The Dust Distribution Immediately Surrounding V Hydrae

Dust surrounding the star V Hydrae has been measured at a 11.15 μm wavelength using the three-telescope Infrared Spatial Interferometer (ISI). The narrowband heterodyne detection system is tuned to a region free of spectral lines due to molecules surrounding the star, and only continuum radiation from the dust and star is measured. Closure-phase data show that the dust is symmetrically distributed around the star. Results obtained in 2006–2007 are well fitted by a model with a Gaussian intensity distribution with HWHM of 49 mas that contributes 0.52 of the total flux and by a uniform disk of radius 287 mas with a total flux fraction of 0.26; the remaining 0.22 of the total flux is due to the star, which is unresolved. Visibility measurements conducted in 1997 show a substantial difference from those of 2006–2007, indicating that the star was surrounded by more dust in 1997.