View here: Details for Multiwavelength coverage requested for V695 Cyg study with HST
Abstract: Dr. Philip Bennett (Dalhousie University) has requested AAVSO observers’ assistance in obtaining photometry (all modes and visual) and spectroscopy of the spectroscopic eclipsing binary red supergiant V695 Cyg (31 Cyg, HR 7735, HD 192577) in support of observations scheduled over the coming months with the Hubble Space Telescope. V695 Cyg is a spectroscopic, eclipsing binary: spectral types K4 Ib + B3 V, with period 3784.34 days (=10.36 years). The K4 Ib red supergiant primary dominates the optical flux, but the hot B-type companion contributes significant flux shortward of 4500 A. HST will observe the evolution of the ultraviolet spectrum at 10 epochs at wavelengths < 3100 A during the partial, total, and near-eclipse phases of 31 Cyg through September 2024. The campaign begins immediately and continues through the end of May with higher cadence and through December 2024 with reduced cadence.
Justification: The goal of this program is to determine the amount of circumstellar absorption from the wind of the red supergiant throughout the eclipse period. These observations will allow the density, velocity, ionization, and temperature structure of the red supergiant’s wind to be mapped, and an accurate mass loss rate determined for this important red supergiant.