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Spaceborne ultraviolet 251–384 nm spectroscopy of a meteor during the 1997 Leonid shower
Author(s) -
Jenniskens Peter,
Tedesco Ed,
Murthy Jayant,
Laux Christophe O.,
Price Stephen
Publication year - 2002
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.2002.tb00878.x
Subject(s) - ionization , electron density , meteor (satellite) , electron temperature , ultraviolet , emission spectrum , plasma , physics , spectral line , spectroscopy , meteor shower , astrophysics , analytical chemistry (journal) , chemistry , astronomy , ion , optics , chromatography , quantum mechanics
— We used the ultraviolet to visible spectrometers onboard the midcourse space experiment to obtain the first ultraviolet spectral measurements of a bright meteor during the 1997 Leonid shower. The meteor was most likely a Leonid with a brightness of about‐2 magnitude at 100 km altitude. In the region between 251 and 310 nm, the two strongest emission lines are from neutral and ionized magnesium. Ionized Ca lines, indicative of a hot T ≅ 10 000 K plasma, are not detected. The Mg and Mg+ line intensity ratio alone does not yield the ionization temperature, which can be determined only by assuming the electron density. A typical air plasma temperature of T = 4400 K would imply a very high electron density: n e = 2.2 times 10 18 m‐ 3 , but at chondritic abundances of Fe/Mg and Si/Mg ≅ 1. For a more reasonable local‐thermodynamic‐equilibrium (LTE) air plasma electron density, the Mg and Mg+ line ratio implies a less than chondritic Fe/Mg = 0.06 abundance ratio and a cool non‐LTE T = 2830 K ionization temperature for the ablation vapor plasma. The present observations do not permit a choice between these alternatives. The new data provide also the first spectral confirmation of the presence of molecular OH and NO emission in meteor spectra.