Meetings & Events
ExoExplorer Science Series: Fuda Nguyen (U. Arizona) & Garrett Levine (Yale)
Date:
February 16, 2024The ExoExplorer Science Series presents talks by cohort members Fuda Nguyen (U. Arizona) & Garrett Levine (Yale) on February 16, 2024, from 11 AM - 12 PM Pacific Standard / 2 PM - 3 PM Eastern Standard. Connection information is below.
Speaker: Fuda Nguyen (U. Arizona)
Title: Latitude-dependent Atmospheric Waves and Long-period Modulations in Luhman 16 B from the Longest Lightcurve of an Extrasolar World
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.
Speaker: Garrett Levine (Yale)
Title: Atmospheric Outflow Variability of Extrasolar Planets
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.
Join from the meeting link
https://jpl.webex.com/jpl/j.php?MTID=mb5474e6e30276e77312dfc854c79f3ed
Join by meeting number
Meeting number (access code): 2762 906 9850
Meeting password: SSpkfjdm323
Tap to join from a mobile device (attendees only)
+1-415-527-5035,,27629069850## United States Toll
Join by phone
+1-415-527-5035 United States Toll
Global call-in numbers
Join from a video system or application
Dial 27629069850@jpl.webex.com
You can also dial 207.182.190.20 and enter your meeting number.
Local: 818-35(4-4044) Toll Free: 844-JPL-WEBX (844-575-9329)