Giora Shaviv

Giora Shaviv

Israel Institute of Technology

Title: The influence of UV radiation on exoplanets’ habitability


Giora Shaviv is an Emeritus Professor at the Israel Institute of technology, Haifa, Israel. He held the Shwartzmann-Medvedi cjair in space sciences. He obtained his B.Sc. In 1959 from the Technion (summa cum laude), his M.Sc. in 1960 (summa cum laude), and Ph.D. in 1965 with thesis subject: fast reactor physics. He has been physics and astronomy department chair in Tel Aviv University, Dean of physics at technion, head of the Asher space research institute. Shaviv served as Vice President and President of the Israel physical Society. Shaviv was elected to the International Academy of Astronautics. His fields of interests are theoretical astrophysics, fundamental process in astrophysics, planetary atmosphere and the greenhouse effect. Shaviv published over 250 papers in the international professional literature and three popular books in Hebrew and two professional books in English.


High level of stellar UV radiation on a planet’s surface may prevent planet’s habitability and limit the width of the habitability zone (HZ). Hence, we wish to estimate the UV Index as a function of the stellar parameters for Earth-like planets within the HZ of main sequence stars. The stellar radiation that impinges the surface is calculated by a 1-dimensional radiative transfer model which couples the photo-chemical reactions in the atmosphere. The calculations show that the oxygen and ozone molecules provide a sufficient protection from the stellar radiation, even for hot host stars, as the UV Index can reach a maximal value of 21 units (about twice higher than on Earth). Furthermore, the UV Index is highest on planets which orbit stars with an effective temperature of about 9,000K, and is lower for hotter and colder stars.