AU Monocerotis (AU Mon; HD 50846; BD
; 
) was discovered to be an
eclipsing binary of Algol type by Hoffmeister (1931). From their spectroscopic
studies, Sahade & Cesco (1945) reported the spectral types of the primary and
secondary components to be B5 and about F0, respectively. Lorenzi (1980a)
published the first photoelectric light curve, in yellow, of this system in the
form of 2616 individual observations. Later he combined these observations into
183 weighted normal points (Lorenzi 1980b; hereafter L80) and corrected them
for a suspected intrinsic variation, with a period of about 411 days and amplitude
of 
, in the system. Assuming symmetry for the eclipse light curve, he obtained
ten normal points from these corrected 183 normals (L80; Table 3 (click here)). These ten
normals were considered by Lorenzi as "representative of an approximate mean light
curve of the eclipsing variations''. Giuricin et al. (1982) solved this light
curve of ten normal points using Wood's WINK program and obtained photometric
elements of the system. Since only a mass function, 
, of 
(Sahade &
Cesco 1945) and not the mass ratio was available to them,
Giuricin et al. (1982)
assumed a plausible value for the mass of the B5 primary component 
and
derived a mass ratio of 0.2 for the system and used this value in their analysis.
In a further study of his observations, Lorenzi (1982, Table 1 (click here) and Fig. 1 (click here))
published the light curve of the variation of the unknown source in the system
and provided twenty seven corrected normal points (symmetrized) including eight
points from his previous study (L80, Table 3 (click here)). Forming an average symmetric light
curve from these points, Lorenzi (1982) solved it for elements using
Russell-Merrill
(1952) method. Recently Popper (1989) obtained spectra of both the components
of AU Mon and published the amplitudes 
and 
of the radial velocity curves,
from which one can get a reliable mass ratio (
) of the system. Hence we felt
it worthwhile to reanalyse the light curve of Lorenzi (L80) using the mass ratio
obtained by Popper (1989) and thus obtain improved elements of AU Mon. In the
following we give details of our analysis and its results.
 |  |
| 38.30 | 0.190 |
| 38.06 | 0.195 |
| 37.96 | 0.1975 |
| 38.00 | 0.200 |
| 38.60 | 0.210 |
| 40.10 | 0.220 |
values obtained from the analysis of the light
curve using 
and different q values. Here both 
and q were treated as fixed parameters
Figure 1: AU Mon: The relation between the mass ratio, q, and .
The solid line is a free hand drawn curve. The minimum occurs at q=0.1985