Hanner M S, Newburn R L, Gehrz R D, Harrison T, Ney E P, Hayward T L
Jet Propulsion Laboratory, USA.
Astrophys J. 1990 Jan 1;348(1 Pt 1):312-21. doi: 10.1086/168237.
Infrared (1-20 micrometers) observations of comet Bradfield (1987s) from three observatories are reported. Silicate emission is prominent in all the data, from heliocentric distance r=0.87 to 1.45 AU. A CVF spectrum at r=1.45 AU shows a peak at 11.3 micrometers identified as crystalline olivine; the spectral shape is similar to that in Halley. Dust optical properties are similar to those of the grains in Halley's jets. Dust production rate near perihelion was approximately 10(6) g s-1 and varied in proportion to (r-2). We suggest that some differences in grain properties among comets could result from differences in the thermal history of the nuclear surface and the relative fraction of the dust particles originating in the subsurface icy layer versus the devolatilized mantle.
报告了来自三个天文台对布拉德菲尔德彗星（1987s）的红外（1 - 20微米）观测结果。从日心距r = 0.87至1.45天文单位，所有数据中硅酸盐发射都很显著。在r = 1.45天文单位处的一个CVF光谱显示在11.3微米处有一个峰值，被确定为结晶橄榄石；光谱形状与哈雷彗星中的相似。尘埃光学性质与哈雷彗星喷流中的颗粒相似。近日点附近的尘埃产生率约为10(6)克每秒，并与（r - 2）成比例变化。我们认为彗星之间颗粒性质的一些差异可能源于核表面热历史的差异以及源自地下冰层与脱挥发分地幔的尘埃颗粒的相对比例。
