objects

Cited by 26 publications

References 52 publications

Unveiling the nature and interaction of the intermediate/high-mass YSOs in IRAS 20343+4129

Unveiling the nature and interaction of the intermediate/high-mass YSOs in IRAS 20343+4129

A SEARCH FOR INFALL EVIDENCE IN EGOs. I. THE NORTHERN SAMPLE

AMMONIA AND CO OUTFLOW AROUND 6.7 GHz METHANOL MASERS

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