The Recent Expansion of Pluto's Atmosphere
Abstract
Stellar occultations -- the passing of a relatively nearby body in front of a background star -- can be used to probe the atmosphere of the closer body with a spatial resolution of a few kilometers. Such observations can yield the scale height, temperature profile, and other information about the structure of the occulting atmosphere. Occultation data acquired for Pluto's atmosphere in 1988 revealed a nearly isothermal atmosphere(sup 2) above a radius of approximately 1,215 km. Below this level, the data could be interpreted as indicating either an extinction layer or the onset of a large thermal gradient, calling into question the fundamental structure of this atmosphere. Another question is to what extent Pluto's atmosphere might be collapsing as it recedes from the Sun (passing perihelion in 1989 in its 248-year orbital period), owing to the extreme sensitivity of the equilibrium surface pressure to the surface temperature. The authors report observations at a variety of visible and infrared wavelengths of an occultation of a star by Pluto in August 2002. These data reveal evidence for extinction in Pluto's atmosphere and show that it has indeed changed, having expanded rather than collapsed, since 1988. (1 table, 4 figures, 30 refs.)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 10, 2003
- Accession Number
- ADA426495
Entities
People
- A. Ates
- A. S. Bosh
- B. A. Babcock
- J. L. Elliot
- M. W. Buie
Organizations
- United States Naval Observatory Flagstaff Station