LANL Abstract:Optical SETI: A Spectroscopic Search for Laser Emission from Nearby Stars

From: Amara Graps (
Date: Tue Feb 12 2002 - 08:15:42 MST

Results from a search for some 'unnatural' emission from nearby stars.


Astrophysics, abstract

From: Geoffrey W. Marcy <>
Date (v1): Thu, 20 Dec 2001 13:32:07 GMT (41kb)
Date (revised v2): Mon, 11 Feb 2002 09:35:16 GMT (41kb)

Optical SETI: A Spectroscopic Search for Laser Emission from Nearby Stars

Authors: Amy E. Reines (1), Geoffrey W. Marcy (1,2) ((1) San Francisco State
University Department of Physics and Astronomy, (2) University of California
Berkeley Department of Astronomy)
Comments: 27 pages, 11 figures, uses aastex.sty

     We have searched for nonastrophysical emission lines in the
     optical spectra of 577 nearby F, G, K, and M main-sequence stars.
     Emission lines of astrophysical origin would also have been
     detected, such as from a time--variable chromosphere or infalling
     comets. We examined ~20 spectra per star obtained during four
     years with the Keck/HIRES spectrometer at a resolution of 5 km/s,
     with a detection threshold 3% of the continuum flux level. We
     searched each spectrum from 4000-5000 angstroms for emission lines
     having widths too narrow to be natural from the host star, as well
     as for lines broadened by astrophysical mechanisms. We would have
     detected lasers that emit a power, P>60 kW, for a typical beam
     width of ~0.01 arcsec (diffraction-limit from a 10-m aperture) if
     directed toward Earth from the star. No lines consisstent with
     laser emission were found.

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Amara Graps, PhD             | Max-Planck-Institut fuer Kernphysik
Heidelberg Cosmic Dust Group | Saupfercheckweg 1
+49-6221-516-543             | 69117 Heidelberg, GERMANY    *
      "Never fight an inanimate object." - P. J. O'Rourke

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