\documentstyle[twoside, epsfig]{article}

\input ibvs2.sty

\begin{document}

\IBVShead{5655}{26 October 2005}

\IBVStitle{Southern RR Lyrae Stars Exhibiting the Blazhko Effect}

\IBVSauth{Wils, Patrick$^1$; S\'odor, \'Ad\'am$^2$}
\IBVSinst{Vereniging Voor Sterrenkunde, Belgium; e-mail: patrick.wils@cronos.be}
\IBVSinst{Konkoly Observatory of the Hungarian Academy of Sciences, P.O. Box 67,
H-1525 Budapest, Hungary; e-mail: sodor@konkoly.hu}

\SIMBADobj{RX Cet}
\SIMBADobj{NSV 420}
\SIMBADobj{SS For}
\SIMBADobj{RV Cet}
\SIMBADobj{RX For}
\SIMBADobj{X Ret}
\SIMBADobj{GSC 5885-0757}
\SIMBADobj{XY Eri}
\SIMBADobj{NSV 1700}
\SIMBADobj{RY Col}
\SIMBADobj{VW Dor}
\SIMBADobj{RX Col}
\SIMBADobj{NSV 4350}
\SIMBADobj{SZ Hya}
\SIMBADobj{GSC 6619-1146}
\SIMBADobj{AF Vel}
\SIMBADobj{SZ Leo}
\SIMBADobj{NSV 5200}
\SIMBADobj{X Crt}
\SIMBADobj{IK Hya}
\SIMBADobj{GSC 6672-0596}
\SIMBADobj{SV Hya}
\SIMBADobj{AM Vir}
\SIMBADobj{GSC 6730-0109}
\SIMBADobj{GSC 5590-0758}
\SIMBADobj{GSC 6756-0012}
\SIMBADobj{GSC 8297-1427}
\SIMBADobj{FU Lup}
\SIMBADobj{NSV 7330}
\SIMBADobj{BT Sco}
\SIMBADobj{V494 Sco}
\SIMBADobj{UV Oct}
\SIMBADobj{CK Aps}
\SIMBADobj{GSC 6811-0414}
\SIMBADobj{S Ara}
\SIMBADobj{WW CrA}
\SIMBADobj{FO Pav}
\SIMBADobj{GSC 7448-0418}
\SIMBADobj{GSC 8814-0696}
\SIMBADobj{RS Oct}
\SIMBADobj{RT Gru}
\SIMBADobj{SS Oct}
\SIMBADobj{GSC 8826-0640}
\SIMBADobj{GSC 6964-0926}
\SIMBADobj{GSC 5828-0847}
\GCVSobj{RX Cet}
\GCVSobj{NSV 420}
\GCVSobj{SS For}
\GCVSobj{RV Cet}
\GCVSobj{RX For}
\GCVSobj{X Ret}
\GCVSobj{XY Eri}
\GCVSobj{NSV 1700}
\GCVSobj{RY Col}
\GCVSobj{VW Dor}
\GCVSobj{RX Col}
\GCVSobj{NSV 4350}
\GCVSobj{SZ Hya}
\GCVSobj{AF Vel}
\GCVSobj{SZ Leo}
\GCVSobj{NSV 5200}
\GCVSobj{X Crt}
\GCVSobj{IK Hya}
\GCVSobj{SV Hya}
\GCVSobj{AM Vir}
\GCVSobj{FU Lup}
\GCVSobj{NSV 7330}
\GCVSobj{BT Sco}
\GCVSobj{V494 Sco}
\GCVSobj{UV Oct}
\GCVSobj{CK Aps}
\GCVSobj{S Ara}
\GCVSobj{WW CrA}
\GCVSobj{FO Pav}
\GCVSobj{RS Oct}
\GCVSobj{RT Gru}
\GCVSobj{SS Oct}

\IBVStyp{  RRab  }
\IBVSkey{Variable stars, RR Lyrae stars, Blazhko effect}
\IBVSabs{Blazhko periods are given for 43 RRab stars based on data from ASAS3.}


\begintext

A fraction of the RR Lyrae variable stars show a cyclic modulation of the amplitude and shape of their light curves, known as the Blazhko effect (Blazhko, 1907). This effect has periods typically of the order of tens of days, and manifests itself as additional frequencies in the periodogram, very close to the main frequency. Its cause is not yet well understood.

Recently a large number of new variables were discovered in the Southern sky by the All Sky Automated Survey (ASAS3; Pojmanski, 2002 and 2003 and Pojmanski and Maciejewski, 2004 and 2005), among which there are a substantial number of RR Lyrae stars. Complete light curves of already known variables were obtained for the first time also. In this paper the RRab stars found by ASAS3 were studied more closely to search for the presence of the Blazhko effect.

We have chosen those RRab stars for detailed study from the ASAS database for which the folded light curve showed signs of modulation by visual inspection, i.e. increased scatter around the rising branch and light maxima. We analyzed the Fourier spectra of the candidate stars' light curve using the abilities of the MUFRAN package (Koll\'ath, 1990). We looked for modulation peaks in the prewhitened Fourier spectra around the pulsation frequency and its harmonics. We also scanned the whole possible modulation frequency range (from 0.0007~c/d to 0.2 c/d) looking for any feasible modulation frequency. During this process we fitted the light curve with the pulsation frequency, its harmonics and the first four trial modulation frequencies (i.e. $f_0\pm f_{\rm mod}$ and $2f_0\pm f_{\rm mod}$), and searched for a modulation frequency which gave significantly reduced {\it rms}\/ scatter of the fit, than the fit with only the pulsation frequency and its harmonics. We also examined whether the light curve folded with the pulsation period at different phases of the modulation showed significant changes in shape and amplitude. We accepted a candidate star to exhibit light curve modulation only if all the three tests were positive with the same modulation frequency.

The stars for which the Blazhko effect was positively identified are presented in Tables~1 and 2. In Table~1 we give new elements for the Blazhko RR Lyrae stars with already published Blazhko period. Here the old Blazhko periods are also given. In Table~2 data of the newly discovered or previously suspected Blazhko stars are given. The tables include the objects' GSC number, ASAS3 coordinates, the pulsation and the Blazhko periods in days and GCVS names (Kholopov et al., 1985) if exist. In Table~3, which is available only electronically\footnote{Available on the IBVS website as {\tt 5633-t3.txt}}, we give the Fourier parameters of the light curve fit for all stars. Table~3 includes the GCVS name or ASAS identifier of the star, the pulsation and modulation frequencies, the amplitudes ($A_1, ...\, A_8$) and phases ($\phi_1, ...\, \phi_8$) of the pulsation frequency and its harmonics, the amplitudes ($A_9, ...\, A_{12}$) and phases ($\phi_9, ...\, \phi_{12}$) of the first four modulation frequencies, the {\it rms}\/ scatter of the fit and the epoch which the phases refer to. The phases correspond to a sine-term solution.

\IBVSedata{5655-t3.txt}
\IBVSdataKey{5655-t3.txt}{}{}

\IBVSecomment{Table 3 with the Fourier parameters of the light curve fits.}

We got ambiguous results for two stars, namely for GSC~6756-0012 and for CK~Aps. They seem to be modulated according to all the three tests, but the effect is very weak compared to the scatter of the measurements. The suspected modulation periods are 74~d and 56~d for GSC~6756-0012 and CK~Aps respectively.

Phase plots at different phases of the Blazhko period are shown in Fig.~1 and Fig.~2 for UV~Oct and NSV~4350 respectively.

Animated figures for some of the stars are electronically available also.



\IBVSfig{9.5cm}{5655-f1.eps}{ASAS3 phased light curves of UV~Oct at different phases of the Blazhko cycle.}
\IBVSfigKey{5655-f1.eps}{UV Oct}{light curve}


Acknowledgements: Sebasti\'an Otero, John Greaves and Johanna Jurcsik are acknowledged for helpful suggestions. This research has utilized the ASAS3 public photometry catalogue, and the SIMBAD and VizieR databases operated at the {\it Centre de Donn\'ees Astronomiques (Strasbourg)}. \'A. S. acknowledges the financial support of OTKA grants T-043504 and T-048961.


\begin{table}
\small
\begin{center}
\label{elements}
\caption{New elements of known Blazhko RR Lyrae stars.}
\begin{tabular}{ccrr@{}lcr@{}llcll} 
\hline
GSC & ASAS ID & $P_{\mathrm puls}$\,[d] & \multicolumn{2}{c}{$P_{\mathrm Bl}$ old\,[d]} & Ref. & \multicolumn{2}{c}{$P_{Bl}$ new\,[d]} & GCVS & Note & \IBVSshortlink{http://archive.princeton.edu/\char126 asas/}{ASAS3} & \\
\hline
8866-1496 & 032520$-$6503.3 & 0.49201 &$>45$       &  & 1 & 161 &    & X Ret     &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/032520-6503.3}{032520-6503.3} \\
7591-1523 & 051508$-$4137.7 & 0.47884 & 90         & :& 2 &  82 &    & RY Col    &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/051508-4137.7}{051508-4137.7} \\
5458-0044 & 091349$-$0919.1 & 0.53723 & 25         &.8& 3 &  26 & .3 & SZ Hya    & * & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/091349-0919.1}{091349-0919.1} & \IBVStablefigure{5655-f3.eps} \\
6675-0028 & 120447$-$2740.7 & 0.65033 &$\approx 30$&  & 4 &  72 &    & IK Hya    &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/120447-2740.7}{120447-2740.7} \\
6730-0109 & 141345$-$2254.7 & 0.44794 &$\approx 26$&  & 5 &  26 & .6 &           & * & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/141345-2254.7}{141345-2254.7} & \IBVStablefigure{5655-f4.eps} \\
9522-0447 & 163225$-$8354.2 & 0.54258 & 82         & :& 1 & 145 &    & UV Oct    & * & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/163225-8354.2}{163225-8354.2} & \IBVStablefigure{5655-f5.eps} \\
\hline
\end{tabular}
\end{center}
{*} Animated figure is available electronically.

References: (1)~Hoffmeister, 1956; (2)~Kinman, 1960; (3)~Kany\'o, 1970; (4)~Andrews et al., 1982; (5)~Wils \& Greaves, 2004.

\IBVSfigKey{5655-f3.eps}{SZ Hya}{light curve}
\IBVSfigKey{5655-f4.eps}{GSC 6730-0109}{light curve}
\IBVSfigKey{5655-f5.eps}{UV Oct}{light curve}

\begin{center}
\label{new}
\caption{Elements of new and suspected Blazhko RRab stars of the ASAS database.}
\vskip2mm
\begin{tabular}{ccrr@{}llclll} 
\hline
GSC & ASAS ID & $P_{\mathrm puls}$\,[d] & \multicolumn{2}{c}{$P_{\mathrm Bl}$\,[d]} & GCVS & Ref. & Note & \IBVSshortlink{http://archive.princeton.edu/\char126 asas/}{ASAS3} & \\
\hline
5847-1684 & 003338$-$1529.2 & 0.57373 & 256 &    & RX Cet    & 1 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/003338-1529.2}{003338-1529.2} \\
7540-0920 & 010949$-$4418.9 & 0.48440 &  62 & .5 & NSV 420   &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/010949-4418.9}{010949-4418.9} \\
6432-1585 & 020752$-$2651.9 & 0.49543 &  34 & .8 & SS For    & 1 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/020752-2651.9}{020752-2651.9} \\
5281-1037 & 021515$-$1048.0 & 0.62341 & 112 &    & RV Cet    & 2 & * & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/021515-1048.0}{021515-1048.0} & \IBVStablefigure{5655-f6.eps} \\
6442-0690 & 031113$-$2629.0 & 0.59731 &  31 & .8 & RX For    & 1 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/031113-2629.0}{031113-2629.0} \\
5885-0757 & 040011$-$1949.6 & 0.60225 & 122 &    &           &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/040011-1949.6}{040011-1949.6} \\
5318-0800 & 041117$-$1350.9 & 0.55426 &  50 &    & XY Eri    & 1 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/041117-1350.9}{041117-1350.9} \\
8082-0469 & 044131$-$5216.6 & 0.54861 &  34 & .0 & NSV 1700  &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/044131-5216.6}{044131-5216.6} \\
8905-0975 & 060746$-$6658.6 & 0.57057 &  25 & .9 & VW Dor    & 1 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/060746-6658.6}{060746-6658.6} \\
7084-0453 & 061315$-$3715.0 & 0.59376 & 130 &    & RX Col    & 1 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/061315-3715.0}{061315-3715.0} \\
9506-1365 & 085448$-$8317.0 & 0.47786 &  36 & .8 & NSV 4350  &   & * & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/085448-8317.0}{085448-8317.0} & \IBVStablefigure{5655-f7.eps} \\
6619-1146 & 102608$-$2315.2 & 0.59826 &  59 &    &           &   & * & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/102608-2315.2}{102608-2315.2} & \IBVStablefigure{5655-f8.eps} \\
8207-1400 & 105303$-$4954.4 & 0.52741 &  59 &    & AF Vel    & 3 & * & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/105303-4954.4}{105303-4954.4} &
 \IBVStablefigure{5655-f9.eps} \\
0847-0851 & 110137$+$0810.0 & 0.53408 & 179 &    & SZ Leo    & 2 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/110137+0810.0}{110137+0810.0} & \\
5515-0451 & 112614$-$1404.1 & 0.50290 &  63 &    & NSV 5200  &   & * & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/112614-1404.1}{112614-1404.1} & \IBVStablefigure{5655-f10.eps} \\
5520-0554 & 114856$-$1026.5 & 0.73284 & 143 &    & X Crt     & 2 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/114856-1026.5}{114856-1026.5} \\
6672-0596 & 121206$-$2612.8 & 0.39878 &  48 & .3 &           &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/121206-2612.8}{121206-2612.8} \\
6686-0081 & 123030$-$2602.9 & 0.47855 &  63 &    & SV Hya    & 1 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/123030-2602.9}{123030-2602.9} \\
6120-0430 & 132333$-$1639.9 & 0.61509 &  49 & .8 & AM Vir    & 2 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/132333-1639.9}{132333-1639.9} \\
5590-0758 & 145315$-$1435.9 & 0.54007 &  41 & .7 &           &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/145315-1435.9}{145315-1435.9} \\
8297-1427 & 150327$-$4756.1 & 0.60058 &  49 & .5 &           &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/150327-4756.1}{150327-4756.1} \\
7833-0197 & 150924$-$4319.6 & 0.38215 &  42 & .4 & FU Lup    &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/150924-4319.6}{150924-4319.6} \\
7842-0863 & 155553$-$4041.7 & 0.58198 &  48 & .8 & NSV 7330  &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/155553-4041.7}{155553-4041.7} \\
5613-0312 & 161256$-$0827.5 & 0.54871 &  78 &    & BT Sco    & 4 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/161256-0827.5}{161256-0827.5} \\
6811-0414 & 170223$-$2422.0 & 0.46137 &  22 & .2 &           &   & * & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/170223-2422.0}{170223-2422.0} & \IBVStablefigure{5655-f11.eps} \\
7376-0369 & 174048$-$3132.6 & 0.42730 & 455 &    & V494 Sco  & 2 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/174048-3132.6}{174048-3132.6} \\
8352-0201 & 175911$-$4926.0 & 0.45186 &  49 & .5 & S Ara     &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/175911-4926.0}{175911-4926.0} \\
7911-1078 & 180537$-$4350.0 & 0.55949 &  35 & .5 & WW CrA    &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/180537-4350.0}{180537-4350.0} \\
9089-0842 & 195142$-$6244.1 & 0.55144 & 571 &    & FO Pav    &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/195142-6244.1}{195142-6244.1} \\
7448-0418 & 195927$-$3400.1 & 0.37972 &  45 & .7 &           &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/195927-3400.1}{195927-3400.1} \\
8814-0696 & 212433$-$5712.1 & 0.60514 & 133 &    &           &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/212433-5712.1}{212433-5712.1} \\
9532-0988 & 214714$-$8739.0 & 0.45800 & 244 &    & RS Oct    & 1 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/214714-8739.0}{214714-8739.0} \\
8437-1538 & 215159$-$4559.1 & 0.51216 &  87 &    & RT Gru    & 5 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/215159-4559.1}{215159-4559.1} \\
9524-1884 & 215335$-$8246.7 & 0.62185 & 145 &    & SS Oct    & 1 &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/215335-8246.7}{215335-8246.7} \\
8826-0640 & 223427$-$5635.4 & 0.61499 &  63 &    &           &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/223427-5635.4}{223427-5635.4} \\
6964-0926 & 225248$-$2442.2 & 0.52956 & 182 &    &           &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/225248-2442.2}{225248-2442.2} \\
5828-0847 & 232031$-$1447.9 & 0.62697 &  54 &    &           &   &   & \IBVSshortlink{http://www.astrouw.edu.pl/cgi-asas/asas_lc/232031-1447.9}{232031-1447.9} \\
\hline
\end{tabular}
\end{center}
{*} Animated figure is available electronically.

References: (1)~Kov\'acs, 2005; (2)~Jurcsik \& Kov\'acs, 1996; (3)~Breger, 1965; (4) Zessewitsch \& Szczepanowska, 1967; (5) Clube et al., 1969. \\
\end{table}

\IBVSfigKey{5655-f6.eps}{RV Cet}{light curve}
\IBVSfigKey{5655-f7.eps}{NSV 4350}{light curve}
\IBVSfigKey{5655-f8.eps}{GSC 6619-1146}{light curve}
\IBVSfigKey{5655-f9.eps}{AF Vel}{light curve}
\IBVSfigKey{5655-f10.eps}{NSV 5200}{light curve}
\IBVSfigKey{5655-f11.eps}{GSC 6811-0414}{light curve}


\IBVSfig{9.5cm}{5655-f2.eps}{ASAS3 phased light curves of NSV~4350 at different phases of the Blazhko cycle.}
\IBVSfigKey{5655-f2.eps}{NSV 4350}{light curve}

\newpage
\references

Andrews, P. J., et al., 1982, in: {\it QJRAS}, {\bf 23}, 610 \ADSBIBCODE{1982QJRAS..23..608.}

Blazhko, S., 1907, {\it Astron. Nachr.}, {\bf 173}, 325

Breger, M., 1965, {\it MNASSA}, {\bf 24}, 72

Clube, S. V. M., Evans, David S., and Jones, D. H. P., 1969, {\it Mem. RAS}, {\bf 72}, 101

Hoffmeister, C., 1956, {\it VSS}, {\bf 3}, 1

Jurcsik, J., Kov\'acs, G., 1996, {\it Astron. \& Astroph.}, {\bf 312}, 111

Kany\'o, S., 1970, {\it IBVS}, No.\,490

Kholopov, P.N. et al., 1985, {\it General Catalogue of Variable Stars} 4th edition Volumes I-III, Moscow, Nauka Publishing House

Kinman, T. D., 1961, {\it Roy. Obs. Bull.}, 37, 151, (Ser. E.)

Kov\'acs, G., 2005, {\it Astron. \& Astroph.}, {\bf 438}, 227

Koll\'ath, Z., 1990, {\it Occ. Techn. Notes Konkoly Obs.}, No. 1, \\ {\tt http://www.konkoly.hu/staff/kollath/mufran.html}

Pojmanski, G., 2002, {\it Acta Astron.}, {\bf 52}, 397

Pojmanski, G., 2003, {\it Acta Astron.}, {\bf 53}, 341. 

Pojmanski, G., Maciejewski, G., 2004, {\it Acta Astron.}, {\bf 54}, 153

Pojmanski, G., Maciejewski, G., 2005, {\it Acta Astron.}, {\bf 55}, 97

Wils, P., Greaves, J., 2004, {\it IBVS}, No.\,5491

Zessewitsch, W., Szczepanowska, A., 1967, {\it Rocznik Astr.}, {\bf 39}, 101

\endreferences


\end{document}
