Hubble Space Telescope Absolute Spectrophotometry of Vega from the Far-Ultraviolet to the Infrared

摘要: The Space Telescope Imaging Spectrograph (STIS) has measured the absolute flux for Vega from 0.17–1.01 μm on Hubble white dwarf (WD) scale. These data are saturated by up to a factor of 80 overexposure but retain linearity precision 0.2% because charge bleeds along columns and is recovered during readout CCD. signal-to-noise ratio per pixel exceeds 1000, resolution R about 500. A V magnitude 0.026 ± 0.008 established Vega, level 3.46 × 10-9 ergs cm-2 s-1 at 5556 A. In regions Balmer Paschen lines, STIS equivalent widths differ pioneering work Hayes in 1985 do agree with predictions Kurucz model atmosphere, so that distribution preferred Hayes. Over full wavelength range, atmosphere calculation shows excellent agreement used extrapolate predicted fluxes into IR region. However, 2% lower than standard Cohen. IUE provide extension 0.17 down 0.12 μm. relative calibration based calculations pure hydrogen WDs, while physics laboratory lamps blackbody ovens. 1% these two independent methods determining stellar distributions suggests both may be correct 0.5–0.8 adds confidence claims 5500 determined better 4% WD models 3