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\begin{document}

\IBVShead{5482}{28 November 2003}

\IBVStitle{Hipparcos Eclipsing Binaries Showing Apsidal Motion}

\IBVSauth{Otero, Sebasti\'an A.}

\IBVSinsto{Grupo Wezen 1 88, Centro de Estudios Astron\'omicos (CEA), Liga Iberoamericana de Astronom\'\i a (LIADA); e-mail: varsao@fullzero.com.ar}


\SIMBADobjAlias{V366 Pup}{HD 57897}
\SIMBADobjAlias{PT Vel}{HD 79154}
\SIMBADobjAlias{V466 Car}{HD 70333}
\IBVStyp{ EA }
\IBVSkey{variable stars, eclipsing binary, periods, apsidal motion}

\IBVSabs{V366 Puppis, PT Velorum and V466 Carinae are found to be }
\IBVSabs{eccentric binaries displaying apsidal motion.}


\begintext

\vspace*{-0.5cm}
Combination of the publicly available Hipparcos data 
(Perryman et al., 1997) from 1989-1993 and ASAS-3 data (Pojmanski, 2002) 
from 2001 to the present allows the detection of apsidal motion in 
three eclipsing binaries discovered by the satellite.
Table 1 lists the main parameters of the stars. The first column gives 
the variable star designation. The following columns show the V band range 
(with the secondary eclipse magnitude between brackets), the period of 
the primary and secondary eclipse respectively, and the variability and 
spectral types.

\vspace*{-0.4cm}
\begin{table}[!hb]
\centerline{\bf Table 1.}
\begin{center}
\begin{tabular}{cccccc}
  Star  &    $V$ magnitude   &    Period I &  Period II&  Type& Sp\\
\hline
V366 Pup&  8.07 $-$8.59 (8.47) &  2.4840254 & 2.483898 &  EA &  B9V*\\
PT Vel &   7.02 $-$7.70:(7.37:) & 1.8020075 & 1.802035 &  EA &  A0V**\\
V466 Car&  7.27 $-$7.55 (7.46) &  3.455800&   3.455887 &  EA &  B8/9V*\\
\hline
\end{tabular}
\end{center}
*Houk \& Cowley, 1975.\\
**Houk, 1978.
\end{table}

Hipparcos observations have been transformed to V using a table by the 
author (Otero, 2001).
The method of bisected chords was used to determine times of minima. 
The accuracy depends on the quantity and quality of the observations. 
Wrong observations (random data points deviating $>$0.05 mag. from the mean 
folded light curve) were discarded before any analysis was made.

Table 2 show times of minima and residuals for all the stars based on 
the primary eclipse period to make the phase shift of the secondary 
eclipse evident.

\begin{table}[!ht]
\small
\centerline{\bf Table 2.}
\begin{center}
\begin{tabular}{ccccc}
Star  &   HJD+2400000($\sigma$) &  $O-C$ &  Min &  Source*\\
\hline
V366 Pup & 47861.900(0.100) &  0.000 &  II &     H\\
         & 48635.365(0.010) & $-$0.002 &   I &     H\\
         & 51905.708(0.030) & $-$0.185 &  II &     A\\
         & 52033.514(0.010) &  0.000 &   I &     A\\
         & 52234.714(0.010) & $-$0.006 &   I &     A\\
         & 52787.502(0.050) & $-$0.220 &  II &     A\\  
PT Vel   & 48294.360(0.020) &  0.000 &  II &     H\\
         & 52425.479(0.020) & $-$0.017 &   I &     A\\   
         & 52651.704(0.020) &  0.090 &  II &     A\\
         & 52789.521(0.020) &  0.019 &   I &     A\\
         & 52922.862(0.010) &  0.012 &   I &     A\\
V466 Car & 48316.908(0.020) &  0.017 &   I &     H\\
         & 48779.943(0.020) & $-$0.025 &   I &     H\\
         & 49047.376(0.020) & $-$0.002 &  II &     H\\
         & 51931.658(0.010) &  0.000 &   I &     A\\
         & 51967.612(0.020) &  0.083 &  II &     A\\
         & 52539.853(0.020) & $-$0.025 &  I  &     A\\
         & 52940.765(0.020) &  0.014 &  I  &     A\\        
\hline
\end{tabular}
\end{center}
*H = Hipparcos; A = ASAS-3
\end{table}

\vspace*{0.5cm}

{\bf Individual stars}

\vspace*{0.5cm}

1) V366 Puppis = NSV 3555 = HIP 35607 = HD 57897 is a known visual binary 
system (WDS07209-4831 AB), with an 8.4 mag. primary and a 9.6 secondary 
7\arcs\ away according to the WDS (Worley et al., 1997).
It was first suspected as a variable star (BV 438) back in 1964 
(Strohmeier et al., 1964a).
Its period could not be solved in the Hipparcos Catalogue.
The primary is the eclipsing binary with the following light elements:

$${\rm Min\, I}  = {\rm HJD} 2447860.351 (\pm 0.001) + 2.4840254 (\pm 0.0000020) \times {\rm E}$$
$${\rm Min II} = {\rm HJD} 2447861.900 (\pm 0.100) + 2.4838980 (\pm 0.0000050) \times {\rm E}$$

Eclipse durations are very different, the secondary during 0.29 and the 
primary 0.11 days. The light curve can be seen in Figure 1a.
The apsidal motion is fast and comparable to that of GL Carinae 
(Gim\'enez \& Clausen, 1986) which shows a 25 years-period. If we use 
the primary eclipse period as a reference, V366 Pup eclipse shifted 
from phase 0.63 in 1989 to phase 0.54 in 2003. Figure 1b shows this 
effect clearly.


\IBVSfig{7cm}{5482-f1.eps}{Light curve of V366 Pup showing Hipparcos (filled circles) and ASAS-3 observations (open circles).}
\IBVSfig{7cm}{5482-f2.eps}{Phase shift in the secondary eclipse of V366 Pup. Filled circles are Hipparcos observations. Open circles and crosses are 2000-2001 and 2002-2003 data from ASAS-3 respectively.}
%%\IBVSfigKey{5482-f1.eps}{V366 Pup}{light curve}
%%\IBVSfigKey{5482-f2.eps}{V366 Pup}{}

2) PT Velorum = NSV 4409 = HIP 45079 = HD 79154 was first suspected 
of variability in 1964 and named BV 469 (Strohmeier et al., 1964b). 
Its eclipsing nature was discovered by Hipparcos which solved a period 
of 1.80201 days. Comparison with ASAS-3 data also revealed apsidal motion.
$${\rm Min\, I}  = {\rm HJD} 2448293.493 (\pm 0.001) + 1.8020075 (\pm 0.0000010) \times {\rm E}$$
$${\rm Min II} = {\rm HJD} 2448294.360 (\pm 0.020) + 1.8020350 (\pm 0.0000010) \times {\rm E}$$

Primary eclipse lasts 0.23 days and secondary 0.17 days. The latter 
shifted from phase 0.48 to 0.53.
Both eclipses lack observations at the instant of minimum light so 
more observations are needed to confirm the amplitude and nature of 
the eclipses.

\IBVSfig{7cm}{5482-f3.eps}{Light curve of PT Vel showing Hipparcos (filled circles) and ASAS-3 observations (open circles).}

%%\IBVSfigKey{5482-f3.eps}{PT Vel}{light curve}


3) V466 Carinae = NSV 4003 = HIP 40666 = HD 70333 was first discovered to 
be variable by Strohmeier (1966) who designated it as BV 821.
Its period was published in the Hipparcos Catalogue. ASAS-3 data again 
show a slight displacement in the secondary eclipse over these ten 
years. However, this is small if compared with the previous cases and 
goes from phase 0.38 to 0.41.
Light elements:
$${\rm Min\, I}  = {\rm HJD} 2448036.971 (\pm 0.02) + 3.455800 (\pm 0.000001) \times {\rm E}$$ 
$${\rm Min II} = {\rm HJD} 2448038.284 (\pm 0.05) + 3.455887 (\pm 0.000002) \times {\rm E}$$


Eclipses seem to be total (this needs confirmation) and last 0.35 
(primary) and 0.27 (secondary) days.

\IBVSfig{7cm}{5482-f4.eps}{Light curve of V466 Car showing Hipparcos (filled circles) and ASAS-3 observations (open circles).}

%%\IBVSfigKey{5482-f4.eps}{V466 Car}{light curve}


{\it Acknowledgements:} This research has made use of the SIMBAD and VizieR 
databases operated at the Centre de Donn\'ees Astronomiques (Strasbourg) 
in France. The author wants to thank John Greaves for his suggestions 
in the preparation of this paper.


\references

Gim\'enez, A., Clausen, J. V., 1986, {\it A\&A}, {\bf 161}, 275 
%%(1986A&A...161..275G) 

Houk, N., Cowley, A. P., 1975, Dept. of Astronomy, Univ. of Michigan 
Ann Arbor, {\it Catalogue of two dimensional spectral types for the HD stars}, 
{\bf Vol. 1} 
\ADSBIBCODE{1975MSS...C01....0H}

Houk, N., 1978, Dept. of Astronomy, Univ. of Michigan Ann Arbor, {\it 
Catalogue of two dimensional spectral types for the HD stars}, {\bf Vol. 2}
\ADSBIBCODE{1978MSS...C02....0H}

Otero, S., 2001, ({\tt http://ar.geocities.com/varsao/conversion\_entre\_hp.htm})

Perryman, M. A. C., et al., 1997, {\it A\&A}, {\bf 323}, L49, The Hipparcos 
Catalogue 
%%(1997A&A...323L..49P)

Pojmanski, G., 2002, {\it Acta Astronomica}, {\bf 52}, 397, The All Sky 
Automated Survey 
%%(2002AcA....52..397P)

Strohmeier, W., Knigge, R., Ott, H., 1964a, {\it IBVS}, No. 62 
%%(1964IBVS...62....1S)

Strohmeier, W., Knigge, R., Ott, H., 1964b, {\it IBVS}, No. 66 
%%(1964IBVS...66....1S)

Strohmeier, W., 1966, {\it IBVS}, No. 158 
%%(1966IBVS..158....1S)

Worley, C. E., Douglass, G. G., 1997, {\it A\&AS}, {\bf 125}, 523, 
The Washington Visual Double Star Catalog, 1996.0 
%%(1997A&AS..125..523W)


\endreferences

\IBVSedata{5482-t2.txt}
%\IBVSdataKey{5482-t2.txt}{}{other}

\end{document}

