Issue |
A&A
Volume 370, Number 3, May II 2001
|
|
---|---|---|
Page(s) | 1056 - 1063 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361:20010292 | |
Published online | 15 May 2001 |
The late-time expansion of the ejecta of SN 1987A
Astrophysics Division, Space Science Department of ESA, ESTEC, NL-2200 AG Noordwijk, The Netherlands e-mail: rjansen@astro.estec.esa.nl; pjakobse@astro.estec.esa.nl
Corresponding author: R. A. Jansen, rjansen@astro.estec.esa.nl
Received:
11
January
2001
Accepted:
19
February
2001
The evolution of the shape and size of the ejecta of SN 1987A is
analyzed over a period of ~8 years based on HST images and
spectra taken between 1278 and 4336 days after the supernova outburst.
We combine both proprietary and archival HST data obtained with
the FOC, WFPC2 and STIS. The low resolution near-UV prism FOC spectrum
obtained at day 3043 has not been described previously. Although the
FWHM of the ejecta grew linearly over the time span studied, the
appearance of the SN envelope also changed markedly with wavelength. At
visible wavelengths ( Å) the ejecta became
progressively more elongated, reaching an ellipticity of
by day 4000. In the near-UV (
Å), the ejecta
remained closely circular (
) and ~50% larger in
angular extent than in the visible. The FOC prism observations show
that the large extent of the SN envelope is confined to a grouping of
resonance lines spanning Mgi
λ2852,
Mgii
2795,2802Åand several Feii multiplets
-thereby confirming that the larger size of the debris in the near-UV
is due to scattering in these optically thick transitions compared to
the optically thin forbidden and semi-forbidden transitions that
dominate the visible spectrum. The available data are not of sufficient
quality to detect the slight deviation from linear expansion expected
for the outermost regions of the near-UV images as predicted by Chugai
et al. ([CITE]).
Key words: supernovae: individual (SN 1987A) / supernova remnants
© ESO, 2001
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