This raises the question, If planets can’t be detected around a star, can their existence be inferred by studying the host star? The researchers found that the answer to this question is a qualified yes, with new methods helping astronomers better understand how the formation of exoplanets is related to the composition of the star they orbit. The second most powerful technique, the radial velocity or Doppler method, has other limitations in its ability to find planets. While most of the known exoplanets have been discovered using this method, this approach is limited because exoplanets can only be detected when their orbit and the observer are perfectly aligned and have short enough orbiting periods.

The most common technique for finding exoplanets, ones that exist outside of the solar system, involves the transit method, when an exoplanet moves between its star and the observer and causes a dip in the star’s brightness. These results were presented at the 238th American Astronomical Society conference and also published in The Astrophysical Journal. The researchers found that the majority of stars in their dataset are similar in composition to the sun, somewhat at odds with earlier work and implying that many stars in the Milky Way could host their own Earth-like planets. The study was led by recent graduate Jacob Nibauer for his senior thesis with Bhuvnesh Jain and was co-supervised by former Penn postdoc Eric Baxter. Researchers from Penn’s Department of Physics and Astronomy have developed a new method for better understanding the relationship between a star’s chemical composition and planet formation.

Star compositions