Central Bureau for Astronomical Telegrams
IAUC 7049: N Oph 1998; V4334 Sgr
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Circular No. 7049
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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NOVA OPHIUCHI 1998
R. J. Rudy, T. K. Tessensohn, S. Mazuk, C. J. Rice, and D. K.
Lynch, Aerospace Corporation; and R. C. Puetter, University of
California at San Diego, report 0.8-2.5-micron spectroscopy of N
Oph 1998 using the Aerospace near-infrared imaging spectrograph and
the 3-m Shane telescope at Lick Observatory on June 19.40, June
21.37, and Oct. 2.15 UT: "On the first night, the Paschen and
Brackett emission lines dominated the spectrum, although He I line
at 1.083 microns was the strongest single line present, and He II
was very weak. There was also an unusual continuum emission
feature present between 1.07 and 1.10 microns that was about twice
the height of the surrounding continuum. Three nights later the
nova's rapid evolution to higher excitation conditions was evident
from the much stronger He II lines that had increased by a factor
of four relative to the hydrogen lines. The C III line at 0.971
micron also appeared the second night, a line that we have
heretofore seen only in Wolf-Rayet stars and that almost certainly
indicates an overabundance of carbon. The strange continuum
feature was also present. About 100 days later on Oct. 2.15, the
emission lines were very weak (5-15 percent of the continuum), and
only a few Paschen features and lines of He II were present. The
unusual continuum feature was absent. In both June and October the
continua, though somewhat different in shape, were blue and
resembled a stellar continuum. There was no evidence of a long-
wavelength upturn indicative of thermal emission from dust. On the
three dates in June and October, the continuum magnitudes at J
(1.25 microns) were 9.4, 10.9, and 15.0, respectively."
V4334 SAGITTARII
W. Liller, Instituto Isaac Newton, Vina del Mar, Chile; H. W.
Duerbeck, Space Telescope Science Institute, Baltimore; and A. van
der Meer and A. van Genderen, Leiden University, report that this
object (cf. IAUC 6825) has undergone another dramatic fading due to
dust formation. V magnitudes by Liller (L; 0.2-m telescope) and by
Duerbeck and van der Meer (D and M; ESO Dutch 0.9-m telescope):
Aug. 12.02 UT, 12.06 (L); 13.99, 12.47 (L); 18.02, 12.56 (L); Sept.
12.98, 13.93 (D); 15.00, 13.91 (L); 17.98, 14.13 (L); Nov. 8.01,
15.11 (M); 9.03, 15.15 (M). Average colors for the last two nights
are U-B = +1.95, B-V = +2.52, V-R = +1.68, V-i (Gunn i) = +3.15.
On eight nights between Sept. 19.0 and Oct. 29.0, the object was
fainter than V = 15.0 (L).
(C) Copyright 1998 CBAT
1998 November 11 (7049) Daniel W. E. Green
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