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\IBVShead{5085}{23 May 2001}

\IBVStitle{Large-amplitude Irregular Variable V559 L\lowercase{yr}}

\IBVSauth{Kato, Taichi$^1$; Uemura, Makoto$^1$; Takamizawa, Kesao$^2$; Kinnunen, Timo$^3$;\\ Nakatani, Hitoshi$^4$; Itoh, Hitoshi$^5$; Sato, Minoru$^6$}

\IBVSinst{Dept.\ of Astronomy, Kyoto University, Kyoto 606-8502, Japan,
e-mail: tkato@kusastro.kyoto-u.ac.jp,\\ \indent uemura@kusastro.kyoto-u.ac.jp}

\IBVSinst{Variable Star Observers League in Japan (VSOLJ), 65-1
Oohinata, Saku-machi, Nagano 384-0502, Japan,\\ \indent 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,\\ \indent 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,\\ \indent Japan, e-mail: PXB02072@nifty.ne.jp}

\IBVSinst{Variable Star Observers League in Japan (VSOLJ), Akita,
Japan}

\SIMBADobj{V559 Lyr}
\IBVStyp{ L }
\IBVSkey{photometry, spectroscopy}

\begintext

V559 Lyr is 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\fmm7 in 1998 March.  The object was then
considered as a possible eclipsing variable, and its suggested classification
was taken over in the 75th 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://www.kusastro.kyoto-u.ac.jp/vsnet/).

The observations were taken photographically by Takamizawa and visually
by four observers.  Takamizawa used twin patrol cameras equipped with
$D=10$~cm $f/4.0$ 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\fmm2).  The overall
uncertainty of estimates will not exceed 0\fmm4, which will not affect
the following discussion.  The total number of positive estimates
was 156.

\IBVSfig{10cm}{5085-f1.ps}{Light curve of V559 Lyr. Open and filled circles
represent photographic and visual observations, respectively}

\IBVSfig{10cm}{5085-f2.ps}{Spectrum of V559 Lyr. The unit in flux is
erg\,s$^{-1}$\,cm$^{-2}$\,\AA$^{-1}$}

\vskip-22pt
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 an 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 a
large-amplitude irregular L-type variable star.

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 
(Alksnis 1991, 1994) are sometimes considered as intermediate stars
between R CrB stars and hydrogen-rich L- and 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 that 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.

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,
{\it AJ}, {\bf 119}, 1901

Alksnis, A., 1991, {\it IAUC}, No.\ 5400

Alksnis, A., 1994, {\it Balt.\ Astron.}, {\bf 3}, 410

Clayton, G. C., 1996, {\it PASP}, {\bf 108}, 225

Kazarovets, E. V., Samus, N. N., Durlevich, O. V., 2000, {\it IBVS}, No.\ 4870

Kilkenny, D., Lloyd Evans, T., Bateson, F. M., Jones, A. F., Lawson, W. A.,
1992, {\it Observatory}, {\bf 112}, 158

Takamizawa, K., 1998, {\it VSNET observations}, No.\ 10379 (available from\\
http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/obs10000/msg00379.html)

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