Observations of formaldehyde in comet Machholz (1988j)
Abstract
The VLA was used in September 1988 to detect the 1 11-1 10 transition of formaldehyde (H 2CO) in emission at 6-cm wavelength (4829.659-MHz rest frequency) from Comet Machholz, a new comet. The cometary line had a small blueshift of -0.76 ± 0.40 km sec -1, which is consistent with the anisotropic outgassing of the nucleus in the solar direction and very similar to the blueshift observed in January 1986 with the VLA for the H 2CO emission line from Comet Halley. The derived H 2CO production rate for Comet Halley was 1.5 × 10 28 mol sec -1, and for Comet Machholz it was about an order of magnitude larger, 2 × 10 29 mol sec -1. Comet Machholz faded considerably only days after these H 2CO observations, which suggests that it fell apart. Indeed, the Comet Machholz H 2CO line is ≈2.5 times wider than the Comet Halley H 2CO line, which may indicate that the comet had started to come apart during these VLA observations.
- Publication:
-
Icarus
- Pub Date:
- July 1990
- DOI:
- 10.1016/0019-1035(90)90218-X
- Bibcode:
- 1990Icar...86..289S
- Keywords:
-
- Comets;
- Formaldehyde;
- Light Emission;
- Very Large Array (Vla);
- Comet Nuclei;
- Halley'S Comet;
- Outgassing;
- COMETS;
- MACHHOLZ;
- 1988J;
- FORMALDEHYDE;
- COMPOSITION;
- EMISSIONS;
- SPECTRA;
- COMET NUCLEI;
- OUTGASSING;
- HALLEY;
- COMPARISONS;
- PRODUCTION RATE;
- INFRARED;
- DIAGRAMS;
- EARTH-BASED OBSERVATIONS;
- PARAMETERS;
- WAVELENGTHS;
- RADIOWAVE METHODS