Dr. Kellen Lawson

Did you always know that you wanted to study astronomy?

Well, I have always been interested in astronomy — but I’ve also been interested in a lot of different academic topics. Early on in college, I spent some time at a crossroads between interests in astronomy, history, and literature (while being envious of “the renaissance man” who could have contributed to all three). I eventually settled on pursuing astronomy in the first year or two of undergrad. While a career in any of these topics would have used many of the analytical skills that I enjoyed, the methods for answering astronomy’s questions — like observing with telescopes or writing software to analyze images — were ultimately more compelling for me.

Photo Credit: John Wisniewski.

Tell us about the research projects you are currently working on.

Most of my time is dedicated to various high-contrast imaging programs with JWST. In high-contrast imaging (HCI), we aim to directly image exoplanets and circumstellar disks in the presence of their much brighter host stars — typically using visible or infrared observations from large-diameter telescopes. This involves a lot of software post-processing to remove diffracted light from the host star before we can see the light from any circumstellar sources hidden beneath. Only around 1% of known exoplanets were found via HCI, but it has produced the overwhelming majority of wide-orbit (>10 AU) or young (<500 million years) planets to date — and so it is invaluable for understanding exoplanet demographics. Meanwhile, studying circumstellar disks gives us unique insights into how and where planets form; morphological disk features, like radial gaps, can reveal unseen planets or other dynamical phenomena, while spectroscopy of disks can provide clues for understanding exoplanetary compositions and demographics.

As our observatories have improved, the incidental detection of disks during exoplanet surveys has become increasingly common. With JWST, we’re detecting disks around roughly 1 in 5 stars. While this is exciting for those of us interested in disk science, it presents challenges for those focused on detecting exoplanets. The presence of a disk degrades the accuracy of our starlight removal techniques, directly affects our ability to spot planets, and biases our derived detection limits (and thus our derived completeness as well). My work on JWST observations is focused on developing and applying methods for accounting for disks in post-processing to solve these issues while also providing exciting disk science as a by-product. In addition to this, I also work with HCI data from the ground-based Subaru Telescope and am helping to develop the post-processing methodology for the Habitable Worlds Observatory. Finally, in the next few weeks, I will be starting a project that aims to use upcoming survey data from the Roman Space Telescope’s Wide Field Imager to discover new exoplanets and disks.

What science question intrigues you the most?

I want to understand the diversity of exoplanetary systems and the factors driving that diversity. We tend to think a lot about how our own planetary system came to be and less about whether that process was typical or what other ways there might be to create a qualitatively similar one. Recently, I’ve been focused on the systems of the lowest mass stars: M dwarfs. While M dwarfs make up around 80% of stars in our galaxy, we know comparatively little about their exoplanetary systems — largely because the intrinsic faintness of these stars makes them difficult targets for observation. Meanwhile, there are a lot of indications that M dwarf systems are dramatically different from those of stars more like the Sun. For example, compared to more massive stars, M dwarfs appear to be at least three times as likely to host Super-Earths (planets more massive than Earth but less massive than the Solar System’s ice giants). So, if we really want to understand what the typical system looks like, we’re going to have to understand the systems of M dwarfs.

Photo Credit: Currie et al. (2022), Lawson et al. (2023), and Lawson et al. (2024), respectively.

What research accomplishment are you most proud of?

Last year, I released a software called “Winnie” for post-processing and analysis of high-contrast imaging observations (especially those containing circumstellar disks). It’s a tool that aims to make some especially tricky aspects of disk-focused post-processing more tractable for the broader community, while also improving the scientific value of HCI studies. I’m proud of this result in part because it’s essentially the culmination of both my PhD thesis work and my work as a NASA Postdoctoral Program fellow. Perhaps more importantly, Winnie represents a realization that I’ve found especially empowering: that we can cast aside the pretense of assembling scientific words into convoluted backronyms and instead just name things whatever we want. In other words: literally nobody can stop me from just naming a piece of software after my dog.

What is one thing you wish everyone knew about your particular field of science?

While high-contrast imaging depends on state-of-the-art telescopes and instrumentation, it is also a very software-driven field. For many people in HCI, our day-to-day work is focused on refining data processing methods — especially the methods for removing host starlight. When we present results that don’t include some big exoplanet discovery, we tend to focus on these cutting-edge methods and similar software breakthroughs. Besides the big discoveries, the achieved planet sensitivity (i.e., what planets we would have seen had they been present) is an extremely important product of HCI, as it informs planet occurrence rates. So, it makes sense that we’re inclined to focus on how we’re improving this aspect. However, for people not used to thinking in linear algebra and image processing terms, this can make the field appear impossibly opaque. What I wish everyone understood is that many exciting HCI discoveries to date could be made using very simple methods. You could find many (if not most) of our imaged exoplanets without using any math beyond pre-algebra and without any computer programming proficiency beyond a one semester “beginner programming” course. We dig deeper because there’s extra scientific value to be had, but I don’t think people should let the cutting-edge techniques scare them away from a casual interest in HCI — or from incorporating it into outreach activities. There are accessible and intuitive methods that nearly anyone could use to recover the image of a distant exoplanet or circumstellar disk.

What advice would you give your younger self?

If given the chance to have a conversation with my younger self, I would shirk the opportunity and avoid my past self at all costs! I’m happy with where I’ve landed and wouldn’t claim to understand which details I could change to improve the bad outcomes without affecting the good ones. Maybe this is a bit of a non-answer — but I think you can dig out some meta-advice here too. The outcomes of people’s lives have nearly infinite variables, and it takes a superhuman talent for introspection to know which ones were truly the most relevant in retrospect. If you ask for advice from someone on a specific issue, keep in mind that their response is the projection of their experiences (and biases) onto your situation. Ultimately, considering this when interpreting advice can be more important than the advice itself (obligatory: in my experience).

Photo Credit: Kellen Lawson.

What do you like to do in your free time?

As a postdoc with a two-year-old, most of my hobbies (like cycling and programming for fun) have been cast aside. When time permits, I still like reading history (especially on Afro-Eurasia from the Hellenistic period through the post-classical period) and literature (especially Yeats, but also the Romantics that influenced him; unrelatedly but not less significantly: Tolkien). I also play various tabletop RPG games with friends (usually as GM). More recently, I mostly play games with my daughter — like “take a bite” or a game she invented called “bonk-a-ball” where she throws a ball at me, says “bonk”, and then runs away.