Mercury resolved spectroscopy from NTT

• Published in: Planetary and space science Vol. 59; no. 15; pp. 1842 - 1852
• Main Authors: Erard, Stéphane, Bézard, Bruno, Doressoundiram, Alain, Despan, Daniela
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2011; Elsevier
• Subjects: Astrophysics; Ground-based observations; Infrared observations; Physics; Planets: Mercury; Spectrophotometry; Techniques: Spectroscopy; Techniques: Spectroscopy; Planets: Mercury; Spectrophotometry; Ground-based observations; Infrared observations
• ISSN: 0032-0633; 1873-5088
• DOI: 10.1016/j.pss.2011.07.004

Mercury has been observed in June 2006 with the SofI instrument at NTT. Resolved spectroscopy was performed in the 0.94 – 2.5 μ m range. The observations were acquired close to a favorable quadrature with maximum elongation, and span mostly the southern hemisphere in the 235–315°E longitude area. In contrast to recent observations from IRTF, the present study does not indicate any pyroxene absorption in the near-infrared range, neither in the 2 μ m region nor at 1 μ m . Detailed spectral analysis allows to derive an upper limit of 1.5% type-A pyroxene (hedenbergite) or 1.1% enstatite (assuming minimum lunar iron content) in the regions observed, at the 700 km scale. Assuming lunar-like maturity effects on band depth, this corresponds to an upper limit of 0.15 and 0.6 wt.% FeO content in silicates, an order of magnitude less than previous estimates. ► Previously reported high-Ca pyroxenes are not confirmed (upper limit ∼ 1.5 % ) ► Mercury space weathering style seems intermediate between the Moon and 433 Eros. ► An upper limit of 0.15–0.6% is derived for FeO content in silicates. ► Submicroscopic iron particles may derive entirely from opaques and meteor.