The Ni/Fe ratio in the Crab Nebula

Journal Article · Tue May 01 04:00:00 EDT 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/185722· OSTI ID:6700496

Hudgins, D; Herter, T; Joyce, R J ^[1]

---

1. Cornell Univ., Ithaca, NY (USA) Kitt Peak National Observatory, Tucson, AZ (USA)

Spectrophotometric observations of the forbidden N II 1.191 micron and forbidden Fe II 1.257 micron lines at position 10 of Fesen and Kirshner in the Crab Nebula are presented. An Ni/Fe ratio of 0.3 is derived by adopting the electron temperature of 16,000 K and an electron density of 850 per cu cm. This ratio is about a factor of 6 higher than the solar ratio but is significantly smaller than the Ni/Fe ratio derived from forbidden Ni II 0.7378 micron and forbidden Fe II 0.8617 micron lines. Both of these ratios can be reconciled by increasing the electron density by a factor of approximately 10. The Ni/Fe ratio from optical lines is left unchanged, while the ratio computed from infrared lines is increased by more than a factor of 4. Since such high densities seem physically implausible, it is more likely that the atomic data for either Ni or Fe, or both, are in error, causing the infrared and optical abundance ratios to disagree. 23 refs.

• OSTI ID: 6700496
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 354; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
CHEMICAL COMPOSITION
COSMIC RADIO SOURCES
CRAB NEBULA
ELECTRON DENSITY
ELEMENT ABUNDANCE
ELEMENTS
EMISSIVITY
INFRARED SPECTRA
IRON
METALS
NEBULAE
NICKEL
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SPECTRA
SPECTROPHOTOMETRY
SUPERNOVA REMNANTS
SURFACE PROPERTIES
TRANSITION ELEMENTS