1:45 PM - 3:15 PM
[O11-P27] Studies of Meteor Plasma Physics by Spectral Observation
Keywords:meteor, spectroscopic observation, Effective Temperature
Abstract
A meteor is a phenomenon in which a small particle moving through the solar system enters the Earth's atmosphere and emits plasma light. Meteors are ejected from comets and active asteroids, so they can deepen our understanding of the parent body and the proto solar system. For this study, a homemade device made from a simple security camera and a grating sheet was used. he goal is to gain a deeper understanding of meteors by observing meteor spectra and investigating the differences in plasma excitation temperature and the emission of each element.
1. Purpose
Measure the effective excitation temperature of the meteor plasma using the emission lines of iron. We will also investigate the relationship between the intensity of emission lines and excitation temperatures of other metals in the meteorite.
2. Research Method
Assuming that the meteor plasma is in thermal equilibrium and that the emission lines in the spectrum are due to electron transitions, the following equation (1) holds for the intensity of each emission line.
I=hcg'AN・(exp(-χ/kT)/4πλB(T))
N : the number of atoms or irons considered in the column along the line of sight,
T : excitation temperature,
B(T): partition function as a function of T,
g’ : statistical weight of the spontaneous emission,
A : probability of the spectral line,
λ : wavelength of the spectral line,
χ : excitation potential of the upper level,
h : Planck’s constant,
c : speed of light,
k : Boltzmann’s constant.
Considering the transition of electrons in this case, the following equation (2) holds.
g'A=(8π2ε2/mcλ2)gf
ε : charge of the electron,
m : mass of the electron,
g : statistical weight of the lower level,
f : absorption oscillator strength.
Using these equations, T can be determined as the slope of a linear equation from χ, log(gf) of the relevant emission line, and the emission line intensity We determined from the observation. (Nagasawa 1978)
For the observation, we used an observation device that we made by attaching a film-type diffraction grating (Figure 1) to a commercially available security camera (Figure 2). Wavelength identification was performed on the obtained meteor spectra (Figure 3) using the spectral database (NIST) and other data (Figure 4). Image analysis was performed using Makali’i and other calculations were performed using Excel. Five meteor spectra were taken during one year. This abstract paper describes an example of the analysis.
The excitation temperature of the meteor plasma was determined from the intensity and the values of χ and log(gf) of the Fe I emission lines in the obtained emission line spectra. Figure 5 shows an example of the approximate curve calculated for the plasma temperature measurement.
3. Results and Discussion
The temperature variation of the meteor plasma is shown in Figure 6. For the Mg I, Na I, and Fe I emission lines, the intensity change was compared with the change in excitation temperature (Figs. 7, 8, and 9). Note that the x-axis values in the figures represent the time variation, which is the line number of the frame used for the measurement and represents the time course.
The phenomenon to be considered is decreasing temperature at x=9 in Figure 6, which represents the temperature change. One possible reason for this could be the partial pixel loss of the camera and the blending of the emission lines due to low dispersion. However, if we consider that this represents a physical change in the plasma, we can make an interesting hypothesis. That is, at x=9, the intensity of the Mg I and Na I emission lines increases, and the meteor intensity strongly. This temperature drop may be due to the temperature change caused by the rapid expansion of the plasma. The increase in emission intensity can be explained by the increase in the volume of the plasma and the increase in the radiating area. x=5 for Mg I and x=6,9 for Na I are the peaks of the intensity, confirming that there is a difference in the emission mechanism. We would like to further investigate the excitement energies of each of them in detail.
From the above, we were able to obtain meaningful data regarding the purpose of this study, which is to estimate the excitation temperature of the plasma and the differences in the behavior of each element. In addition, we are convinced of the usefulness of the research method of this study, which uses a simple security camera and observation equipment made by ourselves using a grating sheet.
4. References
(1)Nagasawa, Analysis of the spectra of Leonid meteors, 1978
(2) NIST(National Institute Standards and Technology)
https://physics.nist.gov/PhysRefData/ASD/lines_form.html 2025.3.25 viewed
A meteor is a phenomenon in which a small particle moving through the solar system enters the Earth's atmosphere and emits plasma light. Meteors are ejected from comets and active asteroids, so they can deepen our understanding of the parent body and the proto solar system. For this study, a homemade device made from a simple security camera and a grating sheet was used. he goal is to gain a deeper understanding of meteors by observing meteor spectra and investigating the differences in plasma excitation temperature and the emission of each element.
1. Purpose
Measure the effective excitation temperature of the meteor plasma using the emission lines of iron. We will also investigate the relationship between the intensity of emission lines and excitation temperatures of other metals in the meteorite.
2. Research Method
Assuming that the meteor plasma is in thermal equilibrium and that the emission lines in the spectrum are due to electron transitions, the following equation (1) holds for the intensity of each emission line.
I=hcg'AN・(exp(-χ/kT)/4πλB(T))
N : the number of atoms or irons considered in the column along the line of sight,
T : excitation temperature,
B(T): partition function as a function of T,
g’ : statistical weight of the spontaneous emission,
A : probability of the spectral line,
λ : wavelength of the spectral line,
χ : excitation potential of the upper level,
h : Planck’s constant,
c : speed of light,
k : Boltzmann’s constant.
Considering the transition of electrons in this case, the following equation (2) holds.
g'A=(8π2ε2/mcλ2)gf
ε : charge of the electron,
m : mass of the electron,
g : statistical weight of the lower level,
f : absorption oscillator strength.
Using these equations, T can be determined as the slope of a linear equation from χ, log(gf) of the relevant emission line, and the emission line intensity We determined from the observation. (Nagasawa 1978)
For the observation, we used an observation device that we made by attaching a film-type diffraction grating (Figure 1) to a commercially available security camera (Figure 2). Wavelength identification was performed on the obtained meteor spectra (Figure 3) using the spectral database (NIST) and other data (Figure 4). Image analysis was performed using Makali’i and other calculations were performed using Excel. Five meteor spectra were taken during one year. This abstract paper describes an example of the analysis.
The excitation temperature of the meteor plasma was determined from the intensity and the values of χ and log(gf) of the Fe I emission lines in the obtained emission line spectra. Figure 5 shows an example of the approximate curve calculated for the plasma temperature measurement.
3. Results and Discussion
The temperature variation of the meteor plasma is shown in Figure 6. For the Mg I, Na I, and Fe I emission lines, the intensity change was compared with the change in excitation temperature (Figs. 7, 8, and 9). Note that the x-axis values in the figures represent the time variation, which is the line number of the frame used for the measurement and represents the time course.
The phenomenon to be considered is decreasing temperature at x=9 in Figure 6, which represents the temperature change. One possible reason for this could be the partial pixel loss of the camera and the blending of the emission lines due to low dispersion. However, if we consider that this represents a physical change in the plasma, we can make an interesting hypothesis. That is, at x=9, the intensity of the Mg I and Na I emission lines increases, and the meteor intensity strongly. This temperature drop may be due to the temperature change caused by the rapid expansion of the plasma. The increase in emission intensity can be explained by the increase in the volume of the plasma and the increase in the radiating area. x=5 for Mg I and x=6,9 for Na I are the peaks of the intensity, confirming that there is a difference in the emission mechanism. We would like to further investigate the excitement energies of each of them in detail.
From the above, we were able to obtain meaningful data regarding the purpose of this study, which is to estimate the excitation temperature of the plasma and the differences in the behavior of each element. In addition, we are convinced of the usefulness of the research method of this study, which uses a simple security camera and observation equipment made by ourselves using a grating sheet.
4. References
(1)Nagasawa, Analysis of the spectra of Leonid meteors, 1978
(2) NIST(National Institute Standards and Technology)
https://physics.nist.gov/PhysRefData/ASD/lines_form.html 2025.3.25 viewed