dipper@utastro.UUCP (Debbie Byrd) (06/29/85)
A star's light can reveal what the star is made of. More -- after this. June 29 The Birthday of Angelo Secchi A star's spectrum is just starlight separated into a continuous rainbow band of colors. Dark lines appear at certain locations on the band -- revealing the chemical composition of that particular star. So -- a star's spectrum is its own personal fingerprint. No two spectra are exactly alike. The first astronomer to suggest classifying stars by their spectra was Father Angelo Secchi -- a Jesuit priest -- born on this date in the year 1819. Secchi noted that stellar spectra fell into general groups based on the position and strength of the dark lines crossing the spectrum. In 1868, he published a catalogue that placed stars into four general groups -- depending on what their spectral patterns looked like. This spectral classification system was eventually greatly extended and refined into the modern system now used by astronomers -- which includes stellar classifications using the temperature and luminosity of stars as well. Besides his work with the spectra of stars, Secchi was the first to observe the dark lines -- known as absorption lines -- in the spectra of the planets Jupiter and Uranus. Later astronomers learned they could use the lines to identify chemical elements present in these planets' atmospheres. So, Angelo Secchi was really a pioneer -- one of the first to pave the way to using the radiation from stars and planets -- to find out what these pinpoints of light in the night are made of. Script by Diana Hadley. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin
ccs009@ucdavis.UUCP (it) (08/15/85)
> A star's light can reveal what the star is made of. More -- after > this. > > June 29 The Birthday of Angelo Secchi > > A star's spectrum is just starlight separated into a continuous rainbow ^^^^^^^^^^ > band of colors. Dark lines appear at certain locations on the band -- If a spectrum has absorption lines then it is not a continuous spectrum but an absorption spectrum(not to be confused with emission spectra which are a completely different animal). > revealing the chemical composition of that particular star. So -- a > star's spectrum is its own personal fingerprint. No two spectra are > exactly alike. >