Magnetic fields in central stars of planetary nebulae?

Jordan, S.; Bagnulo, S.; Werner, K.; O'Toole, S. J.

doi:10.1051/0004-6361/201219175

Cited by 30 publications

(41 citation statements)

References 35 publications

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“…on RR Lyrae stars (Kolenberg & Bagnulo 2009), on hot subdwarfs (see Landstreet et al 2012b, and references therein), and on the central stars of planetary nebulae (Leone et al 2011;Jordan et al 2012). These results are often useful for constraining possible theoretical models of various kinds.…”

Section: Fors Detections Of Stellar Magnetic Fieldsmentioning

confidence: 97%

The FORS1 catalogue of stellar magnetic field measurements

Bagnulo

Fossati

Landstreet

et al. 2015

A&A

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114

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Context. The FORS1 instrument on the ESO Very Large Telescope was used to obtain low-resolution circular polarised spectra of nearly a thousand different stars, with the aim of measuring their mean longitudinal magnetic fields. Magnetic fields were measured by different authors, and using different methods and software tools. Aims. A catalogue of FORS1 magnetic measurements would provide a valuable resource with which to better understand the strengths and limitations of this instrument and of similar low-dispersion, Cassegrain spectropolarimeters. However, FORS1 data reduction has been carried out by a number of different groups using a variety of reduction and analysis techniques. Our understanding of the instrument and our data reduction techniques have both improved over time. A full re-analysis of FORS1 archive data using a consistent and fully documented algorithm would optimise the accuracy and usefulness of a catalogue of field measurements. Methods. Based on the ESO FORS pipeline, we have developed a semi-automatic procedure for magnetic field determinations, which includes self-consistent checks for field detection reliability. We have applied our procedure to the full content of circular spectropolarimetric measurements of the FORS1 archive. Results. We have produced a catalogue of spectro-polarimetric observations and magnetic field measurements for ∼1400 observations of ∼850 different objects. The spectral type of each object has been approximately classified. We have also been able to test different methods for data reduction is a systematic way. The resulting catalogue has been used to produce an estimator for an upper limit to the uncertainty in a field strength measurement of an early type star as a function of the signal-to-noise ratio of the observation. Conclusions. While FORS1 is not necessarily an optimal instrument for the discovery of weak magnetic fields, it is very useful for the systematic study of larger fields, such as those found in Ap/Bp stars and in white dwarfs.

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Section: Fors Detections Of Stellar Magnetic Fieldsmentioning

confidence: 97%

The FORS1 catalogue of stellar magnetic field measurements

Bagnulo

Fossati

Landstreet

et al. 2015

A&A

Self Cite

114

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“…In addition, common-envelope PNe also seem to share a propensity to exhibit low ionization features, knots and filaments embedded in larger, toroidal structures (Miszalski et al 2009a). Shaping of PNe by magnetic fields has also been considered, although (Jordan et al 2012) find no observational evidence for significant magnetic fields in their sample of central stars of aspherical PNe. It has been argued that at least one highly collimated pre-PN can be shaped by magnetic fields (Vlemmings et al 2006).…”

Section: Planetary Nebulae As a Constraint On Ejecta Velocities And Tmentioning

confidence: 99%

Common envelope evolution: where we stand and how we can move forward

Іванова

Justham

Chen

et al. 2013

Astron Astrophys Rev

922

587

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This work aims to present our current best physical understanding of common-envelope evolution (CEE). We highlight areas of consensus and disagree- ment, and stress ideas which should point the way forward for progress in this important but long-standing and largely unconquered problem. Unusually for CEE-related work, we mostly try to avoid relying on results from population synthesis or observations, in order to avoid potentially being misled by previous misunderstandings. As far as possible we debate all the relevant issues starting from physics alone, all the way from the evolution of the binary system immediately before CEE begins to the processes which might occur just after the ejection of the envelope. In particular, we include extensive discussion about the energy sources and sinks operating in CEE, and hence examine the foundations of the standard energy formalism. Special attention is also given to comparing the results of hydrodynamic simulations from different groups and to discussing the potential effect of initial conditions on the differences in the outcomes. We compare current numerical techniques for the problem of CEE and also whether more appropriate tools could and should be produced (including new formulations of computational hydrodynamics, and attempts to include 3D processes within 1D codes). Finally we explore new ways to link CEE with observations. We compare previous simulations of CEE to the recent outburst from V1309 Sco, and discuss to what extent post-common-envelope binaries and nebulae can provide information, e.g. from binary eccentricities, which is not currently being fully exploited.

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“…Models and explanations range from single stars with particular magnetic fields arrangements (Chevalier & Luo 1994;García-Segura et al 1999;Pascoli & Lahoche 2008;Vlemmings 2011Vlemmings , 2012Jordan et al 2012) to the view that almost all planetary nebulae are caused by binary companions (Yungelson et al 1993;Soker & Rappaport 2001;De Marco 2009;Jones et al 2010Jones et al , 2012Douchin et al 2012). The discovery that hot Jupiter exoplanets are common around stars means that large planetary mass companions can also be considered amongst the shaping mechanisms (Nordhaus & Blackman 2006).…”

Section: Introductionmentioning

confidence: 99%

VLT observations of the asymmetric Etched Hourglass Nebula, MyCn 18

Clyne

Redman

Lloyd

et al. 2014

A&A

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Context. The mechanisms that form extreme bipolar planetary nebulae remain unclear. Aims. The physical properties, structure, and dynamics of the bipolar planetary nebula, MyCn 18, are investigated in detail with the aim of understanding the shaping mechanism and evolutionary history of this object. Methods. VLT infrared images, VLT ISAAC infrared spectra, and long-slit optical Echelle spectra are used to investigate MyCn 18. Morpho-kinematic modelling was used to firmly constrain the structure and kinematics of the source. A timescale analysis was used to determine the kinematical age of the nebula and its main components. Results. A spectroscopic study of MyCn 18's central and offset region reveals the detailed make-up of its nebular composition. Molecular hydrogen, atomic helium, and Bracket gamma emission are detected from the central regions of MyCn 18. ISAAC spectra from a slit position along the narrow waist of the nebula demonstrate that the ionised gas resides closer to the centre of the nebula than the molecular emission. A final reconstructed 3D model of MyCn 18 was generated, which provides kinematical information on the expansion velocity of its nebular components by means of position-velocity (P-V) arrays. A kinematical age of the nebula and its components were obtained by the P-V arrays and timescale analysis. Conclusions. The structure and kinematics of MyCn 18 are better understood using an interactive 3D modelling tool called SHAPE. A dimensional and timescale analysis of MyCn 18's major components provides a possible mechanism for the nebula's asymmetry. The putative central star is somewhat offset from the geometric centre of the nebula, which is thought to be the result of a binary system. We speculate that the engulfing and destruction of an exoplanet during the asymptotic giant branch phase may have been a key event in shaping MyCn 18 and generating of its hypersonic knotty outflow.

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Magnetic fields in central stars of planetary nebulae?

Cited by 30 publications

References 35 publications

The FORS1 catalogue of stellar magnetic field measurements

The FORS1 catalogue of stellar magnetic field measurements

Common envelope evolution: where we stand and how we can move forward

VLT observations of the asymmetric Etched Hourglass Nebula, MyCn 18

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