Hydrogen density of the local interstellar medium and an upper limit to the galactic glow determined from Pioneer 10 ultraviolet photometer observations

Journal Article · Mon Aug 01 04:00:00 EDT 1988 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/166617· OSTI ID:7050820

Wu, F M; Gangopadhyay, P; Ogawa, H S; Judge, D L

Pioneer 10 Lyman-alpha data obtained beyond the heliocentric distance of 30 AU are used here to determine the local ISM hydrogen density and downwind Galactic glow. The resulting asymptotic interstellar hydrogen density obtained using a conventional interplanetary model is 0.06/cu cm, and the Galactic Lyman-alpha glow is found to be negligible in the downwind direction. Discrepancies are found between observations and the conventional theoretical predictions of the glow dependence on radial distance. Based solely on data obtained between 30 and 39 AU, a better fit is obtained with a constant density distribution beyond 30 AU. In this case, a density of 0.05/cu cm and Galactic glow of 1.5 R is obtained. These results suggest that a complex density distribution may be more appropriate than either the conventional exponential distribution or the constant distribution. 43 references.

• Research Organization: Southern California, Univ., Los Angeles (USA)
• OSTI ID: 7050820
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 331; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHEMICAL COMPOSITION
DENSITY
ELEMENTS
FLUIDS
GALAXIES
GASES
HELIUM
HYDROGEN
INTERPLANETARY SPACE
INTERSTELLAR SPACE
LUMINOSITY
LYMAN LINES
MILKY WAY
NONMETALS
OPTICAL PROPERTIES
PHOTOMETRY
PHYSICAL PROPERTIES
PIONEER SPACE PROBES
RARE GASES
SPACE
SPACE VEHICLES
VEHICLES