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[vsnet-preprint 23] V559 Lyr preprint
V559 Lyr preprint
Dear Colleagues,
The following preprint on V559 Lyr will appear as IBVS No. 5085.
The figures are available at:
http://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/preprints/V559_Lyr/
Regards,
Taichi Kato
====
\documentstyle[twoside,epsf]{article}
\input{ibvs2.sty}
\begin{document}
\IBVShead{xxxx}{xx May 2001}
\IBVStitletl{Large-amplitude Irregular Variable V559 Lyr}
\IBVSauth{Taichi~Kato$^1$, Makoto~Uemura$^1$, Kesao~Takamizawa$^2$,
Timo~Kinnunen$^3$, \\
Hitoshi~Nakatani$^4$, Hitoshi~Itoh$^5$,Minoru~Sato$^6$}
\vskip 5mm
\IBVSinst{Dept. of Astronomy, Kyoto University, Kyoto 606-8502, Japan,
e-mail: tkato@kusastro.kyoto-u.ac.jp,\\
uemura@kusastro.kyoto-u.ac.jp}
\IBVSinst{Variable Star Observers League in Japan (VSOLJ), 65-1 Oohinata,
Saku-machi, Nagano 384-0502, Japan,
e-mail: k-takamizawa@nifty.ne.jp}
\IBVSinst{Sinirinnantie 16, SF-02660 Espoo, Finland,
e-mail: stars@personal.eunet.fi}
\IBVSinst{Variable Star Observers League in Japan (VSOLJ),
67-8-1-404 Aza-Kitakawara, Nakada-machi, Taihaku-ku, Sendai,
Miyagi 981-1103, Japan,
e-mail: GFD02037@nifty.ne.jp}
\IBVSinst{Variable Star Observers League in Japan (VSOLJ),
1001-105 Nishiterakara, Hachiouji-city, Tokyo 192-0153, Japan
e-mail: PXB02072@nifty.ne.jp}
\IBVSinst{Variable Star Observers League in Japan (VSOLJ),
Akita, Japan}
\IBVSobj{V559 Lyr}
\IBVStyp{L}
\IBVSkey{photometry, spectroscopy}
\begintext
V559 Lyr was a variable star discovered by Takamizawa (1998) as TmzV32.
Takamizawa (1998) noted little variation between 1994 and 1997, but
reported a deep fading by 1.7 mag in 1998 March. The object was then
considered as a possible eclipsing variable, and its suggested classification
was taken over in the 75-th Name List of Variable Stars (Kazarovets et al.
2000). One of the authors (T. Kinnunen) noted a gradual rise until early
1999, which made this classification unlikely. Since the sudden fade and
gradual rise looked more characteristic of an R CrB-type star, we called
for an intensive observing campaign through VSNET Collaboration
(http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/).
\vskip 3mm
The observations were photographically by Takamizawa and visually
by four observers. Takamizawa used twin patrol cameras equipped with
D=10cm f/4.0 telephoto lens and unfiltered T-Max 400 emulsions. Visual
observations were done with 44.5-cm, 20-cm, 30-cm and 40-cm reflectors
by Kinnunen, Nakatani, Itoh and Sato, respectively. All observations
used GSC magnitudes for comparison stars. Calibration of GSC magnitudes
in this field, using Tycho-2 $V$-magnitudes, has yielded a negligible
scatter and zero-point error (typically less than 0.2 mag). The overall
uncertainty of estimates will not exceed 0.4 mag, which will not affect
the following discussion. The total number of positive estimates
was 156.
\IBVSfig{10cm}{fig1.ps}{Light curve of V559 Lyr. Open and filled circles
represent photographic and visual observations, respectively.}
\vskip 3mm
The overall light curve based on these observations is shown in
Figure 1. A well-observed sudden fading between JD 2451250 and 2451300,
following the slow rise (JD 2450900--2451250, mentioned above), is evident.
Although the light curve became more complex after that, the general
tendency of fadings and slower recovery is not inconsistent with
R CrB-type variation. We took a low-resolution spectrum with a 1.88-m
telescope at Okayama Astrophysical Observatory (OAO) on 2000 April 29.
The dispersion was 5.9 \AA/pixel. The reduction was done with IRAF
(IRAF is distributed by the National Optical Astronomy Observatories),
using the flux calibration standard of Feige 34. The spectrum is shown
in Figure 2, which clearly shows an M-type spectrum with TiO absorption
features. The overall feature of the spectrum is consistent with a
normal M 3-5 III star. The spectrum is inconsistent with the R CrB-type
classification, and the star is most likely an large-amplitude irregular
L-type variable star.
\IBVSfig{10cm}{fig2.ps}{Spectrum of V559 Lyr. The unit in flux is
erg s$^{-1}$ cm$^{-2}$ \AA$^{-1}$}
\vskip 3mm
Large-amplitude L- and SR-type stars are relatively rare and, some of
them are cool carbon-rich stars which are considered to occasionally produce
dusts. Some stars, like V517 Oph (Kilkenny et al. 1992) and DY Per
(Alkins 1991, 1994) are sometimes considered as intermediate stars
between R CrB stars and hydrogen-rich L- ann SR-type stars (for a review,
see Clayton 1996). Such stars may be analogous to R CrB-type stars in the
mechanism of occasional deep fadings, but the case is not yet clear for
V559 Lyr. More detailed observations of the chemical composition are
therefore needed. It is noteworthy this variable was included in the
ROTSE test field (Akerlof et al. 2000), but the object was not picked
up as a variable star. Since ROTSE observed the field since 1998, the
object should have shown considerable variation during this period.
A retrospective study on the ROTSE data may reveal more details of
the variability of V559 Lyr.
\vskip 3mm
The authors are grateful to the staffs of Okayama Astrophysical
Observatory for helping our observation.
Part of this work is supported by a Research Fellowship of the
Japan Society for the Promotion of Science for Young Scientists (MU).
\references
Akerlof, C., Amrose, S., Balsano, R., Bloch, J., Casperson, D.,
Fletcher, S., Gisler, G., Hills, J., Kehoe, R., Lee, B., Marshall, S.,
McKay, T., Pawl, A., Schaefer, J., Szymanski, J., Wren, J., 2000,
AJ, 119, 1901
Alkins, A., 1991, IAUC No. 5400
Alkins, A., 1994, Balt. Astron., 3, 410
Clayton, G. C., 1996, PASP, 108, 225
Kazarovets, E. V., Samus, N. N., Durlevich, O. V., 2000, IBVS No. 4870
Kilkenny, D., Lloyd Evans, T., Bateson, F. M., Jones, A. F., Lawson, W. A.,
1992, Observatory, 112, 158
Takamizawa, K., 1998, {\it VSNET observations}, No. 10379 \\
(available from
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/obs10000/msg00379.html).
\end{document}
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