Re: HISTORY: Dyson Shells

Amara Graps (amara@amara.com)
Wed, 25 Aug 1999 20:37:51 +0100

Robert J. Bradbury (bradbury@www.aeiveos.com) Mon, 23 Aug 1999 19:40:04 -0700 (PDT) :

>At any rate, the major consequence of these "results", has
>been that only one astronomer (Dr. J. Jugaku in Japan) has
>seriously looked for Dyson Shells and he has unfortunately
>(in my opinion) focused these searches only on "visible"
>stars (exactly the same as the work being done by the both
>SETI camps [those who believe a radio carrier is the best
>communication method and those who believe that an optical
>carrier, e.g. lasers, is the best communication method]).
>

It seems that you left some observations out. The following is from Anders' Dyson sphere FAQ.

Amara

P.S. I used to work for Fred Witteborn.

  1. Have any Dyson spheres been observed?

I have found the following three searches for Dyson spheres:

     DATE: 1980
     OBSERVER(S): WITTEBORN
     SITE: NASA - U OF A, MT. LEMON
     INSTR. SIZE (M): 1.5
     SEARCH FREQ.(MHz): 8.5 microns - 13.5 microns
     FREQUENCY RESOL.(Hz): 1 micron
     OBJECTS: 20 STARS
     FLUX LIMITS (W/m**2): N MAGNITUDE EXCESS < 1.7
     TOTAL HOURS: 50
     REFERENCE:
     COMMENTS: Search for IR excess due to Dyson spheres around solar
     type stars. Target stars were
     chosen because too faint for spectral type.

     DATE: 1984
     OBSERVER(S): SLYSH
     SITE: SATELLITE
     INSTR. SIZE (M): RADIOMETER
     SEARCH FREQ.(MHz): 37x10**3
     FREQUENCY RESOL.(Hz): 4x10**8
     OBJECTS: ALL SKY 3K BB
     FLUX LIMITS (W/m**2): T/T =< .01
     TOTAL HOURS: 6000
     REFERENCE: 27
     COMMENTS: Lack of fluctuations in 3K background radiation on
     angular scales of 10**-2 Strd. rules
     out optically thick Dyson spheres radiating more than 1 solar

     luminosity within 100 pc.

     DATE: 1987
     OBSERVER(S): TARTER, KARDASHEV & SLYSH
     SITE: VLA
     INSTR. SIZE (M): 26 (9 ANTENNAS)
     SEARCH FREQ.(MHz): 1612.231
     FREQUENCY RESOL.(Hz): 6105
     OBJECTS: G357.3-1.3
     FLUX LIMITS (W/m**2):
     TOTAL HOURS: 1
     REFERENCE:
     COMMENTS: Remote observation (by VLA staff) of IRAS source near
     galactic center to determine if
     source could be nearby Dyson sphere. Source confirmed as OH/IR

     star.

     In short, none have been observed yet.

     References

     Slysh, V. I., Search in the Infrared to Microwave for Astro-
     engineering Activity, in The Search for Extraterrestrial Life: Recent
     Developments, M. D. Papagiannis (Editor), Reidel Pub. Co., Boston,
     Massachusetts, 1985

     Kardashev, N. S., and Zhuravlev, V. I., SETI in Russia, paper presented
     at the IAA/COSPAR/IAF/NASA/AIAA symposium on SETI: A New Endeavor for
     Humankind, The World Space Congress, Washington, D.C., August 30, 1992.
     To appear in a special issue of Acta Astronautica.

     Jugaku, J., and Nishimura, S., A Search for Dyson Spheres Around
     Late-Type Stars in the IRAS Catalog, in Bioastronomy: The Search for
     Extraterrestrial Life, J. Heidemann and M. J. Klein (Eds.), Lectures
     Notes in Physics 390, Springer-Verlag, 1991


***************************************************************
Amara Graps               | Max-Planck-Institut fuer Kernphysik
Interplanetary Dust Group | Saupfercheckweg 1
+49-6221-516-543          | 69117 Heidelberg, GERMANY
Amara.Graps@mpi-hd.mpg.de * http://galileo.mpi-hd.mpg.de/~graps

"Never fight an inanimate object." - P. J. O'Rourke