Ten Micron Photometry of 25 Stars from B8 To M7

A photometer employing a liquid hydrogen-cooled mercury-doped germanium photoconductor whose spectral response is limited to the 8 - 14 µ region by a low pass interference filter and a BaF_2 window coupled with the cell's threshold wavelength has been placed at the east arm Cassegrain focus of the 200 inch Hale telescope. Twenty-five stars have been measured. The earliest star for which two measurements have been obtained is the B8Ia star β Orionis. The latest star is the M7e star X Cygni. The brightest star, L37 X 10^(-14) watts/cm^2, is α Orionis. The carbon star DS Peg was also measured. In a two-color diagram formed with B and V there is an intrinsic increase in dispersion going to later type stars and a systematic trend away from the blackbody relation. The ratios of the stellar fluxes to those expected from blackbodies at the published stellar effective-temperatures and angular diameters are not far from one. A systematic trend exhibited may not be real because of the assumptions involved in inteferometric diameter determinations. DS Peg does not appear overly peculiar in the two-color plots, but X,Cygni falls on the opposite side of the blackbody curve ("blue excess") compared with most of the late type stars. The fluxes presented here have not been corrected for presently uncertain telescope transmission losses which may be important

Surface Temperature Variations during the Lunar Nighttime

A new photometer incorporating a mercury-doped germanium photoconductor has been used with a 19-inch telescope to measure the 8-14- brightness temperatures of the shaded lunar surface. Right- ascension scans carried into the lunar nighttime from the terminator show a characteristic of cooling inconsistent with the occurrence of a thick homogeneous dust layer. It appears th more highiy conducting material either is exposed commonly on the surface or constitutes a substratum generally covered by no more than a centimeter or so of the strongly insulating dust. No difference in nighttime temperature distribution was observed between maria and uplands. However, local areas of higher-thanaverage brightness temperature were encountered. These indicate extensive exposures of consolidated material. Local temperature anomalies of this type are associated with the bright-rayed craters Tycho and Copernicus, but they are distributed over an area larger than that represented by the respective craters. Two other groups of temperature anomalies were found in otherwise undistinguished mare border areas. These observations and others suggest that surface redistribution processes are operative on the lunar surface over at least a 10-meter range, but are not important over distances much in excess of a kilometer