| Title | Model Atmospheres for SN 1987A and the Distance to the Large Magellanic Cloud |
| Authors | Eastman, Ronald G.; Kirshner, Robert P. |
| Bibcode | 1989ApJ...347..771E Search ADS ↗ |
| Abstract | We have applied a code which simultaneously solves the non-LTE equations of statistical equllibrium and the time-independent equation of radiation transport in an expanding atmosphere to analyze the spectrum of SN 1987A. The behavior of a model atmosphere in which the density structure is a power-law function of radius has been studied and compared closely with SN 1987A data. Values of the power-law index, γ = -dlnρ/dln v, in the range 7 <~ γ <~ 11 are consistent with the data. The helium mass fraction in the hydrogen envelope of SN 1987A is not tightly constrained but is likely to be in the range 0.4 <~ Y <~ 0.9. We employ this model atmosphere to derive corrections to the expanding photosphere method for determining distances to supernovae. The distance to the Large Magellanic Cloud derived from SN 1987A observations by this "custom yardstick" is 49 +/- 6 kpc (m - M = 18.45 +/- 0.28), in excellent accord with results for RR Lyrae stars and for Cepheids. This empirical test of the expanding photosphere method provides the basis for hope that it may make a significant contribution to the extragalactic distance scale at cosmologically interesting distances. |
| Objects | 2 Objects Search NED ↙ |
