The lunar radio flux during Leonid meteor showers and lunar eclipse
Significance variations of lunar radio flux at the wavelength of 2.46 cm were detected in Irbene (Latvia) during the maxima of Leonid shower on the Moon in 2000 and 2001. These results were interpreted as detection of lunar radio emission of seismic origin. However, radio observations of the Moon at...
Збережено в:
| Опубліковано в: : | Кинематика и физика небесных тел |
|---|---|
| Дата: | 2005 |
| Автори: | , , , , |
| Формат: | Стаття |
| Мова: | Англійська |
| Опубліковано: |
Головна астрономічна обсерваторія НАН України
2005
|
| Теми: | |
| Онлайн доступ: | https://nasplib.isofts.kiev.ua/handle/123456789/79609 |
| Теги: |
Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | The lunar radio flux during Leonid meteor showers and lunar eclipse / A.E. Volvach, A.A. Berezhnoy, O.B. Khavroshkin, A.V. Kovalenko, G.T. Smirnov // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 82-85. — Бібліогр.: 16 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859623140439621632 |
|---|---|
| author | Volvach, A.E. Berezhnoy, A.A. Khavroshkin, O.B. Kovalenko, A.V. Smirnov, G.T. |
| author_facet | Volvach, A.E. Berezhnoy, A.A. Khavroshkin, O.B. Kovalenko, A.V. Smirnov, G.T. |
| citation_txt | The lunar radio flux during Leonid meteor showers and lunar eclipse / A.E. Volvach, A.A. Berezhnoy, O.B. Khavroshkin, A.V. Kovalenko, G.T. Smirnov // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 82-85. — Бібліогр.: 16 назв. — англ. |
| collection | DSpace DC |
| container_title | Кинематика и физика небесных тел |
| description | Significance variations of lunar radio flux at the wavelength of 2.46 cm were detected in Irbene (Latvia) during the maxima of Leonid shower on the Moon in 2000 and 2001. These results were interpreted as detection of lunar radio emission of seismic origin. However, radio observations of the Moon at the wavelength of 6 cm in Ukraine did not show any signal enhancement of lunar radio flux on November 17–19, 2001. Except meteoroid impacts, the eclipses can lead to increasing of intensity of non-thermal radio emission due to formation of micro cracks in lunar regolith when the regolith temperature during eclipses is quickly changes. The results of simultaneous observations of the full lunar eclipse at the wavelengths of 18 cm and 1.35 cm in Simeiz (Ukraine) and Pushchino (Russia) on November 8–9, 2003 are presented. According to these observations the correlation between fluctuations of lunar radio flux at both wavelengths is absent. Thus, the previously detected fluctuations of lunar flux at the wavelength of 2.6 cm may have the instrumental origin. Lunar origin of detected fluctuations could be confirmed by simultaneous observations at two radio telescopes. Our future goal is try to detect the lunar radio emission of seismic origin at the lower frequencies, because the intensity of such emission during the earthquakes increases with a decreasing frequency.
|
| first_indexed | 2025-11-29T06:37:42Z |
| format | Article |
| fulltext |
THE LUNAR RADIO FLUX DURING LEONID METEOR SHOWERS
AND LUNAR ECLIPSE
A. E. Volvach1, A. A. Berezhnoy2, O. B. Khavroshkin3,
A. V. Kovalenko4, G. T. Smirnov4
1Radio Astronomy Laboratory, Crimean Astrophysical Observatory
RT-22, Katsively, 98688 Yalta, Ukraine
e-mail: volvach@crao.crimea.ua
2Advanced Institute for Science and Engineering, Waseda University
3-4-1 Okubo, Tokyo 169-0071 Japan
3Institute of Earth Physics
10 B. Gruzinskaya Str., 123810 Moscow, Russia
4Pushchino Radioastronomical Observatory
Pushchino, 142290 Moscow Region, Russia
Significance variations of lunar radio flux at the wavelength of 2.46 cm were detected in Irbene
(Latvia) during the maxima of Leonid shower on the Moon in 2000 and 2001. These results were
interpreted as detection of lunar radio emission of seismic origin. However, radio observations of
the Moon at the wavelength of 6 cm in Ukraine did not show any signal enhancement of lunar
radio flux on November 17–19, 2001. Except meteoroid impacts, the eclipses can lead to increasing
of intensity of non-thermal radio emission due to formation of micro cracks in lunar regolith when
the regolith temperature during eclipses is quickly changes. The results of simultaneous observa-
tions of the full lunar eclipse at the wavelengths of 18 cm and 1.35 cm in Simeiz (Ukraine) and
Pushchino (Russia) on November 8–9, 2003 are presented. According to these observations the cor-
relation between fluctuations of lunar radio flux at both wavelengths is absent. Thus, the previ-
ously detected fluctuations of lunar flux at the wavelength of 2.6 cm may have the instrumental
origin. Lunar origin of detected fluctuations could be confirmed by simultaneous observations at
two radio telescopes. Our future goal is try to detect the lunar radio emission of seismic origin at
the lower frequencies, because the intensity of such emission during the earthquakes increases with
a decreasing frequency.
INTRODUCTION
Meteoroid impacts onto the Moon might be observable from the Earth. The meteoroid stream most likely to
be detectable is the Leonids, remnants of the comet 55P/Tempel–Tuttle. Optical flashes from Leonid meteors
hitting the dark side of the Moon were observed in 1999 [6]. An unsuccessful attempt to detect flashes of radio
emission at the wavelength of 3.6 cm during optical flashes caused by Leonid’s impacts onto the Moon in 1999
was carried out by [5].
The main component of the lunar radio emission is the thermal radiation. The lunar thermal radiation has
been rather well investigated and it allowed us to estimate the density and electric properties of the porous lunar
regolith, as well as the temperature regime of the surface layers. The frequency of electromagnetic radiation
of the seismic origin measured before earthquakes ranges from 1 kHz to 1 MHz [3]. Radio emission of seismic
origin can also be detected on the Moon.
Variability of lunar radio emission at 13 and 21 cm was detected on July 29 – August 2, 1999 [4]. During
the Leonid meteoroid shower in 2000 and 2001 the variability of lunar radio flux at the wavelength of 2.46 cm
was detected in Irbene (Latvia) [1]. The increasing of amplitude of the lunar radio flux variations during
Leonid shower is interpreted as a result of excitation of the seismic waves on the Moon and the transformation
of the seismic energy into the electromagnetic radiation. In this article we present the results of the Moon
observations in Ukraine during Leonid shower in 2001 and in Japan in November 1999.
Except for meteoroid impacts, the eclipses can lead to increasing of intensity of non-thermal radio emission
due to formation of micro cracks in lunar regolith when the regolith temperature quickly changes during eclipses.
c© A. E. Volvach, A. A. Berezhnoy, O. B. Khavroshkin, A. V. Kovalenko, G. T. Smirnov, 2004
82
Fig. 1b.
Fig. 1a. Fig. 2a.
Fig. 2b.
Figure 1. Periodogramms of radio flux from the Moon
on November 18, 2001. Curve 1a shows the results of ob-
servations at 09:50–10:45 UT, curve 1b those of at 14:00–
14:55 UT
Figure 2. Periodogramms of radio flux from Cyg A and
the sky on November 18, 2001. Curve 2a shows the re-
sults of the sky observations in Simeiz at 8:32–8:38 UT,
curve 2b those of Cyg A at 13:49–13:55 UT
The results of simultaneous observations of the full lunar eclipse are presented at the wavelengths of 18 cm and
1.35 cm in Simeiz and Pushchino on November 8–9, 2003.
OBSERVATIONS
During Leonid meteor showers
The observations of the Moon at the frequency of 8.2 GHz during Leonid meteor shower in 1999 were carried out
using the 32 m radio telescope of the Kashima Space Research Center, Japan (36◦ N, 141◦ E) on November 15,
16, and 18. The bandwidth of the receiver is 800 MHz, the output time constant is 0.021 ms. Then the averaging
of data was performed with a new output time constant equal to 1 s. The antenna was guided to the center of
the lunar disc. The detailed description of the observations is given in [5]. The calibration sources and sky were
not observed in Kashima. That’s why the additional observations of the Moon at the frequency of 8.415 GHz
were carried out on May 7, 2003 at RT-22 in Crimea (44◦ N, 35◦ E). The bandwidth of the receiver is 2 MHz,
the output time constant is 1 s. The value of the sensitivity threshold for this time resolution is equal to 0.05 K.
The antenna feed was left circular polarized. The antenna was guided to the center of the lunar disc. For
calibration purposes the observations of the sky near the Moon and Vir A were also carried out. The duration
of interrupted observations of each object is 20 min.
During November 17–19, 2001 the observations of the Moon at the wavelength of 6.2 cm were carried out
in Simeiz. The frequency and the bandwidth of the receiver in Simeiz are 4.866 GHz and 2 MHz, respectively.
The diameter of the radio telescope is 22 m, the output time constant is 1 s. The antenna feed was left circular
polarized. The antenna was guided to the center of the lunar disc. The duration of interrupted observations of
the Moon is 1 hour.
83
To verify whether the variations are attributed to the Moon we performed several tests that included recor-
ding signals from strong calibration source Cyg A and recording atmospheric radio emission, when the radio
telescope tracked a position on the sky several degrees off the Moon and Cyg A.
During lunar eclipse
During November 8–9, 2003 the simultaneous observations of the Moon were carried out in Pushchino (55◦ N,
38◦ E) and in Simeiz (44◦ N, 35◦ E). The frequency and the bandwidth of the receiver in Simeiz are 1.666 GHz
and 2 MHz, respectively. The frequency and the bandwidth of the receiver in Pushchino are 22.283 GHz and
6 MHz, respectively. The diameter of both radio telescopes is 22 m, the output time constant is 1 s. The antenna
feed was left circular polarized in both cases. The antenna was guided to the center of the lunar disc.
To verify whether the variations are attributed to the Moon we performed several tests that included recor-
ding signals from strong source Cyg A that is known to be without fast variations and recording the atmospheric
radio emission, when the radio telescope tracked a position on the sky several degrees off the Moon and Cyg A.
RESULTS
The mean amplitude of sporadic fluctuations of lunar radio flux at the frequency of 8.2 GHz was about five
relative units on November 16 and 18, 1999. The amplitude of fluctuations of lunar radio flux did not increase
at the time of predicted maximum of Leonid meteor shower on the Moon. The amplitude of fluctuations of
lunar radio flux was equal to 200–300 relative units on November 16, 1999 at 9:20–10:50 UT. It can be explain
by instrumental effects because Leonid activity was too low at that time interval.
The amplitudes of peak-to peak variations of signal from the Moon at the frequency of 8.4 GHz in Simeiz are
equal to 2 K and comparable to those from the sky and Vir A. Fourier analysis shows the absence of periodicities
of signal from all three objects.
The results of the Moon observations at the wavelength of 6.2 cm are quite different from those of at
the wavelength of 2.46 cm. The amplitude of lunar radio flux variations at the wavelength of 6.2 cm in Simeiz
is equal to 1–2 K during November 17–19, 2001 and did not increase at the time of predicted maxima of Leonid
shower on the Moon. The amplitude of these variations is comparable with that of the sky and Cyg A. Spectral
analysis shows the existence of periodicities of radio flux both from the Moon and from Cyg A and also from
the sky. The values of periods vary chaotically versus time. All these facts confirm instrumental origin of
detected variations.
According to simultaneous observations of the full lunar eclipse at the wavelengths of 18 cm and 1.35 cm in
Simeiz and Pushchino on November 8–9, 2003 the correlation between fluctuations of lunar radio flux at both
wavelengths is absent.
DISCUSSION
The Moon observations at the wavelengths of 3.6 and 6.2 cm do not give support to the lunar origin of detected
variations. It can be explained by weak intensity of lunar radio emission caused by meteoroid bombardment
at the wavelengths of 3.6 and 6.2 cm in comparison with that at the wavelength of 2.46 cm. To confirm
the detecting seismic origin of lunar radio emission at the wavelength of 2.46 cm the additional simultaneous
observations of the Moon at this wavelength are required by using two different radio telescopes.
The important feature of the variable lunar radio flux is its periodicity. The values of periods are situated
between 1.5 and 12 min at the wavelengths of 2.46, 13, and 21 cm [1]. The spectral analysis of the radio signals
variations from the sky, the Moon and Cyg A at the wavelength of 6.2 cm shows a general increase of the spectral
density towards lower frequencies. The periods of oscillations of lunar radio flux at the wavelength of 6.2 cm
range from 1 to 15 min (see Fig. 1). The amplitude of spectral power of the spectra at the wavelength of 6.2 cm
from the sky and Cyg A is comparable with that from the Moon; the spectral maximum of the atmospheric
fluctuations is at periods less than 2 min (see Fig. 2). Unfortunately, the observations of the sky and Cyg A
have been carried out only during 5 min, but it is not enough to study of possible periodicities at 3–15 min
range, where the lunar radio flux shows periodicities. There is fast variability of the values and intensities of
spectral peaks from the Moon, from the sky, and also from Cyg A. It is known that Cyg A has not variability of
its radio flux in 1 min range. This means that the instrumental effects can explain the periodicities of lunar flux
at the wavelength of 6.2 cm. Thus, previously detected periodicities of lunar flux at other wavelengths must be
checked again with simultaneous observations at two isolated antennas.
During impacts of meteoroids with the Moon the thermal radiation emits from the impact-produced fireball.
Just after an impact, the seismic waves are excited, and a part of the seismic energy is transformed to the radio
emission. The unsuccessful search for the impact-produced radio flashes was performed. The upper limit for
the strongest radio flashes is equal to 3 K based on the Simeiz data. We can estimate the upper limit of intensity
84
of the impact-produced radio flashes as 2 · 10−8 J Hz−1 at the wavelength of 6.2 cm. We can suppose that radio
flashes accompanying optical emission have the same duration as optical flashes (0.1 s). Let us assume that
the mass of the biggest meteoroid collided with the Moon at the time interval of our radio observations is 2.5 kg
as estimated by Ortiz et al. 2002. Using the model of Yanagisawa & Kisaichi [6] for thermal radiation from
D ′ flash, caused by the impact of 2.5 kg meteoroid, we can estimate that the flux of thermal radiation from
such impact does not exceed 5 · 10−15 J Hz−1 at the wavelength of 6.2 cm. Thus, the flux of thermal radiation
from the impact-produced fireballs is too low for detection by radio telescopes. This estimation is confirmed
with the radio flashes absence at the frequency of 8.2 GHz at the moments of big meteoroids impacts detected
by Yanagisawa & Kisaichi [6].
The further theoretical, observational, and experimental study of the radio emission of the Moon is necessary
to better understand the nature of the detected variations of lunar radio flux. The future study of the seis-
mic origin of lunar radio emission must be performed at a few radio telescopes for accurate determination of
an influence of the atmospheric fluctuations and instrumental effects. Monitoring of the lunar radio flux can
give information about the time of maximal intensity of the strongest meteoroid showers on the Moon. Un-
fortunately, these moments were not estimated independently with other techniques. For example, the time
determination of Leonid shower maxima on the Moon based on detection of the optical flashes on the Moon
is practically difficult due to poor statistics. For study of the meteoroid bombardment intensity on the Moon
with optical techniques, the methods for detection of the weak flashes must be developed. The LUNAR-A and
SELENE spacecrafts are planned to launch to the Moon in nearest years. The LUNAR-A penetrators with
sensitive seismometers will be installed on the lunar surface; these instruments can determine the moments of
strong moonquakes and the maxima of meteor showers on the Moon. As a correlation between seismic radio
emission and earthquakes is verified by Diakonov & Ulitin on Earth [2], we can expect the appearance of radio
emission of the seismic origin during moonquakes. During moonquakes the release of radioactive gases Rn and
Po from lunar interiors can occur, the SELENE alpha particle spectrometer can detect such events.
Except for meteoroid impacts, the eclipses can lead to increasing of the intensity of non-thermal radio
emission due to formation of micro cracks in lunar regolith when the regolith temperature during eclipses is
quickly changes. According to these observations a correlation between the fluctuations of lunar radio flux
at both wavelengths is absent. Thus, the previously detected fluctuations of the lunar flux at the wavelength
of 2.6 cm may have instrumental origin. The lunar origin of detected fluctuations could be confirmed by
simultaneous observations using two radio telescopes.
CONCLUSION
Previously, it was reported that the strong oscillations of the lunar flux at the wavelength of 2.46 cm occurred
at the moments of the predicted maxima of Leonid meteor shower on the Moon in 2000 and 2001. But
the observations of the Moon at the wavelength of 2.46 cm were carried out at the unique antenna. An absence
of the coincidence data obtained with other radio telescopes means that the instrumental origin of the detected
fluctuations can’t be exclude. To confirm the lunar origin of the variable lunar radio emission the simultaneous
observations of the Moon must be carried out at a few radio telescopes during the lunar eclipses and the strong
meteor showers. The radio flashes caused by collisions of kg meteoroids with the Moon were not detected at
the wavelengths of 3.6 and 6.2 cm, the upper limit for the intensity of such flashes is estimated. In the future it is
highly desirable the simultaneous study of the meteoroid bombardment and the seismic activity of the Moon with
LUNAR-A penetrators, SELENE alpha particle spectrometer, single dish radio observations, and by monitoring
of the optical flashes.
Our future goal is try to detect the lunar radio emission of seismic origin at the lower frequencies, because
the intensity of such emission during earthquakes increases with a decreasing frequency.
[1] Berezhnoy A. A., Bervalds et al. // Baltic Astronomy.–2002.–11.–P. 507.
[2] Diakonov B. P., Ulitin R. V. // Rep. Russian Acad. Sci.–1992.–264.–P. 322.
[3] Gokhberg M. B., Morgunov V. A., Pokhotelov O. A. Earthquake prediction – Seismoelectromagnetic phenomena.–
Amsterdam: Gordon and Breach Publishers, 1995.–P. 193.
[4] Khavroshkin O. B., Tsyplakov V. V., Poperechenko B. A., et al. // Rep. Earth Sci.–2001.–376.–P. 90.
[5] Osaki H., Okubo H., Koyama Y. // J. Commun. Res. Lab.–2001.–48.–P. 159.
[6] Yanagisawa M., Kisaichi N., et al. // Icarus.–2002.–159.–P. 31.
85
|
| id | nasplib_isofts_kiev_ua-123456789-79609 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0233-7665 |
| language | English |
| last_indexed | 2025-11-29T06:37:42Z |
| publishDate | 2005 |
| publisher | Головна астрономічна обсерваторія НАН України |
| record_format | dspace |
| spelling | Volvach, A.E. Berezhnoy, A.A. Khavroshkin, O.B. Kovalenko, A.V. Smirnov, G.T. 2015-04-03T15:19:08Z 2015-04-03T15:19:08Z 2005 The lunar radio flux during Leonid meteor showers and lunar eclipse / A.E. Volvach, A.A. Berezhnoy, O.B. Khavroshkin, A.V. Kovalenko, G.T. Smirnov // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 82-85. — Бібліогр.: 16 назв. — англ. 0233-7665 https://nasplib.isofts.kiev.ua/handle/123456789/79609 Significance variations of lunar radio flux at the wavelength of 2.46 cm were detected in Irbene (Latvia) during the maxima of Leonid shower on the Moon in 2000 and 2001. These results were interpreted as detection of lunar radio emission of seismic origin. However, radio observations of the Moon at the wavelength of 6 cm in Ukraine did not show any signal enhancement of lunar radio flux on November 17–19, 2001. Except meteoroid impacts, the eclipses can lead to increasing of intensity of non-thermal radio emission due to formation of micro cracks in lunar regolith when the regolith temperature during eclipses is quickly changes. The results of simultaneous observations of the full lunar eclipse at the wavelengths of 18 cm and 1.35 cm in Simeiz (Ukraine) and Pushchino (Russia) on November 8–9, 2003 are presented. According to these observations the correlation between fluctuations of lunar radio flux at both wavelengths is absent. Thus, the previously detected fluctuations of lunar flux at the wavelength of 2.6 cm may have the instrumental origin. Lunar origin of detected fluctuations could be confirmed by simultaneous observations at two radio telescopes. Our future goal is try to detect the lunar radio emission of seismic origin at the lower frequencies, because the intensity of such emission during the earthquakes increases with a decreasing frequency. en Головна астрономічна обсерваторія НАН України Кинематика и физика небесных тел MS1: Decameter Radioastronomy The lunar radio flux during Leonid meteor showers and lunar eclipse Article published earlier |
| spellingShingle | The lunar radio flux during Leonid meteor showers and lunar eclipse Volvach, A.E. Berezhnoy, A.A. Khavroshkin, O.B. Kovalenko, A.V. Smirnov, G.T. MS1: Decameter Radioastronomy |
| title | The lunar radio flux during Leonid meteor showers and lunar eclipse |
| title_full | The lunar radio flux during Leonid meteor showers and lunar eclipse |
| title_fullStr | The lunar radio flux during Leonid meteor showers and lunar eclipse |
| title_full_unstemmed | The lunar radio flux during Leonid meteor showers and lunar eclipse |
| title_short | The lunar radio flux during Leonid meteor showers and lunar eclipse |
| title_sort | lunar radio flux during leonid meteor showers and lunar eclipse |
| topic | MS1: Decameter Radioastronomy |
| topic_facet | MS1: Decameter Radioastronomy |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79609 |
| work_keys_str_mv | AT volvachae thelunarradiofluxduringleonidmeteorshowersandlunareclipse AT berezhnoyaa thelunarradiofluxduringleonidmeteorshowersandlunareclipse AT khavroshkinob thelunarradiofluxduringleonidmeteorshowersandlunareclipse AT kovalenkoav thelunarradiofluxduringleonidmeteorshowersandlunareclipse AT smirnovgt thelunarradiofluxduringleonidmeteorshowersandlunareclipse AT volvachae lunarradiofluxduringleonidmeteorshowersandlunareclipse AT berezhnoyaa lunarradiofluxduringleonidmeteorshowersandlunareclipse AT khavroshkinob lunarradiofluxduringleonidmeteorshowersandlunareclipse AT kovalenkoav lunarradiofluxduringleonidmeteorshowersandlunareclipse AT smirnovgt lunarradiofluxduringleonidmeteorshowersandlunareclipse |