Planning a large-scale astronomical mission is a long process. Part of this process is understanding what the mission calls for. A team of researchers from the University of California, Berkeley and the University of California, Riverside has published a paper on the preprint server arXiv that describes a database of exoplanets that could become new targets for NASA’s planetary exploration efforts. The research will be conducted using the HWO Observatory. Thanks to his Decennial Review of Astro2020, NASA decided to develop a 6-meter space telescope capable of high-contrast observations in optical, infrared, and ultraviolet wavelengths. This project became known as HWO. Its main mission is to observe 25 different exoplanets in the habitable zone of its parent star, looking for biosignals. HWO can also perform general astronomy, but knowing which planets to observe is important for this mission.
To accomplish this part of the project, NASA’s Exoplanet Exploration Program created a list of 164 exoplanets that would be most likely to be accessible to HWO. This accessibility was primarily due to the properties of the planet’s host star. In particular, the measurements collected by the authors can be divided into five categories: stellar element abundances, photometry, flare rates, variability estimates, and X-ray emissions. However, there are many nuances within each of these categories. For example, researchers collected elemental composition measurements of his 1,700 stars for 14 different elements. However, we were only able to find X-ray data for 41 of the 168 stars in the catalog. The lack of data is not surprising since scientists have only collected data from other publicly available sources. Some of these sources focused on a few thousand stars and paid less attention to the objects included in the new catalog. The database itself is also modeled after his ExEP Mission Star List (EMSL) database, which was originally developed for his two other major observatories, LUVOIR and HabEx. Each has its own areas of expertise and some overlap with HWO, but the data were not comprehensive enough.