A study of the Keplerian accretion disk and precessing  outflow in the
massive protostar IRAS 20126+4104

Cesaroni, R.; Neri, R.; Olmi, L.; Testi, L.; Walmsley, C. M.; Höfner, P.

doi:10.1051/0004-6361:20041639

Cited by 197 publications

(294 citation statements)

References 22 publications

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“…In conclusion, despite some differences between the old and new best-fit parameters, the corrected data confirm that the jet is very beamed, lies close to the plane of the sky, and is approximately perpendicular to the disk (whose PA is ∼53 ± 7 • , see Cesaroni et al 2005).…”

Section: Disk and Jet Structure In Iras 20126+4104mentioning

confidence: 66%

“…-IRAS 20126+4104 is associated with a Keplerian disk rotating about a ∼7 M protostar (Cesaroni et al 1997Zhang et al 1998); -the disk is also seen in silhouette as a dark lane at nearand mid-IR wavelengths (Sridharan et al 2005;De Buizer et al 2007); -the YSO is powering a bipolar jet/outflow, imaged in a variety of tracers from ∼1 down to ∼100 mas from the star (Wilking et al 1990;Cesaroni et al 1997Cesaroni et al , 1999Cesaroni et al , 2005Shepherd et al 2000;Su et al 2007;Shinnaga et al 2008;Hofner et al 1999Hofner et al , 2007Moscadelli et al 2000Moscadelli et al , 2005Trinidad et al 2005); -the jet/outflow appears to be undergoing precession (Shepherd et al 2000;Cesaroni et al 2005;Lebrón et al 2006), perhaps caused by the presence of another YSO A&A 526, A66 (2011) detected at radio and IR wavelengths (Hofner et al 1999;Sridharan et al 2005).…”

Section: Introductionmentioning

confidence: 99%

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Methanol and water masers in IRAS 20126+4104: the distance, the disk, and the jet

Moscadelli

Cesaroni

Rioja

et al. 2010

A&A

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Context. Knowledge of the distance to high-mass star forming regions is crucial to obtain accurate luminosity and mass estimates of young OB-type (proto)stars and thus better constrain their nature and age. IRAS 20126+4104 is a special case, being the best candidate of a high-mass (proto)star surrounded by an accretion disk. Such a fact may be used to set constraints on theories of highmass star formation, but requires confirmation that the mass and luminosity of IRAS 20126+4104 are indeed typical of a B0.5 star, which in turn requires an accurate estimate of the distance. Aims. The goal of our study is twofold: to determine the distance to IRAS 20126+4104, using the parallax of H 2 O masers associated with the source, and unveil the 3D velocity field of the disk, through proper motion measurements of the 6.7 GHz CH 3 OH masers. At the same time, we can also obtain an estimate of the systemic velocity in the plane of the sky of the disk+star system. Methods. We used the Very Long Baseline Array and the European VLBI Network to observe the 22.2 GHz H 2 O and 6.7 GHz CH 3 OH masers in IRAS 20126+4104 at a number of epochs suitably distributed in time. The absolute positions of the maser features were established with respect to reference quasars, which allowed us to derive absolute proper motions. Results. From the parallax of the H 2 O masers we obtain a distance of 1.64 ± 0.05 kpc, which is very similar to the value adopted so far in the literature (1.7 kpc) and confirms that IRAS 20126+4104 is a high-mass (proto)star. From the CH 3 OH masers we derive the component in the plane of the sky of the systemic velocity of the disk+star system (−16 km s −1 in right-ascension and +7.6 km s −1 in declination). Accurate knowledge of the distance and systemic velocity allows us to improve on the model fit to the H 2 O maser jet presented in a previous study. Finally, we identify two groups of CH 3 OH maser features, one undergoing rotation in the disk and possibly distributed along a narrow ring centered on the star, the other characterised by relative proper motions indicating that the features are moving away from the disk, perpendicular to it. We speculate that the latter group might be tracing the disk material marginally entrained by the jet. Conclusions. VLBI multi-epoch observations with phase referencing are confirmed to be an excellent tool for distance determinations and for the investigation of the structure and 3D velocity field within a few 100 AU from newly born high-mass stars.

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Section: Disk and Jet Structure In Iras 20126+4104mentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Methanol and water masers in IRAS 20126+4104: the distance, the disk, and the jet

Moscadelli

Cesaroni

Rioja

et al. 2010

A&A

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104

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“…High-mass stars (O-and B-type stars with masses > ∼ 8 M ) are crucial for the understanding of many physical phenomena in the Galaxy; however, their first stages of formation are still poorly A&A 569, A11 (2014) identified and studied (e.g., Simon et al 2000), there are only a few convincing disks (with sizes ≤1000 AU) found around B-type protostars (e.g., Schreyer et al 2002;Cesaroni et al 2005Cesaroni et al , 2007Carrasco-González et al 2012;Wang et al 2012). Moreover, convincing evidence of centrifugally supported disks around O-type protostars still remains elusive.…”

Section: Introductionmentioning

confidence: 99%

A necklace of dense cores in the high-mass star forming region G35.20−0.74 N: ALMA observations

Sánchez-Monge

Beltrán

Cesaroni

et al. 2014

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Context. The formation process of high-mass stars (with masses >8 M ) is still poorly understood, and represents a challenge from both the theoretical and observational points of view. The advent of the Atacama Large Millimeter Array (ALMA) is expected to provide observational evidence to better constrain the theoretical scenarios. Aims. The present study aims at characterizing the high-mass star forming region G35.20−0.74 N, which is found associated with at least one massive outflow and contains multiple dense cores, one of them recently found associated with a Keplerian rotating disk. Methods. We used the radio-interferometer ALMA to observe the G35.20−0.74 N region in the submillimeter continuum and line emission at 350 GHz. The observed frequency range covers tracers of dense gas (e.g., H 13 CO + , C 17 O), molecular outflows (e.g., SiO), and hot cores (e.g., CH 3 CN, CH 3 OH). These observations were complemented with infrared and centimeter data. Results. The ALMA 870 μm continuum emission map reveals an elongated dust structure (∼0.15 pc long and ∼0.013 pc wide; full width at half maximum) perpendicular to the large-scale molecular outflow detected in the region, and fragmented into a number of cores with masses ∼1-10 M and sizes ∼1600 AU (spatial resolution ∼960 AU). The cores appear regularly spaced with a separation of ∼0.023 pc. The emission of dense gas tracers such as H 13 CO + or C 17 O is extended and coincident with the dust elongated structure. The three strongest dust cores show emission of complex organic molecules characteristic of hot cores, with temperatures around 200 K, and relative abundances 0.2-2 × 10 −8 for CH 3 CN and 0.6-5 × 10 −6 for CH 3 OH. The two cores with highest mass (cores A and B) show coherent velocity fields, with gradients almost aligned with the dust elongated structure. Those velocity gradients are consistent with Keplerian disks rotating about central masses of 4-18 M . Perpendicular to the velocity gradients we have identified a large-scale precessing jet/outflow associated with core B, and hints of an east-west jet/outflow associated with core A. Conclusions. The elongated dust structure in G35.20−0.74 N is fragmented into a number of dense cores that may form high-mass stars. Based on the velocity field of the dense gas, the orientation of the magnetic field, and the regularly spaced fragmentation, we interpret this elongated structure as the densest part of a 1D filament fragmenting and forming high-mass stars.

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“…They should have low optical depths, and trace only the hot gas around the central protostar, and not its envelope. In the past, molecules such as NH 3 , CH 3 CN, HCOOCH 3 , and C 34 S have been proposed for this purpose (i.e., Zhang et al 1998;Cesaroni et al 1997Cesaroni et al , 1999Beuther et al 2004Beuther et al , 2009). …”

Section: Introductionmentioning

confidence: 99%

On the kinematics of massive star forming regions: the case of IRAS 17233–3606

Leurini

Codella

Zapata

et al. 2011

A&A

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Context. Direct observations of accretion disks around high-mass young stellar objects would help to discriminate between different models of formation of massive stars. However, given the complexity of massive star forming regions, such studies are still limited in number. Additionally, there is still no general consensus on the molecular tracers to be used for such investigations. Aims. Because of its close distance and high luminosity, IRAS 17233−3606 is a potential laboratory to search for traces of rotation in the inner gas around the protostar(s). Therefore, we selected the source for a detailed analysis of its molecular emission at 230 GHz with the SMA. Methods. We systematically investigated the velocity fields of transitions in the SMA spectra which are not affected by overlap with other transitions, and searched for coherent velocity gradients to compare them to the distribution of outflows in the region. Beside CO emission we also used high-angular H 2 images to trace the outflow motions driven by the IRAS 17233−3606 cluster. Results. We find linear velocity gradients in many transitions of the same molecular species and in several molecules. We report the first detection of HNCO in molecular outflows from massive YSOs. We discuss the CH 3 CN velocity gradient taking into account various scenarios: rotation, presence of multiple unresolved sources with different velocities, and outflow(s). Although other interpretations cannot be ruled out, we propose that the CH 3 CN emission might be affected by the outflows of the region. Higher angular observations are needed to discriminate between the different scenarios.Conclusions. The present observations, with the possible association of CH 3 CN with outflows in a few thousands AU around the YSOs' cluster, (i) question the choice of the tracer to probe rotating structures, and (ii) show the importance of the use of H 2 images for detailed studies of kinematics.

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A study of the Keplerian accretion disk and precessing outflow in the massive protostar IRAS 20126+4104

Cited by 197 publications

References 22 publications

Methanol and water masers in IRAS 20126+4104: the distance, the disk, and the jet

Methanol and water masers in IRAS 20126+4104: the distance, the disk, and the jet

A necklace of dense cores in the high-mass star forming region G35.20−0.74 N: ALMA observations

On the kinematics of massive star forming regions: the case of IRAS 17233–3606

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