Open AccessNew limits on H + 3 abundance on Neptune using Keck NIRSPEC
Author(s) -
Melin H.,
Stallard T.,
Miller S.,
Lystrup M. B.,
Trafton L. M.,
Booth T. C.,
Rivers C.
Publication year - 2011
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2010.17468.x
Subject(s) - physics , neptune , astronomy , abundance (ecology) , astrobiology , astrophysics , planet , biology , fishery
Neptune and Uranus are observed with Keck II NIRSPEC in an attempt to detect H + 3 emission from Neptune. In this set of observations, H + 3 emission remains undetected at Neptune, whereas line‐resolved emission from Uranus was observed with a signal‐to‐noise ratio of ∼100. Using this, we have derived an upper limit of the column‐integrated H + 3 density on Neptune of 1.5 ( +4.8 −0.9 )× 10 13 m −2 , assuming a temperature of 550±100 K. This value improves the previous established limit by a factor of 20 and shows that the H + 3 density predicted by the best available model overestimate the density by at least a factor of 3. In addition, the solar reflection continuum of Neptune in the K and L ′ bands is seen to be brighter on the Northern hemisphere by a factor of ∼2, whereas previous observations had noted the solar reflection as being brighter on the Southern hemisphere.