NGC 2867 (also known as Caldwell 90) is an elliptical[5] Type II[7]planetary nebula in the southern constellation of Carina, just over a degree to the NNW of the star Iota Carinae.[8] It was discovered by John Herschel on April 1, 1834. Herschel initially thought he might have found a new planet, but on the following night he checked again and discovered it had not moved.[3] The nebula is located at a distance of 7,270 light-years from the Sun.[2]
The central star of the nebula is of spectral typeWC3[9] and is in the process of evolving into a white dwarf, having previously shed the atmosphere that created the surrounding nebula. It is now a hydrogen deficient GW Vir variable that is undergoing non-radial pulsations with an amplitude of less than 0.3 in magnitude. The star has an estimated temperature of 165+18 −20kK with 5% of the radius of the Sun and is radiating 1,400 times the Sun's luminosity.[5]
The surrounding nebula is fairly typical but does shows carbon enrichment, which suggests the progenitor star was not massive but did pass through third dredge-up. The category of central star has excited a very high degree of ionization in the nebula.[7] The shape of the nebula appears somewhat elongated, which may indicate an interaction with the surrounding interstellar matter. The nebula halo may be a recombination of two separate halos, which could indicate a peculiar mass-loss history.[10]
^ abPeña, M.; Stasińska, G. (July 2001). Aguilar, A.; Carramiñana, A. (eds.). Planetary Nebulae with [WR] nuclei. IX Latin American Regional IAU Meeting, "Focal Points in Latin American Astronomy", held in Tonantzintla, Mexico, Nov 9-13, 1998. Revista Mexicana de Astronomía y Astrofísica, Serie de Conferencias. p. 61. Bibcode:2001RMxAC..11...61P.
^Sinnott, Roger W.; Perryman, Michael A. C. (1997). Millennium Star Atlas. Vol. 2. Sky Publishing Corporation and the European Space Agency. p. 994. ISBN0-933346-83-2.
^Werner, K.; et al. (June 1992). "A spectacular mass-loss event of the central star of Longmore 4". Astronomy and Astrophysics. 259: L69–L72. Bibcode:1992A&A...259L..69W.
^Corradi, R. L. M. (2003). Kwok, Sun; Dopita, Michael; Sutherland, Ralph (eds.). Observations of Planetary Nebulae Haloes. Planetary Nebulae: Their Evolution and Role in the Universe, Proceedings of the 209th Symposium of the International Astronomical Union held at Canberra, Australia, 19-23 November, 2001. Astronomical Society of the Pacific. p. 447. Bibcode:2003IAUS..209..447C.
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