The Crab Nebula Revisited

Woltjer, L.; Véron-Cetty, M. P.

doi:10.1007/978-94-011-0926-0_31

Cited by 4 publications

(5 citation statements)

References 9 publications

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“…These facts, together with our previous work 7,8 on helicity and energy, allow us to conclude that the Taylor state for a low-beta plasma in a spherically symmetric vessel with highly conducting walls must be the spheromak field derived by ChandrasekharKendall 14 and Woltjer 1,15 in the case of a solid ball, and the spheromak-like fields derived in this paper in the case of a spherical shell.…”

Section: Discussionsupporting

confidence: 70%

The spectrum of the curl operator on spherically symmetric domains

et al. 2000

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This paper presents a mathematically complete derivation of the minimum-energy divergence-free vector fields of fixed helicity, defined on and tangent to the boundary of solid balls and spherical shells. These fields satisfy the equation ∇×V = λV , where λ is the eigenvalue of curl having smallest non-zero absolute value among such fields. It is shown that on the ball the energy-minimizers are the axially symmetric spheromak fields found by Woltjer and Chandrasekhar-Kendall, and on spherical shells they are spheromak-like fields. The geometry and topology of these minimum-energy fields, as well as of some higher-energy eigenfields, is illustrated.

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Section: Discussionsupporting

confidence: 70%

The spectrum of the curl operator on spherically symmetric domains

et al. 2000

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“…On the other hand, it is possible that the measured motions do reflect the jet's true expansion properties. The jet is essentially a hollow structure and as shown by Velusamy (1984) and Woltjer & Véron‐Cetty (1987), the jet does contain some faint synchrotron emission, most visible at its southern base. If this plasma induced an acceleration that was largely against the jet's filamentary walls, this might act to expand the jet in the E–W plane and explain why the north‐western jet knots end up east of the centre of expansion while most knots located at the north‐eastern portion of the jet project back west of the centre of expansion.…”

Section: Discussionmentioning

confidence: 92%

“…First detected in the optical by van den Bergh (1970), this optical filamentary jet consists of line‐emitting filaments, especially prominent in [O iii ]λλ4959,5007 (Chevalier & Gull 1975). Although primarily a line‐emission feature, very weak coincident non‐thermal continuum emission was subsequently discovered, first in the radio (Velusamy 1984) and then in the optical (Woltjer & Véron‐Cetty 1987), suggesting the jet itself is also filled with relativistic particles off the pulsar.…”

Section: Introductionmentioning

confidence: 99%

The Crab Nebula's dynamical age as measured from its northern filamentary jet

Rudie

Fesen

Yamada

2008

Monthly Notices of the Royal Astronomical Society

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We present a deep [O iii]λλ4959,5007 image of the northern filamentary jet in the Crab Nebula taken with the 8.2‐m Subaru telescope. Using this image and an image taken with the Kitt Peak National Observatory (KPNO) 4‐m in 1988, we have computed proper motions for 35 locations in the jet. The results suggest that when compared to the main body of the remnant, the jet experienced less outward acceleration from the central pulsar's rapidly expanding synchrotron nebula. The jet's apparent expansion rate yields an undecelerated explosion date for the Crab Nebula of 1055 ± 24 CE, a date much closer to the appearance of the historic 1054 CE guest star than the 1120–1140 CE dates estimated in previous studies using filaments located within the remnant's main nebula. Our proper motion measurements suggest the jet likely formed during the 1054 supernova explosion and represents the remnant's highest velocity knots possibly associated with a suspected N–S bipolar outflow from the supernova explosion.

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“…Contrary to the result for the south finger, there is some spectral softening as one proceeds north, but uncertainty in the outermost spectral index is large. It is possible to imagine particles streaming north along this feature and then along the optical chimney, but the connection between this feature and chimney is not seen in the X-rays, with weak evidence for an optical synchrotron connection as well (Woltjer & Veron-Cetty 1987).…”

Section: Other Faint Outer Featuresmentioning

confidence: 98%

Faint X‐Ray Structure in the Crab Pulsar Wind Nebula

Seward

Tucker

Fesen

2006

ApJ

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We report on a Chandra observation of the Crab Nebula that gives the first clear view of the faint boundary of the Crab's X-ray-emitting pulsar wind nebula. There is structure in all directions. Fingers, loops, bays, and the south pulsar jet all indicate that either filamentary material or the magnetic field is controlling the relativistic electrons. In general, spectra soften as distance from the pulsar increases but do not change rapidly along linear features. This is particularly true for the pulsar jet. The termination of the jet is abrupt; the east side is close to an [O iii] optical filament, which may be blocking propagation on this side. We argue that linear features have ordered magnetic fields and that the structure is determined by the synchrotron lifetime of particles diffusing perpendicular and parallel to the magnetic field. We find no significant evidence for thermal X-rays inside the filamentary envelope.

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The Crab Nebula Revisited

Cited by 4 publications

References 9 publications

The spectrum of the curl operator on spherically symmetric domains

The spectrum of the curl operator on spherically symmetric domains

The Crab Nebula's dynamical age as measured from its northern filamentary jet

Faint X‐Ray Structure in the Crab Pulsar Wind Nebula

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