To understand and predict the nature of planetary atmospheres, it is very important to understand their host star! Different spectral types have a wide range of UV emission, changing atmospheric photochemistry. To learn more about the effects of different main sequence stars on habitable Earth-like planets, I would suggest reviewing the work of Sarah Rugheimer, a former member of the Carl Sagan Institute.

My focus is not only on how different spectral types affect planetary environments and biosignatures, but also how stars in different evolutionary phases differ from one another.

As seen above, although Sun-like stars spend the majority of their lives on the main sequence, it spends a fair bit of time in other evolutionary stages, where different types of planetary environments could occur.

White Dwarfs

White dwarfs are the end states of stars with core masses of less than 1.4 Solar masses, which comprises the majority of the stellar population. Although they start off being extremely hot, they cool down over time and will eventually have a continuous habitable zone for long enough for life to develop and thrive on a planetary surface.

It takes approximately 10 billion years for a white dwarf to cool down from 6,000 to 4,000 K, giving life enough time to develop and evolve. My work involves simulating the climate and atmospheric photochemistry of Earth-like planets orbiting in the habitable zones of white dwarfs during this period of a continuous habitable zone. Cooler white dwarf scenarios are not included because the Universe simply isn't old enough for those to exist!

You can read this my paper on this project in the Astrophysical Journal here, or the the arXiv here. You can also watch my light-hearted AbSciCon talk on from the early stages of this project here!

Post-Main Sequence Stars

Habitability throughout the post-main sequence is an interesting scenario because during this phase of evolution the habitable zone is pushed past the original frost line of the planetary system, where over 99% of the system's water is expected to exist!

Pre-main sequence M-dwarfs

In the era of JWST it seems that the first exoplanetary atmospheres that will be characterized will be around M-stars, so understanding their stellar environments will be essential! Stars that small are very slow to evolve, so their bright pre-main sequence period can last billions of years, potentially "frying" any planets that would later be in the habitable zone during the main sequence.

Direct imaging around high-mass stars
As an undergraduate at the College of Charleston I worked on data reduction for the SEEDS Survey with Dr. Joe Carson. I was fortunate enough to be the first to work on the dataset of the star kappa Andromedae, around which we were able to detect a ~12.8 Jupiter mass companion. The official name of this object is kappa Andromedae b, but as his initial discoverer I fondly refer to him as Derek.

You can watch the mini-Ted talk given by me and the rest of the College of Charleston team here and a brief video made by the college on our research group here.