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\IBVShead{4501}{30 July 1997}

\IBVStitle{V1472 A\lowercase{ql}: A MOST UNUSUAL ECLIPSER?}


\IBVSauth{N.N. SAMUS}
\IBVSinsto{Institute of Astronomy, Russian Academy of Sciences, 48, Pyatnitskaya Str., Moscow 109017, Russia}

\IBVSabs{It is shown that V1472 Aquilae is an eclipsing or}
\IBVSabs{ellipsoidal variable, with a period of 198.716 days.}

\SIMBADobj{V1472 Aql}
\IBVStyp{ EB? }
\IBVSkey{photometry, HIPPARCOS}


\begintext

The variable star V1472 Aql (HR\,7680, HD\,190658) was discovered by
HIPPARCOS (ESA, 1997) and classified as a semiregular variable. It will enter
the forthcoming Namelist of Variable Stars No.\,74. The photometric
observations by HIPPARCOS show a rather regular light curve with the range
from 6.382 to 6.537 (HIPPARCOS magnitudes) and a period of 100\fday 3727039.
With its M2.5III spectral type, the star seems a good candidate to SRA
variables.

However, Lucke and Mayor (1982), from 41 CORAVEL and 4 photographic radial
velocities, found the star to be a spectroscopic binary with the orbital
period equal to 198\fday 716 (approximately twice the presently derived
photometric period) and with $a\sin i=(35.39\pm0.76)\times10^6$ km. In the
abstract of their paper, they state that ``HD\,190658 is an M2III giant which
could fill its Roche lobe and eventually show eclipses. HD\,190658 is also a
high velocity star ($V_0=-112.1$ km\,s$^{-1}$) and has the peculiarity of having
the shortest period (198 days) of any binary of type MIII''.

If we plot the HIPPARCOS magnitudes folded with the spectroscopic period
(see Figure 1), we find a reasonable light curve of an eclipsing or ellipsoidal
variable star, with continuous brightness variation and a possible indication
of different depths of primary and secondary minima. In the ``primary'' minimum,
the scatter of data points is considerable; it may be a hint to a sharper
eclipse overlapping ellipsoidal brightness changes. In this minimum, the red
giant is in front of an unidentified companion, not revealed in CORAVEL
radial velocity observations. If the eclipsing-binary interpretation of the star's
brightness variation is correct, this would make the star a quite unusual
``$\beta$ Lyrae'' variable. The high-velocity red giant's mass could be
rather moderate, and the nature of the companion is not easy to guess.
Note that the star is in fact a triple system: HIPPARCOS observations refer to
both components of ADS 13344, which, according to the BS catalog (Hoffleit and
Jaschek, 1982), is a common-proper-motion pair with $\Delta m=4\fmm 0$ and
2\farcs 7 separation. Additional observations of this peculiar object
are needed. Note that the next ``primary'' minimum is predicted approximately
for August 15, 1997.

I acknowledge that, preparing this note, I used the SIMBAD data base.
Thanks are due to O.V. Durlevich, S.V. Antipin and M.S. Frolov for
assistance and useful discussions.
\vfil \eject

\vskip 1mm
\IBVSfig{10cm}{4501-f1.ps}{
The phased light curve of V1472 Aql from HIPPARCOS photometry and
spectroscopic elements of Lucke and Mayor (1982)}
\vskip 1cm

\references

ESA, 1997, The Hipparcos and Tycho Catalogues, SP-1200, Vol. 17

Hoffleit, D., Jaschek, C., 1982, The Bright Star Catalogue, 4th
Edition

Lucke, P.B., Mayor, M., 1982, {\it Astron. and Astrophys.,} 105, 318


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