A highly collimated jet from the Red Square nebula MWC 922

Bally, John; Zen, Chia,

doi:10.1093/mnras/stz257

Cited by 5 publications

(9 citation statements)

References 16 publications

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“…Adopting an average H 2 density of ≈10 4 -10 5 cm −3 in the hot CO emitting region and using the column density estimated by Wehres et al (2017) we deduce that the size of the intervening CO-emitting region along the line of sight is probably Δ r ≈1-10 au. Note that the density of the hot CO-emitting gas is plausibly intermediate between that in the central H ii region studied here (~10 6 -10 7 cm −3 , § 4) and that of the more extended surrounding nebulosity traced by numerous forbidden and permitted emission lines in the optical (in the range ≈10-10 4 cm −3 , see Wehres et al 2017; Bally & Chia 2019). If we assume that the hot CO gas is located in a hollow cylindrical structure with a representative inner radius of R , and a thickness (Δ r ) and a scale height h ~Δ r , then we deduce a total mass in this component of only MH2hot≈[10−7‐10−8]×R1000auMfalse⊙.…”

Section: Discussionmentioning

confidence: 60%

“…However, we believe that values much larger than ≈1000 au are unlikely since it would imply that the hot CO emission is reaching to, and coexisting with, the less dense and relatively extended optical/NIR nebulosity where the gas is known to be atomic and begins to be dissociated/ionized by the external (ISM) UV radiation field (e.g. Tuthill & Lloyd 2007; Wehres et al 2017; Bally & Chia 2019). The CO-ring scale height, h , is also unlikely to be significantly larger than Δ r since a very long, thin-walled tubular structure would hardly remain stable.…”

Section: Discussionmentioning

confidence: 99%

“…However, there is no trace of a significant amount of cold and dense material surrounding MWC 922. In fact, the recent detection of a parsec-scale jet orthogonal to the equator at optical wavelengths (Bally & Chia 2019) indicates that such a jet has been travelling for ~3000 yr without any sign of strong interaction with ambient material (e.g. this represents yet another dissimilarity with typical YSOs, in which jets surrounded by swept out molecular cavities are commonly observed; see e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Cohen et al 1975; Jura et al 1995; Waters et al 1998; Bujarrabal et al 2016). For a comprehensive description of MWC 922’s characteristics, see, for example, CSC+17 and references therein, or the most recent studies by Wehres et al (2017) and Bally & Chia (2019). These works report on 300 nm-2.5 μ m spectroscopy of the rich emission line spectrum in this target, including the detection of PAH and CO first and second overtone emission (Wehres et al 2017), and deep narrow-band optical imaging showing the presence of a ~[0.8-10]×10 4 years old, pc-scale jet perpendicular to the disk and expanding at ~500 km s −1 (Bally & Chia 2019).…”

Section: Introductionmentioning

confidence: 99%

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A rotating fast bipolar wind and disk system around the B[e]-type star MWC 922

Contreras

Báez-Rubio

Alcolea

et al. 2019

A&A

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We present interferometric observations with the Atacama Large Millimeter Array (ALMA) of the free-free continuum and recombination line emission at 1 and 3 mm of the "Red Square Nebula" surrounding the B[e]-type star MWC922. The unknown distance to the source is usually taken to be d=1.7-3 kpc. The unprecedented angular resolution (upto∼0.″02) and exquisite sensitivity of these data unveil, for the first time, the structure and kinematics of the emerging, compact ionized region at its center. We imaged the line emission of H30α and H39α, previously detected with single-dish observations, as well as of H51ϵ, H55γ, and H63δ, detected for the first time in this work. The line emission is seen over a full velocity range of ~180 km s−1 arising in a region of diameter <0.″14 (less than a few hundred au) in the maser line H30α, which is the most intense transition reported here. We resolve the spatio-kinematic structure of a nearly edge-on disk rotating around a central mass of ~10 M⊙ (d=1.7 kpc) or ~18 M⊙ (d=3 kpc), assuming Keplerian rotation. Our data also unveil a fast (~100 km s−1) bipolar ejection (a jet?) orthogonal to the disk. In addition, a slow (<15 km s−1) wind may be lifting off the disk. Both, the slow and the fast winds are found to be rotating in a similar manner to the ionized layers of the disk. This represents the first empirical proof of rotation in a bipolar wind expanding at high velocity (~100 km s−1). The launching radius of the fast wind is found to be <30-51 au i.e., smaller than the inner rim of the ionized disk probed by our observations. We believe that the fast wind is actively being launched, probably by a disk-mediated mechanism in a (accretion?) disk around a possible compact companion. We have modelled our observations using the radiative transfer code MORELI. This has enabled us to describe with unparalleled detail the physical conditions and kinematics in the inner layers of MWC 922, which has revealed itself as an ideal laboratory for studying the interplay of disk rotation and jet-launching. Although the nature of MWC 922 remains unclear, we believe it could be a ~15 M⊙ post-main sequence star in a mass-exchanging binary system. If this is the case, a more realistic value of the distance may be d~3 kpc.

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Section: Discussionmentioning

confidence: 60%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A rotating fast bipolar wind and disk system around the B[e]-type star MWC 922

Contreras

Báez-Rubio

Alcolea

et al. 2019

A&A

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“…However, numerous observations report very ordered outflows, where the outflow axis is straight on parsec scales (e.g. Bally & Chia 2019). For theoretical astrophysics, it would be of great interest to have some observationally informed statistics of complex versus straight outflows as a benchmark for the simulations.…”

Section: Outflow Directionsmentioning

confidence: 99%

Protostellar Outflows: a window to the past

Rohde,

Walch,

Seifried

et al. 2022

Preprint

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During the early phases of low-mass star formation, episodic accretion causes the ejection of high-velocity outflow bullets, which carry a fossil record of the driving protostar's accretion history. We present 44 SPH simulations of 1 M cores, covering a wide range of initial conditions, and follow the cores for five free-fall times. Individual protostars are represented by sink particles, and the sink particles launch episodic outflows using a subgrid model. The O algorithm is used to identify individual episodic bullets within the outflows. The parameters of the overall outflow and the individual bullets are then used to estimate the age and energetics of the outflow, and the accretion events that triggered it; and to evaluate how reliable these estimates are, if observational uncertainties and selection effects (like inclination) are neglected. Of the commonly used methods for estimating outflow ages, it appears that those based on the length and speed of advance of the lobe are the most reliable in the early phases of evolution, and those based on the width of the outflow cavity and the speed of advance are most reliable during the later phases. We describe a new method that is almost as accurate as these methods, and reliable throughout the evolution. In addition we show how the accretion history of the protostar can be accurately reconstructed from the dynamics of the bullets if each lobe contains at least two bullets. The outflows entrain about ten times more mass than originally ejected by the protostar.

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Investigating unusual Hα features towards the Scutum Supershell

Alsulami,

Einecke,

Rowell

et al. 2024

Publ. Astron. Soc. Aust.

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We investigate the unusual H $\alpha$ features found towards the Scutum Supershell via recent arc-minute and arc-second resolution imaging. These multi-degree features resemble a long central spine ending in a bow-shock morphology. We performed a multi–wavelength study in [S II] optical, radio continuum, infrared continuum, Hi, CO, X-ray, and gamma-ray emissions. Interestingly, we found the Galactic worm GW 16.9−3.8 Hi feature appears within the Scutum Supershell, and likely influences the spine morphology. Furthermore, the rightmost edge of the bow-shock H $\alpha$ emission overlaps with [S II] line emission, 4.85 GHz radio, and both 60 and 100 $\mu$ m infrared continuum emissions, suggesting some potential for excitation by shock heating. We estimated the photo-ionisation from O-type and B-type stars in the region (including those from the OB associations Ser OB1B, Ser OB2, and Sct OB3) and found that this mechanism could supply the excitation to account for the observed H $\alpha$ luminosity of the spine and bow-shock of $\sim$ 1–2 $\times 10^{36}\,\mathrm{erg\,s}^{-1}$ (d/2.5 kpc) $^2$ . Recent MHD simulations by Drozdov et al. (2022) demonstrate the potential for supernova events to drive outflow and bow-shock types of features of the same energetic nature and physical scale as the H $\alpha$ emission we observe here. While this clearly requires many supernova events over time, we speculate that one contributing event could have come from the presumably energetic supernova (hypernova) birth of the magnetar tentatively identified in the X-ray binary LS 5039.

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A highly collimated jet from the Red Square nebula MWC 922

Cited by 5 publications

References 16 publications

A rotating fast bipolar wind and disk system around the B[e]-type star MWC 922

A rotating fast bipolar wind and disk system around the B[e]-type star MWC 922

Protostellar Outflows: a window to the past

Investigating unusual Hα features towards the Scutum Supershell

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