Volume 430, Number 2, February I 2005
|Page(s)||L37 - L40|
|Published online||20 January 2005|
Letter to the Editor
A dual origin for Neptune's carbon monoxide?
Laboratoire d'Études Spatiales et d'Instrumentation en Astrophysique (LESIA), Observatoire de Paris, 92195 Meudon, France e-mail: firstname.lastname@example.org
2 Institut de Radio-Astronomie Millimétrique, 18080 Granada, Spain
Accepted: 14 December 2004
Heterodyne observations of Neptune have provided a measurement of the CO(2–1) line profile with a total bandpass of almost 8 GHz and a resolution of 4 MHz. The lineshape indicates that the CO mole fraction in Neptune's atmosphere is not uniform, but increases by a factor of ~2 from the troposphere/lower stratosphere (0.5 ppm at mbar) to the upper stratosphere (1 ppm at mbar). This indicates the existence of both external and internal sources of CO. The equivalent flux associated with the external source is ~ cm-2 s-1. We propose that the stratospheric CO results from a large (2 km) cometary impact that occurred ~200 years ago, although there remains problems with this hypothesis.
Key words: planets and satellites: Neptune / radio-lines: solar system
© ESO, 2005
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.