Observations of Shocked H[TINF]2[/TINF] and Entrained CO in Outflows from Luminous Young Stars

Davis, C. J.; Moriarty‐Schieven, G. H.; Eislöffel, J.; Hoare, M. G.; Ray, T. P.

doi:10.1086/300259

Cited by 92 publications

(158 citation statements)

References 63 publications

Supporting

Mentioning

139

Contrasting

Order By: Relevance

“…Compared to the blue-shifted absorption observed by Keto (1991) and Zheng et al (2001) in the lowexcitation NH 3 lines that is indicative of outflowing gas motions, Qiu et al (2011) detected first red-shifted absorption toward the main mm core which they interprete as signature of ongoing infall. Furthermore, the general structure of their proposed multiple outflows is consistent with the northwest-southeast outflow previously reported by, e.g., Keto (1991); Davis et al (1998); Klaassen et al (2011). Our data now resolve the region at again an order of magnitude higher spatial resolution, allowing us to study the central core in unprecedented detail.…”

Section: Introductionsupporting

confidence: 88%

“…About ∼80 south of NGC 7538IRS1 (Fig. 1), it roughly coincides with a far-infrared source with luminosity ∼1.5 × 10 4 L (Werner et al 1979;Thronson & Harper 1979) corresponding to Several potential disk and outflow axis reported in the literature are presented (Davis et al 1998;De Buizer & Minier 2005;Sandell et al 2009;Pestalozzi et al 2004Pestalozzi et al , 2009Sandell & Wright 2010, see Introduction for more details). The open stars, square, triangle and six-pointed star mark the positions of the OH, H 2 O, class ii CH 3 OH and H 2 CO masers (Argon et al 2000;Kameya et al 1990;Pestalozzi et al 2006;Hoffman et al 2003).…”

Section: Introductionsupporting

confidence: 62%

“…While Campbell (1984) and Sandell et al (2009) report an ionized jet in north-south direction, Minier et al (2000) and Pestalozzi et al (2004Pestalozzi et al ( , 2009 present CH 3 OH maser observations indicative of an accretion disk almost perpendicular to the outflow. Partly different interpretations arise from midinfrared continuum imaging (De Buizer & Minier 2005): they detected elongated mid-infrared emission in northwest-southeast direction aligned with a bipolar outflow reported in CO by Davis et al (1998), and even earlier in NH 3 by Keto (1991) who also performed radiation transfer calculations for the region. This large-scale mid-infrared emission may stem from the inner walls of the outflow.…”

Section: Introductionmentioning

confidence: 97%

See 2 more Smart Citations

The high-mass disk candidates NGC 7538IRS1 and NGC 7538S

Beuther

Linz

Henning

2012

A&A

View full text Add to dashboard Cite

Context. The nature of embedded accretion disks around forming high-mass stars is one of the missing puzzle pieces for a general understanding of the formation of the most massive and luminous stars. Aims. We want to dissect the small-scale structure of the dust continuum and kinematic gas emission toward two of the most prominent high-mass disk candidates. Methods. Using the Plateau de Bure Interferometer at ∼1.36 mm wavelengths in its most extended configuration we probe the dust and gas emission at ∼0.3 , corresponding to linear resolution elements of ∼800 AU.Results. Even at that high spatial resolution NGC 7538IRS1 remains a single compact and massive gas core with extraordinarily high column densities, corresponding to visual extinctions on the order of 10 5 mag, and average densities within the central 2000 AU of ∼2.1 × 10 9 cm −3 that have not been measured before. We identify a velocity gradient across in northeast-southwest direction that is consistent with the mid-infrared emission, but we do not find a gradient that corresponds to the proposed CH 3 OH maser disk. The spectral line data toward NGC 7538IRS1 reveal strong blue-and red-shifted absorption toward the mm continuum peak position. While the blue-shifted absorption is consistent with an outflow along the line of sight, the red-shifted absorption allows us to estimate high infall rates on the order of 10 −2 M yr −1 . Although we cannot prove that the gas will be accreted in the end, the data are consistent with ongoing star formation activity in a scaled-up low-mass star formation scenario. Compared to that, NGC 7538S fragments in a hierarchical fashion into several sub-sources. While the kinematics of the main mm peak are dominated by the accompanying jet, we find rotational signatures from a secondary peak. Furthermore, strong spectral line differences exist between the sub-sources which is indicative of different evolutionary stages within the same large-scale gas clump. Conclusions. NGC 7538IRS1 is one of the most extreme high-mass disk candidates known today. The large concentration of mass into a small area combined with the high infall rates are unusual and likely allow continued accretion. While the absorption is interesting for the infall studies, higher-excited lines that do not suffer from the absorption are needed to better study the disk kinematics. In contrast to that, NGC 7538S appears as a more typical high-mass star formation region that fragments into several sources. Many of them will form low-to intermediate-mass stars. The strongest mm continuum peak is likely capable to form a high-mass star, however, likely of lower mass than NGC 7538IRS1.

show abstract

Section: Introductionsupporting

confidence: 88%

Section: Introductionsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

The high-mass disk candidates NGC 7538IRS1 and NGC 7538S

Beuther

Linz

Henning

2012

A&A

View full text Add to dashboard Cite

show abstract

“…Infrared images taken at wavelengths shorter than 20 km, however, manifest remarkable di †erences between these two cores. The point sources in IRS 1(SMM), as well as their surrounding nebulosity, can easily be identiÐed at 2.2 km, but only a faint extended emission is found in IRS 11(SMM) at the same wavelength (e.g., Davis et al 1998). Even at 10È20 km there is no detectable source in IRS 11(SMM) (Werner et al 1979).…”

Section: Relationship Between Core Evolution Andmentioning

confidence: 99%

Submillimeter Imaging Polarimetry of the NGC 7538 Region

Momose

Tamura

Kameya

et al. 2001

ApJ

View full text Add to dashboard Cite

Imaging polarimetry of the 850 km continuum emission in the NGC 7538 region, obtained with the SCUBA Polarimeter, is presented. The polarization map is interpreted in terms of thermal radiation by magnetically aligned dust grains. Two prominent cores associated with IRS 1 and IRS 11, IRS 1(SMM), and IRS 11(SMM), are found in the surface brightness map. Although these cores look similar in surface brightness, their polarization shows striking di †erences. In IRS 11(SMM), the polarization vectors are extremely well-ordered, and the degrees of polarization are quite high with an average of D3.9%. In IRS 1(SMM), on the other hand, the directions of polarization vectors are locally disturbed, and the degrees of polarization are much lower than those of IRS 11(SMM). These di †erences suggest that small scale Ñuctuations of the magnetic Ðeld are more prominent in IRS 1(SMM). This can be interpreted in terms of the di †erence in evolutionary stage of the cores. Inside IRS 1(SMM), which seems to be at a later evolutionary stage than IRS 11(SMM), substructures such as subclumps or a cluster of infrared sources have already formed. Small scale Ñuctuations in the magnetic Ðeld could have developed during the formation of these substructures. The distribution of magnetic Ðeld directions derived from our polarization map agrees well with those of molecular outÑows associated with IRS 1(SMM) and IRS 11(SMM). Comparisons of energy densities between the magnetic Ðeld and the outÑows show that the magnetic Ðeld probably plays an important role in guiding the directions of the outÑows.

show abstract

“…The brightest source is NGC 7538-IRS 1, whose central star has been suggested to be an O6 star of about 30 M with systemic local standard of rest velocity V lsr = −58 km s −1 (Campbell & Thompson 1984;Sandell et al 2009;Puga et al 2010). Several high-velocity molecular bipolar outflows were detected in NGC 7538 and one of these is elongated 0.3 pc from IRS 1 (position angle PA = 140 • ) with a velocity of 250 km s −1 and a mass of 82.8 M (Kameya et al 1989;Gaume et al 1995;Davis et al 1998;Qiu et al 2011). VLA continuum observations by Campbell (1984) indicate that the PA of the outflow decreases away from IRS 1; i.e., 180 • at 0.…”

Section: Introductionmentioning

confidence: 99%

The properties and polarization of the H₂O and CH₃OH maser environment of NGC 7538-IRS 1

Surcis

Vlemmings

Torres

et al. 2011

A&A

View full text Add to dashboard Cite

Context. NGC 7538 is a complex massive star-forming region. The region is composed of several radio continuum sources, one of which is IRS 1, a high-mass protostar, from which a 0.3 pc molecular bipolar outflow was detected. Several maser species have been detected around IRS 1. The CH 3 OH masers have been suggested to trace a Keplerian-disk, while the H 2 O masers are almost aligned to the outflow. More recent results suggested that the region hosts a torus and potentially a disk, but with a different inclination than the Keplerian-disk that is supposed to be traced by the CH 3 OH masers. Aims. Tracing the magnetic field close to protostars is fundamental for determining the orientation of the disk/torus. Recent studies showed that during the protostellar phase of high-mass star formation the magnetic field is oriented along the outflows and around or on the surfaces of the disk/torus. The observations of polarized maser emissions at milliarcsecond resolution can make a crucial contribution to understanding the orientation of the magnetic field and, consequently, the orientation of the disk/torus in NGC 7538-IRS 1. Methods. The NRAO Very Long Baseline Array was used to measure the linear polarization and the Zeeman-splitting of the 22 GHz H 2 O masers toward NGC 7538-IRS 1. The European VLBI Network and the MERLIN telescopes were used to measure the linear polarization and the Zeeman-splitting of the 6.7 GHz CH 3 OH masers toward the same region. Results. We detected 17 H 2 O masers and 49 CH 3 OH masers at high angular resolution. We detected linear polarization emission toward two H 2 O masers and toward twenty CH 3 OH masers. The CH 3 OH masers, most of which only show a core structure, seem to trace rotating and potentially infalling gas in the inner part of a torus. Significant Zeeman-splitting was measured in three CH 3 OH masers. No significant (3σ) magnetic field strength was measured using the H 2 O masers. We also propose a new description of the structure of the NGC 7538-IRS 1 maser region.

show abstract

Observations of Shocked H[TINF]2[/TINF] and Entrained CO in Outflows from Luminous Young Stars

Cited by 92 publications

References 63 publications

The high-mass disk candidates NGC 7538IRS1 and NGC 7538S

The high-mass disk candidates NGC 7538IRS1 and NGC 7538S

Submillimeter Imaging Polarimetry of the NGC 7538 Region

The properties and polarization of the H₂O and CH₃OH maser environment of NGC 7538-IRS 1

Contact Info

Product

Resources

About

Observations of Shocked H[TINF]2[/TINF] and Entrained CO in Outflows from Luminous Young Stars

Cited by 92 publications

References 63 publications

The high-mass disk candidates NGC 7538IRS1 and NGC 7538S

The high-mass disk candidates NGC 7538IRS1 and NGC 7538S

Submillimeter Imaging Polarimetry of the NGC 7538 Region

The properties and polarization of the H2O and CH3OH maser environment of NGC 7538-IRS 1

Contact Info

Product

Resources

About

The properties and polarization of the H₂O and CH₃OH maser environment of NGC 7538-IRS 1