Engineering topics
Publications and source records attributed to Toller, G. N..
In the following we present material in tabular and graphical form, with the aim to allow the non specialist to obtain a realistic estimate of the diffuse night sky brightness over a wide range of wavelengths from the far UV longward of Ly to the far-infrared.
The Diffuse Infrared Background Experiment (DIRBE) of the Cosmic Background Explorer (COBE) has mapped the surface brightness distributions of the Galactic plane at wavelengths from 1.25 to 240 micrometers. In these maps the latitude of peak brightness, as a function of longitude, traces a roughly sinusoidal curve of period approximately 360 deg. In the far-infrared, where emission by interstellar dust dominates the surface brightness, this curve agrees well with that derived from maps of the velocity-integrated H 1, suggesting that the layers of dust and neutral atomic hydrogen are similarly displaced from the Galactic plane. In the near-infrared (lambda less than 5 micrometers), where old disk stars dominate the emission, the brightness crest exhibits the same phase but roughly half the amplitude. The reduced amplitude of the warp in stellar light could result from a lesser warping of the stellar disk, or from a more rapid falloff of the density of stars relative to the density of gas, possibly due to a radial truncation of the disk.
Space based photometric determinations of the extragalactic background light (EBL) are compared with galaxy count determinations of EBL brightness. The results of various EBL studies at blue and visual wavelengths are summarized, and an upper limit of 3.9 S-sub-10 (V)-sub-G2V at the 2 sigma level is placed on the brightness of the extragalactic background at 4400 A. EBL data in regions near the north and south galactic poles are also presented, the first such data obtained from heliocentric distances where the zodiacal light is negligible. Several paradigms consistent with the inferred EBL limits are mentioned, including less galactic evolution or masking of galactic evolution, galaxy formation at very high redshifts, and dusty primeval galaxies decreasing optical EBL and increasing infrared EBL. Models promulgating all primeval galaxies as high-luminosity objects undergoing bursts of star formation are incompatible with the EBL observations.
Brightnesses measured by the Pioneer 10 imaging photopolarimeter in two regions of sky were compared on sky maps at sun-spacecraft distances from 2.4 to 4.8 AU to determine the spatial extent of the zodiacal light. Data in the ecliptic at elongations greater than 90 deg show negligible contribution to the zodiacal light beyond 3.3 AU, the 2:1 Jupiter resonance. The zodiacal light brightness at 2.4 AU is less than 10% of that observed at 1 AU.