ORCID Profile
0000-0002-4250-0957
Current Organisations
Harvard-Smithsonian Center for Astrophysics
,
University of California Santa Cruz
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Springer Science and Business Media LLC
Date: 09-01-2023
DOI: 10.1038/S41586-022-05677-Y
Abstract: Transmission spectroscopy 1–3 of exoplanets has revealed signatures of water vapour, aerosols and alkali metals in a few dozen exoplanet atmospheres 4,5 . However, these previous inferences with the Hubble and Spitzer Space Telescopes were hindered by the observations’ relatively narrow wavelength range and spectral resolving power, which precluded the unambiguous identification of other chemical species—in particular the primary carbon-bearing molecules 6,7 . Here we report a broad-wavelength 0.5–5.5 µm atmospheric transmission spectrum of WASP-39b 8 , a 1,200 K, roughly Saturn-mass, Jupiter-radius exoplanet, measured with the JWST NIRSpec’s PRISM mode 9 as part of the JWST Transiting Exoplanet Community Early Release Science Team Program 10–12 . We robustly detect several chemical species at high significance, including Na (19 σ ), H 2 O (33 σ ), CO 2 (28 σ ) and CO (7 σ ). The non-detection of CH 4 , combined with a strong CO 2 feature, favours atmospheric models with a super-solar atmospheric metallicity. An unanticipated absorption feature at 4 µm is best explained by SO 2 (2.7 σ ), which could be a tracer of atmospheric photochemistry. These observations demonstrate JWST’s sensitivity to a rich ersity of exoplanet compositions and chemical processes.
Publisher: Research Square Platform LLC
Date: 26-09-2022
DOI: 10.21203/RS.3.RS-2092302/V1
Abstract: Transmission spectroscopy of exoplanets has revealed signatures of water vapor, aerosols, and alkali metals in a few dozen exoplanet atmospheres. However, these previous inferences with the Hubble and Spitzer Space Telescopes were hindered by the observations’ relatively narrow wavelength range and spectral resolving power, which precluded the unambiguous identification of other chemical species—in particular the primary carbon-bearing molecules. Here we report a broad-wavelength 0.5–5.5 μm atmospheric transmission spectrum of WASP-39 b, a 1200 K, roughly Saturn-mass, Jupiter-radius exoplanet, measured with JWST NIRSpec’s PRISM mode as part of the JWST Transiting Exoplanet Community Early Release Science Team program. We robustly detect multiple chemical species at high significance, including Na (19σ), H2O (33σ), CO2 (28σ), and CO (7σ). The non-detection of CH4, combined with a strong CO2 feature, favours atmospheric models with a super-Solar atmospheric metallicity. An unanticipated absorption feature at 4μm is best explained by SO2 (2.7σ), which could be a tracer of atmospheric photochemistry. These observations demonstrate JWST’s sensitivity to a rich ersity of exoplanet compositions and chemical processes.
Publisher: American Astronomical Society
Date: 10-2020
Abstract: For solar system objects, ultraviolet spectroscopy has been critical in identifying sources of stratospheric heating and measuring the abundances of a variety of hydrocarbon and sulfur-bearing species, produced via photochemical mechanisms, as well as oxygen and ozone. To date, fewer than 20 exoplanets have been probed in this critical wavelength range (0.2–0.4 μ m). Here we use data from Hubble’s newly implemented WFC3 UVIS G280 grism to probe the atmosphere of the hot Jupiter HAT-P-41b in the ultraviolet through optical in combination with observations at infrared wavelengths. We analyze and interpret HAT-P-41b’s 0.2–5.0 μ m transmission spectrum using a broad range of methodologies including multiple treatments of data systematics as well as comparisons with atmospheric forward, cloud microphysical, and multiple atmospheric retrieval models. Although some analysis and interpretation methods favor the presence of clouds or potentially a combination of Na, VO, AlO, and CrH to explain the ultraviolet through optical portions of HAT-P-41b’s transmission spectrum, we find that the presence of a significant H − opacity provides the most robust explanation. We obtain a constraint for the abundance of H − , , in HAT-P-41b’s atmosphere, which is several orders of magnitude larger than predictions from equilibrium chemistry for a ∼1700–1950 K hot Jupiter. We show that a combination of photochemical and collisional processes on hot hydrogen-dominated exoplanets can readily supply the necessary amount of H − and suggest that such processes are at work in HAT-P-41b and the atmospheres of many other hot Jupiters.
Location: United States of America
Location: United States of America
No related grants have been discovered for Diana Powell.