Isolated versus common envelope dynamos in planetary nebula progenitors

Nordhaus, Jason; Blackman, Eric G.; Frank, Adam

doi:10.1111/j.1365-2966.2007.11417.x

Cited by 149 publications

(195 citation statements)

References 38 publications

(68 reference statements)

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“…Nordhaus et al (2007) have estimated the need for a stellar companion Barthès et al (2000), (c) Pollard & Cottrell (1995), (d) Giridhar et al (2000), (e) Stasińska et al (2006) , (f) Luck et al (1990), (g) Table 2. Observing log of the sample presenting for each object the observing date, number of Stokes V sequences, length of the sub-exposures and peak signal-to-noise ratio.…”

Section: The Samplementioning

confidence: 99%

First detection of surface magnetic fields in post-AGB stars: the cases of U Monocerotis and R Scuti

Sabin¹,

Wade²,

Lèbre³

2014

Monthly Notices of the Royal Astronomical Society

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While several observational investigations have revealed the presence of magnetic fields in the circumstellar envelopes, jets and outflows of post-Asymptotic Giant Branch stars (PAGBs) and planetary nebulae (PNe), none has clearly demonstrated their presence at the stellar surface. The lack of information on the strength of the surface magnetic fields prevents us from performing any thorough assessment of their dynamic capability (i.e. material mixing, envelope shaping, etc). We present new high resolution spectropolarimetric (Stokes V ) observations of a sample of PAGB stars, realised with the instruments ESPaDOnS and Narval, where we searched for the presence of photospheric magnetic fields. Out of the seven targets investigated the RV Tauri stars U Mon and R Sct display a clear Zeeman signature and return a definite detection after performing a least squares deconvolution (LSD) analysis. The remaining five PAGBs show no significant detection. We derived longitudinal magnetic fields of 10.2 ± 1.7 G for U Mon and 0.6 ± 0.6 G for R Sct. In both cases the Stokes profiles point towards an interaction of the magnetic field with the atmosphere dynamics. This first discovery of weak magnetic fields (i.e. ∼10 gauss level) at the stellar surface of PAGB stars opens the door to a better understanding of magnetism in evolved stars.

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Section: The Samplementioning

confidence: 99%

First detection of surface magnetic fields in post-AGB stars: the cases of U Monocerotis and R Scuti

Sabin¹,

Wade²,

Lèbre³

2014

Monthly Notices of the Royal Astronomical Society

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“…Highly axisymmetric, non-spherical forms in particular are very difficult to explain without a binary engine that is capable of supplying sufficient angular momentum to heavily shape the nebula (Nordhaus, Blackman & Frank 2007). The binary hypothesis encapsulated by De Marco (2009) simply states that PNe derive from binary progenitors more easily than from single progenitors.…”

Section: Introductionmentioning

confidence: 99%

Binary planetary nebulae nuclei towards the Galactic bulge

Miszalski

Acker

Parker

et al. 2009

A&A

146

218

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Considerable effort has been applied towards understanding the precise shaping mechanisms responsible for the diverse range of morphologies exhibited by planetary nebulae (PNe). A binary companion is increasingly gaining support as a dominant shaping mechanism, however morphological studies of the few PNe that we know for certain were shaped by binary evolution are scarce or biased. Newly discovered binary central stars (CSPN) from the OGLE-III photometric variability survey have significantly increased the sample of post common-envelope (CE) nebulae available for morphological analysis. We present Gemini South narrow-band images for most of the new sample to complement existing data in a qualitative morphological study of 30 post-CE nebulae. Nearly 30% of nebulae have canonical bipolar morphologies, however this rises to 60% once inclination effects are incorporated with the aid of geometric models. This is the strongest observational evidence yet linking CE evolution to bipolar morphologies. A higher than average proportion of the sample shows low-ionisation knots, filaments or jets suggestive of a binary origin. These features are also common around emission-line nuclei which may be explained by speculative binary formation scenarios for H-deficient CSPN.

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“…Moreover, the mass ejection on a preferred axis requires an extra agent to collimate the flow. The possible mechanisms that could both provide the missing energy to drive the fast flows and that could collimate it on a preferred axis are: (i) a companion to the star (either a binary stellar companion or massive planet) and its tidal forces, (ii) disk interaction and (iii) magnetic fields -or a combination of these (Balick & Frank 2002;Nordhaus et al 2007, and references therein).…”

Section: Introductionmentioning

confidence: 99%

Rotten Egg nebula: the magnetic field of a binary evolved star

Leal-Ferreira¹,

Vlemmings²,

Diamond³

et al. 2012

A&A

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Context. Most of the planetary nebulae (PNe) observed are not spherical. The loss of spherical symmetry occurs somewhere between the asymptotic giant branch (AGB) phase and the PNe phase. The cause of this change of morphology is not yet well understood, but magnetic fields are one of the possible agents. The origin of the magnetic field remains to be determined, and potentially requires the presence of a massive companion to the AGB star. Therefore, further detections of the magnetic field around evolved stars, and in particular those thought to be part of a binary system, are crucial to improve our understanding of the origin and role of magnetism during the late stages of stellar evolution. One such binary is the pre-PN OH231.8+4.2, around which a magnetic field has previously been detected in the OH maser region of the outer circumstellar envelope. Aims. We aim to detect and infer the properties of the magnetic field of the pre-PN OH231.8+4.2 in the H 2 O maser region that probes the region close to the central star. This source is a confirmed binary with collimated outflows and an envelope containing several maser species. Methods. In this work we observed the 6 1,6 −5 2,3 H 2 O maser rotational transition to determine its linear and circular polarization. As a result of Zeeman splitting, the properties of the magnetic field can be derived from maser polarization analysis. The H 2 O maser emissions of OH231.8+4.2 are located within the inner regions of the source (at a few tens of AU). Results. We detected 30 H 2 O maser features around OH231.8+4.2. The masers occur in two distinct regions that are moving apart with a velocity on the sky of 2.3 mas/year. Taking into account the inclination angle of the source with the line of sight, this corresponds to an average separation velocity of 21 km s −1 . Based on the velocity gradient of the maser emission, the masers appear to be dragged along the direction of the nebula jet. Linear polarization is present in three of the features, and circular polarization is detected in the two brightest features. The circular polarization results imply a magnetic field strength of |B || | ∼ 45 mG. Conclusions. We confirm the presence of a magnetic field around OH231.8+4.2, and report the first measurements of its strength within a few tens of AU of the stellar pair. Assuming a toroidal magnetic field, this imples B ∼ 2.5 G on the stellar surface. The morphology of the field is not yet determined, but the high scatter found in the directions of the linear polarization vectors could indicate that the masers occur near the tangent points of a toroidal field.

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Isolated versus common envelope dynamos in planetary nebula progenitors

Cited by 149 publications

References 38 publications

First detection of surface magnetic fields in post-AGB stars: the cases of U Monocerotis and R Scuti

First detection of surface magnetic fields in post-AGB stars: the cases of U Monocerotis and R Scuti

Binary planetary nebulae nuclei towards the Galactic bulge

Rotten Egg nebula: the magnetic field of a binary evolved star

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