C/1995 O1 (Hale-Bopp): Gas Production Curves And Their Interpretation |
| |
| Authors: | BOCKELÉE-MORVAN D RICKMAN H |
| |
| Institution: | (1) Observatoire de Meudon, 5, Place Jules Janssen, F92190 Meudon, France;(2) Astronomiska Observatoriet, Box 515, S-75120 Uppsala, Sweden |
| |
| Abstract: | The discovery of C/1995 O1 (Hale-Bopp) at 7 AU from the Sun provided the first opportunity to follow the activity of a bright
comet over a large range of heliocentric distances rh. Production rates of a number of parent molecules and daughter species have been monitored both pre- and postperihelion.
CO was found to be the major driver of the activity far from the Sun, surpassed by water within 3 AU whose production rate
reached 1031 s−1 at perihelion. Gas production curves obtained for various species show several behaviours with rh.
Gas production curves contain important information concerning the physical state of cometary ices, the structure of the nucleus
and all the processes taking place inside the nucleus leading to outgassing. They are relevant to the study of several other
phenomena such as the sublimation from icy grains, dust mantling or seasonal effects. For some species, such as H2CO or HNC, they permit to constrain their origin in the coma.
We discuss models of subsurface gas production in distant comets and predictions of how such a source may vary as the comet
moves along its orbit, approaching perihelion and receding again. Features in the observed gas production curves of comet
Hale-Bopp are generally interpretable in terms of either subsurface production (typical example: CO at large rh) or free sublimation (typical example: H2O). Possible implications for the vertical stratification of the cometary ices are reviewed, and preference is found for a
model with crystallization of amorphous ice close to the nuclear surface.
This revised version was published online in July 2006 with corrections to the Cover Date. |
| |
| Keywords: | Comets cometary activity cometary nucleus sublimation processes numerical modelling |
| 本文献已被 SpringerLink 等数据库收录！ |
|
