Taylor J. Bell

Overview

Welcome to my academic webpage! As of September 2021, I am a BAERI Postdoc at NASA Ames where I am working with Thomas Greene and many others on JWST Guaranteed Time Observations with the MIRI and NIRCam instruments. My focus is on the optimal reduction and decorrelation of our team's observations to provide precise measurements of exoplanetary atmospheres with a focus on planets smaller and cooler than those typically observed by Hubble or Spitzer. I am also co-leading the publication of the MIRI/LRS phase curve of WASP-43b collected as a part of The JWST Transiting Exoplanet Community Early Release Science Program.

Previously, I was a Ph.D. student in the Department of Physics at McGill University. My supervisors were Nicolas Cowan from McGill University and Pierre Bastien from Université de Montréal. My Ph.D. research focused on the characterization of exoplanet atmospheres, with a focus on ultra-hot Jupiters. Throughout my degree, I made use of data from the Hubble Space Telescope and the Spitzer Space Telescope to study hot Jupiter atmospheres. I also dabbled with modelling the atmospheres of highly-irradiated exoplanets. One of my other projects used the newly comissioned POMM at the Observatoire du Mont-Mégantic to study the polarization of light reflected by known hot Jupiters.

I received a B.Sc. Honours in Physics at the University of Saskatchewan in 2016, specializing in astronomy. In the summer of 2014, my first NSERC USRA project at McMaster University under the supervision of Doug Welch and Alison Sills aimed to create a modern, uniform catalogue of variable stars in Milky Way globular clusters. My second NSERC USRA at the University of Toronto was supervised by Howard Yee and Allison Noble. In this project, I studied the effect of environmental density and galactic stellar mass on the star formation rate of z~1 galaxies. My undergraduate research project, supervised by Doug Welch, tried to find evidence of binarity in Type II Cepheid variable stars in Milky Way globular clusters.

A Comprehensive Reanalysis of Spitzer Phase Curves

Spitzer/IRAC observations are affected by strong detector systematics which can be larger than the astrophysical signals we seek to measure. Historically there has been significant disagreement as to which detector model is best able to cleanly remove the systematic noise present in phase curve observations, with each research group having their own preferred technique and software. In this work, we seek to resolve this conflict through a uniform reanalysis of previously published Spitzer/IRAC phase curves with many different detector models.

Mass Loss From the Ultra-Hot Jupiter WASP-12b

Previous Spitzer/IRAC phase curve observations of WASP-12b showed a feature never seen before at infrared wavelengths. While phase curve observations typically have just a single peak per orbit, the phase curve of WASP-12b was double-peaked at one wavelength of light but single peaked at another wavelength. In this work, I analyzed a repeated set of observations which show that this finding is reproducible. After considering many possible explanations as to the source of this double-peaked phase curve, we conclude that the most likely scenario is that we are seeing carbon monoxide emission from a stream of gas stripped from the planet's atmosphere.

A Latent Heat Analogue on Ultra-Hot Jupiters

Hot Jupiters are believed to have rotation periods which match their orbital periods (called synchronously rotating: a special form of tidal locking). This gives the planets a permanent dayside and a permanent nightside. Guided by the second law of thermodynamics, the atmospheres of exoplanets tend to redistribute heat from the hot daysides of these planets to the far colder nightsides through winds. It is typically expected that hotter planets will have colder nightsides as the winds become less efficient at transporting heat at higher temperatures. In this work, I describe a previously unaccounted for effect which increases the heat transport efficiency of winds in the atmospheres of ultra-hot Jupiters: the thermal dissociation of molecular hydrogen.

WASP-12b Secondary Eclipse Observation

An international team of researchers which I led analyzed new Hubble observations of WASP-12b to search for light reflected by the gas giant exoplanet. These observations show that little-to-no light is reflected at optical wavelengths which tells us that the planet would look as dark as fresh asphalt or charcoal, if we could take a look at it. This provides interesting insight into the atmospheric conditions of the planet's exceedingly hot dayside.

Globular Clusters & Variable Stars

To test theories of Type II Cepheid formation, I studied the spatial distribution of these pulsating stars within the best-studied Milky Way Globular clusters to determine whether or not there is evidence that they are frequently found orbiting another star within a binary system.

Star Formation in z~1 Galaxy Clusters

How does the star formation rate of galaxies depend on their stellar mass and the density of their environment? To answer this question and study the evolution of galaxy clusters, I analyzed 8 billion year old photons collected by the Spitzer Space Telescope.