MBCAA Observatory
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KZ Hya: a pulsating binary (improved)Observed: 9 Feb, 11, 14 March, 19 Apr 2007Michel Bonnardeau
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ToM (HJD - 2454000) | uncertainties (day) |
141.5583 | 0.001 |
171.4927 | 0.001 |
174.409 | 0.001 |
174.468 | 0.001 |
174.5275 | 0.001 |
210.4127 | 0.001 |
In 2004 and 2005-2006 I observed 11 times of maximum. I re-determine these ToM
with a better precision (2004 and
2005-2006):
ToM (HJD - 2453000) | uncertainties (day) |
121.4115 | 0.001 |
123.375 | 0.0015 |
144.3815 | 0.0015 |
728.7275 | 0.001 |
729.6795 | 0.001 |
761.5775 | 0.0015 |
761.6375 | 0.002 |
808.4135 | 0.001 |
808.473 | 0.001 |
808.532 | 0.001 |
833.408 | 0.001 |
The 90 times of maximum of Liu Yanying et al (1991) [LY91] and my 11 measurements
of 2004-2006 were used
to derive the pulsation parameters: P=0.059,511,264d, t0=2,442,516.15584HJD,
beta=-3.38*10^-13. With this ephemeris, one has the O-C diagram:
Red circles: my 2004-2006 measurements;
Black circles: my 2007 measurements;
Blue squares: from ASAS data; Magenta
diamond: from ROTSE data; Green diamond:
from AAVSO data.
The ASAS, ROTSE, AAVSO data are not individual times of maximum but average
values over 1 yr; they were derived HERE.
In 2006 I derived
an ephemeris that used the equations of LY91 for the binary motion. Now,
I use improved equations
to fit (by hand) the parameters for the light-travel time effect. The
results are:
Orbital period | 7.934 yr |
a*sin(i) (semi-major axis * sin(inclination)) | 0.889 au |
Eccentricity | 0.455 |
Periastron longitude (from node line) | 333° |
Time of passage at periastron | 2,442,895.9 HJD (19760427.4) |
The resulting O-C diagram in phase:
Red dots: the times of maximum of LY91;
Red circles: my 2004-2006 measurements;
Black circles: my 2007 measurements;
Cyan curve: the binary light-travel time
effect.
and as a function of time:
Red dots: the 90 times of maximum of LY91;
Red circles: my 2004-2006 measurements;
Black circles: my 2007 measurements;
Blue: from ASAS data;
Magenta: from ROTSE data;
Green: from AAVSO data;
Cyan curve: the binary light-travel time
effect.
The ASAS, ROTSE, AAVSO data are not individual times of maximum but average
values over 1 yr; they were derived HERE.
The differences with the 2006
calculations come from:
Liu Yanying, Jiang Shiyang, Cao Ming (1991) IBVS 3606 [LY91].
Light-travel time effects in binary systems.
Pulsating stars and its links.
Telescope and camera configuration.
Computer and software configuration.
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