arXiv subjects

Jamie Dietrich

Publications and source records attributed to Jamie Dietrich.

6 recordsLinked to original sources

arXiv2026

Upgrading LBTI/NOMIC with a quadruple annular groove phase mask and GeoSnap detector for imaging nearby, habitable-zone exoplanets

The Large Binocular Telescope Interferometer (LBTI)'s Nulling-Optimized Mid-Infrared Camera (NOMIC) is among the most capable thermal-infrared imaging systems available for high-contrast, high-angular-resolution astronomical observations. Here we describe two in-progress upgrades to LBTI/NOMIC: (1) the design, fabrication, and installation of a quadruple annular groove phase mask (Q-AGPM) coronagraph, and (2) the installation of a 13 micron-cutoff Teledyne GeoSnap array. The Q-AGPM is the first coronagraph to be installed within NOMIC and one of the first optimized for N-band (~11 micron) observations. It places four annular groove phase masks on a single diamond substrate so that, in the LBTI dual-aperture imaging mode, each of the two telescope beams can be chopped between a pair of masks without loss of observing efficiency. The GeoSnap array will replace NOMIC's original AQUARIUS array, delivering higher quantum efficiency, larger well depth, faster and more linear readout, and freedom from the excess low-frequency noise that requires aggressive chopping. Together these upgrades substantially improve the achievable contrast and sensitivity at small angular separations. We also present a high-contrast Fizeau imaging sequence obtained with LBTI's new FFTCam fringe tracker, which confirms the interferometric gain over a single aperture through injection/recovery tests: relative to an equal-time single aperture exposure, the S/N = 3 contrast is a factor of ~2-4 deeper across 0.2-1 arcsec, spanning the contrast- and background-limited regimes. Finally, we describe the role of the upgraded LBTI/NOMIC instrument within the Breakthrough Watch program at the University of Arizona, which aims to perform the deepest observations yet of the habitable zones of the nearest single Sun-like stars.

astro-ph.IM↗

arXiv2026

Predictive Rankings of the Probability for Temperate Terrestrial Worlds for the HWO ExEP Mission Star List

The Habitable Worlds Observatory (HWO) is NASA's flagship mission design from the Decadal Survey on Astronomy and Astrophysics 2020, meant to observe temperate terrestrial planets via direct imaging and use direct spectroscopy of exoplanet reflected light to investigate their atmospheres for biosignatures. However, there are no known stars in the solar neighborhood conducive to direct imaging observations that are currently known to host rocky planets in their circumstellar habitable zones. Thus, HWO will most likely be running a blind survey; however, prioritizing the rankings of its target stars will help to potentially increase the yield of temperate terrestrial planets observed. Here we use simulated planetary systems with both small and giant planets to test which stellar systems among the HWO Exoplanet Exploration Program (ExEP) Mission Star List are most likely to host a rocky planet with the right temperature to sustain life on its surface. Assuming a simple model of planetary systems with small planets well-ordered in period interior to giant planets based on their respective occurrence rates, we find that some systems are upwards of 50% likely to host a temperate terrestrial planet. We also consider the possibility of a giant planet in or just beyond the circumstellar habitable zone that could host a temperate terrestrial moon capable of hosting life. Additional observations to refine the occurrence rates of small planets at orbital distances $\lesssim$ 1 AU and conditional rates between small and giant planets will refine these analyses and provide updates to these rankings.

astro-ph.EP↗

arXiv2025

Are We There Yet? Challenges in Quantifying the Frequency of Earth Analogs in the Habitable Zone

Searching for life elsewhere in the universe is one of the most highly prioritized pursuits in astronomy today. However, the ability to observe evidence of Earth-like life through biosignatures is limited by the number of planets in the solar neighborhood with conditions similar to Earth. The occurrence rate of Earth-like planets in the habitable zones of Sun-like stars, $\eta_{\oplus}$, is therefore crucial for addressing the apparent lack of consensus on its value in the literature. Here we present a review of the current understanding of $\eta_{\oplus}$. We first provide definitions for parameters that contribute to $\eta_{\oplus}$. Then, we discuss the previous and current estimated parameter values and the context of the limitations on the analyses that produced these estimates. We compile an extensive list of the factors that go into any calculation of $\eta_{\oplus}$, and how detection techniques and surveys differ in their sensitivity and ability to accurately constrain $\eta_{\oplus}$. Understanding and refining the value of $\eta_{\oplus}$ is crucial for upcoming missions and telescopes, such as the planned Habitable Worlds Observatory and the Large Interferometer for Exoplanets, which aim to search for biosignatures on exoplanets in the solar neighborhood.

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arXiv2024

SPORES-HWO. II. Companion Mass Limits and Updated Planet Properties for 120 Future Exoplanet Imaging Targets from 35 yr of Precise Doppler Monitoring

A goal of the future Habitable Worlds Observatory (HWO) is to directly image and spectroscopically characterize true Earth-analogs. However, if a large fraction of HWO target stars host unknown dynamically disruptive giant planets in their habitable zones (HZs), then additional targets that are farther away will need to be surveyed, potentially requiring a larger-aperture telescope and a coronagraph with a smaller inner working angle. Therefore, the sooner we constrain the presence of massive planets orbiting potential HWO target stars, the easier and less costly it will be to adjust key aspects of HWO's architecture. In this work, we uniformly analyze over 153,000 public radial velocity (RV) observations of 120 potential HWO target stars to derive mass limits on planetary companions. The RVs were measured by 23 spectrographs located at 15 observatories around the world, with the first observations going back to 1987. Based on empirical search completeness tests, we determine that undetected Jupiter-mass (Saturn-mass) planets may be hiding in up to 38% (53%) of the HZs of targets in the ExEP Mission Star List. The median mass sensitivity limit in the middle of the conservative HZ is approximately 48 $\rm M_\oplus$. We also provide updated parameters for 53 known companions, and we detect at least 26 additional RV signals corresponding to stellar activity and 4 signals that are planet candidates. We note that 44 of the ExEP stars lack substantial RV monitoring history, and we advocate for community-coordinated observing campaigns of these stars using moderate-precision RV facilities.

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arXiv2024

Searching for Additional Planets in TESS Multi-Planet Systems: Testing Empirical Models Based on Kepler Data

Multi-planet system architectures are frequently used to constrain possible formation and evolutionary pathways of observed exoplanets. Therefore, understanding the predictive and descriptive power of empirical models of these systems is critical to understanding their formation histories. Additionally, if empirical models can reproduce architectures over a range of scales, transit and radial velocity observations can be more easily and effectively used to inform future microlensing, astrometric, and direct imaging surveys. We analyze 52 TESS multi-planet systems previously studied using Dynamite (Dietrich & Apai 2020), who used TESS data alongside empirical models based on Kepler planets to predict additional planets in each system. We analyze additional TESS data to search for these predicted planets. We thereby evaluate the degree to which these models can be used to predict planets in TESS multi-planet systems. Specifically, we study whether a period ratio method or clustered period model is more predictive. We find that the period ratio model predictions are most consistent with the planets discovered since 2020, accounting for detection sensitivity. However, neither model is highly predictive, highlighting the need for additional data and nuanced models to describe the full population. Improved eccentricity and dynamical stability prescriptions incorporated into Dynamite provide a modest improvement in the prediction accuracy. We also find that the current sample of 183 TESS multi-planet systems are are highly dynamically packed, and appear truncated relative to detection biases. These attributes are consistent with the Kepler sample, and suggest a highly efficient formation process.

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arXiv2024

Assessing Exoplanetary System Architectures with DYNAMITE Including Observational Upper Limits

The information gathered from observing planetary systems is not limited to the discovery of planets, but also includes the observational upper limits constraining the presence of any additional planets. Incorporating these upper limits into statistical analyses of individual systems can significantly improve our ability to find hidden planets in these systems by narrowing the parameter space in which to search. Here I include radial velocity (RV), transit, and transit timing variation (TTV) upper limits on additional planets in known multi-planet systems into the DYNAMITE software package and test their impact on the predicted planets for these systems. The tests are run on systems with previous DYNAMITE analysis and with updated known planet parameters in the 2-3 years since the original predictions. I find that the RV limits provide the strongest constraints on additional planets, lowering the likelihood of finding them within orbital periods of ~10-100 days in the inner planetary systems, as well as truncating the likely planet size (radius and/or mass) distributions towards planets smaller than those currently observed. Transit and TTV limits also provide information on the size and inclination distributions of both the known and predicted planets in the system. Utilizing these limits on a wider range of systems in the near future will help determine which systems might be able to host temperate terrestrial planets and contribute to the search for extraterrestrial biosignatures.

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