The Disk Physical Conditions of 48 Persei Constrained by Contemporaneous Hα Spectroscopy and Interferometry

We utilize a multi-step modeling process to produce synthetic interferometric and spectroscopic observables, which are then compared to their observed counterparts. Our extensive set of interferometric observations of the Be star 48 Per, totaling 291 data points, were obtained at the Navy Precision Optical Interferometer from 2006 November 07 to 23. Our models were further constrained by comparison with contemporaneous Hα line spectroscopy obtained at the John S. Hall Telescope at the Lowell Observatory on 2006 November 1. Theoretical spectral energy distributions, SEDs, for 48 Per were confirmed by comparison with observations over a wavelength regime of 0.4–60 μm from Touhami et al. and Vieira et al. Our best-fitting combined model from Hα spectroscopy, Hα interferometry, and SED fitting has a power-law density fall off, n, of 2.3 and an initial density at the stellar surface of ${\rho }_0=1.0\times {10}^{-11}$ $g{cm}^{-3}$ with an inclination constrained by Hα spectroscopy and interferometry of ${45}^{{}^{\circ }}\pm 5^{\circ }$. The position angle for the system, measured east from north, is 114° ± 18°. Our best-fit model shows that the disk emission originates in a moderately large disk with a radius of 25 R _*, which is consistent with a disk mass of approximately 5 × 10²⁴ g or 3 × 10⁻¹⁰ M _*. Finally, we compare our results with previous studies of 48 Per by Quirrenbach et al. and find agreement, whereas our disk size does not agree with Delaa et al., based on a much smaller visibility set.