Astronomy and Astrophysics – Astrophysics
Scientific paper
2000-09-26
Astronomy and Astrophysics
Astrophysics
25 pages, 6 figures, to appear in December 1, 2000 Astrophysical Journal
Scientific paper
10.1086/317809
Two-dimensional spectra of Supernova 1987A were obtained on 1998 November 14-15 (4282 days after outburst) with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). The slit sampled portions of the inner circumstellar ring at the east and west ansae as well as small sections of both the northern and southern outer rings. The temperature and density at these locations are estimated by nebular analysis of [N II], [O III], and [S II] emission line ratios, and with time-dependent photoionization/recombination models. The results from these two methods are mutually consistent. The electron density in the inner ring is ~ 4000 cm-3 for S II, with progressively lower densities for N II and O III. The electron temperatures determined from [N II] and [O III] line ratios are ~11,000 K and \~22,000 K, respectively. These results are consistent with evolutionary trends in the circumstellar gas from similar measurements at earlier epochs. We find that emission lines from the outer rings come from gas of lower density (n_e \la 2000 cm-3) than that which emits the same line in the inner ring. The N/O ratio appears to be the same in all three rings. Our results also suggest that the CNO abundances in the northern outer ring are the same as in the inner ring, contrary to earlier results of Panagia et al. (1996). Physical conditions in the southern outer ring are less certain because of poorer signal-to-noise data. The STIS spectra also reveal a weak Ha emission redshifted by ~100 km s-1 at p.a. 103\arcdeg that coincides with the recently discovered new regions that are brightening (Lawrence et al. 2000). This indicates that the shock interaction in the SE section of the inner ring commenced over a year before it became apparent in HST images.
Gull Theodore R.
Iping Rosina C.
Lundqvist Peter
Maran Stephen P.
Pun Chun. S. J.
No associations
LandOfFree
Physical Conditions in Circumstellar Gas surrounding SN 1987A 12 Years After Outburst does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Physical Conditions in Circumstellar Gas surrounding SN 1987A 12 Years After Outburst, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Physical Conditions in Circumstellar Gas surrounding SN 1987A 12 Years After Outburst will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-482290