Central Bureau for Astronomical Telegrams
IAUC 3680: ECLIPSING AM HERCULIS-TYPE MAGNETIC BINARY; 1982 DA
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Read IAUC 3681
Circular No. 3680
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-864-5758
ECLIPSING AM HERCULIS-TYPE MAGNETIC BINARY
P. Biermann, Max Planck Institut fur Radioastronomie, Bonn;
and H. Kuhr, J. Liebert, H. Stockman, P. Strittmatter and S. Tapia,
University of Arizona, report that a new AM Her-type binary system
has been identified with the unresolved serendipitous Einstein
x-ray source near NGC 3607 (P. Biermann, P. Kronberg and B. Madore
1982, Ap. J. Lett. in press). The x-ray source was found to be
strongly modulated with a period of ~ 90 min. During 1981
Dec.-1982 Feb. the nearby faint stellar object at R.A. = 11h14m38s.07, Decl. =
+18o14'05".1 (+/- 0".5, equinox 1950.0) was observed to show strong
periodic circular and linear polarization. The optical spectrum
was neutral in color and showed strong emission lines of H, He II,
He I and other ions, also strongly modulated with the binary period.
The circular polarization varied between -35 and +10 percent. A
linear polarization pulse occurred coincident with the change of
circular polarization from negative to positive. The magnetic
ephemeris from five linear polarization pulses spanning 897 cycles
is: HJD = 2444968.9747 (+/- 0.0007) + 0.062365 (+/- 0.000001) E. The
object varied between mv 17.5 (when negatively polarized) and 19
(when positively circularly polarized) but also showed an
apparently total optical eclipse for ~ 4 min in the middle of the phase of
negative circular polarization. The eclipse center precedes the
linear pulse by 0.33 of a period and yields a consistent and more
accurate ephemeris (from seven eclipses, 897 cycles): HJD =
2444968.0215 (+/- 0.0002) + 0.0623613 (+/- 0.0000005) E.
1982 DA
A third independent discovery of this object has been reported
by F. Dossin with the Provence-Liege Schmidt. The following
ephemeris continuation (cf. IAUC 3675) utilizes observations that will
appear in the Apr. 8 batch of MPCs:
1981 ET R. A. (1950) Decl. Delta r Mag.
Apr. 1 10 47.05 +37 02.2 0.808 1.648 17.2
11 10 51.56 +37 53.6
21 10 58.95 +37 46.2 1.023 1.722 18.0
May 1 11 08.74 +36 56.0
11 11 20.40 +35 34.9 1.262 1.800 18.5
21 11 33.41 +33 51.5
31 11 47.43 +31 51.6 1.512 1.879 19.0
1982 March 19 (3680) Brian G. Marsden
Read IAUC 3681
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