Steven Giacalone

Department of Astronomy | UC Berkeley

About Me

I'm a Ph.D. candidate in the UC Berkeley Department of Astronomy. I search for and study extrasolar planets using statistical modeling and data from various ground-based and space telescopes. My advisor is Professor Courtney Dressing.

I graduated from the University of Chicago in 2017 with a B.A. in Physics with specialization in Astrophysics. While in Chicago, I studied planetary migration and dust transport in protoplanetary disks with Professor Arieh Königl.


Implications of High-Eccentricity Migration

High-eccentricty migration, the process by which the orbits of highly eccentric planets circularize and decay due to tidal interactions with the host star, has been proposed as an explanation for the occurrence of planets with orbital periods of a only few days. In order to determine how common this might be, I tested key predictions of the process by simulating the orbital evolution of a population of highly eccentric exoplanets. I found that not only can this process reproduce the orbital characteristics of observed giant exoplanets, but it can also act as a formation mechanism for short-period, Earth-sized planets through the tidal stripping of giant planet atmospheres when they come too close to their host stars. (Image Credit: M. Weiss/CfA)

For more information, see the papers A Test of the High-eccentricity Migration Scenario for Close-in Planets and On the Origin of Dynamically Isolated Hot Earths.

Dust Transport in Protoplanetary Disk Winds

The process governing radial mixing of dust in protoplanetary disks has long been a subject of scrutiny. One proposed mechanism is the outward transport of dust within a magnetocentrifugal wind lanuched from the surface of the disk. By simulating this process, I show that this wind can efficiently transport micron-sized grains from the inner disk to the outer disk. In addition, I find that this process can reproduce the distributions of crystalline silicates observed in protoplanetary disks. (Image Credit: NASA/JPL-Caltech)

For more information, see the paper Dust Transport and Processing in Centrifugally Driven Protoplanetary Disk Winds.

Statistical Validation of Transiting Exoplanet Candidates

Transiting exoplanet validation is the process by which one statistically argues that a transit-like event is due to an exoplanet, rather than an astrophysical false positive like an eclipsing binary star. By vetting planet candidates with a validation algorithm, one can select the best exoplanets for mass measurement, atmospheric characterization, and other forms of follow-up. With the launch of the Transiting Exoplanet Survey Satellite (TESS), which is searching for planets around bright stars that are particularly amenable to follow-up observations, this process has become especially pertinent. With the design of the TESS mission in mind, I designed TRICERATOPS, a tool capable of effectively validating TESS planet candidates. (Image Credit: MIT)

For more information, see the papers Vetting of 384 TESS Objects of Interest with TRICERATOPS and Statistical Validation of 12 Planet Candidates and Validation of 13 Hot and Potentially Terrestrial TESS Planets.

Planets orbiting A-type stars

A vast majority of known exoplanets orbit stars with surface temperatures cooler than about 7500 K. By searching for and characterizing planets orbiting hotter stars, we can paint a more complete picture of how planets form and evolve. Using TESS, I'm searching for planets orbiting A-type stars, hot stars with surface temperatures between 7500 K and 10000 K, in order to determine how common short-period planets are around them and infer how planets evolve in these highly irradiated environments. (Image Credit: Steven Giacalone)

For more information, see the papers HD 56414 b: A Warm Neptune Transiting an A-type Star.


View my publications on ADS.

Download a pdf of my CV here (up-to-date as of September 2022).

Contact Info