ASTROPHYSICAL LASER SPECTROSCOPY

Abstract

Stimulated emission concepts proved very useful and productive in astrophysics. This fact was convisingly verified in the microwave region of the spectrum (the discovery of astrophysical masers on a number of simple molecules [1-3]). We extends this trend to the visible region along two lines. First, we present the results of our investigations that have, in our opinion, lead to the discovery of optically pumped AstroPhysical Lasers (APL) [4] active in the quantum transitions of the Fe II ion [5, 6] and OI atom [7] in the range 0.8-1.0 jum in the vicinity of Eta Carinae most luminious and massive star of our Galaxy. The resonance optical pumping of high-lying states in Fe II and OI owes to the accidental coincidence between their absorption lines and the intense HI Lya and Ly/7 emission lines, respectively. Secondly, we consider the possibility of measuring the true (sub-Doppler) width of the narrow astrophysical lasers lines by Brown-Twiss-Townes heterodyne correlation interferometry and spectroscopy using spatially-separated telescopes and a diode laser as a local heterodyne coupled by an optical fiber to the telescopes [8]. This can simultaneously ensure a spectral resolution at the level of 1 MHz and angular resolution at the level of 0.001-0.1 arcsec.