Investigation of dust properties of the proto-planetary nebula IRAS 18276−1431

Murakawa, K.; Izumiura, Hideyuki; Oudmaijer, R. D.; Maud, L. T.

doi:10.1093/mnras/stt118

Cited by 5 publications

(4 citation statements)

References 51 publications

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“…Since the polarizations are high and do not change much in the H-and K S -bands, the fraction of small particles is expected to be higher than that of the interstellar population. In our separated paper (Murakawa et al 2012), we found a similar result in PPN I18276 and that a size distribution function with a steep power index provides a good estimate: 0.05 μm ≤ a and n (a) ∝ a −5.5 exp (−a/a c ), where a c is the cut-off size (Kim et al 1994). In I16342, a c = 5.0 μm fits the H and K S band polarizations.…”

Section: Dust Particlessupporting

confidence: 68%

Dust shell model of the water fountain source IRAS 16342–3814

Murakawa

Izumiura²

2012

A&A

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Aims. We investigate the circumstellar dust shell of the water fountain source IRAS 16342-3814. Methods. We performed two-dimensional radiative transfer modeling of the dust shell, taking into account previously observed spectral energy distributions (SEDs) and our new J-band imaging and H-and K S -band imaging polarimetry obtained using the VLT/NACO instrument. Results. Previous observations expect an optically thick torus in the equatorial plane because of a striking bipolar appearance and a large viewing angle of 30−40 • . However, models with such a torus as well as a bipolar lobe and an AGB shell cannot fit the SED and the images simultaneously. We find that an additional optically and geometrically thick disk located inside a massive torus solves this problem. The masses of the disk and the torus are estimated to be 0.01 M at the a max = 100 μm dust and 1 M at a max = 10 μm dust, respectively. Conclusions. We discuss a possible formation scenario for the disk and torus based on a similar mechanism to the equatorial back flow. IRAS 16342-3814 is expected to undergo mass loss at a high rate. The radiation from the central star is shielded by the dust that was ejected in the subsequent mass loss event. As a result, the radiation pressure on dust particles cannot govern the motion of the particles anymore. The mass loss flow can be concentrated in the equatorial plane by help of an interaction, which might be the gravitational attraction by the companion, if it exists in IRAS 16342-3814. A fraction of the ejecta is captured in a circum-companion or circum-binary disk and the remains are escaping from the central star(s) and form the massive torus.

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Section: Dust Particlessupporting

confidence: 68%

Dust shell model of the water fountain source IRAS 16342–3814

Murakawa

Izumiura²

2012

A&A

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“…Later imaging in the optical and (near-)IR confirmed this view (e.g. Sánchez Contreras et al 2007;Gledhill et al 2011;Lagadec et al 2011;Murakawa et al 2013). Observations of H 2 and CO emission in the near-IR suggest a bipolar outflow velocity of ∼ 95 km s −1 .…”

Section: Oh 177-20mentioning

confidence: 86%

“…No fast outflow is detected in the submillimetre CO emission. In Murakawa et al (2013), a model was created to match the near-IR spectral energy distribution and polarised emission. They conclude, assuming a distance of 3 kpc, that most of the dust resides in a torus with inner and outer radii of 30 and 1000 au.…”

Section: Oh 177-20mentioning

confidence: 99%

Polarisation of molecular lines in the circumstellar envelope of the post-asymptotic giant branch star OH 17.7–2.0

Vlemmings

Tafoya

2023

A&A

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Context. The role of magnetic field in shaping planetary nebulae (PNe), either directly or indirectly after being enhanced by binary interaction, has long been a topic of debate. Large-scale magnetic fields around pre-PNe have been inferred from polarisation observations of masers. However, because masers probe very specific regions, it is still unclear if the maser results are representative of the intrinsic magnetic field in the circumstellar envelope (CSE). Aims. Molecular line polarisation of non-maser lines can provide important information about the magnetic field. A comparison between the magnetic field morphology determined from maser observations and that observed in the more diffuse CO gas can reveal if the two tracers probe the same magnetic field. Methods. We compared observations taken with the Atacama Large Millimeter/submillimeter Array (ALMA) of molecular line polarisation around the post-asymptotic giant branch (post-AGB) or pre-PN star OH 17.7−2.0 with previous observations of polarisation in the 1612 MHz OH maser region. Earlier mid-infrared observations indicate that OH 17.7−2.0 is a young bipolar pre-PN, with both a torus and bipolar outflow cavities embedded in a remnant AGB envelope. Results. We detect CO J = 2 − 1 molecular line polarisation at a level of ∼4% that displays an ordered linear polarisation structure. We find that, correcting for Faraday rotation of the OH maser linear polarisation vectors, the OH and CO linearly polarised emission trace the same large-scale magnetic field. A structure function analysis of the CO linear polarisation reveals a plane-of-the-sky magnetic field strength of B⊥ ∼ 1 mG in the CO region, consistent with previous OH Zeeman observations. Conclusions. The consistency of the ALMA CO molecular line polarisation observation with maser observations indicate that both can be used to determine the magnetic field strength and morphology in CSEs. The new observations indicate that the magnetic field has a strong toroidal field component projected on the torus structure and a poloidal field component along the outflow cavity. The existence of a strong, ordered, magnetic-field around OH 17.7−2.0 indicates that the magnetic field is likely involved in the formation of this bipolar pre-PN.

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“…However hints of the hyperwind can already be seen in the models of IRAS 17150−3224 and other post-AGB sources (e.g. IRAS 16432−3814 in Dijkstra et al 2003or IRAS 18276−1431in Murakawa et al 2013. Meixner et al (2002) show that, at its highest, the mass-loss rate of IRAS 17150−3224 must have been of the order of 8.5 × 10 −3 M /yr.…”

Section: Introductionmentioning

confidence: 98%

Micron-sized forsterite grains in the pre-planetary nebula of IRAS 17150−3224

Vries

Maaskant

Min

et al. 2015

A&A

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Aims. We study the grain properties and location of the forsterite crystals in the circumstellar environment of the pre-planetary nebula (PPN) IRAS 17150−3224 in order to learn more about the as yet poorly understood evolutionary phase prior to the PPN. Methods. We use the best-fit model for IRAS 17150−3224 of Meixner et al. (2002, ApJ, 571, 936) and add forsterite to this model. We investigate different spatial distributions and grain sizes of the forsterite crystals in the circumstellar environment. We compare the spectral bands of forsterite in the mid-infrared and at 69 µm in radiative transport models to those in ISO-SWS and Herschel/ PACS observations. Results. We can reproduce the non-detection of the mid-infrared bands and the detection of the 69 µm feature with models where the forsterite is distributed in the whole outflow, in the superwind region, or in the AGB-wind region emitted previous to the superwind, but we cannot discriminate between these three models. To reproduce the observed spectral bands with these three models, the forsterite crystals need to be dominated by a grain size population of 2 µm up to 6 µm. We also tested models where the forsterite is located in a torus region or where it is concentrated in the equatorial plane, in a disk-like fashion. These models show either absorption features that are too strong or a 69 µm band that is too weak, respectively, so we exclude these cases. We observe a blue shoulder on the 69 µm band that cannot be explained by forsterite and we suggest a possible population of micron-sized ortho-enstatite grains. We hypothesise that the large forsterite crystals were formed after the superwind phase of IRAS 17150−3224, where the star developed an as yet unknown hyperwind with an extremely high mass-loss rate ( 10 −3 M /yr). The high densities of such a hyperwind could be responsible for the efficient grain growth of both amorphous and crystalline dust in the outflow. Several mechanisms are discussed that might explain the lower-limit of ∼2 µm found for the forsterite grains, but none are satisfactory. Among the mechanisms explored is a possible selection effect due to radiation pressure based on photon scattering on micron-sized grains.

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Investigation of dust properties of the proto-planetary nebula IRAS 18276−1431

Cited by 5 publications

References 51 publications

Dust shell model of the water fountain source IRAS 16342–3814

Dust shell model of the water fountain source IRAS 16342–3814

Polarisation of molecular lines in the circumstellar envelope of the post-asymptotic giant branch star OH 17.7–2.0

Micron-sized forsterite grains in the pre-planetary nebula of IRAS 17150−3224

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