Apex Co (9-8) Mapping of an Extremely High Velocity and Jet-Like Outflow in a High-Mass Star-Forming Region

Qiu, Keping; Wyrowski, F.; Menten, K. M.; Güsten, R.; Leurini, S.; Leinz, C.

doi:10.1088/2041-8205/743/1/l25

Cited by 30 publications

(30 citation statements)

References 34 publications

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“…The blue component observed in this work may in fact trace swept-up envelope material ( < ∼ 10 km s −1 from the systemic velocity) rather than fast outflowing gas that is farther separated from the parent envelope, see, e.g., Van der Tak et al (1999) for AFGL 2591, or Qiu et al (2011) andGómez-Ruiz et al (2012) for other protostars. Our outflow conditions are compatible with the temperature and density derived for the warmest of the three outflow components in L1157-B1, as found by Lefloch et al (2012).…”

Section: Outflow Gasmentioning

confidence: 82%

The HIFI spectral survey of AFGL 2591 (CHESS)

Wiel

Pagani

Tak

et al. 2013

A&A

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Context. Linear rotor molecules such as CO, HCO+ and HCN are important probes of star-forming gas. For these species, temperatures of < ∼ 50 K are sufficient to produce emission lines that are observable from the ground at (sub)millimeter wavelengths. Molecular gas in the environment of massive protostellar objects, however, is known to reach temperatures of several hundred K. To probe this, space-based far-infrared observations are required. Aims. We aim to reveal the gas energetics in the circumstellar environment of the prototypical high-mass protostellar object AFGL 2591. Methods. Rotational spectral line signatures of CO species, HCO + , CS, HCN and HNC from a 490-1240 GHz survey with Herschel/HIFI, complemented by ground-based JCMT and IRAM 30 m spectra, cover transitions in the energy range (E up /k) between 5 K and ∼300 K. Selected frequency settings in the highest frequency HIFI bands (up to 1850 GHz) extend this range to 750 K for 12 C 16 O. The resolved spectral line profiles are used to separate and study various kinematic components. Observed line intensities are compared with a numerical model that calculates excitation balance and radiative transfer based on spherical geometry. Results. The line profiles show two emission components, the widest and bluest of which is attributed to an approaching outflow and the other to the envelope. We find evidence for progressively more redshifted and wider line profiles from the envelope gas with increasing energy level. This trend is qualitatively explained by residual outflow contribution picked up in the systematically decreasing beam size. Integrated line intensities for each species decrease as E up /k increases from < ∼ 50 to ∼700 K. The H 2 density and temperature of the outflow gas are constrained to ∼10 5 -10 6 cm −3 and 60-200 K. In addition, we derive a temperature between 9 and 17 K and N(H 2 ) ∼ 3 × 10 21 cm −2 for a known foreground cloud seen in absorption, and N(H 2 ) < ∼ 10 19 cm −2 for a second foreground component. Conclusions. Our spherical envelope model systematically underproduces observed line emission at E up /k > ∼ 150 K for all species. This indicates that warm gas should be added to the model and that the model's geometry should provide low optical depth pathways for line emission from this warm gas to escape, for example in the form of UV heated outflow cavity walls viewed at a favorable inclination angle. Physical and chemical conditions derived for the outflow gas are similar to those in the protostellar envelope, possibly indicating that the modest velocity ( < ∼ 10 km s −1 ) outflow component consists of recently swept-up gas.

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Section: Outflow Gasmentioning

confidence: 82%

The HIFI spectral survey of AFGL 2591 (CHESS)

Wiel

Pagani

Tak

et al. 2013

A&A

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“…Besides, several maser lines have been observed from NH 3 (Beuther et al 2007), CH 3 OH (Walsh et al 1998) and H 2 O (Migenes et al 1999) as well as bipolar outflows in CO (Leurini et al 2006;Qiu et al 2011) and SiO (Gibb et al 2007). This source is part of the CHESS program (Chemical HErschel Surveys of Star forming regions), a key program of the Herschel Space Observatory (Ceccarelli et al 2010).…”

Section: Introductionmentioning

confidence: 97%

Molecular line survey of the high-mass star-forming region NGC 6334I withHerschel/HIFI and the Submillimeter Array

Zernickel

Schilke

Schmiedeke

et al. 2012

A&A

107

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Aims. We aim at deriving the molecular abundances and temperatures of the hot molecular cores in the high-mass star-forming region NGC 6334I and consequently deriving their physical and astrochemical conditions. Methods. In the framework of the Herschel guaranteed time key program CHESS (Chemical HErschel Surveys of Star forming regions), NGC 6334I is investigated by using the Heterodyne Instrument for the Far-Infrared (HIFI) aboard the Herschel Space Observatory. A spectral line survey is carried out in the frequency range 480-1907 GHz, and further auxiliary interferometric data from the Submillimeter Array (SMA) in the 230 GHz band provide spatial information for disentangling the different physical components contributing to the HIFI spectrum. The spectral lines in the processed Herschel data are identified with the aid of former surveys and spectral line catalogs. The observed spectrum is then compared to a simulated synthetic spectrum, assuming local thermal equilibrium, and best fit parameters are derived using a model optimization package. Results. A total of 46 molecules are identified, with 31 isotopologues, resulting in about 4300 emission and absorption lines. Highenergy levels (E u > 1000 K) of the dominant emitter methanol and vibrationally excited HCN (ν 2 = 1) are detected. The number of unidentified lines remains low with 75, or <2% of the lines detected. The modeling suggests that several spectral features need two or more components to be fitted properly. Other components could be assigned to cold foreground clouds or to outflows, most visible in the SiO and H 2 O emission. A chemical variation between the two embedded hot cores is found, with more N-bearing molecules identified in SMA1 and O-bearing molecules in SMA2. Conclusions. Spectral line surveys give powerful insights into the study of the interstellar medium. Different molecules trace different physical conditions like the inner hot core, the envelope, the outflows or the cold foreground clouds. The derived molecular abundances provide further constraints for astrochemical models.

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“…1). This ridge itself is actively forming high-mass stars as revealed by compact radio emission, ultra-compact H II regions, maser sources, and molecular outflows identified along or next to its crest (Sandell 2000;McCutcheon et al 2000;Muñoz et al 2007;Qiu et al 2011). The NGC 6334 filament has a line mass M line ∼ 1000 M /pc (> M line,crit ) with column densities N H 2 10 23 cm −2 over most of its 10 pc long crest (André et al 2016) and it is fragmented into a series of relatively massive cores with a mean mass ∼ 10 M (e.g., Shimajiri et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Dust polarized emission observations of NGC 6334

Arzoumanian¹,

Furuya²,

Hasegawa³

et al. 2021

A&A

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Context. Molecular filaments and hubs have received special attention recently thanks to new studies showing their key role in star formation. While the (column) density and velocity structures of both filaments and hubs have been carefully studied, their magnetic field (B-field) properties have yet to be characterized. Consequently, the role of B-fields in the formation and evolution of hub-filament systems is not well constrained. Aims. We aim to understand the role of the B-field and its interplay with turbulence and gravity in the dynamical evolution of the NGC 6334 filament network that harbours cluster-forming hubs and high-mass star formation. Methods. We present new observations of the dust polarized emission at 850 μm toward the 2 pc × 10 pc map of NGC 6334 at a spatial resolution of 0.09 pc obtained with the James Clerk Maxwell Telescope (JCMT) as part of the B-field In STar-forming Region Observations (BISTRO) survey. We study the distribution and dispersion of the polarized intensity (PI), the polarization fraction (PF), and the plane-of-the-sky B-field angle (χB_POS) toward the whole region, along the 10 pc-long ridge and along the sub-filaments connected to the ridge and the hubs. We derived the power spectra of the intensity and χBPOS along the ridge crest and compared them with the results obtained from simulated filaments. Results. The observations span ~3 orders of magnitude in Stokes I and PI and ~2 orders of magnitude in PF (from ~0.2 to ~ 20%). A large scatter in PI and PF is observed for a given value of I. Our analyses show a complex B-field structure when observed over the whole region (~ 10 pc); however, at smaller scales (~1 pc), χBPOS varies coherently along the crests of the filament network. The observed power spectrum of χBPOS can be well represented with a power law function with a slope of − 1.33 ± 0.23, which is ~20% shallower than that of I. We find that this result is compatible with the properties of simulated filaments and may indicate the physical processes at play in the formation and evolution of star-forming filaments. Along the sub-filaments, χBPOS rotates frombeing mostly perpendicular or randomly oriented with respect to the crests to mostly parallel as the sub-filaments merge with the ridge and hubs. This variation of the B-field structure along the sub-filaments may be tracing local velocity flows of infalling matter in the ridge and hubs. Our analysis also suggests a variation in the energy balance along the crests of these sub-filaments, from magnetically critical or supercritical at their far ends to magnetically subcritical near the ridge and hubs. We also detect an increase in PF toward the high-column density (NH2 ≳ 1023 cm−2) star cluster-forming hubs. These latter large PF values may be explained by the increase in grain alignment efficiency due to stellar radiation from the newborn stars, combined with an ordered B-field structure. Conclusions. These observational results reveal for the first time the characteristics of the small-scale (down to ~ 0.1 pc) B-field structure of a 10 pc-long hub-filament system. Our analyses show variations in the polarization properties along the sub-filaments that may be tracing the evolution of their physical properties during their interaction with the ridge and hubs. We also detect an impact of feedback from young high-mass stars on the local B-field structure and the polarization properties, which could put constraints on possible models for dust grain alignment and provide important hints as to the interplay between the star formation activity and interstellar B-fields.

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Apex Co (9-8) Mapping of an Extremely High Velocity and Jet-Like Outflow in a High-Mass Star-Forming Region

Cited by 30 publications

References 34 publications

The HIFI spectral survey of AFGL 2591 (CHESS)

The HIFI spectral survey of AFGL 2591 (CHESS)

Molecular line survey of the high-mass star-forming region NGC 6334I withHerschel/HIFI and the Submillimeter Array

Dust polarized emission observations of NGC 6334

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