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\IBVShead{4666}{29 January 1999}

\IBVStitle{The variable M giant GSC 0375-00202 $\equiv$ V866 H\lowercase{er}}

\IBVSauth{M.~Rejkuba$^{1}$, U.~Munari$^{2}$, T.~Tomov$^{2,3}$}
\vskip 0.3cm plus 0.1cm minus 0.1cm

\IBVSinst{Departamento de Astronom\'{\i}a y Astrof\'{\i}sica, Pontificia
          Universidad Cat\'{o}lica de Chile, Casilla 104, Santiago 22, Chile}
\IBVSinst{Osservatorio Astronomico di Padova, Sede di Asiago, via
          dell'Osservatorio 8, I-36012 Asiago (Vicenza), Italy}
\IBVSinst{Visiting Professor, Consiglio Nazionale delle Ricerche d'Italia,
          Unit\`a di Ricerca Padova-Asiago}

\SIMBADobj{V866 Her}
\IBVStyp{ * }
\IBVSkey{spectroscopy}


\begintext


The variability of V866\,Her (= Antipin V9 = GSC\,0375-00202 =
IRAS\,16582+4115) has been discovered by Antipin (1994). He found a
moderate amplitude and irregular variability, remarked about the star's
red color on Palomar charts and reported a 12\fmm1 $\leq B_{pg}
\leq14$\fmm2 range.

In 1995 and 1996 we obtained several spectra of V866\,Her with the
Padova \& Asiago Astronomical Observatories' 1.82 m telescope equipped
with the Boller\,\&\,Chivens+CCD and Echelle+CCD spectrographs. The
spectra were extracted and calibrated in a standard fashion using the
IRAF\IBVSfm\ reduction package on a PC running under the Linux
operating system. The journal of observations is given in Table~1.

\IBVSfoot{IRAF is distributed by the National Optical Astronomy
Observatories, which are operated by the Association of Universities
for Research in Astronomy, Inc., under cooperative agreement with the
National Science Foundation.}

\begin{table}[h]
\caption{Journal of observations}
\begin{center}
\begin{tabular}{ccccc}
\hline
Date & JD & Exp.\ time & Resolution & Instrument \\
     & 2400000+ & [sec] & [\AA]   &  \\       
\hline
11. Mar.\ 1995 & 49787.61 & 20+200  & 18 & B\&C + CCD \\
21. Mar.\ 1995 & 49798.50 & 900     & 0.3& Echelle + CCD \\
22. July 1995 & 49921.44 & 240     & 18 & B\&C + CCD \\
15. Oct.\ 1995 & 50006.26 & 60+180  & 18 & B\&C + CCD \\
14. May 1996 & 50218.39 & 180+180 & 18 & B\&C + CCD \\
09. July 1996 & 50274.35 & 60+240  & 18 & B\&C + CCD \\
\hline
\end{tabular}
\end{center}
\end{table}

The low-resolution spectra of V866\,Her, dominated by molecular
absorption bands, are typical for O-rich late type giants
(cf.\ Figure~1). A comparison with the M-giant spectra from the Silva
\& Cornell (1992) atlas show an excellent match to the M6III spectral
type (cf.\ Figure~2). The continuum in the Echelle+CCD is very much the
one expected from a M giant and no trace of emission lines is found
(cf.\ Figure~3 where a comparison is made with T~CrB in the H$\alpha$
region).

\IBVSfig{10cm}{4666-f1.eps}{The low-resolution spectra of V866\,Her.
The dates in the up left corner are arranged from top to bottom in the
same way as the spectra.}

\IBVSfig{10cm}{4666-f2.eps}{The spectrum of V866\,Her compared to
a M6III standard from Silva \& Cornell (1992).} 



\IBVSfig{10cm}{4666-f3.eps}{The H$\alpha$ Echelle order for V866\,Her compared to that of T\,CrB observed the same night. In V866\,Her there is evidently no trace of even the weakest H$\alpha$ in emission.}

\IBVSfig{10cm}{4666-f4.eps}{The NaI resonance doublet absorption
lines as observed in the Echelle spectrum of V866\,Her. The stellar and
interstellar components are marked.}


The heliocentric radial velocity of V866\,Her measured on the Echelle
spectrum is RV$_{\odot} = -84.2 \pm 0.3$~km\,s$^{-1}$,
suggesting a relationship to the spheroidal galactic component. The NaI
doublet shows two components (cf.\ Figure~4), one at RV$_{\odot} = -85.3
\pm 0.25$~km\,s$^{-1}$ (therefore of stellar origin) and another at
V$_{\odot} = -23.9 \pm 2.8$~km\,s$^{-1}$ of a most probable
interstellar origin.


The equivalent width of the interstellar NaI~D absorptions in the
V866\,Her Echelle spectrum is 0.18\,\AA, which corresponds to a
reddening of $E_{B-V} = 0.06$~mag according to the Munari \&
Zwitter (1997) calibration. It is worth to note that the Burstein \&
Heiles' (1982) global maps give a value $E_{B-V} = 0.0$ in the
direction of V866\,Her, which is evidently not the case given the
presence of fairly strong interstellar NaI~D lines.  Combining a mean
$\langle B_{pg}\rangle =13\fmm0$ with a color $B-V = 1.58$~mag
appropriate for a M6III and the absolute $M_V$ magnitudes for the M
giants belonging to the spheroidal galactic component ($M_V= -1.6$ mag,
Frogel and Whitford 1987), a distance to V866\,Her of 3.7~kpc is found.
The galactic coordinates of V866\,Her are $l = 65\fdeg54$,
$b = +37\fdeg 86$, which means a distance of $z = 2.3$~kpc from the
galactic plane. The latter is typical of a galactic Halo
object, in agreement with the above evidence from radial velocity.
Therefore V866\,Her is an old star of $M \leq 1.0 M_\odot$ mass.

\references

Antipin, S.V., 1994, {\it IBVS}, No.\,4125 

Burnstein, D., Heiles, C., 1982, {\it AJ}, {\bf 87}, 1165

Frogel, J.A., Whitford, A.E., 1987, {\it ApJ}, {\bf 320}, 199

Munari, U., Zwitter, T., 1997, {\it A\&A}, {\bf 318}, 269

Silva, D.R., Cornell, M.E., 1992, {\it ApJS}, {\bf 81}, 865

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