On the alignment of PNe and local magnetic field at the Galactic centre: magnetohydrodynamical numerical simulations

Falceta‐Gonçalves, D.; Monteiro, H.

doi:10.1093/mnras/stt2393

Cited by 8 publications

(5 citation statements)

References 68 publications

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“…This alignment could have some implications for other studies of GBPNe (see e.g. Rees & Zijlstra 2013;Falceta-Gonçalves & Monteiro 2014;Danehkar & Parker 2016).…”

Section: Kinematic Resultsmentioning

confidence: 54%

Fast, Low-Ionization Emission Regions of the Planetary Nebula M2-42

Danehkar

Parker

Steffen

2016

The Astronomical Journal

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Spatially resolved observations of the planetary nebula M2-42 (PN G008.2−04.8) obtained with the Wide Field Spectrograph on the Australian National University 2.3 m telescope have revealed the remarkable features of bipolar collimated jets emerging from its main structure. Velocity-resolved channel maps derived from the [N ii] λ6584 emission line disentangle different morphological components of the nebula. This information is used to develop a three-dimensional morpho-kinematic model, which consists of an equatorial dense torus and a pair of asymmetric bipolar outflows. The expansion velocity of about 20 km s −1 is measured from the spectrum integrated over the main shell. However, the deprojected velocities of the jets are found to be in the range of 80-160 km s −1 with respect to the nebular center. It is found that the mean density of the collimated outflows, 595 ± 125 cm −3 , is five times lower than that of the main shell, 3150 cm −3 , whereas their singly ionized nitrogen and sulfur abundances are about three times higher than those determined from the dense shell. The results indicate that the features of the collimated jets are typical of fast, low-ionization emission regions.

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“…This alignment could have some implications for other studies of GBPNe (see e.g. Rees & Zijlstra 2013;Falceta-Gonçalves & Monteiro 2014;Danehkar & Parker 2016).…”

Section: Kinematic Resultsmentioning

confidence: 54%

Fast, Low-Ionization Emission Regions of the Planetary Nebula M2-42

Danehkar

Parker

Steffen

2016

The Astronomical Journal

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“…For a PN expansion speed of 20 km s −1 , this would mean that the PN reaches the wind termination shock after only 5500 years, which is well within the lifetime of a typical PN. Falceta-Gonçalves & Monteiro (2014) showed simulations of PNe interacting with interstellar magnetic fields and concluded that only very strong fields ( 500 µG) could significantly influence the shape of PNe. However, the study by Falceta-Gonçalves & Monteiro (2014) focused on bipolar PNe.…”

Section: Premisementioning

confidence: 99%

Eyes in the sky

Marle

Cox

Decin

2014

A&A

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Context. The extended circumstellar envelopes (CSEs) of evolved low-mass stars display a large variety of morphologies. Understanding the various mechanisms that give rise to these extended structures is important to trace their mass-loss history. Aims. Here, we aim to examine the role of the interstellar magnetic field in shaping the extended morphologies of slow dusty winds of asymptotic giant branch (AGB) stars in an effort to pin-point the origin of so-called eye shaped CSEs of three carbon-rich AGB stars. In addition, we seek to understand if this pre-planetary nebula (PN) shaping can be responsible for asymmetries observed in PNe. Methods. Hydrodynamical simulations are used to study the effect of typical interstellar magnetic fields on the free-expanding spherical stellar winds as they sweep up the local interstellar medium (ISM). Results. The simulations show that typical Galactic interstellar magnetic fields of 5 to 10 µG are sufficient to alter the spherical expanding shells of AGB stars to appear as the characteristic eye shape revealed by far-infrared observations. The typical sizes of the simulated eyes are in accordance with the observed physical sizes. However, the eye shapes are transient in nature. Depending on the stellar and interstellar conditions, they develop after 20 000 to 200 000 yrs and last for about 50 000 to 500 000 yrs, assuming that the star is at rest relative to the local interstellar medium. Once formed, the eye shape develops lateral outflows parallel to the magnetic field. The explosion of a PN in the centre of the eye-shaped dust shell gives rise to an asymmetrical nebula with prominent inward pointing Rayleigh-Taylor instabilities. Conclusions. Interstellar magnetic fields can clearly affect the shaping of wind-ISM interaction shells. The occurrence of the eyes is most strongly influenced by stellar space motion and ISM density. Observability of this transient phase is favoured for lines-of-sight perpendicular to the interstellar magnetic field direction. The simulations indicate that shaping of the pre-PN envelope can strongly affect the shape and size of PNe.

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“…CO) are obtained at a temperature range of T = 10 − 10 8 K and gas densities up to 10 12 cm −3 , assuming solar metallicity Z = 1Z⊙. The set of equations is solved using the GODUNOV code 1 (see Kowal & Lazarian 2010;Falceta-Gonçalves et al 2010a,b,c;Kowal et al 2011a,b;Ruiz et al 2013;Santos-Lima et al 2014;Falceta-Gonçalves & Monteiro 2014). The spatial reconstruction is obtained by means of the 5 th order monotonicity-preserving (MP) method (He et al 2011), with approximate HLLC Riemann solver (Mignone & Bodo 2006).…”

Section: Governing Equations and Model Setupmentioning

confidence: 99%

The onset of large-scale turbulence in the interstellar medium of spiral galaxies

Falceta‐Gonçalves¹,

Bonnell²,

Kowal³

et al. 2014

Monthly Notices of the Royal Astronomical Society

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Turbulence is ubiquitous in the interstellar medium (ISM) of the Milky Way and other spiral galaxies. The energy source for this turbulence has been much debated with many possible origins proposed. The universality of turbulence, its reported largescale driving, and that it occurs also in starless molecular clouds, challenges models invoking any stellar source. A more general process is needed to explain the observations. In this work we study the role of galactic spiral arms. This is accomplished by means of three-dimensional hydrodynamical simulations which follow the dynamical evolution of interstellar diffuse clouds (∼ 100cm −3 ) interacting with the gravitational potential field of the spiral pattern. We find that the tidal effects of the arm's potential on the cloud result in internal vorticity, fragmentation and hydrodynamical instabilities. The triggered turbulence result in large-scale driving, on sizes of the ISM inhomogeneities, i.e. as large as ∼ 100pc, and efficiencies in converting potential energy into turbulence in the range ∼ 10 to 25 % per arm crossing. This efficiency is much higher than those found in previous models. The statistics of the turbulence in our simulations are strikingly similar to the observed power spectrum and Larson scaling relations of molecular clouds and the general ISM. The dependency found from different models indicate that the ISM turbulence is mainly related to local spiral arm properties, such as its mass density and width. This correlation seems in agreement with recent high angular resolution observations of spiral galaxies, e.g. M51 and M33.

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On the alignment of PNe and local magnetic field at the Galactic centre: magnetohydrodynamical numerical simulations

Cited by 8 publications

References 68 publications

Fast, Low-Ionization Emission Regions of the Planetary Nebula M2-42

Fast, Low-Ionization Emission Regions of the Planetary Nebula M2-42

Eyes in the sky

The onset of large-scale turbulence in the interstellar medium of spiral galaxies

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