The Application of Highly Accurate Laboratory Wavelengths to Abundance and Isotope Measurements in B Stars

Abstract

The relative positions of absorption lines in stellar spectra observed at high dispersion and high signal-to-noise with the Hubble Space Telescope's Goddard High Resolution Spectrograph (HST/GHRS) can often be measured with a precision of about 0.001 Å. Similar capabilities are expected from the Space Telescope Imaging Spectrograph (STIS). Under what circumstances do such astronomical data justify the acquisition of laboratory data with comparable accuracy?We will review a number of our GHRS spectra of B stars where such laboratory data have been critical to achieving our scientific goals. Studies of isotope ratios are one case where precision wavelengths are essential, and we will discuss our work on heavy element isotope anomalies in the HgMn stars χ Lupi and HR 7775, as well as work on boron isotope ratios in early-B stars. In some cases the interpretation and even the identification of an individual absorption feature can be critically influenced by the laboratory data.