Accession Number:

ADA426495

Title:

The Recent Expansion of Pluto's Atmosphere

Descriptive Note:

Letter to the editor

Corporate Author:

NAVAL OBSERVATORY FLAGSTAFF AZ

Report Date:

2003-07-10

Pagination or Media Count:

5.0

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 Plutos atmosphere in 1988 revealed a nearly isothermal atmospheresup 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 Plutos 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 Plutos atmosphere and show that it has indeed changed, having expanded rather than collapsed, since 1988. 1 table, 4 figures, 30 refs.

Subject Categories:

  • Astronomy
  • Astrophysics
  • Atomic and Molecular Physics and Spectroscopy
  • Thermodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE