Pluto's Increasing Atmospheric Pressure
Abstract
In 2007, the occultation of a V=13.2 magnitude star was successfully observed from Mt. John Observatory, Mt. Canopus Observatory and our 14-inch Meade portable system in Musselroe Bay, New Zealand. We simultaneously fit an isothermal model atmosphere (Eliot and Young, 1992) to the main drop and recovery of the observed occultation light curves to derive global atmospheric parameters and a geometric solution. The data is well fit by a spherical atmospheric model with no need to fit for an oblate profile. The isothermal atmospheric solution gives a temperature of 112 ± 1 K and a pressure of 2.4 ± 0.1 microbar at a radius of 1275 km. This is an increase in temperature of 8 K and a 28% increase in pressure at our reference radius over 13 months (the previous stellar occultation was in June 2006, Young et al. 2008) with no significant change in half-light radius. Due to the increase in temperature and hence scale height, we expect the surface pressure did not increase as dramatically. The sensitivity of atmospheric pressure to changes in isothermal temperature will be discussed.
This work was supported by NASA planetary astronomy grant NNG05GF05G and NSF major research instrumentation grant AST0321338.- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #41
- Pub Date:
- September 2009
- Bibcode:
- 2009DPS....41.0607O