J/A+A/704/A241 Calibrated spectra of 31 fireballs (Vojacek+, 2025)
Spectroscopic analysis of hydrogen and silicon in bright fireballs:
New insights into meteoroid composition.
Vojacek V., Borovicka J., Spurny P.
<Astron. Astrophys. 704, A241 (2025)>
=2025A&A...704A.241V 2025A&A...704A.241V (SIMBAD/NED BibCode)
ADC_Keywords: Solar system ; Meteorites ; Spectra, optical
Keywords: meteorites - meteors - meteoroids
Abstract:
We present a study of high-temperature spectral component in meteor
fireballs, with particular focus on neutral hydrogen (Halpha at
656.28nm) and ionised silicon (Si II-2 doublet at 634.71nm and
637.14nm). Analysing spectra from the European Fireball Network (EN)
that exhibit Halpha and Si II-2 emissions, we investigate the
relationship between hydrogen and silicon abundances across different
meteoroid types. Plasma temperature of high-temperature component
remains independent of meteor velocity. This allows us to directly
compare relative intensities of hydrogen, bound in more volatile
materials, with silicon, bound in less volatile materials, in bodies
with different velocities.
We analysed 31 meteor spectra from the EN, focusing on Hα
(656.28nm) and Si II-2 (634.71nm, 637.14nm) emissions to determine
the elemental abundances and their relationships with the meteor
parameters. The spectroscopic data were reduced following established
procedures to derive the line intensities. We employed direct line
integration and applied ionisation corrections through Saha equations
to estimate the relative atomic abundances.
Our results confirmed that the H/Si value remains largely independent
of meteor velocity. We show a positive correlation with photometric
mass for cometary meteoroids, suggesting that larger bodies better
preserve their volatile content, namely hydrogen. This correlation
persists across the meteor showers, showing a physical process related
to volatile preservation rather than specific parent body composition.
Our data suggest that the abundance of hydrogen in large cometary
meteoroids is not only higher than in CI chondrites, but is also
comparable to or higher than the measured abundances in small
particles of dust from Halley's comet, depending on the assumed
plasma conditions. This work brought new constraints on the
distribution and preservation of volatile elements in Solar System
bodies and new insights into the potential delivery mechanisms of
water to Earth.
The H/Si values show no correlation with meteor velocity, but increase
with photometric mass for cometary meteoroids. The prevalence of
hydrogen in larger cometary meteoroids supports models where comets
could be significant contributors to Earth's volatile inventory.
Description:
Calibrated spectra of 31 fireballs observed by EN.
Spectra range are from 600nm to 700nm.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 73 31 Catalogue of meteor spectra
sp/* . 31 Individual spectra
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See also:
J/A+AS/103/83 : Line identifications in a fireball spectrum (Borovicka 1994)
J/ApJ/702/489 : ROTSE obs. of gamma-ray burst afterglows (Rykoff+, 2009)
J/A+A/667/A157 : 824 fireballs observed in 2017-2018 (Borovicka+, 2022)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- FileName Spectrum file name
18- 32 A15 --- Meteor Meteor identifier (ENyymmdd_hhmmss)
42- 48 F7.3 nm lambdaMin Minimum wavelength
58- 64 F7.3 nm lambdaMax Maximum wavelength
70- 73 I4 --- Npts Number of spectral points
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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3- 10 F8.4 nm lambda Wavelength
17- 23 F7.2 W/sr/nm Flux Spectral flux density
(Watts per steradian per nm)
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Acknowledgements:
Vlastimil Vojacek, vojacek(at)asu.cas.cz
(End) Patricia Vannier [CDS] 24-Oct-2025