NASA Astrobiology Institute (NAI)

1. Expanding the List of Target Stars for Next Generation SETI Searches

   Project Investigators: Peter Backus, Rocco Mancinelli, Jill Tarter

   Summary

   For decades the conventional wisdom considered M dwarf stars unsuitable hosts for habitable planets. We convened an interdisciplinary workshop of thirty scientists to reconsider the issue. They concluded that life could evolve on planets orbiting higher mass M dwarfs. This improves the prospects for finding extraterrestrial life since M dwarfs account for about 75% of all stars. Based on these results, we are preparing a list of more than a million “target” stars for a search for extraterrestrial intelligence (SETI) project.

   Astrobiology Roadmap Objectives:

   • Objective 1.1: Models of formation and evolution of habitable planets
   • Objective 1.2: Indirect and direct astronomical observations of extrasolar habitable planets
   • Objective 4.3: Effects of extraterrestrial events upon the biosphere
   • Objective 6.2: Adaptation and evolution of life beyond Earth
   • Objective 7.2: Biosignatures to be sought in nearby planetary systems

   Project Progress

   Peter Backus, Jill Tarter, Rocco Mancinelli- We are applying the results of our NAI workshop on the Habitability of Planets Orbiting M Stars as we compile a list of “target” stars for SETI on the Allen Telescope Array. Under our supervision, a student in the Research Experience for Undergraduates program is sifting through a catalogue of more than a billion stars. We will continue this work and refine the derived target list based on research published subsequent to the workshop. We will publish this new catalog of roughly a million “Habstars”, stars suitable to host habitable planets, extending the work of Turnbull and Tarter (2003a,b). This paper will include an update of the published conclusions of the workshop (Tarter, et al., 2007).

Publications

Backus, P.R. & Harp, G.R.a.t.A.T.  (2007).  The Search for Extraterrestrial Intelligence On The Allen Telescope Array: Implications For The Square Kilometer Array.  Bulletin of the AAS, #133.05.

Backus, P.R. & Kilsdonk, T.N.a.t.A.T.  (2007).  RFI in the 0.5 to 10.8 GHz Band at the Allen Telescope Array.  Bulletin of the AAS, #255.05.

Backus, P.R.a.t.S.T.  (2008).  SonATA: SETI on the ATA, 8(2):384.

Tarter, J.C.  (Dec. 2007).  The Evolution of Life in the Universe: Are We Alone?.  Proceedings of the International Astronomical Union, 2:14-29.

Tarter, J.C., Backus, P.R., Mancinelli, R.L., Aurnou, J.M., Backman, D.E., Basri, G.S., Boss, A.P., Clarke, A., Deming, D., Doyle, L.R., Feigelson, E.D., Freund, F., Grinspoon, D.H., Haberle, R.M., Hauck, S.A.I., Heath, M.J., Henry, T.J., Hollingsworth, J.L., Joshi, M.M., Kilston, S., Liu, M.C., Meikle, E., Reid, I.N., Rothschild, L.J., Scalo, J.M., Segura, A., Tang, C.M., Tiedje, J.M., Turnbull, M.C., Walkowicz, L.M., Weber, A.L. & Young, R.E.  (2007).  A Re-appraisal of the Habitability of Planets Around M Dwarf Stars.  Astrobiology, 7:30-65.