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\input ibvs2.sty

\begin{document}

\IBVShead{4869}{31 March 2000}

\IBVStitle{Pulsations of V927 Herculis}

\IBVSauth{Hintz, Eric G.; Garvin, Matthew B.}

\IBVSinsto{Brigham Young University, Dept.\ of Physics \&
Astronomy, Provo, Utah, 84602, USA \\ \indent e-mail:
doctor@tardis.byu.edu, mbg2@email.byu.edu}

\SIMBADobjAlias{V927 Her}{SAO 30162}

\begintext

V927 Herculis ($\alpha_{2000} = 16\hr56\mm19\fsec9$,
$\delta_{2000} =+50\deg07\arcm36\farcs8$, HIP 82883, HD 234366,
GSC 03506-01493) was found to be a variable star by the HIPPARCOS
satellite. The Variability Annex of the HIPPARCOS Catalogue (ESA
1997) reports V927 Her to have a period of 0\fday130528 with $H_{p}$
magnitudes ranging between 10.125 to 10.233.  The spectral type is
listed as F5, but no further classification is given. Duerbeck
(1997) lists V927 Her (although it is identified as V925 Her) as an
F5 V and classifies it as a pulsator, which would make it a
$\delta$ Scuti candidate.

As part of our ongoing $\delta$ Scuti star program we selected
stars from the Variability Annex of the HIPPARCOS Catalogue that
showed $\delta$ Scuti type characteristics. During the summer of
1999 several of these variable stars were observed with the David
Derrick Telescope of the Orson Pratt Observatory at Brigham Young
University (Hereafter DDT). Observations were made with a Pictor
416XT CCD mounted at the Newtonian focus of the telescope. This
gave a plate scale of 0.93 arcsec/pixel. Observations were made
through a standard Johnson $V$ filter modeled after Bessell
(1990). In this paper we will report only the observations of V927
Her. Five nights of data were obtained between 20 May and 22 July
1999. The CCD field for the DDT is shown in Fig.~1.

All frames were reduced using standard IRAF functions. Apparent
magnitudes were determined using the comparison star (GSC
03506-01588 ($V$ = 10.56), \hbox{TYCHO 3506-1588-1} ($V_{J}$ = 10.54))
labeled Comp~1 in Fig.~1. From this we found an average magnitude
of V927 Her of $V_{J}$ = 9.92.

From the light curves produced six times of maximum light were
determined. These times are given in Table~1. From a linear
regression we found an ephemeris for V927 Her as given in Eq.~1.
This value is in agreement with the value from HIPPARCOS.
\begin{equation}
{\rm HJD_{max}} = 2451318.7659 + 0.13053\mathbin{(\pm} 0.00001) \times E.
\end{equation}

\IBVSfig{9cm}{4869-f1.ps}{CCD field of V927 Her with comparison
star labeled. The field of view is $8\arcm\times12\arcm$.}

\IBVSfig{10cm}{4869-f2.ps}{Phased light curve of V927 Herculis}

\vskip-22pt
Using Eq.~1 the data were phased and the curve is shown in Fig.~2.
Clearly the amplitude of V927 Her is not constant.  The amplitude
varies from 0.05 to 0.14, with the magnitude of minimum light
staying at a roughly constant value of 9.98. Due to this variable
amplitude we choose to examine the data with the frequency search
program Period98. From Period98 we found the presence of only two
reliable frequencies in the data $f_{1} = 7.6628$ c/d ($P_{1} =
0\fday130512$) and $f_{2} = 8.0020$ c/d ($P_{2} = 0\fday124981$).  This
yields a period ratio of 0.96. A third frequency of $f = 0.57$ c/d
was found that is not equivalent to $f_{2} - f_{1}$.  However,
this third frequency is not considered reliable. If confirmed the
third frequency is $\gamma$ Doradus like (Kaye et al.\ 1999). If
the third period could be confirmed V927 Her would have to be
considered a Hybrid.

The current data set is too small, and from a single site, for any
major conclusions to be drawn. A set of Str{\" o}mgren data to
determine physical parameters and data from multiple sites would
be useful to define the nature of this star.

\begin{table}
\caption{New times of maximum light for V927 Herculis}
\begin{center}
\begin{tabular}{cc}
\hline HJD & \lower6pt\hbox{Cycle}
\\[-3pt] 2400000.0\,+ & \\ \hline
    51318.7673   & 0\\
    51341.7384   & 176\\
    51341.8715   & 177\\
    51348.7862   & 230\\
    51363.7932   & 345\\
    51381.6850   & 482\\
\hline
\end{tabular}
\end{center}
\end{table}

\bigskip

\references

Bessell, M. S. 1990, {\it PASP}, {\bf 102}, 1181

Duerbeck, H.W. 1997, {\it IBVS}, No.\ 4513

ESA, 1997, The HIPPARCOS Catalogue, ESA, SP-1200

Kaye, A.B., Handler, G., Krisciunas, K., Poretti, E., and Zerbi,
F.M., 1999, {\it PASP}, {\bf 111}, 840



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