Speaker
Dr
Kevin France
(University of Colorado)
Description
In this talk, I will present the most sensitive ultraviolet observations of Supernova
1987A to date. Imaging spectroscopy from the HST-Cosmic Origins Spectrograph show
many narrow (FWHM ∼ 300 km/s) emission lines from the circumstellar ring, broad (FWHM
~ 10000-20000 km/s) emission lines from the reverse shock, and ultraviolet continuum
emission. The high signal-to-noise (> 40 per resolution element) Ly-alpha velocity
profile is dominated by resonant boosting of Ly-alpha photons emitted from the
circumstellar ring. The ultraviolet continuum at wavelengths > 1350A can be explained
by H I two-photon emission from circumstellar ring gas. We confirm an earlier,
tentative detection of N V 1240 emission from the reverse shock and we present the
first detections of broad He II 1640, C IV 1550, and N IV] 1486 emission lines from
the reverse shock. The helium abundance in the high-velocity material is He/H = 0.14
+/- 0.06. The N V/H-alpha line ratio requires partial ion-electron equilibration (Te≈
0.14 – 0.35 Tp). We find that the C/N abundance ratio in the gas crossing the reverse
shock is significantly lower than that in the circumstellar ring, and possible
explanations are discussed.
Primary author
Dr
Kevin France
(University of Colorado)
