Central Bureau for Astronomical Telegrams

Central Bureau for Astronomical Telegrams -- Image credits

IAUC 6608: NOVALIKE Var IN Sgr; LMC X-4

The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).

Read IAUC 6607 SEARCH Read IAUC 6609

View IAUC 6608 in .dvi or .ps format.
IAUC number 

                                                 Circular No. 6608
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)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/cfa/ps/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)


NOVALIKE VARIABLE IN SAGITTARIUS
     S. Kimeswenger, H. Gratl, and F. Kerber, University of
Innsbruck; P. Fouque, Observatoire de Paris, Meudon; S. Kohle,
Radioastronomisches Institut, Universitaet Bonn; and S. Steele,
University of Toronto Southern Observatory (UTSO), write:  "We have
followed the evolution of of Sakurai's object (IAUC 6322, 6601)
since Apr. 1996.  Infrared-imaging photometry (IJK) obtained on
1997 Mar. 24.25 UT at the ESO 1-m telescope (+ DeNIS infrared
survey instrument) shows that the flux has increased by 100 percent
in I, 315 percent in J, and 940 percent in K (I = 9.29, J = 7.86, K
= 6.24), as compared to earlier observations (see Kerber et al.
1997, IAU Symp. 180; Duerbeck and Benetti (1996, Ap.J. 468, L111).
Visual (BVRIc) CCD photometry obtained on Mar. 28.29-28.33 with the
Dutch 0.90-m telescope at La Silla and the 0.60-m UTSO telescope at
Las Campanas shows that the object has faded by about 40 percent in
B, is constant at V, and has increased 75 and 100 percent in R and
I, respectively (B = 12.58, V = 11.17, R = 9.96, I = 9.26).  The
observed spectral distribution cannot be explained by a single
stellar component.  Using the color temperature of about 5000 K
obtained from the visual data, we find that the near-infrared
excess (of about a factor of 4 at 2.1 microns) can be explained by
a blackbody of about 1800 K producing a specific output 30 times
larger than the stellar source, evidently the signature of hot,
extended, circumstellar dust."


LMC X-4
     D. Dal Fiume, F. Frontera, and M. Orlandini, TESRE, Bologna;
A. Santangelo, S. Del Sordo, IFCAI, Palermo; L. Piro, IAS, Frascati;
A. Coletta, G. Celidonio, G. D'Andreta, G. Gandolfi, G. Spoliti,
and D. Ricci, BeppoSAX, Rome; and J. M. Muller, SRON, Utrecht,
report:  "The BeppoSAX Wide Field Cameras detected five major
flares from the x-ray pulsar LMC X-4 during Mar. 21.7882-21.7981 UT.
The most prominent flare reached a flux level of about 300 mCrab
(2-26 keV).  The duration of each flare was about 100 s.  The pre-
/post-flaring flux level of LMC X-4 is estimated at about 28 mCrab
(2-26 keV).  The x-ray emission from LMC X-4 during flares is
remarkably softer than in the pre-/post-flaring phases.  Our
detection is consistent both in shape and intensity with the
earlier GINGA  detection (Levine et al. 1991, Ap.J. 381, 101).
There is no appreciable gamma-ray flux increase corresponding to
the observed flares, with a 90-percent upper limit of 110 mCrab
above 40 keV."

                      (C) Copyright 1997 CBAT
1997 March 29                  (6608)            Daniel W. E. Green

Read IAUC 6607 SEARCH Read IAUC 6609

View IAUC 6608 in .dvi or .ps format.

Our Web policy. Index to the CBAT/MPC/ICQ pages.

Valid HTML 4.01!