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The Planet-Disk Connection: from Protoplanetary Disks to Planetary Atmospheres


Wallack, Nicole Lisa (2022) The Planet-Disk Connection: from Protoplanetary Disks to Planetary Atmospheres. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/m484-et60.


When gas giant planets form, they influence the structure of the surrounding gas disk, which in turn shapes the final compositions of their gas envelopes. My thesis work combines two distinct techniques in order to better understand planet formation and evolution. As a planet accretes its atmosphere, information about its formation history is encoded in its composition (metallicity and C/O ratio). Taking advantage of equilibrium chemistry expectations of carbon bearing molecules for cool (T<~1000K) planets, in Chapter 2 we probe the atmospheric metallicities of this population of planets using Spitzer secondary eclipses. Expanding this sample set to all short-period gas giant planets with Spitzer thermal emission detections in Chapter 3, we can further explore which system parameters had the most impact on the infrared spectral slopes of these objects. In parallel with these projects, I also carried out a search for planets in protoplanetary disks using direct imaging in Chapter 4. As these planets accrete gas, they also carve out gaps in the protoplanetary disk, leaving hints as to where in the disk they formed. We conducted a multi-year direct imaging survey of more than 40 stars hosting protoplanetary disks in order to detect embedded gas giant planets and better constrain planet-disk interactions. These two approaches represent two distinct, yet complementary, methods of studying the formation histories of giant planets.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Planetary system formation; Exoplanet atmospheric composition; Infrared photometry; Protoplanetary disks
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Planetary Sciences
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Knutson, Heather A.
Thesis Committee:
  • Blake, Geoffrey A. (chair)
  • Knutson, Heather A.
  • Mawet, Dimitri
  • Batygin, Konstantin
  • Yung, Yuk L.
Defense Date:27 May 2022
Record Number:CaltechTHESIS:06052022-175041539
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Ch. 2 adapted for Ch. 3
Wallack, Nicole Lisa0000-0003-0354-0187
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14942
Deposited By: Nicole Wallack
Deposited On:07 Jun 2022 21:46
Last Modified:02 Dec 2022 19:40

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