Central Bureau for Astronomical Telegrams
IAUC 7184: V382 Vel; XTE J1550-564
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Circular No. 7184
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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V382 VELORUM
S. Nakano, Sumoto, Japan, reports that T. Furuta, Kagiya-cho,
Tokai, recorded a prediscovery image of V382 Vel = N Vel 1999 on
Fuji Color Super G400 film taken during his travel in New Zealand.
His films yield the following magnitude estimates: May 20.57 UT,
[13 (30-min exposure with 50-mm f/2.8 camera lens); 21.64, 4.3
(30-min exposure with 16-mm f/2.8 fish-eye lens). B. Sumner
reports that M. Rudd, Mount Martha, Victoria, has also identified a
prediscovery image of this nova (at mag 3.6 from comparison with
phi Vel and pi Cen, according to Sumner) on a 5-min exposure taken
with Kodak Gold Flexiclear 400 film (28-mm camera lens) on May
21.715. Visual magnitude estimates, some communicated via T. A.
Napoleao, Sao Paulo, Brazil: May 25.939 UT, 3.8 (J. G. de S.
Aguiar, Campinas, Brazil); 26.25, 3.9 (S. J. O'Meara, Volcano, HI);
27.542, 4.1 (A. Pearce, Nedlands, W. Australia); 28.024, 4.5 (A.
Alves, Florianopolis, Brazil); 28.41, 4.7 (R. H. McNaught,
Bugaldie, N.S.W.); 29.990, 4.8 (Napoleao); 30.442, 4.7 (Pearce);
31.344, 5.2 (D. A. J. Seargent, The Entrance, N.S.W.); June 1.163,
5.2 (J. Garcia, Rama Caida, Argentina).
XTE J1550-564
R. Soria, Research School of Astronomy and Astrophysics,
Australian National University; and K. Wu, Special Research Centre
for Theoretical Astrophysics, University of Sydney, write: "We have
obtained a high-resolution spectrum (FWHM = 0.12 nm) of the optical
counterpart of the x-ray transient XTE J1550-564 on Apr. 10 with
the Anglo-Australian Telescope at Siding Spring Observatory (SSO),
and B, V, R, and I images on Apr. 22 and May 23 with the SSO 1.02-m
telescope. The optical spectrum is now dominated by stellar
features typical of a G6-G8 IV star: we detect narrow absorption
lines at H-alpha (EW = 0.1 nm, FWHM = 50 km/s) and H-beta, while no
emission is detected from He II 468.6-nm and the Bowen blend. We
measure EW = 0.023 +/- 0.002 nm and 0.18 +/- 0.01 nm for the
interstellar lines at 661.3 and 628.4 nm, respectively, and we
estimate E(B-V) = 1.0 +/- 0.1 (cf. IAUC 7113). Our photometric
measurements on May 23.5 UT yield B = 21.83 +/- 0.15, V = 20.02 +/-
0.04, R = 18.97 +/- 0.04, I = 17.68 +/- 0.04. If the Roche-lobe-
filling secondary star of XTE J1550-564 is a G8 subgiant, it has a
mass of 1.20 +/- 0.05 solar masses, mean density of 0.06 that of
the sun, and absolute magnitude M_V = 3.15 +/- 0.05. Consequently
we suggest a distance of 6.0 +/- 0.7 kpc for the system, and a
binary period of 1.5 +/- 0.1 days. More optical observations of
this blackhole candidate are encouraged, now that the x-ray source
is in the 'off' state."
(C) Copyright 1999 CBAT
1999 June 1 (7184) Daniel W. E. Green
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