First results of Herschel/PACS observations of Neptune
Abstract
We report on the initial analysis of a Herschel/PACS full range spectrum of Neptune, covering the 51-220 micrometer range with a mean resolving power of ~ 3000, and complemented by a dedicated observation of CH4 at 120 micrometers. Numerous spectral features due to HD (R(0) and R(1)), H2O, CH4, and CO are present, but so far no new species have been found. Our results indicate that (i) Neptune's mean thermal profile is warmer by ~ 3 K than inferred from the Voyager radio-occultation; (ii) the D/H mixing ratio is (4.5+/-1) X 10**-5, confirming the enrichment of Neptune in deuterium over the protosolar value (~ 2.1 X 10**-5); (iii) the CH4 mixing ratio in the mid stratosphere is (1.5+/-0.2) X 10**-3, and CH4 appears to decrease in the lower stratosphere at a rate consistent with local saturation, in agreement with the scenario of CH4 stratospheric injection from Neptune's warm south polar region; (iv) the H2O stratospheric column is (2.1+/-0.5) X 10**14 cm-2 but its vertical distribution is still to be determined, so the H2O external flux remains uncertain by over an order of magnitude; and (v) the CO stratospheric abundance is about twice the tropospheric value, confirming the dual origin of CO suspected from ground-based millimeter/submillimeter observations.
Cite
@article{arxiv.1006.0114,
title = {First results of Herschel/PACS observations of Neptune},
author = {E. Lellouch and P. Hartogh and H. Feuchtgruber and B. Vandenbussche and T. de Graauw and R. Moreno and C. Jarchow and T. Cavalié and G. Orton and M. Banaszkiewicz and M. I. Blecka and D. Bockelée-Morvan and J. Crovisier and T. Encrenaz and T. Fulton and M. Küppers and L. M. Lara and D. C. Lis and A. S. Medvedev and M. Rengel and H. Sagawa and B. Swinyard and S. Szutowicz and F. Bensch and E. Bergin and F. Billebaud and N. Biver and G. A. Blake and J. A. D. L. Blommaert and J. Cernicharo and R. Courtin and G. R. Davis and L. Decin and P. Encrenaz and A. Gonzalez and E. Jehin and M. Kidger and D. Naylor and G. Portyankina and R. Schieder and S. Sidher and N. Thomas and M. de Val-Borro and E. Verdugo and C. Waelkens and H. Walker and H. Aarts and C. Comito and J. H. Kawamura and A. Maestrini and T. Peacocke and R. Teipen and T. Tils and K. Wildeman},
journal= {arXiv preprint arXiv:1006.0114},
year = {2015}
}
Comments
Accepted for publication in Astronomy & Astrophysics (special issue on Herschel first results)