The laboratory analysis of and its application to the Bi-rich HgMn star HR 7775

Atomic Astrophysics, Department of Astronomy, Lund University, Box 43, 22100 Lund, Sweden

Corresponding author: L. Dolk, linus.dolk@astro.lu.se

Received: 20 February 2002
Accepted: 11 April 2002

Abstract

The bismuth spectrum emitted from a hollow cathode discharge has been recorded with a Fourier Transform Spectrometer (FTS). Accurate wavelengths have been determined for 104 lines, and several new energy levels have been found, while the accuracy of previously known level energies have been improved. The hyperfine structure of all observed lines has been analyzed, yielding hyperfine constants A and B for 56  levels. With the aid of the laboratory measurements the optical region spectrum of the HgMn star HR 7775 has been studied for all observable lines. The wavelengths and hfs constants established from the laboratory work have been combined with theoretical gf values to identify spectral lines and make an abundance estimation of bismuth. It has been established that bismuth is present in HR 7775 at an enhancement level of approximately 5 orders of magnitude relative to the meteoritic abundance, consistent with previous observations in the ultraviolet region of this star. Astrophysical gf values are presented for a number of lines.