What does a “typical” exosolar system look like? We know that we don’t think that our familiar planets do not include the entire class of planets we found elsewhere (Hot Jupiter! Mini Neptin!) and we don’t think we look like our solar system. And because our way of discovery is heavily biased towards planets orbiting near host stars, we don’t have a strong sense that we may actually be hiding in a more distant orbit.
A new study released Thursday will discuss searching for what is called a “microlens” event. There, it acts as a gravitational lens that enlarges the planet’s orbiting stars, temporarily brightening. These events are difficult to capture, but can potentially indicate the presence of planets in distant orbits. Researchers behind the new work show that there is a significant population of rocky, super-Earth, moving in orbit as well as Jupiter and Saturn’s orbit.
The lens is micro
The two main methods used to discover exoplanets are called transport speed and radial bone velocity. Transit methods can indicate that simply watching a star immerse in the light it sends to Earth will orbit to cover only a small portion of the star. For radial velocity, look for a red or blue shift in the light received from the star. It is caused by planets pulling stars in different directions along orbit.
Obviously, the effects of planetary gravity are stronger when closer to the host star. And because stars can be temporarily dimmed for all kinds of reasons, they usually set the criteria for discovery that involves observing multiple passages. It also means shorter orbital periods, so there is bias towards discovering planets close to the host planet. As a result, most of what we know about the exosolar system comes from planets that are much closer to the host star than Earth. Even the farthest objects discovered by Kepler mission orbit are almost as far as Mars.
