Central Bureau for Astronomical Telegrams
IAUC 6387: EMISSION OBJECT IN Cyg; 4U 1728-34
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Circular No. 6387
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
Phone 617-495-7244/7440/7444 (for emergency use only)
EMISSION OBJECT IN CYGNUS
E. S. Parsamian, Byurakan Astrophysical Observatory and
Instituto de Astronomia, Universidad Nacional Autonoma de Mexico,
reports: "During long-slit (3" x 360") spectral observations (range
450-700 nm, resolution 0.55 nm/pixel) of V1478 Cyg on the 2.12-m
telescope (+ Landessternwarte Faint Object Spectograph and Camera)
at Guillermo Haro Observatory, Cananea, on 1995 July 4.23, 5.37,
6.39, 7.30, 9.21, and Sept. 18.35 UT, I discovered a high-velocity
object 33" (+/- 2") south of V1478 Cyg = MWC 349 (cf. Hamann and
Simon 1988, Ap.J. 327, 876). The object is located at R.A. =
20h32m45s.63, Decl. = +40o39'03".6 (equinox 2000.0) and has an
emission-line spectrum and faint red continuum similar to V1478
Cyg. A few identified lines (H-alpha, He II, He I) show a
blueshift of about 1000-2000 km/s (possibly variable from night to
night) with respect to the same lines in V1478 Cyg (whose V(LSR) =
+8 km/s). H-alpha seems to be double-peaked with peak separation
about 800 km/s. The source of the blueshifted line is tentatively
identified with a weak object seen on the red Palomar Sky Survey
plate, 32" south of V1478 Cyg. As the object lies close to the
axis of outflow from V1478 Cyg, perhaps there is a connection. The
relative fluxes in 10E-13 erg cmE-2 sE-1 for the H-alpha lines
(using the star Kopff 27 as a standard) of the new object are: 1995
July 4.227, 3.41; 4.246, 3.76; 5.389, 1.30; 5.399, 93.3."
4U 1728-34
T. Strohmayer, W. Zhang, A. Smale, and C. Day, Universities
Space Research Association (USRA) and the Laboratory for High
Energy Astrophysics, Goddard Space Flight Center (LHEA/GSFC); J.
Swank, LHEA/GSFC; L. Titarchuk, George Mason University and LHEA/
GSFC; and U. Lee, Tohoku University, report: "Of the seven bursts
that we have observed from 4U 1728-34 during a recent campaign with
RXTE, five show oscillations with a frequency of 363 Hz. In the
first few seconds of two of the seven bursts, the oscillations do
not appear to be coherent. The oscillation frequency drifts by as
much as 0.5 Hz. During the other three bursts, the coherence of
the oscillations is only limited by the durations of the bursts.
The fractional rms of the oscillations ranges from 1.5 to 5 percent.
We have also found in the same data set two simultaneously-present
kHz quasiperiodic oscillations (QPOs), one of which has been
reported earlier (IAUC 6320). The centroid frequencies of the two
QPOs change with intensity and time, but their difference appears to
be always near 363 Hz. These observations are consistent with a
neutron star spin period of 2.75 ms."
(C) Copyright 1996 CBAT
1996 April 26 (6387) Daniel W. E. Green
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