Supernova 1987A in the Large Magellanic Cloud
Abstract
S. Cristiani and C. Gouiffes, European Southern Observatory; R. Hanuschik, Bochum University; and P. Magain, ESO, report: "Spectra taken at intermediate resolution (0.2-0.3 nm) between Mar. 14 and 22, with the spectrum scanner attached to the Bochum University 0.61-m telescope and with the ESO 1.5-m telescope at La Silla, showed changes in the P-Cyg profile of H-alpha. On Mar. 15, a weak bump at 647 nm appeared on the previously-very-smooth P-Cyg profile (near the bottom of the absorption) which developed in the following days, assuming a peaked structure and reaching the continuum level about Mar. 20. A comparison with previous spectra suggests that this is an additional emission feature. Spectra taken with the CAT 1.4-m telescope (resolution 80000) do not show smaller- scale structures. The precise wavelength of the relative maximum in the spectrum is 647.0 nm, followed by a minimum at 648.8 nm. The FWHM of the two features is 1.45 and 2.10 nm, respectively. If identified with H-alpha, the emission corresponds to a velocity of -4500 km/s. No corresponding structures have been observed in the P-Cyg profiles of H-beta and Ca 860-nm. Those observations suggest a distortion in the spherical symmetric outflow of the explosion, which can be confirmed by polarization observations of the H-alpha profile." Provisional photoelectric photometry by J. Dawe and R. H. McNaught with the Australian National University 0.61-m reflector at Siding Spring Observatory: Mar. 20.456 UT, V = 4.12, B-V = +1.58, U-B = +2.04. Further visual magnitude estimates: Mar. 19.39, 4.1 (McNaught); 19.52, 4.0 (T. Beresford, Adelaide, South Australia); 20.45, 4.0 (McNaught); 20.48, 3.9 (Beresford).
- Publication:
-
International Astronomical Union Circular
- Pub Date:
- March 1987
- Bibcode:
- 1987IAUC.4350....1C