\documentstyle[twoside]{article}

\input ibvs2.sty

\begin{document}
\IBVShead{4993}{2 December 2000}

\IBVStitle{On the Variability of G0--G9 Stars}

\IBVSauth{Adelman, S.J.$^1$; Davis, J.M.$^2$; Lee, A.S.$^3$}

\IBVSinst{Department of Physics, The Citadel, 171 Moultrie Street, Charleston, 
SC 29409, USA,\\ \indent email: adelmans@citadel.edu}
\IBVSinst{Department of Physics, The Citadel, 171 Moultrie Street, Charleston, 
SC 29409, USA,\\ \indent email: davisj@citadel.edu}
\IBVSinst{Department of Physics, The Citadel, 171 Moultrie Street, Charleston, 
SC 29409, USA,\\ \indent email: 2leea@citadel.edu}

\IBVStyp{ G }
\IBVSkey{photometry}
\IBVSabs{We investigate the Hipparcos Satellite photometry of G0-G9 stars. Most}
\IBVSabs{are not particularly variable over the 3 year observing period, but may}
\IBVSabs{be over a longer time. Stars for which further study is desirable are identified.}

\begintext

This paper examines the Hipparcos photometry (ESA 1997) of the G0-G9
stars in the Bright Star Catalogue, 5th edition (Hoffleit \& Warren
1991) and the Supplement of the 4th edition (Hoffleit et al.\ 1983).
The stars investigated include Cepheids, Algol type variables, BY
Draconis stars, FK Com variables, irregular and slow irregular
variables, R CrB stars, semi-regular variables, microvariables, stars
which need additional observations to determine their variability type,
and constant stars. Hipparcos photometry does not confirm the reported
variability of some stars which might indicate a change in the stellar
behavior or reflect the quality of previous photometry.

The mean amplitudes of various spectral types with at least 3 class
members given in Table 1 are indicative of variability. Stars with
spurious variability due to duplicity are excluded. When one allows
for known variables and statistics and compares these values with those
found for other spectral types, these values indicate that the G stars
are not particularly variable. Their means are similar to those found
for B6--B9 III stars (Adelman, Gentry, \& Sudiana 2000), for A0--A2 III--V
stars (Adelman, Flores, \& Patel (2000), A3--A7 III and A3--F0 IV stars
(Adelman 2000a), and K0--K4 III stars (Adelman 2000b). Even the
supergiants are not particularly variable which continues the trend
seen among the A and F supergiants (Adelman, Cay, Cay, \& Kocer 2000).
Our values are slightly smaller than those of Maeder (1980) whose mean
$V$ amplitudes are 0\fmm030 for G0--G9 Ib stars and 0\fmm025 for G0--G9
II stars. As Hipparcos obtained data for a period of 3 years, longer
period variability such as solar cycles have only been partially
sampled and the total variability may be greater.

Table 2 (available electronically from the IBVS site as 4993-t2.txt and
4993-t2.tex) contains the values for individual stars including those
which were not used in compiling these means. It shows for each star
the HR number (if any), names (Bayer, Flamsteed, and/or variable star
designations), the $V$ magnitude from the Bright Star Catalog and its
Supplement, the spectral type, the Hipparcos number, the standard error
(mag), the amplitude (mag), and comments (type of variable and some
NSV numbers if there was not space in the Names column).

\IBVSedata{4993-t2.txt}

\IBVSetable{4993-t2.tex}

Table 3 lists stars with amplitudes of variability of 0\fmm04 and
greater which are more variable than the other G stars. Some are
well-known variables while others particularly those with amplitudes of
order 0\fmm04 require additional observations.

{\it Acknowledgements.}
SJA wishes to thank the Citadel Development Foundation for their support. 

\vfill
\begin{center}
{\normalsize Table 1: The mean amplitudes of various types of G0 through G9 stars}
\vskip2mm
\begin{tabular}{lccl}
\hline
Spectral & \lower6pt\hbox{Number} & Mean amplitude & \lower6pt\hbox{Comment} \\[-3pt]
class & & (mag) \\
\hline
G0Ib & 5 & 0.024${}\pm{}$0.009 & \\
G0Ib--II & 3 & 0.020${}\pm{}$0.000 & \\
G2Ib & 5 & 0.024${}\pm{}$0.005 & \\
G2Ib--II & 4 & 0.022${}\pm{}$0.010 & \\
G3Ib & 5 & 0.020${}\pm{}$0.007 & \\
G5Ib & 5 & 0.172${}\pm{}$0.334 & 0.022${}\pm{}$0.005 without S Sge\\
G8Ib & 6 & 0.030${}\pm{}$0.006 & \\
G5II & 11 & 0.023${}\pm{}$0.006 & \\
G6II & 4 & 0.015${}\pm{}$0.006 & \\
G8II & 16 & 0.023${}\pm{}$0.004 & \\
G7II--III & 3 & 0.023${}\pm{}$0.006 & \\
G8II--III & 16 & 0.023${}\pm{}$0.008 & \\
G9II--III & 3 & 0.020${}\pm{}$0.000 & \\
G0III & 6 & 0.023${}\pm{}$0.008 & \\
G2III & 4 & 0.022${}\pm{}$0.005 & \\
G3III & 5 & 0.028${}\pm{}$0.008 & \\
G4III & 6 & 0.020${}\pm{}$0.000 & \\
G5III & 37 & 0.025${}\pm{}$0.010 & \\
G6III & 21 & 0.024${}\pm{}$0.007 & \\
G7III & 28 & 0.023${}\pm{}$0.007 & \\
G7+III & 3 & 0.020${}\pm{}$0.000 & \\
G7.5III & 4 & 0.020${}\pm{}$0.008 & \\
G8III & 218 & 0.024${}\pm{}$0.014 & \\ 
G8+III & 5 & 0.020${}\pm{}$0.012 & \\
G8.5III & 15 & 0.018${}\pm{}$0.007 & \\
G8--K0III & 27 & 0.024${}\pm{}$0.007 & \\
G9--III & 3 & 0.017${}\pm{}$0.006 & \\
G9III & 76 & 0.022${}\pm{}$0.007 & \\
G9.5III & 9 & 0.020${}\pm{}$0.007 & \\
G5III--IV & 3 & 0.020${}\pm{}$0.010 & \\
G8III--IV & 18 & 0.034${}\pm{}$0.044 & 0.024${}\pm{}$0.005 without $\lambda$~And\\
G9III-IV & 7 & 0.021${}\pm{}$0.004 &\\
G0IV & 6 & 0.032${}\pm{}$0.026 & 0.022${}\pm{}$0.011 without HR 6105\\
G1IV & 3 & 0.020${}\pm{}$0.010 &\\
G2IV & 6 & 0.023${}\pm{}$0.019 & 0.016${}\pm{}$0.005 without $\phi$~Vir\\
G2.5IV & 3 & 0.020${}\pm{}$0.000 &\\
G3IV & 5 & 0.020${}\pm{}$0.007 &\\
G5IV & 17 & 0.028${}\pm{}$0.010 & 0.026${}\pm{}$0.006 without HR 7639\\
G6IV & 3 & 0.020${}\pm{}$0.000 & \\
G8IV & 18 & 0.030${}\pm{}$0.019 & 0.024${}\pm{}$0.006 without HR 878 \& HR 1362\\
G8--K0IV & 4 & 0.030${}\pm{}$0.000 &\\
G9IV & 4 & 0.025${}\pm{}$0.006 &\\
\hline
\end{tabular}
\end{center}

\eject

\begin{center}
{\normalsize Table 1 (cont.)}
\vskip2mm
\begin{tabular}{lccl}
\hline
Spectral & \lower6pt\hbox{Number} & Mean amplitude & \lower6pt\hbox{Comment} \\[-3pt]
class & & (mag) \\
\hline
G0IV--V & 3 & 0.037${}\pm{}$0.006 &\\
G0V & 40 & 0.029${}\pm{}$0.024 & 0.025${}\pm{}$0.008 without $\sigma$~CrB\\
G1V & 16 & 0.024${}\pm{}$0.006 &\\
G1.5Vb & 3 & 0.023${}\pm{}$0.015 &\\
G2V & 14 & 0.026${}\pm{}$0.008 &\\
G2.5V & 3 & 0.027${}\pm{}$0.006 &\\
G3V & 14 & 0.024${}\pm{}$0.006 &\\
G4V & 13 & 0.028${}\pm{}$0.009 &\\
G5V & 18 & 0.029${}\pm{}$0.012 &\\
G6V & 6 & 0.030${}\pm{}$0.021 & 0.022${}\pm{}$0.008 without HR 2162\\
G7V & 3 & 0.030${}\pm{}$0.010 &\\ 
G8V & 12 & 0.034${}\pm{}$0.034 & 0.025${}\pm{}$0.005 without HR 4550\\ 
G9V & 6 & 0.040${}\pm{}$0.025 & 0.030${}\pm{}$0.007 without V711 Tau\\ \hline
\end{tabular}
\end{center}

\vfill

\begin{center}
{\normalsize Table 3: Stars with amplitudes greater than 0\fmm03}
\vskip2mm
\begin{tabular}{lrlrccl}
\hline
\lower6pt\hbox{Name} & HD & Spectral & HIP & SE & Amp. & \lower6pt\hbox{Comments}\\[-3pt]
& No. & Type & No. & (mag)& (mag) & \\
\hline
U Sgr & 170764 & G1.5Ib & 90836 & 0.0683 & 0.72 & DCEP\\
10 S Sge & 188727 & G5Ib & 98085 & 0.0616 & 0.77 & DCEP\\
56 Peg & 218356 & G8Ib &114155 & 0.0011 & 0.04 & U\\
R CrB & 141527 & G0Iep & 77442 & 0.0075 & 0.56 & RCB\\
RY Sgr & 180093 & G0Ipe(C1,0) & 94730 &0.1050 &1.74& RCB\\
HR 2641 & 52703 & G8II--III &33774 & 0.0012 & 0.04 & MV\\
HR 3043 & 63660 & G0III & 38146 & 0.0006 & 0.04 & U\\
HR 4006 & 88639 & G3IIIFe-1&50109 & 0.0006 & 0.04 & U\\
$\iota$~Tuc & 6793 & G5III & 5268 & 0.0028 & 0.06 & U\\
HR 3922 & 85945 & G5III & 48802 & 0.0014 & 0.04 & U\\
$\epsilon$~UMi&153751 &G5III & 82080 & 0.0012 & 0.05 & EA\\
HR 3636 & 78668 & G6III & 44936 & 0.0007 & 0.04 & MV\\
$\chi$~Eri& 11937 & G8IIIbCNIV& 9007& 0.0025 & 0.04 & U\\
GZ Eri & 27362 & G8III & 20075 & 0.0043 & 0.16 & L\\
V403 Aur & 39743 & G8III & 28162 & 0.0057 & 0.13 & I\\
NSV 3072 & 47973 & G8III & 31765 & 0.0047 & 0.08 & U\\
72$\tau$~Cnc& 78235 & G8III & 44818 & 0.0013 & 0.04 & MV\\
HR 5896 & 141853 & G8III & 77689 & 0.0009 & 0.04 & \\
NSV 7785 & 148897 & G8IIICN-2CH-1& 80843&0.0010 & 0.04 &P\\
HR 7010 & 172424 & G8III & 91523 & 0.0009 & 0.04 &\\
$\xi$~Her & 163993 & G8+III & 87933 & 0.0012 & 0.04 & SR\\
HR 3907 & 85505 & G9III & 48413 & 0.0015 & 0.04 & \\
47 o Dra & 175306 & G9IIIFe-0.5&92512&0.0009 & 0.04 & RS\\
HR 7325 & 181122 & G9III & 94916 & 0.0009 & 0.04 & \\
24 DK UMa & 82210 & G4III--IV& 46977 & 0.0013 & 0.05 & RS\\
16~$\lambda$~And&222107&G8III--IV&116584& 0.0142 & 0.21 & RS\\
HR 780 & 16589 & G0IV & 12300 & 0.0010 & 0.04 & U\\
HR 6105 & 147722 & G0IV & 80399 & 0.0008 & 0.08 & U\\
\hline
\end{tabular}
\end{center}

\eject

\begin{center}
{\normalsize Table 3 (cont.)}
\vskip2mm
\begin{tabular}{lrlrccl}
\hline
\lower6pt\hbox{Name} & HD & Spectral & HIP & SE & Amp. & \lower6pt\hbox{Comments}\\[-3pt]
& No. & Type & No. & (mag)& (mag) & \\
\hline
105~$\phi$~Vir&126868&G2IV & 70755 & 0.0028 & 0.06 & U\\
HR 1936 & 37501 & G5IV & 26190 & 0.0013 & 0.04 & \\
HR 7683 & 190771 & G5IV & 98921 & 0.0017 & 0.06 & U\\
HR 978 & 20277 & G8IV & 15241 & 0.0030 & 0.08 & U\\
HR 1362 & 27536 & G8IV: & 20263 & 0.0045 & 0.08 & U\\
HR 913 & 18894 & G0IV--V & 14124 & 0.0009 & 0.04 & \\
HR 5740 & 137510 & G0IV--V & 75535 & 0.0008 & 0.04 & \\
18 Cet & 4307 & G0V & 3559 & 0.0008 & 0.04 & \\
HR 4980 & 114630 & G0V & 64478 & 0.0008 & 0.04 & U\\
39 Ser & 142267 & G0VFe-0.5&77801 & 0.0014 & 0.04 & \\
17$\sigma$~CrB&146361&G0VCaIIe& 79607 & 0.0028 & 0.17 & RS\\
HR 8635 & 214953 & G0V &112117 & 0.0007 & 0.04 & \\
$\pi^{1}$~UMa&72905 & G1.5Vb & 42438 & 0.0010 & 0.04 & MV\\
9 BE Cet & 1835 & G2V & 1803 & 0.0016 & 0.04 & BY\\
HR 2290 & 44594 & G3V & 30104 & 0.0008 & 0.04 & \\
HR 2882 & 59967 & G4V & 36515 & 0.0020 & 0.05 & U\\
96~$\kappa^{1}$~Cet&20630&G5V & 15457 & 0.0022 & 0.04 & P\\
39 Tau & 25680 & G5V & 19076 & 0.0013 & 0.06 & U\\
HR 6748 &165185 & G5V & 88694 & 0.0013 & 0.04 & U\\
HR 7330 &181321 & G5V & 95149 & 0.0019 & 0.04 & \\
HR 8148 &202940 & G5V &105312 & 0.0011 & 0.04 & \\
HR 2162 & 41824 & G6V & 28796 & 0.0022 & 0.07 & U\\
HR 4864 &111395 & G7V & 62523 & 0.0011 & 0.04 & \\
HR 4550 &103095 & G8Vp & 57939 & 0.0009 & 0.14 & U\\
V711 Tau & 22468 & G9V & 16846 & 0.0035 & 0.09 & RS\\
\hline
\end{tabular}
\end{center}

\references

Adelman, S. J., 2000a, {\it IBVS}, No.\ 4969

Adelman, S. J., 2000b, {\it IBVS}, No.\ 4958

Adelman, S. J., Cay, I. H., Cay, M. T., Kocer, D., 2000, {\it IBVS}, No.\ 4947

Adelman, S. J., Flores, R. S. C., Jr., Patel, V., 2000, {\it IBVS}, No.\ 4984

Adelman, S. J., Gentry, M. L., Sudiana, I. M., 2000, {\it IBVS}, No.\ 4968

Adelman, S. J., Y\"{u}ce, K., Engin, S., 2000, {\it IBVS}, No.\ 4946 

ESA, 1997, {\it The Hipparcos and Tycho Catalogs}, SP-1200

Hoffleit, D., Warren, W. H., Jr., 1991, {\it The Bright Star Catalogue}, 5th 
Rev. Ed., ADC Selected Astronomical Catalogs, Vol. 1, NASA Goddard Space 
Flight Center

Hoffleit, D., Saladyga, P., Wlasuk, P., 1983, {\it A Supplement to the Bright 
Star Catalogue}, Yale University Observatory, New Haven, CT

Maeder, A., 1980, {\it A\&A}, {\bf 90}, 311

\end{document}


