Von: Dahm, Michael [marvin.siriuscorp@planet-interkom.de]
Gesendet: 15. Januar 2000 12:18
Die RR Lyrae Art und Periode des Programm-Sterns DD Dra sind von Agerer und
Lichtenknecker erstmals beschrieben worden. Weil es auf Platten der
Sonneberger Himmelsüberwachung nicht gelang die Zeiten maximaler Helligkeit
mit einer Periode darzustellen wurde vermutet, daß DD Dra zu den RRd-Sternen
mit Perioden von einem Viertel und einem Drittel Tag Länge gehören könnte.
Neue lichtelektrische Maxima zeigen eine stabile Lichtkurve, weshalb die
Zugehörigkeit zu den doppelperiodischen RRd-Sternen ausgeschlossen werden
kann. Allerdings ist die Periode von DD Dra sehr stark veränderlich mit
einem Wert von 0,3267145 vor JD 2450000. Danach gelten die Elemente
Max := (HJD) 2451352,4984(13) + 0,3267934(12) * E.
Damit gehört DD Dra zu den RRc-Sternen mit einer stark veränderlichen
Periode wie RV CrB. Für diesen Vertreter, der ebenfalls alle paar Jahre
einen Periodensprung zeigt, sind wegen fehlender Beobachtungen im Moment
keine instantanen Elemente verfügbar.
COMMISSION 27 OF THE I.A.U.
INFORMATION BULLETIN ON VARIABLE STARS
Number 3213
Konkoly Observatory
Budapest
8 July 1988
HU ISSN 0374 - 0676
TWO-COLOUR LIGHT CURVES AND PRELIMINARY ELEMENTS
FOR CV Dra, DD Dra
We report upon preliminary results of our photoelectric observations of two
variable stars in Draco. The instrument used was the fully-automatic driven
0.35 m Schmidt-Cassegrain telescope at F. Agerer's private observatory. The
photometer was equipped with an EMI 9781B tube and Schott filters BG12(1mm)
+GG385(2mm) for the B and GG495(1mm) for the V colour. The size of the dia-
phragm was 32". All measurement operations were performed fully automatic
and controlled by a microcomputer programmed in FORTH (cf. Agerer, 1988).
CV Draconis
CV Dra = BV 341 = BD +57d1776 (8.8) = HD 159559 (F5) was discovered by
Strohmeier and Knigge (1960) as a short period variable, with the range 9.5m
-10.1m (pg). No further details were given. Nikulina (1961) thereupon inves-
tigated this star on sky-patrol plates. However, she could not confirm any
periodicity and classified the star as a rapid irregular variable. With
these data CV Dra was included for the first time in the 4th edition of the
GCVS (Kholopov et al., 1985). Recently, J. Fabregat (Locher, 1988) communi-
cated two times of minimum light observed visually by him which prompted us
to put CV Dra on our observation program.
SAO 030449 (A2) was chosen as the comparison star and SAO 030426 (K5)
as a control star. According to our observations during eight nights CV Dra
is an eclipsing binary of W-UMa type. From five photoelectric minima obser-
ved by us (Agerer and Lichtenknecker, 1988) and the two visual minima we
derive preliminary elements as:
Min I = JD 2447305.437 + 0.617617d*E.
The amplitudes in V are 0.43m resp. 0.40m for Min I and Min II. The B
and V light curves, with Delta mag in the instrumental system, are shown in
Fig. 1. Minimum II appears to be marginally displaced against phase 0.5.
DD Draconis
DD Dra = BV 234 was discovered by Strohmeier (1958) as variable in the
limits 11.2m-12.0m (pg) and classified as a long period variable. However,
on reconsideration Filatov (1960) stated that it is really an eclipsing
binary. From nine photographic plate minima (i.e. epochs of faint light) he
derived the elements Min = JD 2431587.248 + 0.784ùE. This very inaccurate-
ly determined period motivated us to observe DD Draconis.
The comparison star used was an Anonyma 1.5' west and 7.9' north of the
variable, as a control star we chose SAO 018015 (K2). From our observations
during three nights we conclude that DD Dra is a pulsating variable of type
RRc for which we can give first preliminary elements as:
Max = JD 2447304.459 + 0.32675d*E.
The amplitude of light variation was 0.54m in V and 0.66m in B. B and V
light curves of DD Dra, with Delta_mag in the instrumental system, are shown in
Fig. 2.
A detailed presentation of our observations is in preparation (Agerer and
Lichtenknecker, 1988) and will be available on request from the "Berliner
Arbeitsgemeinschaft fur Veranderliche Sterne (BAV)", Munsterdamm 90, D-1000
Berlin 41.
F. AGERER D. LICHTENKNECKER
Dorfstr. 19 Paul Bellefroidlaan 29
D-8311 Zweikirchen/Tiefenb., B-3500 Hasselt, Belgium
F.R.G.
References:
Agerer, F.: 1988, BAV Rundbrief 37(2), 60
Agerer, F., Lichtenknecker, D.: 1988, BAV Mitt. Nr. 49, in preparation
Filatov, G.S.: 1960, Astron. Tsirk. No. 215, 20
Kholopov, P.N., Samus', N.N., Frolov, M.S., Goranskij, V.P., Gorynya,N.A.,
Kazarovets, E.V., Kireeva, N.N., Kukarkina, N.P., Kurochkin, N.E.,
Medvedeva, G.I., Perova, N.B., Rastorguev, A.S., Shugarov, S.Yu.: 1985,
General Catalogue of Variable Stars, 4th Ed., Vol. II, Nauka, Moscow
Locher, K.: 1988, BBSAG Bull. No. 87
Nikulina, T.G.: 1961, Astron. Tsirk. No. 227, 17
Strohmeier, W.: 1958, K1. Veroff. Remeis-Sternw. Bamberg Nr. 24
Strohmeier, W., Knigge, R.: 1960, Veroff. Remeis-Sternw. Bamberg Bd. 5 Nr. 6
