The infrared flux method and its use for study of α Boo, μ Her and β Dra; relation to the Vega 1.2–5 μm infrared excess

The effective temperatures of α Boo, μ Her, and β Dra are determined using the infrared flux method. The determinations are based on the high-quality spectrophotometric data obtained from an aircraft by Strecker, Erickson & Witteborn, the new infrared calibration of Vega obtained from observations made at Tenerife between 1979 and 1983, the use of a Reticon spectrometer to determine the integrated fluxes in the region 370–950 nm, and the use of model atmospheres constructed with the MARCS code developed by Gustafsson et al. Temperatures for α Boo and μ Her are also given using the Dreiling & Bell (DB) Vega calibration in association with the Hanbury-Brown, Davis & Allen angular diameter for Vega. The large and uncertain reddening for β Dra prevents the accurate determination of a reliable temperature for this star. The Tenerife and Dreiling & Bell infrared calibrations for Vega are considered in relation to the apparent variation of effective temperature with wavelength for α Boo and μ Her given by the infrared flux method, in an effort to distinguish between them. It is concluded that improved spectrophotometry is needed for this, with particular attention paid to the proper identification of continuum windows.