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Energetic Chemistry in the Atmospheres of Brown Dwarfs
Energetic Chemistry in the Atmospheres of Brown Dwarfs
상세정보
- 자료유형
- 학위논문 서양
- 최종처리일시
- 20260202103627
- ISBN
- 9798315781349
- DDC
- 523
- 서명/저자
- Energetic Chemistry in the Atmospheres of Brown Dwarfs
- 발행사항
- [Sl] : University of California, Los Angeles, 2025
- 발행사항
- Ann Arbor : ProQuest Dissertations & Theses, 2025
- 형태사항
- 148 p
- 주기사항
- Source: Dissertations Abstracts International, Volume: 86-12, Section: B.
- 주기사항
- Advisor: Fitzgerald, Michael P.
- 학위논문주기
- Thesis (Ph.D.)--University of California, Los Angeles, 2025.
- 초록/해제
- 요약Brown dwarfs are a unique laboratory for understanding atmospheric physics in planetary-mass objects. Though they form similarly to stars, brown dwarfs have cooler temperatures and lower masses, making their atmospheres often more analogous to those of giant planets. While significant progress has been made in characterizing their bulk properties and lower atmospheres, the upper atmospheres of brown dwarfs remain largely unexplored. Upper atmospheric regions are critical because they mediate interactions between the space environment, atmosphere, and planetary interior, absorbing high-energy radiation externally, while internally coupling with magnetic fields and exchanging energy with the lower atmosphere through radiative transfer and atmospheric waves.This dissertation investigates the properties and evolution of brown dwarf atmospheres, with a focus on energetic chemistry in the upper atmosphere, using a combination of new observations, theoretical modeling, and instrumentation development. I begin with new observations of the benchmark brown dwarf HD 33632 Ab, examining the importance of clouds, disequilibrium chemistry, and composition in comparing near-infrared spectra with evolutionary models. Next, I present the first high-resolution spectroscopic search for upper atmospheric H3+ emission in the near-infrared L band, placing upper limits on its emission and probing potential differences in auroral chemistry between brown dwarfs and giant planets. I then model the photochemical and thermal response of brown dwarf upper atmospheres to energetic flares from active M dwarf companions, predicting observable spectral signatures. Finally, I describe image simulations in support of the upcoming High-resolution Infrared Spectrograph for Exoplanet Characterization (HISPEC) instrument at Keck Observatory, which will enable next-generation high-resolution studies of exoplanet and brown dwarf atmospheres. Collectively, these studies underscore the complexity and current gaps in our understanding of brown dwarf upper atmospheres and help lay the foundation for future advances in the field.
- 일반주제명
- Astrophysics
- 일반주제명
- Astronomy
- 일반주제명
- Physics
- 키워드
- Brown dwarfs
- 키워드
- Giant exoplanets
- 기타저자
- University of California, Los Angeles Astronomy and Astrophysics 00EB
- 기본자료저록
- Dissertations Abstracts International. 86-12B.
- 전자적 위치 및 접속
- 로그인 후 원문을 볼 수 있습니다.
MARC
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■00520260202103627
■006m o d
■007cr#unu||||||||
■020 ▼a9798315781349
■035 ▼a(MiAaPQ)AAI32046488
■040 ▼aMiAaPQ▼cMiAaPQ
■0820 ▼a523
■1001 ▼aGibbs, Aidan Bryce.
■24510▼aEnergetic Chemistry in the Atmospheres of Brown Dwarfs
■260 ▼a[Sl]▼bUniversity of California, Los Angeles▼c2025
■260 1▼aAnn Arbor▼bProQuest Dissertations & Theses▼c2025
■300 ▼a148 p
■500 ▼aSource: Dissertations Abstracts International, Volume: 86-12, Section: B.
■500 ▼aAdvisor: Fitzgerald, Michael P.
■5021 ▼aThesis (Ph.D.)--University of California, Los Angeles, 2025.
■520 ▼aBrown dwarfs are a unique laboratory for understanding atmospheric physics in planetary-mass objects. Though they form similarly to stars, brown dwarfs have cooler temperatures and lower masses, making their atmospheres often more analogous to those of giant planets. While significant progress has been made in characterizing their bulk properties and lower atmospheres, the upper atmospheres of brown dwarfs remain largely unexplored. Upper atmospheric regions are critical because they mediate interactions between the space environment, atmosphere, and planetary interior, absorbing high-energy radiation externally, while internally coupling with magnetic fields and exchanging energy with the lower atmosphere through radiative transfer and atmospheric waves.This dissertation investigates the properties and evolution of brown dwarf atmospheres, with a focus on energetic chemistry in the upper atmosphere, using a combination of new observations, theoretical modeling, and instrumentation development. I begin with new observations of the benchmark brown dwarf HD 33632 Ab, examining the importance of clouds, disequilibrium chemistry, and composition in comparing near-infrared spectra with evolutionary models. Next, I present the first high-resolution spectroscopic search for upper atmospheric H3+ emission in the near-infrared L band, placing upper limits on its emission and probing potential differences in auroral chemistry between brown dwarfs and giant planets. I then model the photochemical and thermal response of brown dwarf upper atmospheres to energetic flares from active M dwarf companions, predicting observable spectral signatures. Finally, I describe image simulations in support of the upcoming High-resolution Infrared Spectrograph for Exoplanet Characterization (HISPEC) instrument at Keck Observatory, which will enable next-generation high-resolution studies of exoplanet and brown dwarf atmospheres. Collectively, these studies underscore the complexity and current gaps in our understanding of brown dwarf upper atmospheres and help lay the foundation for future advances in the field.
■590 ▼aSchool code: 0031.
■650 4▼aAstrophysics
■650 4▼aAstronomy
■650 4▼aPhysics
■653 ▼aBrown dwarfs
■653 ▼aGiant exoplanets
■653 ▼aInfrared spectroscopy
■653 ▼aPlanetary atmospheres
■690 ▼a0596
■690 ▼a0606
■690 ▼a0605
■71020▼aUniversity of California, Los Angeles▼bAstronomy and Astrophysics 00EB.
■7730 ▼tDissertations Abstracts International▼g86-12B.
■790 ▼a0031
■791 ▼aPh.D.
■792 ▼a2025
■793 ▼aEnglish
■85640▼uhttp://www.riss.kr/pdu/ddodLink.do?id=T17357986▼nKERIS▼z이 자료의 원문은 한국교육학술정보원에서 제공합니다.
