- Restrictions on Access:
- Restricted (Penn State Only).
- Since the discovery of the first exoplanets in the early 1990s we have seen explosive growth in the field of exoplanetary science, hand-in-hand with technological improvements. We now know of over 4,000 exoplanets, most of which have been detected with two detection techniques: the transit method, and the Doppler Radial Velocity (RV) method. In this thesis, I discuss our efforts to further improve on these techniques to through the development of next-generation astronomical instrumentation.First, I discuss a path to obtain hitherto unachievable differential photometric precisions from the ground using custom-fabricated Engineered Diffusers. Such diffusers mold the focal plane image of a star into a broad and stable top-hat shape, minimizing photometric errors due to non-uniform pixel response, atmospheric seeing effects, imperfect guiding, and telescope-induced variable aberrations seen in defocusing. This reshaping significantly increases the achievable dynamic range of our observations, increasing our observing efficiency and thus better averages over scintillation. In using this technique we have demonstrated 62ppm precision in 30 minute bins on the bright star 16 Cyg A using the Engineered Diffuser we installed on the 3.5m ARC Telescope at Apache Point Observatorywithin a factor of two of Kepler's photometric precision on the same star. We discuss our precision diffuser-assisted follow-up observations of nearby transiting exoplanets, allowing us to better characterize their orbital parameters. This technology is inexpensive, scalable, easily adaptable, and is already being used at a number of different observatories for precision ground-based photometric follow-up of transiting planets.Second, I discuss the design and development of two next-generation radial velocity spectrographs: the Habitable-zone Planet Finder (HPF), a near-infrared (NIR) high-resolution stabilized Doppler spectrograph we recently installed at the 10m Hobby-Eberly Telescope at McDonald Observatory in Texas, and NEID, a precision red-optical high-resolution stabilized Doppler Spectrograph to be installed on the 3.5m WIYN Telescope at Kitt Peak National Observatory in Arizona in late 2019. In particular, I discuss the design and performance of the HPF and NEID environmental control systems, which have demonstrated sub-milli-Kelvin temperature stability and ~1microTorr pressure stability long-term, both of which are essential for precision RVs. Further, I discuss the commissioning and early HPF on-sky RV precision demonstrations. In particular, I discuss our RV extractions demonstrating 1.53 m/s RV precision over months on the nearby-bright M4.5-dwarf Barnard's Star, marking some of the highest RV precisions achieved in the NIR to date.Additionally, I discuss two recent projects that combine these two technologies to demonstrate their scientific utility on-sky.I discuss the validation of a 2 Earth radii sub-Neptune-sized planet around the nearby high proper motion M2.5 dwarf G 9-40, using high-precision NIR RV observations with HPF, precision diffuser-assisted ground-based photometry with a custom narrow-band photometric filter on the ARCTIC imager at APO, and adaptive optics imaging using the ShaneAO system at the 3m Shane Telescope at Lick Observatory. At a distance of 27.9pc, G 9-40b is currently the second closest transiting planet discovered by the K2 mission to date, and amongst top small M-dwarf planet candidates for transmission spectroscopy with JWST in the future. We also discuss our implementation of an empirical spectral matching algorithm using high-resolution NIR HPF spectra, which we use to estimate spectroscopic stellar parameters of the host star, which can easily be used to estimate stellar parameters of other M-dwarf stars observed with HPF.Additionally, I discuss the full 3D orbital solution of the Neptune-sized M-dwarf planet K2-25b orbiting its M4.5 dwarf star in the 650-800Myr old Hyades cluster. Through jointly fitting the available K2 data, precision ground-based diffuser-assisted transits from ARCTIC at APO and the Half-Degree Imager (HDI) on the 0.9m Telescope at Kitt Peak, and precision NIR RVs from HPF, we provide the first mass constraint of K2-25b with a mass of M~50 Earth masses. Further, in three transits we detect the Rossiter-McLaughlin effect of K2-25b, with a sky-projected obliquity of ~3 degrees (consistent with 0 degrees), and true 3D obliquity of ~9 degrees (consistent with 0 at 2 sigma). These observations mark one of the first mass constraint of an exoplanet in a cluster, and the second obliquity measurement of an M-dwarf planetary system, giving us key insights into the formation and subsequent dynamical history of the system.
- Dissertation Note:
- Ph.D. Pennsylvania State University 2019.
- Technical Details:
- The full text of the dissertation is available as an Adobe Acrobat .pdf file ; Adobe Acrobat Reader required to view the file.
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