Three-dimensional structure of the Crab Nebula

Clark, David H.; Murdin, Paul; Wood, Roger M.; Gilmozzi, R.; Danziger, John; Furr, A. W.

doi:10.1093/mnras/204.2.415

Cited by 32 publications

(25 citation statements)

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“…Total exposure times were typically 3000 s. The 1996 2.4 m telescope images were taken through the H and off-band (k c ¼ 6450 8) filters and consisted of two 800 s exposures in each filter for the four image regions. Wilson & Weiler 1976;(8) Reynolds & Aller 1988;(9) Davidson & Fesen 1985;(10) Green & Gull 1982;(11) Roberts et al 1993;(12) Clark et al 1983;(13) Fesen & Ketelsen 1985;(14) Lawrence et al 1995;(15) Fesen et al 1988;(16) this paper; (17) Green 1986;(18) Green 2004;(19) Green 1994;(20) Ivanov et al 2004;(21) Toor & Seward 1974;(22) Torii et al 2000;(23) Wu 1981;(24) Blair et al 1992;(25) Sollerman et al 2000;(26) Fesen et al 1988. A set of H filter images ( FWHM ¼ 90 8) were also taken on 2005 October 6 with the MDM 2.4 m telescope in order to measure proper motions of the remnant's emission features. A 2048 ; 2048 Tektronix CCD detector was used with 0.275 00 pixels and an effective 7:5 0 ; 7:5 0 field of view.…”

Section: Imagingmentioning

confidence: 99%

“…Subsequent optical spectra taken of nearly 50 filaments revealed radial velocities from +1000 to À1075 km s À1 but also a surprising number of low-velocity knots (v ¼ AE300 km s À1 ) located throughout the remnant including near the remnant's center (Fesen 1983;Fesen et al 1988). These radial velocity measurements lead to an estimated maximum expansion velocity of around AE1000 km s À1 , roughly half the Crab's 1500Y2500 km s À1 expansion velocity ( Woltjer 1972;Clark et al 1983;Fesen & Ketelsen 1985;Lawrence et al 1995).…”

Section: Introductionmentioning

confidence: 97%

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Optical Imaging and Spectroscopy of the Galactic Supernova Remnant 3C 58 (G130.7+3.1)

Fesen

Rudie

Hurford

et al. 2008

ASTROPHYS J SUPPL S

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We present a comprehensive imaging and spectroscopic survey of optical emission knots associated with the young Galactic supernova remnant 3C 58. H images show hundreds of clumpy filaments and knots arranged in a complex structure covering a nearly circular area roughly 400 00 in diameter. A quite different emission structure is seen in [O iii], where the brightest features are less clumpy and largely confined to the remnant's northwest quadrant. Measured radial velocities of over 450 knots reveal two distinct kinematic populations; one with average and peak expansion velocities of 770 and 1100 km s À1 , respectively, forming a thick shell, and the other showing jvj 250 km s À1 . High-velocity knots (jvj ! 500 km s À1 ) exhibit a strong bipolar expansion pattern with redshifted and blueshifted knots located in northeastern and southwestern regions, respectively. These knots also show strong [N ii]/H line emission ratios, suggesting enhanced N/H. In contrast, the slower expanding knot population shows much lower [N ii]/H line ratios and likely represents circumstellar mass loss material from the 3C 58 progenitor. Proper-motion estimates using images spanning a 28 yr time interval suggest positional shifts of between 0.5 00 and 2.0 00 , implying proper motions of 0.02 00 Y0.07 00 yr À1 . These values agree with previous estimates but are much less than the %0.2 00 yr À1 expected if 3C 58 were associated with historic guest star of 1181 CE. Subject headingg s: ISM: individual (3C 58) -ISM: kinematics and dynamics -supernova remnants

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Section: Imagingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Optical Imaging and Spectroscopy of the Galactic Supernova Remnant 3C 58 (G130.7+3.1)

Fesen

Rudie

Hurford

et al. 2008

ASTROPHYS J SUPPL S

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“…For [O iii ], the most detailed investigations in terms of mapping the nebula have been carried out by Clark et al (1983) and Lawrence et al (1995). With their limited spectral resolution (∼320 km s −1 ), Lawrence et al (1995) found [O iii ] λ5007 emission close to the line of sight to the pulsar for their lowest (−1435 km s −1 ) and highest (+1430 km s −1 ) velocities probed (cf.…”

Section: Discussionmentioning

confidence: 99%

“…Table 3). Clark et al (1983) had a better spectral resolution, ≈30 km s −1 , but the signal‐to‐noise appears to be lower. They detected [O iii ] λ5007 out to ∼+1600 km s −1 (see Table 3), but saw no clear emission in [O iii ] λ4959 for the near side.…”

Section: Discussionmentioning

confidence: 99%

Constraints on fast ejecta in the Crab supernova remnant from optical spectral lines

Lundqvist

Tziamtzis

2012

Monthly Notices of the Royal Astronomical Society

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The low kinetic energy and mass of the Crab supernova remnant challenge our understanding of core‐collapse supernova explosions. A possibility is that the Crab nebula is surrounded by a shell of fast ejecta containing the ‘missing’ kinetic energy and mass. The only direct evidence for such a fast shell comes from an absorption feature in the Crab pulsar spectrum as a result of C ivλ1550. The velocities inferred from the C iv line absorption extend to at least ∼2500 km s−1, which is about twice as fast as the expansion of main shell of the remnant in our direction. We have searched for additional evidence of fast‐moving ejecta in the optical spectra obtained with the FORS1 instrument at the European Southern Observatory (ESO) 8.2‐m Very Large Telescope (VLT) and with the Andalucia Faint Object Spectrograph and Camera (ALFOSC) at the 2.56‐m Nordic Optical Telescope (NOT), with the focus on absorption in Ca iiλλ3934,3968, and emission components in [O iii] λλ4959,5007. The data are compared with the C ivλ1550 absorption, and with theoretical expectations derived from shell models with ballistic gas motion, and a power‐law density profile of the fast ejecta. Along the line of sight to the pulsar, we find that no gas in the nebula moves faster towards us than ≈1400 km s−1. We identify this gas as part of the known main shell of the remnant. This velocity agrees with previous results showing that the Crab nebula is moving slowly in this direction. It is slower than the velocity of 1680 km s−1 used in the models of Sollerman et al. as a minimum velocity of the presumed fast shell of supernova ejecta to account for the C iv line absorption. We find faster moving gas within 3–10 arcsec north and south of the pulsar, where the fastest gas moving towards us, as traced by [O iii], has a velocity of 1650–1700 km s−1. The fastest [O iii] emitting gas along the line of sight to the pulsar, on the rear side of the nebula, has a velocity of ≈+1800 km s−1, which is higher than the velocity previously recorded for that direction. However, neither the [O iii] nor Ca ii lines display any signatures of fast shell ejecta at the velocities inferred from the C iv line absorption. To fully rule out the possibility that a chimney‐like structure directed towards us could be responsible for the C iv line absorption, we need deep observations taken with 8–10‐m class telescopes with good spectral resolution. We show that a spectral resolution better than ∼200 km s−1 is needed to draw any conclusions on emission lines from gas moving towards us, along the line of sight of the pulsar, faster than ≈1700 km s−1. To probe the fast shell ejecta, new observations from the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) should be substantially more powerful than the previous HST Space Telescope Imaging Spectrograph (STIS) data to fully explore the C ivλ1550 absorption‐line profile.

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“…A dynamical model of the Crab proposed by Clark et al (1983 ) from fairly complete velocity mapping, suggests that filaments tend to lie on the inner or outer surface of an expanding thick shell (or it could be 2 very thin shells) . The velocity difference between the 2 surfaces is of the order of 270 km/sec.…”

Section: Historical Sn and Their Remnantsmentioning

confidence: 99%

Nucleosynthesis and Its Implications on Nuclear and Particle Physics

Audouze¹,

Mathieu²

1986

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Three-dimensional structure of the Crab Nebula

Cited by 32 publications

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Optical Imaging and Spectroscopy of the Galactic Supernova Remnant 3C 58 (G130.7+3.1)

Optical Imaging and Spectroscopy of the Galactic Supernova Remnant 3C 58 (G130.7+3.1)

Constraints on fast ejecta in the Crab supernova remnant from optical spectral lines

Nucleosynthesis and Its Implications on Nuclear and Particle Physics

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