A cometary hydrogen model: comparison with OGO-5 measurements of comet Bennett (1970 II).
Abstract
A model is constructed for the hydrogen cloud of Comet Bennett (1970 II) based on highly sensitive observations of its Lyman alpha emission by a photometer on board OGO-5 and taking into account the cometary motion, field gradients, solar L-alpha profile, and finite lifetime of the H atoms along their trajectories. The solar L-alpha flux is determined independently of instrumental calibration using the strong curvature of the hydrogen cloud in the orbital plane of the comet, and the cometary production rate of hydrogen atoms is calculated. The combination of two equally weighted Maxwellian velocity distributions with mean velocities of 7 and 21 km/sec is found to match the photometer scans across the comet better than any single Maxwellian distribution. A complete L-alpha isophote map is presented for the model hydrogen cloud on Mar. 20, 1970.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 1975
- Bibcode:
- 1975A&A....39....7K
- Keywords:
-
- Astronomical Models;
- Comet Heads;
- Hydrogen Clouds;
- Ogo-5;
- Comet Tails;
- Cosmic Dust;
- Lyman Alpha Radiation;
- Satellite Observation;
- Spaceborne Astronomy;
- Astrophysics