Central Bureau for Astronomical Telegrams
IAUC 7717: V445 Pup
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Circular No. 7717
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)
V445 PUPPIS
M. P. Rupen, V. Dhawan, and A. Mioduszewski, National Radio
Astronomy Observatory, report: "Observations with the Very Large
Array (VLA) at 8.46 GHz on Sept. 9 show a 9.6-mJy point source (rms
0.095 mJy/beam) at R.A. = 7h37m56s.87, Decl. = -25o56'58".9
(equinox 2000.0; uncertainty 0".1-0".2 in each coordinate). This
agrees with the optical position of V445 Pup (IAUC 7556).
Observations at the same frequency on Jan. 18 gave no detection
(rms 0.095 mJy/beam). VLA data taken on Sept. 11 and 12 confirm
the detection and show a slowly decaying source (exponential
timescale of 25 +/- 3 days) with a power-law spectrum (flux density
proportional to nu**-0.7, where nu is the frequency) between 5 and
15 GHz. The 1.425-GHz flux density, however, is lower than a
simple extrapolation would suggest, giving an inferred foreground
opacity of 0.4 at that frequency. If this is correct, either the
source is small enough (milliarcsec) for synchrotron
self-absorption, or there is a great deal of ionized gas providing
free-free absorption along the line-of-sight. The radio emission
probably comes either from a recent energetic event, or from the
development of a shock associated with the Dec. 2000 outburst.
Observations at optical, infrared, and x-ray wavelengths would be
very useful in tracing the origin of the radio emission."
R. M. Wagner, LBT Observatory; G. Schwarz, Steward Observatory;
S. G. Starrfield, Arizona State University; and C. B. Foltz, MMT
Observatory, write: "Spectra (range 400-950 nm, resolution 0.85 nm)
of V445 Pup, obtained on Apr. 15-16 UT (just prior to conjunction
with the sun) using the Bok 2.3-m telescope on Kitt Peak, show
strengthening emission lines of carbon compared to our previous
reports (cf. IAUC 7556, 7571). The emission lines include C I
(multiplets 3, 9-10) and C II (multiplets 1-3, 5-6, 14-16, 19-20),
as well as features arising from Fe II, O I, Mg I, Mg II, N I, Ca I,
Ca II, and perhaps Na I (described previously). Emission lines
arising from He I (587.5, 667.8, 706.5, and 728.1 nm) are also
present (cf. IAUC 7556). The equivalent width of the C II line at
658 nm was 4.6 nm. A spectrum (range 390-540 nm, resolution 0.14
nm) obtained on Mar. 29 by S. Howell and P. Szkody with the 6.5-m
MMT shows that many of these features exhibit P-Cyg profiles in
which the absorption components are relatively sharp (FWHM 130
km/s; terminal velocity -600 km/s), while the emission components
exhibit considerable structure and long red tails extending to
about +3800 km/s, suggesting an asymmetric outburst. A broad and
weak emission feature (equivalent width 0.32 nm) at 486.1 nm might
be H-beta. Additional spectroscopic observations are urgently
requested."
(C) Copyright 2001 CBAT
2001 September 13 (7717) Daniel W. E. Green
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