Spectroscopic anatomy of a meteor trail cross section with the European Southern Observatory Very Large Telescope

Abstract

A meteor spectrum was recorded serendipitously at the European Southern Obrervatory (ESO) Very Large Telescope (VLT) during a long exposure in long-slit spectroscopic mode with FORS1. The -8 magnitude fireball crossed the narrow 1Î x 7î slit during the observation of a high z supernova in normal service mode operation on May 12, 2002. The spectrum covered the range of 6371050 nm, where the meteors air plasma emissions from N2, N, and O dominate. Carbon atom emission was not detected in the relatively unexplored wavelength range above 900 nm, but the observed upper limit was only 3 sigma less than expected from the dissociation of atmospheric CO2. The meteor trail was resolved along the slit, and the emission had a Gaussian distribution with a dimension of FWHM = 7.0 (+/- 0.4) * sin(alpha) * H (km)/90 m, where alpha is the unknown angle between the orientation of the meteor path and slit and H the assumed altitude of the meteor in km. To our knowledge, this is the first observation of a spatially resolved spectrum across a meteor trail. Unlike model predictions, the plasma excitation temperature varied only from about 4,300 to 4,365 K across the trail, based on the ratio of atomic and molecular nitrogen emissions. Unfortunately, we conclude that this was because the meteor at 100 km altitude was out of focus.