New Horizons Constraints on Charon's Present Day Atmosphere

Abstract

We report on a variety of standard techniques used by New Horizons including a solar ultraviolet occultation, ultraviolet airglow observations, and high-phase look-back particulate search imaging to search for an atmosphere around Pluto's large moon Charon during its flyby in July 2015. Analyzing these datasets, no evidence for a present day atmosphere has been found for 14 potential atomic and molecular species, all of which are now constrained to have pressures below 0.3 nanobar, as we describe below, these are much more stringent upper limits than the previously available 15-110 nanobar constraints (e.g., Sicardy et al. 2006); for example, we find a 3$\sigma$ upper limit for an N${}_2$ atmosphere on Charon is 4.2 picobars and a 3$\sigma$ upper limit for the brightness of any atmospheric haze on Charon of I/F=2.6x10${}^{-5}$. A radio occultation search for an atmosphere around Charon was also conducted by New Horizons but will be published separately by other authors.

arXiv comment17 pages, 7 figures. Submitted to Icarus, in revision

References in corpus (7)

• The Pluto system: Initial results from its exploration by New Horizons
• Surface Compositions Across Pluto and Charon
• The Geology of Pluto and Charon Through the Eyes of New Horizons
• The Atmosphere of Pluto as Observed by New Horizons
• Long-Range Reconnaissance Imager on New Horizons
• ALICE: The Ultraviolet Imaging Spectrograph aboard the New Horizons Pluto-Kuiper Belt Mission
• Structure and Composition of Pluto's atmosphere from the New Horizons Solar Ultraviolet Occultation

Cited by in corpus (7)

• Impact Craters on Pluto and Charon Indicate a Deficit of Small Kuiper Belt Objects
• The Pluto System After New Horizons
• Haze in Pluto's Atmosphere
• Formation of Charon's Red Poles From Seasonally Cold-Trapped Volatiles
• Measuring temperature and ammonia hydrate ice on Charon in 2015 from Keck/OSIRIS spectra
• Volatile evolution and atmospheres of Trans-Neptunian Objects
• N${}_2$ accretion, metamorphism of organic nitrogen, or both processes likely contributed to the origin of Pluto's N${}_2$