Near-infrared observations of the bipolar outflow source G35.2N

Dent, W. R. F.; Little, L. T.; Satô, Shirô; Ohishi, Masatoshi; Yamashita, Takuya

doi:10.1093/mnras/217.2.217

Cited by 12 publications

(13 citation statements)

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“…The 3.6 μm/4.5 μm ratios (lower panel) also vary from ∼0.2 close to the centre to ∼0.6 at RP ∼ 15 arcsec, implying significantly larger 4.5 μm fluxes than those at 3.6 μm– a reverse of what would be expected where grain reflection is dominant, or where bremsstrahlung continuum is the primary emission mechanism. This may imply that there are further components of emission within the 4.5 μm band, similar to those which have been mentioned in , or that extinction is very high indeed; an hypothesis would be consistent with the results of Dent et al (1985b), Heaton & Little (1988) and Walther et al (1990), who find levels of extinction varying between A V ∼ 17 and 30 mag. Similarly, it seems possible that the illuminating star for the bipolar reflecting lobes may have an extinction A V > 50 mag (Dent et al 1985b; Walther et al 1990).…”

Section: Mir and Nir Observations Of Bipolar Nebulaesupporting

confidence: 83%

“…This may imply that there are further components of emission within the 4.5 μm band, similar to those which have been mentioned in , or that extinction is very high indeed; an hypothesis would be consistent with the results of Dent et al (1985b), Heaton & Little (1988) and Walther et al (1990), who find levels of extinction varying between A V ∼ 17 and 30 mag. Similarly, it seems possible that the illuminating star for the bipolar reflecting lobes may have an extinction A V > 50 mag (Dent et al 1985b; Walther et al 1990).…”

Section: Mir and Nir Observations Of Bipolar Nebulaesupporting

confidence: 83%

“…It has, first of all, been investigated over a broad range of frequencies, including studies at millimetric, radio and NIR wavelengths. Little et al (1985), Brebner et al (1987) and Dent et al (1985a,b) have found evidence for a dense rotating central ring which is perpendicular to the bipolar CO flow (Dent et al 1985a,b; Gibb et al 2003). There is also evidence for a highly collimated radio jet having a spectral index α= 0.8, typical of what is determined for stellar winds (Heaton & Little 1988).…”

Section: Mir and Nir Observations Of Bipolar Nebulaementioning

confidence: 99%

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The mid- and near-infrared structures of seven young stellar bipolar outflows

Phillips¹,

Perez-Grana²

2009

Monthly Notices of the Royal Astronomical Society

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Bipolar outflows appear to represent the ubiquitous products of post‐ and pre‐main‐sequence stellar evolution. However, although the outflows around young stellar objects (YSOs) have been observed over a broad range of wavelengths, from the ultraviolet through to the radio, there has been very little mapping of these sources at mid‐infrared (MIR) wavelengths. The recent advent of the Spitzer Space Telescope (SST) now permits us to correct this deficiency, and we present maps, profiles and images of seven bipolar sources, six of which appear to be new to the literature. It is found that although the bipolars have differing morphologies, reflecting the differing phases of their evolution, they nevertheless have many properties in common. These include the evidence for central tori of neutral material, in some cases associated with appreciable levels of extinction. We also note evidence for exterior photodissociation regimes (PDRs) about the ionized flows, responsible for strong polycyclic aromatic hydrocarbon (PAH) band emission in the 5.8 and 8 μm bands. Such PDRs are also likely to be responsible for appreciable variations in flux ratios with position within the sources. Finally, it is noted that a large fraction of the sources are associated with stars in the earliest phases of their evolution – Class 0 and I stars in which infalling material is important, and dominates their spectral energy distributions in the MIR. One of the sources (G035.2−00.7) has previously been observed at visual, near‐infrared (NIR) and millimetric wavelengths, whence it has been proposed that the spatio‐kinematic properties of the source are best explained in terms of multiple nuclear outflows, and/or precession of an ionized jet. Our present results suggest that the characteristics of this source are much simpler than has previously been inferred, and suggest that the outflow can be described in terms of a very low‐collimation bipolar outflow. Finally, we have also compared the present MIR results with NIR mapping from the Two Micron All Sky Survey (2MASS). These show that whilst the structures of the sources are comparable within these differing wavelength regimes, there are differences attributable to grain extinction and shock or fluorescently excited H2.

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Section: Mir and Nir Observations Of Bipolar Nebulaesupporting

confidence: 83%

Section: Mir and Nir Observations Of Bipolar Nebulaesupporting

confidence: 83%

Section: Mir and Nir Observations Of Bipolar Nebulaementioning

confidence: 99%

See 1 more Smart Citation

The mid- and near-infrared structures of seven young stellar bipolar outflows

Phillips¹,

Perez-Grana²

2009

Monthly Notices of the Royal Astronomical Society

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“…Gibb et al (2003) also discuss that the large-scale CO outflow seen by Dent et al (1985) is not at the same position angle (132 ) as this radio jet (0 ). Their observations also reveal that there are likely several sources in the field that have outflows that contribute to the large-scale CO distribution.…”

Section: G3520à074 (Iras 18556+0136)mentioning

confidence: 94%

Observations of Massive Star‐Forming Regions with Water Masers: Mid‐Infrared Imaging

Buizer

Radomski

Telesco

et al. 2005

ASTROPHYS J SUPPL S

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We present here a mid-infrared imaging survey of 26 sites of water maser emission. Observations were obtained at the Infrared Telescope Facility 3 m telescope with the University of Florida mid-infrared imager/spectrometer OSCIR, and the JPL mid-infrared camera MIRLIN. The main purpose of the survey was to explore the relationship between water masers and the massive star formation process. It is generally believed that water masers predominantly trace outflows and embedded massive stellar objects, but may also exist in circumstellar disks around young stars. We investigate each of these possibilities in light of our mid-infrared imaging. We find that midinfrared emission seems to be more closely associated with water and OH maser emission than cm radio continuum emission from UC H ii regions. We also find from the sample of sources in our survey that, like groups of methanol masers, both water and OH masers have a proclivity for grouping into linear or elongated distributions. We conclude that the vast majority of linearly distributed masers are not tracing circumstellar disks, but outflows and shocks instead.

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“…This direction is coincident with the orientation (PA ≈ 58 • ) of a bipolar outflow observed in 12 CO (e.g., Dent et al 1985a;Gibb et al 2003;Birks et al 2006;López-Sepulcre et al 2009;Qiu et al 2013). The 12 CO (1-0) line emission appears to trace also a N-S collimated flow (see Birks et al 2006), coinciding with a thermal radio jet (e.g., Heaton & Little 1988;Gibb et al 2003) seen also at IR wavelengths (e.g., Dent et al 1985b;Walther et al 1990;Fuller et al 2001;De Buizer 2006;Zhang et al 2013). The different orientations between the poorly collimated NE-SW outflow and the N-S jet have been interpreted as manifestations of the same flow undergoing precession (e.g., Little et al 1998;Gibb et al 2003), or as emission coming from a number of flows driven by the different sources forming in the G35.20N complex (e.g., Gibb et al 2003;Birks et al 2006).…”

Section: Introductionmentioning

confidence: 96%

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

A&A

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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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Near-infrared observations of the bipolar outflow source G35.2N

Cited by 12 publications

References 0 publications

The mid- and near-infrared structures of seven young stellar bipolar outflows

The mid- and near-infrared structures of seven young stellar bipolar outflows

Observations of Massive Star‐Forming Regions with Water Masers: Mid‐Infrared Imaging

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

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