Due to intense research within the last two decades, which factor(s) in the (original) Drake equation is/are now relatively well known? A) Birth rate of stars with environments suitable for hosting life B) Fractions of stars having such planets C) Number of planets per stellar system with an habitable environment D) Fraction of habitable planets on which life actually evolved E) Answers A), B), and C)
To determine which factor(s) in the original Drake equation are relatively well known due to intense research within the last two decades, we can break down each factor and assess the current understanding:
A) Birth rate of stars with environments suitable for hosting life: This factor refers to the rate at which stars form in our galaxy that have the right conditions to support life. While we have made significant progress in understanding star formation, determining the exact birth rate of stars with life-supporting environments is still challenging. However, astronomers have been able to estimate this factor to some extent.
B) Fractions of stars having planets: Over the past two decades, the discovery of exoplanets (planets orbiting stars outside our solar system) has increased significantly. The development of technology, such as the Kepler space telescope, has allowed astronomers to detect thousands of exoplanets. Based on these findings, we now know that a large fraction of stars possess planets. The fraction is estimated to be quite high, suggesting that planets around stars are a common occurrence.
C) Number of planets per stellar system with a habitable environment: Determining the exact number of planets with a habitable environment in each stellar system is still a challenging task. However, with the increasing number of exoplanet detections, we have been able to estimate the prevalence of different types of planets, including those within the habitable zone (the region around a star where conditions may be suitable for liquid water and, therefore, potentially life).
D) Fraction of habitable planets on which life actually evolved: Assessing whether life has evolved on habitable planets is a complex question that remains unresolved. While there have been attempts to study habitable environments and assess the potential for life, we currently do not have a confirmed answer.
E) Considering the above explanations, the factors that are relatively well known due to intense research within the last two decades are A) Birth rate of stars with environments suitable for hosting life, B) Fractions of stars having such planets, and C) Number of planets per stellar system with a habitable environment.