학술논문
Detection and Bulk Properties of the HR 8799 Planets with High Resolution Spectroscopy
Document Type
Working Paper
Author
Wang, Jason J.; Ruffio, Jean-Baptiste; Morris, Evan; Delorme, Jacques-Robert; Jovanovic, Nemanja; Pezzato, Jacklyn; Echeverri, Daniel; Finnerty, Luke; Hood, Callie; Zanazzi, J. J.; Bryan, Marta L.; Bond, Charlotte Z.; Cetre, Sylvain; Martin, Emily C.; Mawet, Dimitri; Skemer, Andy; Baker, Ashley; Xuan, Jerry W.; Wallace, J. Kent; Wang, Ji; Bartos, Randall; Blake, Geoffrey A.; Boden, Andy; Buzard, Cam; Calvin, Benjamin; Chun, Mark; Doppmann, Greg; Dupuy, Trent J.; Duchêne, Gaspard; Feng, Y. Katherina; Fitzgerald, Michael P.; Fortney, Jonathan; Freedman, Richard S.; Knutson, Heather; Konopacky, Quinn; Lilley, Scott; Liu, Michael C.; Lopez, Ronald; Lupu, Roxana; Marley, Mark S.; Meshkat, Tiffany; Miles, Brittany; Millar-Blanchaer, Maxwell; Ragland, Sam; Roy, Arpita; Ruane, Garreth; Sappey, Ben; Schofield, Tobias; Weiss, Lauren; Wetherell, Edward; Wizinowich, Peter; Ygouf, Marie
Source
Subject
Language
Abstract
Using the Keck Planet Imager and Characterizer (KPIC), we obtained high-resolution (R$\sim$35,000) $K$-band spectra of the four planets orbiting HR 8799. We clearly detected \water{} and CO in the atmospheres of HR 8799 c, d, and e, and tentatively detected a combination of CO and \water{} in b. These are the most challenging directly imaged exoplanets that have been observed at high spectral resolution to date when considering both their angular separations and flux ratios. We developed a forward modeling framework that allows us to jointly fit the spectra of the planets and the diffracted starlight simultaneously in a likelihood-based approach and obtained posterior probabilities on their effective temperatures, surface gravities, radial velocities, and spins. We measured $v\sin(i)$ values of $10.1^{+2.8}_{-2.7}$~km/s for HR 8799 d and $15.0^{+2.3}_{-2.6}$~km/s for HR 8799 e, and placed an upper limit of $< 14$~km/s of HR 8799 c. Under two different assumptions of their obliquities, we found tentative evidence that rotation velocity is anti-correlated with companion mass, which could indicate that magnetic braking with a circumplanetary disk at early times is less efficient at spinning down lower mass planets.
Comment: 31 pages, 12 figures, Accepted to AJ
Comment: 31 pages, 12 figures, Accepted to AJ