Sanduleak's Star: A Possible Supernova Progenitor in the LMC
Abstract
The pronounced enhancement of nitrogen relative to carbon emission in the SWP 1200-2000 wavelength range of Sanduleak's Star in the Large Magellanic Cloud is strikingly similar to the emission line spectrum which characterizes the SCondensation in -Carinae, and provides one of the first clear examples of an object which exhibits evidence for CNO processing in another galaxy. Far-UV spectra obtained previously with IUE of Sanduleak's Star (LMC Anonymous) provides compelling evidence that the surface composition of this star contains highly processed nuclear-synthesized material. LORES-SWP spectra obtained nearly three years apart indicate that C IV emission is variable, while the emission lines of N V, N IV] and N III] appear to remain essentially constant. The progenitor stars of Type II supernova are believed to undergo a significant phase of mass loss via a high velocity wind, in which core-envelope mixing results in a significant overabundance of nitrogen relative to carbon at the stellar surface, prior to core collapse. Thus, the supernova remnant is expected to contain enhanced nitrogen. The 14N/12C ratio of LMC Anonymous has been found previously to lie in the range 70 to 150, which brackets the value determined for the remnant of the recent supernova in the LMC. The similarity of LMC Anonymous with Eta-Carinae in the far-UV provides further indications that Sanduleak's Star could become a Type II supernova. IUE observations are proposed to further investigate the properties of this unusual object for possible time-dependent effects in the abundance of carbon.
- Publication:
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IUE Proposal
- Pub Date:
- 1995
- Bibcode:
- 1995iue..prop.4987M