\documentstyle[twoside, epsf]{article}

\input ibvs2.sty

\begin{document}
\IBVShead{4984}{10 November 2000}

\IBVStitle{On the Variability of A0--A2 Luminosity Class III--V Stars}

\IBVSauth{Adelman, S.J.; Flores, R.S.C., Jr.; Patel, V.J.}

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

\IBVStyp{ A }
\IBVSkey{photometry}
\IBVSabs{We study the Hipparcos Satellite photometry of A0-A2 luminosity class}
\IBVSabs{III-V stars. Most are not particularly variable. A few}
\IBVSabs{stars for which further study is desirable are identified.}

\begintext

This paper investigates the Hipparcos photometry (ESA 1997) of luminosity class
III--V A0--A2 stars from the Bright Star Catalogue, 5th edition (Hoffleit \& 
Warren 1991) and the Supplement of the 4th edition (Hoffleit et al.\ 1983).
These stars include $\delta$ Scuti variables, eclipsing binaries, SX Phe stars, 
ellipsoidal variables, and a few CP stars (although most studied by Adelman (1998) 
were excluded) along with microvariables and many stars which need additional 
observations to determine their variability type. 

Table 1 lists the mean amplitudes of various spectral types which have at least 
3 class members. These values indicate the mean variability. We excluded 
stars with spurious variability due to duplicity. A few values were calculated
again when they included stars whose amplitudes were much larger than those 
typical of their spectral type. The mean amplitudes are smaller than those of 
the corresponding supergiants (Adelman \& Albayrak 1997 and Adelman, Cay, Cay, \& 
Kocer 2000) and are generally comparable with the smallest such values 
previously seen in similar papers among the late B III--V stars (Adelman, Gentry, 
\& Sudiana 2000), the A3--F0 III--V stars (Adelman 2000a), and the K0--K4 III stars 
(Adelman 2000b).

Table 2 (available electronically from the IBVS site as 4984-t2.txt and
4984-t2.tex) contains the values for the individual A0--A2 III--V stars
including those which were not used in compiling these means. It lists
for each star the HR number (if any), names (Bayer, Flamsteed, or
variable star designations), the $V$ magnitude from the Bright Star
Catalogue and its Supplement, the spectral type, the Hipparcos number,
the standard error (mag), the amplitude (mag), and comments (type of
variable using the GCVS and NSV designations). The NSV number is
included in the comments field if another name is given in the names
column. 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 the previous photometry. Table 2 also contains
stars with amplitudes of 0\fmm01 which are candidates for use as
standards.

\IBVSedata{4984-t2.txt}

\IBVSetable{4984-t2.tex}

Table 3 lists selected stars with amplitudes of variability significantly 
greater than those of stars with the same spectral types, usually a factor of 
1.67 greater than the type mean, typically 0\fmm04. Some are well-known variables. 
Many of those with amplitudes of 0\fmm04 require further study. We doubt that 
$\alpha$ CMa (Sirius) is really variable. 

\begin{table}
\caption{The mean amplitudes of various types of A0--A2 stars}
\begin{center}
\begin{tabular}{lccl}
\hline
Spectral & \lower6pt\hbox{Number} & Mean amplitude & \lower6pt\hbox{Comment} \\[-3pt]
class & & (mag) & \\
\hline
A0III & 23 & 0.025${}\pm{}$0.006 & \\
A1III & 4 & 0.025${}\pm{}$0.006 & \\
A2III & 12 & 0.022${}\pm{}$0.006 & \\
A0III--IV & 3 & 0.027${}\pm{}$0.012 & \\ 
A2III--IV & 4 & 0.028${}\pm{}$0.005 & \\
A0IV & 22 & 0.030${}\pm{}$0.051 & \\
 & 21 & 0.020${}\pm{}$0.004 & without $\chi^{2}$~Hya\\ 
A1IV & 10 & 0.022${}\pm{}$0.006 & \\
A2IV & 34 & 0.029${}\pm{}$0.032 & \\
 & 32 & 0.022${}\pm{}$0.006 & without YZ Cas \& $\beta$~Aur\\ 
A2IV--V & 3 & 0.023${}\pm{}$0.012 & \\
A0V & 238 & 0.025${}\pm{}$0.024 & \\
 & 231 & 0.022${}\pm{}$0.007 & without 7 stars\\
A0--1V & 6 & 0.028${}\pm{}$0.008 & \\
A1V & 200 & 0.024${}\pm{}$0.017 & \\
 & 197 & 0.022${}\pm{}$0.007 & without TU Hor, $\alpha$ CMa, \& 75 KS Peg \\
A1--2V & 4 & 0.030${}\pm{}$0.000 & \\
A2V & 199 & 0.027${}\pm{}$0.043 & \\
 & 196 & 0.023${}\pm{}$0.009 & without 31 Cam, V2368 Oph, \& SX Phe \\
A2--A3V & 6 & 0.082${}\pm{}$0.146 & \\
 & 5 & 0.022${}\pm{}$0.004 & without ES Lib\\
\hline
\end{tabular}
\end{center}
\end{table}

\addtocounter{table}{1}
\begin{table}
\caption{Some stars with amplitudes great than stars of similar spectral type}
\begin{center}
\begin{tabular}{lrlrccl}
\hline
\lower6pt\hbox{Name} & HD & Spectral & HIP & SE & Amp. & \lower6pt\hbox{Comments} \\[-3.8pt]
 & No. & Type & No. & (mag) & (mag) & \\
\hline
HR 444 & 9484 & A0III & 7222 & 0.0010 & 0.04 & \\
HR 3962 & 87318 & A0III--IV & 49294 & 0.0010 & 0.04 & \\
$\chi^{2}$~Hya&96314&A0IV & 54255 & 0.0041 & 0.26 & EB\\
21 YZ Cas & 4161 & A2IV & 3572 & 0.0008 & 0.20 & EA/DM\\
34~$\beta$~Aur&40183&A2IV & 28360 & 0.0006 & 0.07 & EA\\
 & 23642 & A0Vp* & 17704 & 0.0013 & 0.04 & \\
 & 24966 & A0V & 18437 & 0.0009 & 0.04 & \\
HR 1524 & 30397 & A0V & 22136 & 0.0009 & 0.04 & \\
IW CMa & 45382 & A0V & 30583 & 0.0011 & 0.09 & U\\
HR 2328 & 45380 & A0Vn & 30675 & 0.0141 & 0.04 & U\\
 & 50126 & A0V & 32715 & 0.0011 & 0.04 & \\
PS Pup & 60168 & A0V & 36608 & 0.0022 & 0.10 & EA\\
HR 3019 & 63112 & A0V & 37951 & 0.0008 & 0.04 & \\
BU CMi & 65241 & A0V & 38945 & 0.0020 & 0.10 & NSV 3829, EA\\
37 OW Hya & 83650 & A0Vn & 47427 & 0.0015 & 0.33 & EA\\
HR 4428 & 99922 & A0V & 56078 & 0.0020 & 0.12 & U\\
 &113457 & A0V & 63839 & 0.0008 & 0.04 & \\
 &203112 & A0V &105237 & 0.0009 & 0.04 & \\
$\delta$~Scl&223352& A0V &117452 & 0.0014 & 0.09 & \\
 &152521 & A0/1V & 82792 & 0.0017 & 0.04 & \\
BD Phe & 11413 & A1Vp & 8593 & 0.0017 & 0.04 & DSCT\\
HR 597 & 12467 & A1V & 10054 & 0.0009 & 0.04 & \\
HR 875 & 18331 & A1Vn & 13717 & 0.0016 & 0.06 & \\
TU Hor & 21981 & A1V & 16339 & 0.0053 & 0.14 & ELL\\
 NSV 1359 & 24071 & A1V & 17797 & 0.0006 & 0.05 & U\\
9~$\alpha$~CMa&48915& A1Vm & 32349 & 0.0024 & 0.19 & \\
 34 Hya & 83373 & A1V & 47249 & 0.0009 & 0.04 & \\
 HR 4805 &109860 & A1V & 61637 & 0.0010 & 0.04 & \\
 &131637 & A1V & 73102 & 0.0008 & 0.04 & \\
 &133330 & A1V & 73635 & 0.0009 & 0.04 & \\
75 KS Peg &222133 & A1Vn &116611 & 0.0045 & 0.10 & EB\\
V357 And & 5066 & A2V & 4129 & 0.0025 & 0.06 & P\\
 & 14172 & A2V & 10856 & 0.0009 & 0.04 & \\
 32 Eri & 24554 & A2V & 18255 & 0.0011 & 0.06 & U\\
 HR 1324 & 26961 & A2V & 20070 & 0.0031 & 0.06 & ELL\\
 & 35859 & A2V & 25298 & 0.0010 & 0.04 & \\
31 Cam & 39220 & A2V & 27971 & 0.0029 & 0.16 & EB\\
 HR 3335 & 71581 & A2V & 41475 & 0.0011 & 0.04 & EA/DM\\
 &102481 & A2V & 57556 & 0.0009 & 0.04 & \\
 HR 6169 &149632 & A2V & 81231 & 0.0009 & 0.04 & \\
V2368 Oph &156208 & A2V & 84479 & 0.0008 & 0.13 & NSV 8438, EA\\
 HR 7857 &195922 & A2Vnn &101473 & 0.0015 & 0.04 & U\\
 SX Phe &223065 & A2V &117254 & 0.0216 & 0.59 & SXPHE\\
 VZ Psc &214484 & A2Vp &111809 & 0.0005 & 0.04 & EA\\
ES Lib &135681 & A2/3V & 74765 & 0.0188 & 0.38 & EB/KE\\
\hline
\end{tabular}
\end{center}
\end{table}

{\it Acknowledgements.\/} SJA wishes to thank the Citadel Development
Foundation for their support. RSCF has a US Marine Corps Scholarship.

\references

Adelman, S. J., 1998, {\it A\&AS}, {\bf 132}, 93

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

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

Adelman, S. J., Albayrak, B., 1997, {\it IBVS}, No.\ 4541

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

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

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


\end{document}

