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18h ago

Scientists Map the Uneven Limb of a Hot Jupiter Using Transmission Strings

Published Wednesday in Nature Astronomy, the team applied JWST spectra to show WASP-17b’s atmosphere is slightly egg-shaped and to test models of heat and wind transport

The shape of WASP-17b’s atmosphere mapped using transmission strings. The planet has a broad banded jet around the equator with vast wind speeds which transport material and heat from the permanently irradiated dayside to the permanently shadowed nightside. The atmosphere over the equator of the evening limb (left) is hot as it is transported from the dayside of the planet, while the atmosphere on the right has cooled as it traversed the nightside and passes back to the dayside via the morning limb. Using transmission strings Dr Alderson and her team measured the shape of this transmitting limb as a function of angle across the poles of the planet for the first time. Credit Engine House and Hannah Wakeford

Overview

  • A Cornell-led team published a peer-reviewed paper Oct. 14 that applies a new transit-mapping technique called transmission strings to JWST TST DREAMS data to spatially resolve an exoplanet’s limb.
  • The map shows WASP-17b’s transmitting atmosphere is not a perfect circle but mildly asymmetric, with one side more extended consistent with strong equatorial jets.
  • Spectra extracted around the planet’s edge reveal temperature and composition shifts from day to night and from equator to pole that match prior theoretical predictions and circulation models.
  • The transmission strings method, developed at the University of Bristol, samples starlight through different angles of the limb instead of averaging the whole ring, letting researchers localize atmospheric features.
  • Team members say this proof-of-concept, supported by NASA, UKRI/STFC and the Klarman Fellowship, creates a roadmap for three-dimensional and weather-scale mapping of more exoplanets and for comparing atmospheric dynamics across the growing catalog.