자료유형  

 학위논문

Control Number  

0016931677

International Standard Book Number  

9798379708122

Dewey Decimal Classification Number  

520

Main Entry-Personal Name  

Feinstein, Adina Daniela.

Publication, Distribution, etc. (Imprint  

[S.l.] : The University of Chicago., 2023

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2023

Physical Description  

1 online resource(305 p.)

General Note  

Source: Dissertations Abstracts International, Volume: 84-12, Section: B.

General Note  

Advisor: Bean, Jacob L.

Dissertation Note  

Thesis (Ph.D.)--The University of Chicago, 2023.

Restrictions on Access Note  

This item must not be sold to any third party vendors.

Summary, Etc.  

요약Intense, high energy stellar irradiation is believed to control the atmospheric mass loss of short-period planets. These effects are most dramatic in the early stages of planetary evolution, when young stars produce higher levels of X-ray and Ultraviolet radiation, and exhibit more short-term high-energy bursts of radiation called stellar flares. Observing how close-in planets react to these environments is key to understanding planetary evolution. In this dissertation, I present four studies of young stellar activity and planetary atmospheres as viewed in UV, optical, and infrared wavelengths. First, I present a study of stellar flares from five hours of Hubble Space Telescope Cosmic Origins Spectrograph (1070-1360 A) observations of the ∼ 25 Myr M dwarf AU Microscopii (AU Mic). I detect 12 flares in the far-UV "white-light" curve with energies ranging from 1029 − 1032 ergs. To contextualize these observations for AU Mic b and c, I estimate the additional atmospheric mass lost in the presence of flares. I find the atmospheric mass-loss is ∼ 108 g/s, with instantaneous increases by up to 1012 g/s in the presence of superflares.Second, I present a study of ground-based optical observations of a transit of V1298 Tau c, a 30 − 40 Myr super-Neptune planet. I observed a full transit of V1298 Tau c with Gemini-North/GRACES and measure an obliquity of λ = 5◦ ± 15◦ via Doppler tomography. The tomographic signal is only seen in the chromospherically driven core of the Ca II IRT, which may be the result of star-planet interactions. I find that excess absorption of the Hα line decreases smoothly during the transit. While this could be a tentative detection of hot gas escaping the planet, I show this variation can also be explained by the presence of surface heterogeneities.Third, I present a survey of stellar flares in optical/infrared broad-band observations from the Transiting Exoplanet Survey Satellite (TESS). I developed and applied a novel convolutional neural network of flare detection to 3200 young stars to evaluate flare rates as a function of age and spectral type. I find that flare rates and amplitudes decrease for stars tage 50 Myr across all temperatures Teff ≥ 4000 K, while stars from 2300 ≤ Teff 4000 K show no evolution across 800 Myr. Additionally, I applied this new network to all stars observed during the TESS primary mission.Last, I present the first transmission spectrum of the hot-Saturn WASP-39 b as observed with JWST Near InfaRed Imager and Slitless Spectrograph. The spectrum spans 0.6 − 2.8µm in wavelength and reveals multiple water absorption bands, the potassium resonance doublet, as well as signatures of clouds. I find the atmospheric composition of WASP-39b, favors a heavy element enhancement of ∼ 10 − 30x the solar value, a sub-solar carbon-to-oxygen ratio, and a solar-to-super-solar potassium-to-oxygen ratio. The observations are best explained by wavelength-dependent, non-gray clouds with inhomogeneous coverage of the planet's terminator.

Subject Added Entry-Topical Term  

Astronomy.

Subject Added Entry-Topical Term  

Astrophysics.

Subject Added Entry-Topical Term  

Condensed matter physics.

Subject Added Entry-Topical Term  

Computational physics.

Index Term-Uncontrolled  

Atmospheres

Index Term-Uncontrolled  

Exoplanets

Index Term-Uncontrolled  

Stars

Index Term-Uncontrolled  

Stellar flares

Index Term-Uncontrolled  

Transmission spectrum

Added Entry-Corporate Name  

The University of Chicago Astronomy and Astrophysics

Host Item Entry  

Dissertations Abstracts International. 84-12B.

Host Item Entry  

Dissertation Abstract International

Electronic Location and Access  

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Control Number  

joongbu:642850