%& --translate-file=il2-pl
\documentstyle[twoside,epsf]{article}

\input ibvs2.sty

\begin{document}
\IBVShead{0000}{30 June 2009}

\IBVStitletl{Spectroscopy of eclipsing binary HD~65498 }{Third component detected}

\IBVSauth{S\c{E}KALSKA, JUSTYNA$^1$; DIMITROV, WOJCIECH$^1$; KRUSZEWSKI, ADRIAN$^1$; PRZYBYSZEWSKA, ANNA$^1$; KURZAWA, KRYSTIAN$^1$; \.ZYWUCKA, NATALIA$^1$; BORCZYK, WOJCIECH$^1$; BARTCZAK, PRZEMYS\L{}AW$^1$; HIRSCH, ROMAN$^1$; FAGAS, MONIKA$^1$; KAMI\'NSKI, KRZYSZTOF$^1$; KWIATKOWSKI, TOMASZ$^1$; RO\.ZEK, AGATA$^1$; SCHWARZENBERG-CZERNY, ALEKSANDER$^{1,2}$}

\IBVSinst{Astronomical Observatory, Adam Mickiewicz University, S\l{}oneczna 36, 60-186 Pozna\'n, Poland}
\IBVSinst{Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw, Poland}

\SIMBADobj{HD 65498}

\begintext


This paper\footnotemark ~presents the results of spectroscopic observations of HD 65498 (DY Lynx). The object is listed in Simbad database as an 
eclipsing binary of Algol type with V magnitude of $9\fmm67$ and color index $(B-V)=0\fmm56$.
Eclipsing nature of HD65498 was detected by SAVS (Semi Automatded Variability Search) described in Maciejewski et al. 2003.
 The light curve is typical for detached binaries and suggests similar components and partial eclipses with amplitude 0.4 mag. 
 The period of HD 65498 is 31.5 hours and the ephemeris is:

\begin{equation}
\begin{array}{r@{}r@{}l}
{\rm Min.~I = HJD~}2452704.48836 & {} + 1\fday31324 & {} \times E.  \\
\pm 0.00054 & {} \pm 0.00006 &  \\
\end{array}
\end{equation}

\footnotetext{Based on PST spectroscopic and SAVS photometric data}


To determine the spectral type of the star spectroscopic observations were made. The obtained spectrum corresponds to F5V star.
There are also seven measurements of the times of minima (Gurol B. et al., 2007, Brat L. et al., 2008, Brat L., et al., 2009)

We have observed the object spectroscopically with PST (Pozna\'n Spectroscopic Telescope), described in Baranowski et al. 2009, 
which is equipped with 0.5m mirror
and fiber-fed echelle spectrograph. The exposure times were 1800s and the spectra cover range from 4500 to 8250 \AA.
The thorium argon lamp provides calibration of the spectra with sigma RV of 100m/s.
The spectrograph box is thermally stabilized on the level of 0.1 deg.
Data reduction was performed with IRAF echelle package based script. For the RV measurement we have used IRAF FXCOR task . 
Cross correlation functions reveal three peaks (Figure 4). 
Two of them (low and broad) are connected with the eclipsing pair and the central one - the detected third component (the peak is high and narrow). 
We examined the profile of $H_{\alpha}$ (Figure 3) and $H_{\beta}$ and their shape is also tripple.

The light curve and radial velocities enable us to obtain Wilson-Devinney model of the system (Wilson \& Devinney 1971). 
We treat the third body as a third light. The time span of our spectra is about two months so 
they can be affected by the light time effect. The third component can be dynamically conected 
with the eclipsing pair or just on the same line of sight. Radial velocities of the third component are decreasing with time. 
The reason can be the mutual orbital motion.

Our spectroscopic data is shifted wzgledem the ephemeris. 
In order to make a simultaneous solution 
we calculated a new ephemeris based on both fotometric and spectroscopic observations:

\begin{equation}
\begin{array}{r@{}r@{}l}
{\rm Min.~I = HJD~}2452704.489 & {} + 1\fday313187 & {} \times E.  \\
\pm 0.001 & {} \pm 0.000003 &  \\
\end{array}
\end{equation}

Time span between spectroscopic and photometric data is about 6 years and the ephemeris is probably 
affected by light time effect.

The eclipsing pair consists of two similar components with masses $1.02 M_{\odot}, 1.05 M_{\odot}$ and 
radii $1.28 R_{\odot}, 1.26 R_{\odot}$, respectively (Table 2). 
The components are slightly evolved. We have no direct information on the color index of the eclipsing pair. 
We apply temperature of the first component from evolutionary tracks for obtained values of mass and radii. 
The temperature of the second component was fitted during the modeling. 
We found third light to be $0.364\pm0.016$ (normalization $l_1+l_2+l_3=1$). The color index of the system 
($B-V=0.47\pm0.05$, Tycho) suggest that the third component is hotter than the ecclipsing pair. The temperature must be higher than 
6500 K due to the mixing of light of the tree components (the eclipsing pair is cooler).
The new spectroscopic data in coming years will pozwoli to measure the mutual orbit, and also the mass of the 
third body, it must be higher than one solar mass. The new photometric data can be used to measure the light time
efect, measuring the times of minima of the eclipsing pair.



%available observations and evolutionary tracks. The color index of the system is %$B-V=0.48$ corresponding to temperature of 6450K (F6.5). It's a result of mixing the %light of treee components. The masses and radii of the eclipsing pair components %corespond to the age of ? Gyr. We applied temperatures to the eclipsing pair from %evolutionary tracks.
%Using simple equation and basing on the system B-V index we found the color of the %third component.
%We estimate the masses and radii of the component taking into account this color index %and age of the system.

\vskip 1cm

\centerline{Table 1. Radial velocities measurements}
\vskip 3mm
\begin{center}
\begin{tabular}{cccc}
\hline
HJD (+2454900) & RV1 (km/s) & RV2 (km/s) & RV3 (km/s)\\
\hline
12.319274 & -103.9 & 145.7 & 58.0\\
12.474967 & -54.6 & 91.6 & 58.3\\
12.504987 & -37.2 & 95.7 & 59.3\\
16.330385 & -81.7 & 121.4 & 56.6\\
16.356517 & -70.6 & 111.0 & 57.2\\
16.383448 & -61.0 & 120 & 58.4\\
24.527291 & 91.8 & -14.4 & 55.4\\
24.569706 & 93.1 & -45.8 & 55.6\\
25.413819 & -110.1 & 155.3 & 55.6\\
25.440946 & -114.6 & 157.3 & 55.5\\
35.327167 & 133.0 & -100.7 & 52.3\\
35.353276 & 128.1 & -93.4 & 51.9\\
35.379281 & 117.5 & -79.4 & 52.5\\
\hline
\end{tabular}
\end{center}

\vskip 5cm

%\vskip 1cm

\centerline{Table 2. Preliminary solution for the eclipsing pair.} 

\vskip 3mm
\begin{center}
\begin{tabular}{cccc}
\hline
parameter & component 1 & component 2\\
\hline
$i$ & \multicolumn{2}{c}{$89^{\circ}.2\pm1^{\circ}.5$}\\
$q$ & \multicolumn{2}{c}{$1.03\pm0.13$}\\
$a(R_{\odot})$ & \multicolumn{2}{c}{$6.42\pm0.09$}\\
$V_{\gamma} ~(km/s)$ & \multicolumn{2}{c}{$23.2\pm1.4$}\\
$\Omega$ & $6.07\pm0.22$ & $6.27\pm0.62$\\
$l_V$ &  $0.330\pm0.016$ & $0.306\pm0.016$\\ 
$T(K)$ & $5400$(fixed) & $5340\pm10$\\
$M(M_{\odot})$ & $1.017\pm0.050$ & $1.048\pm0.050$\\
$R(R_{\odot})$ & $1.280\pm0.054$ & $1.260\pm0.123$\\
\hline
\end{tabular}
\end{center}

\vskip 1cm

\IBVSfig{10cm}{LC_en.eps}{Light curve of HD 65498 compared with the synthetic curve.}

\vskip 1cm

\IBVSfig{10cm}{RV_en.eps}{Radial velocity curve for the three components of HD65498. The solid line presents RV measurements for the eclipsing pair and the dashed line for the third component.}

\vskip 1cm

%\vskip 1cm

%\centerline{Table 3}
%\vskip 3mm
%\begin{center}
%\begin{tabular}{cccc}
%\hline
%parameter & component 1 & component 2\\
%\hline
%$R_{pole}(R_{\odot})$ & $1.270\pm0.053$ & $1.247\pm0.119$\\
%$R_{point}(R_{\odot})$ & $1.299\pm0.074$ & $1.272\pm0.162$\\
%$R_{side}(R_{\odot})$ & $1.281\pm0.054$ & $1.256\pm0.123$\\
%$R_{back}(R_{\odot})$ & $1.295\pm0.054$ & $1.268\pm0.111$\\
%\hline
%\end{tabular}
%\end{center}

%\vskip 1cm


\IBVSfig{10cm}{Halpha.eps}{The $H_{\alpha}$ line profile (smooted) is tripple, we can see two and
 shallow lines conected with the eclipsing pair and deep central line - the third component. }

\IBVSfig{10cm}{ccf.eps}{The crosscorrelation function for the same spectrum as in figure 3.
 We have the low and broad peaks of the eclipsing pair and high and thin peak of the third component.}




\references
Gurol B., et al., 2007, {\it IBVS}, No. 5791

Brat L., et al., 2008, {\it OEJV}, 94

Brat L., et al., 2009, {\it OEJV}, 107

Maciejewski, G.,Czart, K., Niedzielski, A., Karska, A., 2003, {\it IBVS}, No. 5431\\
(http://www.astri.uni.torun.pl/$\sim$gm/SAVS)

Wilson, S. E., Devinney, E. J., 1971, {\it ApJ}, {\bf 166}, 605

Pr\v{s}a, A., Zwitter, T., 2005 {\it ApJ}, {\bf 628}, 426

Baranowski, R., et al., 2009, {\it MNRAS}, {\bf 396}, 2194\\
(http://www.astro.amu.edu.pl/PST/)





\endreferences


\end{document}
