lgbouma

Young Planets in Star Clusters

While thousands of exoplanets are known, most orbit anonymous stars in the Milky Way that are between one and ten billion years old. I have been using TESS, Gaia, and Kepler to find and study planets around stars in clusters younger than one billion years. The stellar ensembles in which these planets reside enable precise age measurements, which helps us put together a timeline for planet evolution.

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Kepler and the Behemoth: Three Mini-Neptunes in a 40 Million Year Old Association [Paper],
with R. Kerr, J. Curtis, H. Isaacson, and friends, in AJ (2022)

A 38 Million Year Old Neptune-Sized Planet in the Kepler Field [Paper]
with J. Curtis, K. Masuda, L. Hillenbrand, and friends, in AJ (2022)

Cluster Difference Imaging Photometric Survey. II. TOI 837: A Young Validated Planet in IC 2602 [Paper]
with J. Hartman, R. Brahm, P. Evans, and friends, in AJ (2020)

PTFO 8-8695: Two Stars, Two Signals, No Planet [Paper]
with J. Winn, G. Ricker, R. Vanderspek and friends,, in AJ (2020)

Cluster Difference Imaging Photometric Survey. I. Light Curves of Stars in Open Clusters from TESS Sectors 6 and 7 [Paper, light curves, planet candidates, supplementary documentation]
with J. Hartman, W. Bhatti, J Winn, and G. Bakos, in ApJS (2019)

Ages of Field Stars

While stars in clusters yield gold-standard ages for a select set of planets, age-dating methods applicable to field stars might let us study planet evolution for a much larger sample of planets. Rotation-based age dating is one of the most promising methods to age-date FGK stars on the main-sequence.

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The Empirical Limits of Gyrochronology [Paper, software package, movie #1, movie #2]
with E. Palumbo and L. Hillenbrand, in ApJL (2023).

Complex Periodic Variables

The “complex periodic variables” are young and low-mass stars that show highly structured and periodic optical light curves. We believe that they are explained by clumps of either gas or dust that are forced to corotate with the star for hundreds of stellar rotation cycles. The origin and composition of this circumstellar material is unknown. Resolving the issue will likely deepen our understanding of stellar physics, and clarify the circumstellar environments to which close-in exoplanets are subject early in their lives.

Pandora's click
Transient Corotating Clumps Around Adolescent Low-Mass Stars From Four Years of TESS [Paper]
with R. Jayaraman, S. Rappaport, L. Rebull, and friends, AJ (2024).

Dissolving Star Clusters

Stars form in clusters when molecular clouds collapse. After the gas from the birth cloud disperses, most of the stars escape the cluster’s gravitational pull and gradually populate the galactic disk. Using many of the same tools that I use to study exoplanets, I also study cluster dissolution. The near-term goals are to reconstruct the initial cluster configurations, and to understand the processes that dictate the shapes, sizes, and orientations of these loosely aggregated groups of stars. A long-term goal is to understand whether we might be able to identify and study stars in the Sun’s birth cluster.

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Stellar Rotation and Structure of the α Persei Complex: When Does Gyrochronology Start to Work? [Paper]
led by A. Boyle, in AJ (2023)

Rotation and Lithium Confirmation of a 500 Parsec Halo for the Open Cluster NGC 2516 [Paper, supplementary data]
with J. Curtis, J. Hartman, J. Winn, and G. Bakos, in AJ (2021)

Long-term Fates of Hot Jupiters

Tides are expected to cause hot Jupiters to inspiral into their stars and be torn apart, but it is not clear how long this takes. Beyond determining the lifespan of hot Jupiters, the answer also has implications for whether the Earth will be consumed by the Sun in the distant future.

Related contributions

WASP-4 is Accelerating Toward the Earth [Paper]
with J. Winn, A. Howard, S. Howell and friends, in ApJL (2020)

WASP-4b Arrived Early for the TESS Mission [Paper]
with J. Winn, C. Baxter, W. Bhatti, and friends, in AJ (2019)

Empirical Tidal Dissipation in Exoplanet Hosts From Tidal Spin-up [Paper]
led by K. Penev, with J. Winn and J. Hartman, in AJ (2018)

Design and Analysis of Transit Surveys

I’m broadly interested in the design, execution, and analysis of planet-hunting surveys, particularly using the transit method.

Related work

Biases in Planet Occurrence Caused by Unresolved Binaries in Transit Surveys [Paper]
with K. Masuda and J. Winn, in AJ (2018)

Planet Detection Simulations for Several Possible TESS Extended Missions [White paper, data products]
with J. Winn, J. Kosiarek, and P. McCullough, arXiv:1705.08891.