Two Talks

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Two Talks

Wednesday, January 31, 2024, 12:00pm - 01:00pm

This repeat is an exception to the normal repeat pattern

Marvin Morgan, The University of Texas at Austin
Signs of Similar Stellar Obliquity Distributions for Hot and Warm Jupiters Orbiting Cool Stars

Abstract

Transiting giant planets provide a natural opportunity to examine stellar obliquities. Hot Jupiters orbiting Sun-like stars show a tendency for obliquity alignment, which suggests that obliquities are rarely excited or that tidal realignment is common. However, the stellar obliquity distribution is less clear for giant planets at wider separations where realignment mechanisms are not expected to operate. I will present results of the underlying inclination distributions among 47 cool stars harboring hot and warm Jupiters using hierarchical Bayesian modeling. We find that the inferred minimum misalignment distributions of hot Jupiters spanning a/R = 3-20 ( ~0.01-0.1 AU) and warm Jupiters spanning a/R = 20-400 ( ~0.1-1.9 AU) are mutually consistent. Most cool stars hosting warm and hot Jupiters are consistent with spin-orbit alignment. However, the similarity of misalignment rates suggests that either misalignments are primordial, or both misaligned hot and warm Jupiters experience the same underlying processes.

Melanie Rowland, The University of Texas at Austin
Protosolar D/H Abundance in the Coldest Brown Dwarf

Abstract

Y dwarfs are the coldest class of brown dwarfs and have similar effective temperatures to temperate exoplanets, with the coldest Y dwarfs having the same masses as giant planets. We can therefore use their atmospheres as proxies for planetary atmospheres, testing our understanding of physics and chemistry for these complex, cool worlds. JWST NIRSpec observations of these objects are revolutionizing the characterization of these worlds with high SNR, moderate resolution spectra. Here, we will show atmospheric retrieval results using public GTO data of the coldest known Y dwarf, WISE 0855 (using NIRSpec G395M spectra), which has an effective temperature of ~250 K. We will present a detection of deuterium in an atmosphere outside of the solar system via a relative measurement of deuterated methane (CH3D) and standard methane. From this, we infer the D/H ratio of a substellar object outside the solar system for the first time. We discuss our interpretation of these results and the implications for brown dwarf and giant exoplanet formation and evolution.

Location: PMA 15.216B and online