Honors Thesis Presentations: Riley Rosener and Rohan Gupta

1:30–2:30 pm ERC 401

Riley Rosener "On the Detectability of Emission from Exoplanet Outflows"

Riley Rosener

Exoplanets close to their host stars experience high amounts of irradiation, causing drastic atmo2 spheric escape that can be measured as a gas outflow from the planet using certain chemical tracers. 3 To date, exoplanet atmospheric escape has thus far only been probed using transmission spectroscopy 4 to measure line absorption. While it is theoretically possible to measure outflows via emission spec5 troscopy, the observability of these signatures may limit the practical application of this method. In 6 this work, we investigate different strategies of observing atmospheric outflow emission, finding that Hα and He∗ 7 consistently give the highest signal-to-noise ratio (SNR) across all planets tested. We 8 consider a variety of exoplanets with confirmed detections of the 10833˚A metastable helium absorption 9 line and other outflow tracers. We use the updated and improved PyTPCI (The-PLUTO-CLOUDY 10 Interface) software and wrapper with enhanced stability and usability to run combined 1D photochem11 istry, spectrum synthesis, and hydrodynamics simulations of our chosen exoplanet systems. Using these 12 results and information about the observational facilities that are most sensitive to each diagnostic, 13 we calculate the resultant signal-to-noise ratio, eclipse depth, optical depth, bremsstrahlung flux, and 14 theoretical mass loss rates for our target systems. Ultimately, we find that these signals will not be 15 large enough to detect and distinguish during the secondary eclipse using existing facilities in less than 16 5 transits. We find a maximum predicted signal-to-noise ratio of 2.4 from the hot Jupiter HD 189733b at 10× solar metallicity in the He∗ 17 line. For future observational campaigns, our work suggests focus18 ing on bright, well-characterized systems like hot Jupiters HD 189733b and HD 209458b, so that any 19 potential emission signals are maximized. Although these emissions are not currently detectable with 20 Keck and HST, they may be within reach of the next generation of extremely large telescopes.

Rohan Gupta "Wavelength Calibration of the Extreme Precision Radial Velocity Spectrograph MAROON-X using a Laser Frequency Comb and a Fabry-Perot etalon"

Rohan Gupta

The requirement of ever-increasing precision in radial velocity measurements places increasing demands on the wavelength calibration schemes. MAROON-X in the past has used a combined thorium argon and etalon wavelength calibration scheme that has been able to simultaneously leverage the global accuracy of the thorium argon lamp and the high local information content of a Fabry-Perot etalon. While this calibration scheme was able to meet the stringent precision requirements for radial velocity measurements of short period planets, it was unable to meet the long-term stability demands for MAROON-X. The installation of a laser frequency comb at MAROON-X allows for significant improvement in long-term stability, while simultaneously improving the accuracy of the calibration. This work details the calibrations sources and techniques to derive a wavelength solution and drift correction for MAROON-X and describes the first steps of implementing the laser frequency comb spectra into this scheme.

Event Type


May 24