Kepler-16b Artists concept banner <h2>Presentations</h2>

Presentations

The following are talks given by the ExoExplorers and ExoGuides. Recordings of the webinars, along with transcripts, will be posted as soon as possible after the events. When available, slides may be downloaded.

ExoExplorer Science Series

Presentation Archive


ExoExplorer Fuda Nguyen (U. Arizona)

Latitude-dependent Atmospheric Waves and Long-period Modulations in Luhman 16 B from the Longest Lightcurve of an Extrasolar World (PDF - 7.5 MB)

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Abstract: We present the longest photometric monitoring of up to 1200-hours of the brown-dwarf binaries Luhman 16AB, documenting ±5% variability with periods under 10-hours. We show that short-period rotational modulation around 5-hour (k=1) and 2.5-hour (k=2) dominate the variability, where the planetary-scale waves model of k=1 and k=2 waves fit the lightcurve extremely well. We explain the difference in the narrowed range of k=2 periods compared to k=1 periods using models of zonal banding in Solar System giants (Jupiter and Saturn) and suggest that this difference arises from higher wind speed distribution at low latitudes compared to mid-to-high latitudes. Lastly, we show that Luhman 16 AB exhibits long-period ±5% variability with periods up to 100-hour - potentially coming from polar regions in the atmospheres? Our results are consistent with past GCMs, demonstrating that zonal-banding, latitude-dependent waves, and slowly varying atmospheric features could be present in Luhman 16 AB.



ExoExplorer Garrett Levine (Yale)

Atmospheric Outflow Variability of Extrasolar Planets (PDF - 1.3 MB)

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Abstract: XUV-driven photoevaporation is a leading hypothesis on the astrophysical processes that sculpt the observed distribution of short-period planetary radii. In recent years, direct evidence of atmospheric escape has been detected via in-transit transmission of the metastable He triplet near 10830 Å. Dozens of planets have been probed with this tracer, mostly as single-epoch snapshots. Since the stellar XUV that underlies planetary mass-loss is time-variable, it is necessary to understand the outflows’ responses to changes in the incident flux. Here, we report results from an ongoing longitudinal study to characterize the time-variability of WASP-69b’s atmospheric outflow. In August and September 2023, we obtained contemporaneous metastable He data from Palomar/WIRC along with X-ray and mid-UV data from the Swift Observatory. Together, these data lead to a comprehensive characterization of WASP-69b’s hydrodynamical state in the epoch of observation. By comparison to archival metastable He data and archival high-energy data from XMM-Newton, we assess the time variability of WASP-69b’s mass-loss rate on timescales commensurate with typical stellar activity cycles.




ExoGuide Talks

Coming soon!