Publications

1. VanWyngarden, M., & Cloutier, R. (2024). Modeling Multiple Radius Valley Emergence Mechanisms with Multi-transiting Systems. AJ, 168(4), 154.
   PDF DOI BIB ABSTRACT

   @article{2024AJ68154V,
     title = {Modeling Multiple Radius Valley Emergence Mechanisms with Multi-transiting Systems},
     author = {{VanWyngarden}, Madison and {Cloutier}, Ryan},
     journal = {AJ},
     volume = {168},
     number = {4},
     pages = {154},
     year = {2024},
     doi = {10.3847/1538-3881/ad6903},
     file = {exoplanets.pdf}
   }
   

     Close-in planets smaller than Neptune form two distinct populations composed of rocky super-Earths and sub-Neptunes that may host primordial H/He envelopes. The origin of the radius valley separating these two planet populations remains an open question and has been posited to emerge either directly from the planet formation process or via subsequent atmospheric escape. Multitransiting systems that span the radius valley are known to be useful diagnostics of XUV-driven mass loss. Here, we extend this framework to test XUV-driven photoevaporation, core-powered mass loss, and an accretion-limited primordial radius valley model. Focusing on multitransiting systems allows us to eliminate unobservable quantities that are shared within individual systems such as stellar XUV luminosity histories and the properties of the protoplanetary disk. We test each proposed radius valley emergence mechanism on all 221 known multitransiting systems and calculate the minimum masses of the systems’ enveloped planets to be consistent with the models. We compare our model predictions to 75 systems with measured masses and find that the majority of systems can be explained by any of the three proposed mechanisms. We also examine model consistency as a function of stellar mass and stellar metallicity but find no significant trends. More multitransiting systems with mass characterizations are required before multitransiting systems can serve as a viable diagnostic of radius valley emergence models. Our software for the model evaluations presented herein is available on GitHub and may be applied to future multitransiting system discoveries.

2. Romero, A. D., Kepler, S. O., Hermes, J. J., Amaral, L. A., Uzundag, M., Bognár, Z., Bell, K. J., VanWyngarden, M., Baran, A., Pelisoli, I., Oliveira, G. da R., Koester, D., Klippel, T. S., Fraga, L., Bradley, P. A., Vučković, M., Heintz, T. M., Reding, J. S., Kaiser, B. C., & Charpinet, S. (2022). Discovery of 74 new bright ZZ Ceti stars in the first three years of TESS. MNRAS, 511(2), 1574–1590.
   PDF DOI BIB ABSTRACT

   @article{2022MNRAS5111574R,
     title = {Discovery of 74 new bright ZZ Ceti stars in the first three years of TESS},
     author = {{Romero}, Alejandra D. and {Kepler}, S.~O. and {Hermes}, J.~J. and {Amaral}, Larissa Antunes and {Uzundag}, Murat and {Bogn{\'a}r}, Zs{\'o}fia and {Bell}, Keaton J. and {VanWyngarden}, Madison and {Baran}, Andy and {Pelisoli}, Ingrid and {Oliveira}, Gabriela da Rosa and {Koester}, Detlev and {Klippel}, T.~S. and {Fraga}, Luciano and {Bradley}, Paul A. and {Vu{\v{c}}kovi{\'c}}, Maja and {Heintz}, Tyler M. and {Reding}, Joshua S. and {Kaiser}, B.~C. and {Charpinet}, St{\'e}phane},
     journal = {MNRAS},
     volume = {511},
     number = {2},
     pages = {1574-1590},
     year = {2022},
     doi = {10.1093/mnras/stac093},
     file = {zzceti.pdf}
   }
   

     We report the discovery of 74 new pulsating DA white dwarf stars, or ZZ Cetis, from the data obtained by the Transiting Exoplanet Survey Satellite mission, from Sectors 1 to 39, corresponding to the first 3 cycles. This includes objects from the Southern hemisphere (Sectors 1-13 and 27-39) and the Northern hemisphere (Sectors 14-26), observed with 120 s- and 20 s-cadence. Our sample likely includes 13 low-mass and one extremely low-mass white dwarf candidate, considering the mass determinations from fitting Gaia magnitudes and parallax. In addition, we present follow-up time series photometry from ground-based telescopes for 11 objects, which allowed us to detect a larger number of periods. For each object, we analysed the period spectra and performed an asteroseismological analysis, and we estimate the structure parameters of the sample, i.e. stellar mass, effective temperature, and hydrogen envelope mass. We estimate a mean asteroseismological mass of ⟨Msis⟩ = 0.635 ± 0.015 M⊙, excluding the candidate low or extremely low-mass objects. This value is in agreement with the mean mass using estimates from Gaia data, which is ⟨Mphot⟩ = 0.631 ± 0.040 M⊙, and with the mean mass of previously known ZZ Cetis of ⟨M*⟩ = 0.644 ± 0.034 M⊙. Our sample of 74 new bright ZZ Cetis increases the number of known ZZ Cetis by 20 per cent.