In this series of posts, we sit down with a few of the keynote speakers of the 245th AAS meeting to learn more about them and their research. You can see a full schedule of their talks here, and read our other interviews here!
“When I talk to the public, I like to say I ‘de-twinkle stars.'” As an Associate Professor of Astronomy at Amherst College, Dr. Kate Follette leads a group focusing on directly imaging exoplanets using adaptive optics (A.O.) and other hardware and software techniques. Dr. Follette explains how this ‘de-twinkling’ process is quite nuanced and holds tremendous power for finding and studying exoplanets. So, how does one directly image an exoplanet? And why is ‘de-twinkling’ so important?
To directly image an exoplanet, one must measure the light reflected or emitted by that planet’s atmosphere. This is challenging because the light from a planet outside our Solar System is extremely dim, and these planets also orbit much brighter stars, which, from the vantage point of the Earth, are right next to each other. To account for this, one must find a precise way to block out the light from the star while still capturing the light from the planet. Dr. Follette explains, “One of the first things you must do to image an exoplanet is take a really stable image, then throw away 99.999% of the image. So we play all kinds of these observational techniques and hardware and software games to suppress the starlight.” This is done in part with hardware such as coronagraphs, designed to block a star’s light so a telescope can observe the environment around it, hopefully including planets. However, an additional challenge for Earth-based telescopes is that the Earth’s atmosphere distorts all incoming light from space (i.e., stars twinkle). This makes picking out a dim planet next to a bright star even more challenging. Adaptive optics is a way of correcting for that distortion. Dr. Follette explains, “From the telescope, one can measure the distortions of starlight (or laser light, in the case of insufficient signal from the star) due to the atmosphere can then be used to “correct” the astronomical observation.”
Dr. Follette explains how her research group addresses some challenging technological feats needed to image exoplanets (and she has written an introductory guide to the technology of direct imaging aimed at undergraduates and early graduate students, as well as a jargon guide). For example, it makes sense to directly image young exoplanets in the infrared (IR) because these planets emit more light in the IR. Because they are hotter, most stars emit their peak radiation in visible light, so the brightness ratio between young planets and stars is more favorable for a direct image in the IR.
Dr. Follette discusses how her group is particularly interested in understanding false positives in direct imaging algorithms, which she will discuss in her AAS plenary lecture. In this case, a false positive is when a planetary direct imaging algorithm claims a detection when a planet is not there. Dr. Follette explains how, in many cases, these false positives can indicate other interesting phenomena, like dust clumps in circumstellar disks: “There is a chicken and egg thing where we see a lot of substructure in disks that you could explain with the presence of planets. The substructure might be incited by the gravitational influence of a planet, but you also need concentrations of disk material to form planets. So, are disk clumps planet precursors, or induced by planets already there? They’re all actually pretty interesting.”
So, how did Dr. Follette end up at the forefront of this field? She attended Middlebury College, a small liberal arts college, for her bachelor’s degree. After that, graduate school wasn’t always a given, and she is unreserved about the many paths she explored. She mentions that a few of the life experiences and career paths she pursued included researching cultural astronomy in Japan for a year, studying biology and chemistry and taking the MCAT with a plan of going to medical school, and spending a few years teaching. After those experiences, she discovered that Astronomy was what she wanted to think about every day, and she decided to pursue her Ph.D. at the Steward Observatory at the University of Arizona. It was there that she discovered her love of exoplanets. About beginning graduate school at Arizona, she says, “All I knew was I wanted to use big telescopes, but my first project wasn’t observational, and it wasn’t in exoplanets either. But listening to colloquia over my first year of grad school, I was constantly fascinated by exoplanet science.”
Her liberal arts background manifests in other ways. For example, she also directs a research group in science education! Much of her and her group’s work focuses on understanding how people learn everyday numerical and mathematical skills in general education (introductory non-major) science classes. Dr. Follette says her motivation for focusing on this aspect of education stems from the fact that her interest in Astronomy was sparked by just such a course, as well as a deeper desire to understand what causes some students to discount their ability to succeed in STEM fields. She says, “The general education science class is such an important vehicle for improving our field because we know that numerical skill deficits, as well as cognitive and affective barriers like math anxiety and low numerical self-efficacy, drive people out of STEM. Education research is rigorous and hard, and I think people don’t give social scientists enough credit.”
Her advice is frank to young people interested in astronomy academic careers: “There’s a lot that’s broken in academia. It’s not worth taking an academic career path if it’s going to hurt you in the long run, physically, mentally, or emotionally. Know who you are, and find a career that allows you to be who you are, wholly and unapologetically.” She has particularly pointed advice for students from small liberal arts colleges like herself: “Exposure to physics content is only a fraction of what astronomers need. I think a liberal arts education better recognizes that science doesn’t happen in a vacuum, and that technical skills and knowledge aren’t all we need to be successful. Even as a beginning graduate student, you must give journal club presentations, write fellowship proposals, talk about your work, and design posters. A breadth of skills, particularly writing and presentation skills, will serve you well. I think liberal arts training teaches that very well.”
To learn more about exoplanet direct imaging and planetary formation, check out Dr. Follette’s talk at 4:40 PM – 5:30 PM EST on Monday, January 13th!
Astrobite edited by: Archana Aravindan
