I use a combination of multi-wavelength observations and modeling tools to study how exoplanetary systems form and evolve. Below is a subset of my publications. You can find a full list here.

  • Behmard, A., M. Ness, E. Cunningham, M. Bedell, 2022, Elemental Abundances of Kepler Objects of Interest in APOGEE DR17, AJ, in review, ArXiv:2210.14187

  • Behmard, A., et al. 2022, Planet Engulfment Detections are Rare According to Observations and Stellar Modeling, MNRAS, in review, ArXiv:2210.12121

  • Behmard, A., J. Sevilla, J. Fuller, 2022, Planet Engulfment Signatures in Twin Stars, MNRAS, accepted, ArXiv:2210.11679 

  • Sevilla, J., Behmard, A., J. Fuller, 2022, Long-Term Lithium Abundance Signatures Following Planet Engulfment, MNRAS, 516, 3, ArXiv:2207.13232

  • Behmard, A., F. Dai, A. Howard, 2022, Stellar Companions To TESS Objects of Interest: A Test of Planet-Companion Alignment, AJ, 163, 160, ArXiv:2202.01798

  • Behmard, A., E. Petigura, A. Howard, 2019, Data-Driven Spectroscopy of Cool Stars at High Spectral Resolution, ApJ, 876, 68, ArXiv:1904.00094 

  • Behmard, A., D. Graninger, E. Fayolle, J. Bergner, K. Öberg, 2019, Desorption Kinetics and Binding Energies of Small Hydrocarbons, ApJ, 875, 73, ArXiv:1903.09720

Current research

Image credit: NASA, ESA, Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), Westerlund 2 Science Team

I use large spectroscopic surveys (e.g., APOGEE) of stars to investigate planet formation on a galactic scale Stellar photospheric abundances are powerful - they can be used to link stars back to their birth clusters and trace the chemo-dynamical history of the Milky Way. Abundance patterns can also shed light on how host star chemistry is affected by processes like planet formation. Quantifying such abundance trends can benefit from large stellar samples capable of boosting abundance pattern statistics across many stars. We're looking at the compositions of planet host stars observed with the Apache Point Observatory Galactic Evolution Experiment (APOGEE) DR17. For more details, see our paper! Also check out the short outreach talk I gave at the Caltech 3 Minute Thesis competition on this topic, linked below.

Image credit: NASA/JPL-Caltech

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I examine how planet formation processes like engulfment alter host star compositions System dynamics can cause planets to be engulfed by their host stars. After engulfment, the stellar photosphere abundance pattern will reflect accretion of rocky planetary material. But how often does engulfment happen, and how does it affect planetary system evolution? To test this, we carried out a Keck-HIRES survey of 36 systems where one star is a known planet host. We found little evidence for engulfment, which can be explained by our MESA stellar evolution code simulations, which predict that observable engulfment signatures are pretty short-lived, and will rarely be detected in systems that are several Gyr old. Instead, the photospheric abundance patterns we found from our survey seem to be primordial, which may have implications for the validity of “chemical tagging” - a technique used in galactic archaeology for tracing stars back to their birth clusters. I've published two papers on this work. For a recent presentation on this work, check out my ExoExplorers talk linked below.

Image credit: NASA/JPL-Caltech

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I model stellar spectra of cool (<5200 K) stars with data-driven methods Traditional methods of determining stellar properties (masses, radii, elemental abundances, etc.) based in spectral synthesis are bogged down by observational constraints or only work accurately within a subset of the HR diagram. Cool stars (

Image credit: NASA/JPL-Caltech