  The remarkable pre-main-sequence object V718 Per (HMW 15, H187) in the young
cluster IC 348 periodically undergoes long-lasting eclipses caused by variable
amounts of circumstellar dust in the line-of-sight to the star. It has been
speculated that the star is a close binary and similar to another unusual
eclipsing object, KH 15D. We have submitted V718 Per to a detailed photometric
and spectroscopic study to find out more about the properties of the stellar
object and the occulting circumstellar material, and to look for signatures of
a possible binary component. Our photometric data show that the eclipses are
very symmetric and persistent, and that the extinction deviates only little
from what is expected for normal interstellar material. The spectroscopic data,
obtained at minimum as well as at maximum brightness, indicate a primordial
abundance of Li and a surface effective temperature of about 5200 K.
Remarkably, the in-eclipse spectrum shows a significant broadening of the
photospheric absorption lines, as well as a weak increase in emission
components of H-alpha and the Ca II IR triplet. We did not detect any atomic or
molecular features from to the occulting body in the in-eclipse spectrum. We
also found no evidence of radial velocity changes in V718 Per to within about
+/- 80 m/s, which for an edge-on system corresponds to a maximum companion mass
of 6 Jupiter masses. Our observations suggest that V718 Per is a single star,
and thus very different from KH 15D. We conclude that V718 Per is surrounded by
an edge-on circumstellar disk with an irregular mass distribution orbiting at a
distance of 3.3 AU from the star, presumably at the inner disk edge. We ascribe
the broadening of photospheric absorption lines during the eclipse to forward
scattering of stellar light in the circumstellar dust feature.
