Nitrogen-rich and Sulfur-rich Gas in the Crab Nebula

MacAlpine, G. M.; Lawrence, Stephen S.; Sears, R. L.; Sosin, Matthew S.; Henry, R. B. C.

doi:10.1086/177279

Cited by 21 publications

(33 citation statements)

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“…As mentioned in x 1, MacAlpine et al (1996) identified regions in the Crab Nebula with either very strong or very weak [N ii] emission (see their Fig. 1).…”

Section: The Range Of Nuclear Processing and Confirmation Of Regions mentioning

confidence: 58%

“…The slit positions employed for this project are illustrated in Figure 1. Each involves alignment through the pulsar and another star, and they are the same as some of the slit orientations used by MacAlpine et al (1996), in which extensive N-rich and N-poor gas components were first identified. However, the spectral coverage extends farther to the red for the optical observations presented here.…”

Section: Observationsmentioning

confidence: 99%

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A Spectroscopic Study of Nuclear Processing and the Production of Anomalously Strong Lines in the Crab Nebula

et al. 2006

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We present and discuss correlations for optical and near-infrared (5500Y10030 8) line intensity measurements at many positions in the Crab Nebula. These correlations suggest the existence of gas produced by a range of nuclear processing, from material in which synthesis ended with the CNO cycle, to some helium burning and nitrogen depletion, to regions containing enriched products of oxygen burning. The latter exhibit a gradual, linear rise of [Ni ii] emission with increasing argon enrichment, whereas gas with less nuclear processing shows markedly different [Ni ii] emission characteristics, including the highest derived abundances. This suggests two origins for stable, neutron-rich nickel in the nebula: a type of ''alpha-rich freeze out'' in the more highly processed material and possibly removal of ions from the neutron star in other regions. In addition, the data indicate that anomalously strong observed [C i] emission comes from broad, low-ionization H þ to H 0 transition zones. Although the strongest He i emission could also be enhanced in similar low-ionization gas, correlations between relevant line ratios argue against that interpretation, strengthening the case for an exceptionally high helium mass fraction in some locations.

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“…As mentioned in x 1, MacAlpine et al (1996) identified regions in the Crab Nebula with either very strong or very weak [N ii] emission (see their Fig. 1).…”

Section: The Range Of Nuclear Processing and Confirmation Of Regions mentioning

confidence: 58%

Section: Observationsmentioning

confidence: 99%

A Spectroscopic Study of Nuclear Processing and the Production of Anomalously Strong Lines in the Crab Nebula

et al. 2006

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“…Instead, it indicates high N/H abundances at least several times solar ( MacAlpine et al 1996;Zanin & Kerber 2000). Similarly, strong [ N ii] line emission is seen in stellar mass loss material processed by the CNO cycle like than seen in Wolf-Rayet nebulae (e.g., NGC 6888, Kwitter 1981) and in young SNRs (e.g., the QSFs in Cas A; van den Bergh 1971; Peimbert & van den Bergh 1971;Fesen 2001) including the Crab Nebula ( Fesen & Kirshner 1982;MacAlpine et al 1989;MacAlpine et al 1996).…”

Section: C 58 Knot Chemical Abundancesmentioning

confidence: 99%

“…Both remnants exhibit a thick shell of $800 to 1200 km s À1 velocity ejecta with strong [N ii] line emission relative to H (Fesen & Kirshner 1982;MacAlpine et al 1996).…”

Section: Similarity Of 3c 58 With the Crab Nebulamentioning

confidence: 99%

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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“…[Nii]/Hα ≥ 6) seen in some nebulae Kerber et al 1998;Tajitsu et al 1999;Frew, Parker & Russeil 2006), with the exception of a few individual knots in very young SNRs like the Crab Nebula (MacAlpine et al 1996) and a handful of LBV ejecta such as the outer knots around η Car (e.g. Smith & Morse 2004).…”

Section: Diagnostic Toolsmentioning

confidence: 99%

Planetary Nebulae: Observational Properties, Mimics and Diagnostics

Frew

Parker

2010

Publ. – Astron. Soc. Aust

185

262

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Abstract:The total number of true, likely and possible planetary nebulae (PN) now known in the Milky Way is nearly 3000, double the number known a decade ago. The new discoveries are a legacy of the recent availability of wide field, narrowband imaging surveys, primarily in the light of H-alpha. In this paper, we summarise the various PN discovery techniques, and give an overview of the many types of objects which mimic PN and which appear as contaminants in both Galactic and extragalactic samples. Much improved discrimination of classical PN from their mimics is now possible based on the wide variety of high-quality multiwavelength data sets that are now available. We offer improved taxonomic and observational definitions for the PN phenomenon based on evaluation of these better diagnostic capabilities. However, we note that evidence is increasing that the PN phenomenon is heterogeneous, and PN are likely to be formed from multiple evolutionary scenarios. In particular, the relationships between some collimated symbiotic outflows and bipolar PN remain uncertain.

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Nitrogen-rich and Sulfur-rich Gas in the Crab Nebula

Cited by 21 publications

References 0 publications

A Spectroscopic Study of Nuclear Processing and the Production of Anomalously Strong Lines in the Crab Nebula

A Spectroscopic Study of Nuclear Processing and the Production of Anomalously Strong Lines in the Crab Nebula

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

Planetary Nebulae: Observational Properties, Mimics and Diagnostics

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