Central Bureau for Astronomical Telegrams
IAUC 3400: SS 433; Notice
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Circular No. 3400
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-864-5758
SS 433
P. Murdin and D. H. Clark, Royal Greenwich Observatory, report
that IPCS spectra taken with the South African Astronomical Observatory's
1.9-m telescope of the eastern filament of W50, independently
discovered by van den Bergh (IAUC 3393) and visible on the Palomar
Sky Survey E plate, show that nitrogen emission is mostly responsible
for the apparent H-alpha photographed by him. The ratio N II/H-alpha ~ 7,
Pup A being the only other known optical remnant showing such nitrogen
enhancement. Identification of the nebulosity as the SNR W50 is
confirmed by a large S II/H-alpha ratio. The red lines are only lines
detected in a low-dispersion spectrum suggesting a large reddening,
like that of SS 433 (Clark and Murdin 1978, Nature 276, 44). This
is further evidence that W50 and SS 433 are associated.
J. R. D. Lepine, M. Melnikoff, M. Maia, C. A. Torres and P.
Marques dos Santos, CRMM-Observatorio Nacional, Rio de Janeiro, report
observations at 21.6 and 43 GHz of the H-alpha emission object SS
433, which has shown variable radio emission with negative spectral
index at lower frequencies (cf. IAUC 3256). The observations were
made with the Itapetinga radio telescope on June 7, 21 and Aug. 23
at 21.6 GHz and on June 28, 29, July 12 and Aug. 23 at 43 GHz,
using Vir A and the H II region H2-3 as calibrators. The fluxes
obtained were constant within the errors, indicating that no flare
occurred at the times of observation. The weighted means of the
21.6-GHz and 43-GHz flux densities were 0.56 +/- 0.08 Jy and 2.51 +/-
0.48 Jy, respectively, with a resulting spectral index of 2.16 +/-
0.34, which is typical of optically thick thermal emission. It
seems then that a central component with positive spectral index
dominates at high radio frequencies, while below 10 GHz most of the
radio emission is synchrotron emission from the supernova remnant.
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1979 September 10 (3400) Brian G. Marsden
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