arXiv subjects

Austin Ware

Publications and source records attributed to Austin Ware.

4 recordsLinked to original sources

arXiv2026

The Companions to B and A Stars Snapshot (C-BASS) Survey: I. Discovery of a Young Brown Dwarf Companion to HIP 17453

We report the detection of a new brown dwarf companion to HIP 17453 A, a chemically peculiar A0V star located at a distance of 81 pc. HIP 17453 A was observed with high-resolution adaptive optics imaging using the Near-Infrared Camera 2 on the Keck II telescope as part of the Companions to B and A Stars Snapshot (C-BASS) survey over a ten-year baseline, revealing the presence of a companion with proper motion consistent with the primary. We estimate the age of the HIP 17453 system as 280 $\pm$ 125 Myr, and with follow-up intermediate resolution (R~1800) spectroscopic observations with the Gemini Near Infra-Red Spectrograph (GNIRS) on the Gemini-North telescope, we found the spectrum of HIP 17453 B to be consistent with a spectral type of L2 $\pm$ 1. Through interpolation of Sonora Diamondback evolutionary models, we calculate an effective temperature of $1953^{+84}_{-78}$ K and mass of $53^{+10}_{-8}$ $M_{Jup}$ for HIP 17453 B, which corresponds to a mass ratio of $q = 0.024 \pm 0.004$ for the HIP 17453 system. With its intermediate mass and young age, HIP 17453 B joins a small set of benchmark brown dwarf companions around early-type stars that are suitable for follow-up atmospheric and evolutionary studies.

astro-ph.SR↗

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

Continuous Habitable Zone Metric for Prioritizing Habitable Worlds Observatory Targets

Future direct imaging space telescopes, such as NASA's Habitable Worlds Observatory (HWO), will be the first capable of both detecting and characterizing terrestrial exoplanets in the habitable zones (HZ) of nearby Sun-like stars. Since this will require a significant amount of time and resources for even a single system or exoplanet, the likelihood that a system will host detectable life should be considered when prioritizing observations. One method of prioritization is to estimate the likelihood that an exoplanet has remained continuously within the HZ long enough for life to emerge and make a detectable impact on the atmosphere. We utilize a Bayesian method to calculate the likelihood that a given orbital radius around a star is currently in the 2 Gyr continuous habitable zone (CHZ$_2$), the approximate time it took life on Earth to significantly oxygenate the atmosphere. We apply this method to the 164 stars in the NASA Exoplanet Exploration Program Mission Star List (EMSL) for HWO, representing a preliminary sample of Sun-like stars with HZs most accessible to a future direct imaging mission. By considering the CHZ$_2$ likelihood at all orbital radii outside a hypothetical inner working angle for HWO, we define a metric for prioritizing targets according to the accessibility and total extent of the CHZ$_2$. We find that the CHZ$_2$ metric peaks between $3-4$ Gyr for late-F and early-G dwarfs, but tentatively determine that stars earlier than $\sim {F3}$ or hotter than $\sim 6600$ K are unlikely to have a CHZ$_2$ at the time of observation.

astro-ph.EP↗

arXiv2022

Continuous Habitable Zones: Using Bayesian Methods to Prioritize Characterization of Potentially Habitable Worlds

The number of potentially habitable planets continues to increase, but we lack the time and resources to characterize all of them. With $\sim$30 known potentially habitable planets and an ever-growing number of candidate and confirmed planets, a robust statistical framework for prioritizing characterization of these planets is desirable. Using the $\sim$2 Gy it took life on Earth to make a detectable impact on the atmosphere as a benchmark, we use a Bayesian statistical method to determine the probability that a given radius around a star has been continuously habitable for 2 Gy. We perform this analysis on 9 potentially habitable exoplanets with planetary radii $<$1.8 R$_\oplus$ and/or planetary masses $<$10 M$_\oplus$ around 9 low-mass host stars ($\sim$0.5-1.1 M$_\odot$) with measured stellar mass and metallicity, as well as Venus, Earth, and Mars. Ages for the host stars are generated by the analysis. The technique is also used to provide age estimates for 2768 low-mass stars (0.5-1.3 M$_\odot$) in the TESS Continuous Viewing Zones.

astro-ph.EP↗