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Sun in Time Project

Problem description:

The ?Sun in Time? program was established by Dorren and Guinan (1994) to study the magnetic evolution of the Sun using a homogeneous sample of single nearby G0-V main sequence stars which have known rotation periods and well-determined physical properties, including temperatures, luminosities, metal abundances and ages. The sample of solar proxies contains stars that cover most of the Sun?s main sequence lifetime from 130 Myr to 8.5 Gyr. One of the primary goals of the ?Sun in Time program is to reconstruct the spectral irradiance evolution of the Sun. To this end, a large amount of multiwavelength (X-ray, EUV, FUV, UV, optical) data have already been collected.

Details of the data sets and the flux calibration procedure employed are provided in Ribas et al.  (2005). Full spectral irradiance tables have already been completed for five of the stars in the ?Sun in Time? sample (EK Dra (130 Myr), π1 UMa (300 Myr), κ1 Cet (750 Myr), β Com (1.6 Gyr), β Hyi (6.7 Gyr)) and show an excellent correlation between the emitted flux and stellar age.

 

Fig.1: Solar-normalized fluxes vs. ae for different stages of the evolution of solar-type stars (Ribas et al. 2005)

 

A presenatation which summarizes the "Sun in Time" project can be found on Ribas (2005) which was presented at the International Space Science Institute (ISSI) in Bern at a meeting of the ISSI Team "Evolution of Habitable Planets" in 2005.

An actual article related to the evolution of the solar radiation environment related to the ?Sun in Time? project by Dr. Manuel Güdel can be found on:
http://solarphysics.livingreviews.org/Articles/lrsp-2007-3/

References:

References related to the Sun in Time Project:

  • Dorren, J. D., and E. F. Guinan. The Sun in time: detecting and modelling magnetic inhomogenities on solar-type stars. In: The Sun as a Variable Star [J. M. Pap, C. Frölich, H. S.
    Hudson, and S. K. Solanki, Eds.] pp. 206-216, Cambridge University Press, Cambridge (1994).
  • Ribas, I., Guinan, E. F., M. Güdel, and M. Audard. Evolution of the solar activity over time and effects on planetary atmospheres. I. High-energy irradiances (1 ? 1700 Å). ApJ., 622, 680 ? 694 (2005).

Other relevant references:

  • Ayres, T. R. 1997. Evolution of the solar ionizing flux. J. Geophys. Res., 102, 1641?1651 (1997).
  • Zahnle, K. J., and J. C. G. Walker 1982. The evolution of solar ultraviolet luminosity. Rev. Geophys., 20, 280 -292 (1982).

Contacts of relevant researchers:

  • Dr. Ignasi Ribas:
    Institut d?Estudis Espacials de Catalunya /CSIC, Campus UAB, Facultat de Ciències, Torre C5-parell-2a planta, 08193 Bellaterra, Spain
    Email: iribas(at)ieec.fcr.es
  • Dr. Manuel Güdel:
    Lecturer (Privatdozent), Astrophysics, Institute of Astronomy, SEC F5, ETH Zentrum,
    CH-8092 Zürich, Switzerland
    Email: guedel(at)astro.phys.ethz.ch