\documentstyle[twoside, epsf]{article} 
 
\input ibvs2.sty 
 
\begin{document} 
\IBVShead{5474}{3 November 2003}
 
\IBVStitle{New Variable Star in the Field of EM C\lowercase{yg}}
 
\IBVSauth{Spogli, Corrado$^1$; Fiorucci, Massimo$^1$; Dolci, Mauro$^2$; Raimondo, Gabriella$^2$ } 
 
\IBVSinst{Dipartimento di Fisica, Universit\`a di Perugia, Via A. Pascoli 06123 Perugia, Italy} 
\IBVSinst{INAF - Teramo Astronomical Observatory, Collurania, Teramo, Italy} 
 
\IBVSabs{A new variable object is identified in the field of EM Cyg. Color}
\IBVSabs{indices are very red, and the near-infrared spectrum shows the}
\IBVSabs{feature of a cool late-type star, probably a semiregular LPV.}
                                  

\begintext 

During the analysis of our photometric images in the field of EM Cyg, 
we have found an unidentified extremely red object 
($V-I_c \simeq 5$) that shows variations of some tenths of magnitude.
The position is RA = 19\hr 38\mm 48\fsec3, 
DEC = +30\deg 28\arcm 58\arcs\ (J2000); Fig. 1 shows the finding chart.

\IBVSfig{9cm}{5474-f1.eps}{Finding chart of the new variable, centered on
the dwarf nova EM Cyg. North is on the top, East on the left; the field is
$5\arcm\times5\arcm$ wide.}
%%\IBVSfigKey{5474-f1.eps}{EM Cyg}{finding chart}

From the archival data of the Perugia and Teramo Observatories, we have
verified that the object has been variable since the first CCD frames
(in 1997) obtained for the monitoring of the dwarf nova EM Cyg.
However, the identification is recent because of the slow variations.

\IBVSfig{9cm}{5474-f2.eps}{I$_c$ light curve from July to October, 1997}
%%\IBVSfigKey{5474-f2.eps}{EM Cyg}{light curve}

\IBVSfig{9cm}{5474-f3.eps}{I$_c$ light curve from August to October, 2000}
%%\IBVSfigKey{5474-f3.eps}{EM Cyg}{light curve}


\IBVSfig{9cm}{5474-f4.eps}{$I-J$ spectrum of the variable. We have identified
the TiO 0.85$\mu$m, VO 1.06$\mu$m, TiO 1.10$\mu$m bands}
%%\IBVSfigKey{5474-f4.eps}{EM Cyg}{spectrum}

\IBVSfig{9cm}{5474-f5.eps}{The spectral energy distribution of the variable
is consistent with a 2800-3000 K star. In the H part of the spectrum 
we have identified the nine CO bands from 1.55 to 1.72 $\mu$m.}
%%\IBVSfigKey{5474-f5.eps}{EM Cyg}{spectrum}


The photometric data were obtained with the 0.72 m telescope at the
Teramo Astronomical Observatory, and the 0.40 m Automatic Imaging Telescope at
the Perugia University Observatory. Both telescopes are equipped with
CCD camera and $BVR_cI_c$ Johnson-Cousins broad-band filters.
The instruments used and the photometric 
techniques have already been described in Spogli et al. (1998, 2000). 
The data are obtained in differential photometry using the calibration stars 
reported by Misselt (1996), and Spogli et al. (2003).
Figs 2 and 3 show the I$_c$ light curve of the variable during 1997 and
2000. Variability is confirmed also with the sparse data obtained in 1998, 
and 2002. The R$_c$I$_c$ extreme values and the mean color indexes are 
summarized in Table 1. Our V data do not cover all the variation amplitude,
while in the B band the source is fainter than 18.5 mag. However, results are
uncertain for the presence of a faint star near the variable.

\vskip 0.2 cm
\centerline{\bf Table 1}
\vskip 3mm
\begin{center}
\begin{tabular}{ccccc|ccc}
\hline
\hline
R$_c$ max & R$_c$ min &~~& I$_c$ max & I$_c$ min & $\langle V-R_c\rangle$ & $\langle R_c-I_c\rangle$ & $\langle V-I_c\rangle$\\
13.7   & 14.8     &  &   11.0    &  11.8    &   2.0   &     3.1   &   5.1    \\
\hline
\end{tabular}
\end{center}
\vskip 2mm

From the maps of dust infrared emission (Schlegel et al., 1998) we can
estimate the reddening: A$_B\simeq2.2$, A$_V\simeq1.7$, A$_R\simeq1.3$,
A$_I\simeq1.0$.
It is evident that the source is very red, and this reddening cannot
be due to interstellar absorption alone. It was positively detected
by 2MASS (J = 8.55$\pm$0.02, H = 7.56$\pm$0.02, Ks = 7.04$\pm$0.02,
Cutri et al. 2003), and MSX (A = 0.20$\pm$0.02 Jy, Egan et al. 1999).
There is also a radio source centered $\simeq$10 arcsecs near the 
variable, but it is not clear if the radio emission is correlated to 
the variable star. The NVSS Catalogue (Condon et al., 1998) reports
an extended 1.4GHz source with major and minor axes less than 31.4 
and 25.9 arcsecs, respectively. Also the WENSS Catalogue (de Bruyn et
al., 1998) reports the presence of a 325 MHz source with a positional
accuracy of 5-10 arcsecs.

For a proper identification of the variable, we have used the SWIRCAM
low-resolution spectrometer ($R\sim300$) at the AZT-24 1.1m telescope
of the Campo Imperatore Observatory. The observations were made in
September 4$^{\rm th}$, 2002. Figs 4 and 5 show that the source
is a cool-star (${\rm T_{eff}}$ = 2800-3000 K), with large TiO, VO and CO absorption
bands. Our conclusion is that the star is a long-period variable, probably
a semi-regular. From the observations of this year we expect to have more
constraints to find the average period.

\references

Condon, J. J., Cotton, W. D., Greisen, E. W., et al., 1998, AJ 115, 1693
%\BIBCODE{1998AJ....115.1693C}

Cutri R.M., Skrutskie M.F., Van Dyk S., et al. 2003,
University of Massachusetts and Infrared Processing and Analysis Center
(IPAC/California Institute of Technology) (2003)
\ADSBIBCODE{2003yCat.2246....0C}

de Bruyn G., Miley G., Rengelink R., et al., 1998,
WENSS Collaboration NFRA/ASTRON and Leiden Observatory
\ADSBIBCODE{2000yCat.8062....0D}

Egan M.P., Price S.D., Moshir M.M., et al., 1999,
Air Force Research Lab. Technical Rep. AFRL-VS-TR-1999-1522
\ADSBIBCODE{2001yCat.5107.....E}

Misselt, K. A., 1996, PASP, 108, 146
%\BIBCODE{1996PASP..108..146M}

Schlegel, D. J., Finkbeiner, D. P., Davis, M., 1998, ApJ 500, 525
%\BIBCODE{1998ApJ...500..525S}

Spogli, C., Fiorucci, M., Raimondo, G., 2000, IBVS, 4944
%\BIBCODE{2000IBVS.4944....1S}

Spogli, C., Fiorucci, M., Raimondo, G., 2003, IBVS, 5365
%\BIBCODE{2003IBVS.5365....1S}

Spogli, C., Fiorucci, M., Tosti, G., 1998, A\&AS, 130, 485 
%\BIBCODE{1998A&AS..130..485S}

\endreferences

\end{document}
