Central Bureau for Astronomical Telegrams
IAUC 5614: N Cyg 1992
The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).
Read IAUC 5615
.dvi or
.ps format.
Circular No. 5614
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
NOVA CYGNI 1992
S. N. Shore and T. B. Ake, III, Goddard High Resolution
Spectrograph (GHRS) team and Computer Sciences Corporation (CSC); S.
Starrfield, Arizona State University; G. Sonneborn, Goddard Space
Flight Center, NASA; R. Gonzalez-Riestra, International Ultraviolet
Explorer Observatory, European Space Agency, Madrid; S. Kraemer,
Space Telescope Imaging Spectrograph team and CSC; and B. Altner,
Applied Research Corporation report: "Observations of Nova Cyg
1992 were obtained with the GHRS on Sept. 8.2 UT with a spectral
resolution of 15~000. The line profiles of N IV] 148.7-nm, Ne IV]
160.2-nm, He II 164.0-nm, N III] 175.0-nm, Si III] 189.2-nm, and C
III] 190.8-nm show that the nova ejecta are composed of a complex
of individual knots. These are nearly symmetric about line center.
The nonresonance lines all have a saddle appearance, which suggests
that the ejecta are nonspherical and probably bipolar. The individual
emission features are resolved with velocity widths ranging
between 100 and 200 km/s. Ionization variations are detected using
the N IV] to N III] ratio. The highest velocity ejecta are more
ionized than those at low velocity. The Si III] to C III] ratio
indicates that the approaching material has a higher density than
the receding part of the ejecta. He II 164.0-nm is broader than
any of the other lines, with a velocity width of about 3700 km/s
(full width zero intensity). He II and Ne IV] show similar line
profile features, suggesting that the ejecta are well mixed in neon.
The GHRS spectra show a flat continuum at about 5 x 10E-13 erg
cmE-2 sE-1 AE-1. Contemporaneous observations taken on Sept. 7.7
with the International Ultraviolet Explorer satellite yield the
following fluxes (10E-11 erg cmE-2 sE-1): Lyman-alpha 121.6-nm,
2.40; N V 124.0-nm, 9.58; Si IV/O IV 140.0-nm, 8.18; N IV] 148.7-nm,
17.39; C IV 155.0-nm, 5.75; Ne V] 157.5-nm, 1.64; Ne IV] 160.2-nm,
6.28; He II 164.0-nm, 4.90; O III] 166.5-nm, 8.79; N III] 175.0-nm,
14.42; Si III] 189.2-nm, 0.31; and C III] 190.8-nm, 3.17. Al III
186.0-nm is definitely present. The integrated 120- to 200-nm flux
continues to decline at a steady rate of about 10 percent per week.
Long-wavelength observations show the presence of a broad [Na V]
207.0-nm line. There is a strong unidentified line at 215.0 nm
that has been present since the ejecta became optically thin."
Selected visual magnitude estimates: Sept. 6.78 UT, 9.4 (E.
Schweitzer, Strasbourg, France); 8.16, 9.0 (W. G. Dillon, Missouri
City, TX); 11.99, 9.0 (B. H. Granslo, Fjellhamar, Norway).
1992 September 17 (5614) Daniel W. E. Green
Read IAUC 5615
.dvi or
.ps format.
Our Web policy. Index to the CBAT/MPC/ICQ pages.
