On changes in the spectra of Comet C/1999 S4 (LINEAR) on July 22−28, 2002
Some spectra of Comet C/1999 S4 (LINEAR) are obtained with the UAGS spectrograph (long slit and CCD) installed on the 1-m Zeiss reflector of the SAO RAS (the Northern Caucasus, Nizhny Arkhyz) on July 23/24, 26/27, and 27/28, 2000. Sophisticated identification of emission lines in the spectra of Come...
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| Cite this: | On changes in the spectra of Comet C/1999 S4 (LINEAR) on July 22−28, 2002 / L.S. Chubko, K.I. Churyumov, I.V. Lukyanyk, V.V. Kleshchonok // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 504-508. — Бібліогр.: 8 назв. — англ. |
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Chubko, L.S. Churyumov, K.I. Lukyanyk, I.V. Kleshchonok, V.V. 2015-04-03T20:00:34Z 2015-04-03T20:00:34Z 2005 On changes in the spectra of Comet C/1999 S4 (LINEAR) on July 22−28, 2002 / L.S. Chubko, K.I. Churyumov, I.V. Lukyanyk, V.V. Kleshchonok // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 504-508. — Бібліогр.: 8 назв. — англ. 0233-7665 https://nasplib.isofts.kiev.ua/handle/123456789/79710 Some spectra of Comet C/1999 S4 (LINEAR) are obtained with the UAGS spectrograph (long slit and CCD) installed on the 1-m Zeiss reflector of the SAO RAS (the Northern Caucasus, Nizhny Arkhyz) on July 23/24, 26/27, and 27/28, 2000. Sophisticated identification of emission lines in the spectra of Comet C/1999 S4 (LINEAR) is made. Emission lines of the molecules C₂, C₃, CN, NH, CH, NH₂, CO⁺, H₂O⁺, and others were identified in the spectra of Comet C/1999 S4 (LINEAR) derived on July 22/23, 2000 before splitting the cometary nucleus. Analysis of the CCD spectra obtained on July 27/28, 2000 reveals very weak emission lines superposed on the solar reflection spectrum, unlike the case of spectra obtained with the same instrument on July 22/23. From analysis of the surface brightness profile of C₂ along the slit, the velocity of expansion of two secondary fragments (V = 10 km/hr) and energy of fragment expansion (E = 8.7 · 10¹⁵ erg) are estimated. The luminescence cometary continuum is detected by a level of 26% at 5000 Å in the spectra of the comet. Possible mechanisms of nucleus splitting are discussed. en Головна астрономічна обсерваторія НАН України Кинематика и физика небесных тел MS5: Dynamics and Physics of Solar System Bodies On changes in the spectra of Comet C/1999 S4 (LINEAR) on July 22−28, 2002 Article published earlier |
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On changes in the spectra of Comet C/1999 S4 (LINEAR) on July 22−28, 2002 |
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On changes in the spectra of Comet C/1999 S4 (LINEAR) on July 22−28, 2002 Chubko, L.S. Churyumov, K.I. Lukyanyk, I.V. Kleshchonok, V.V. MS5: Dynamics and Physics of Solar System Bodies |
| title_short |
On changes in the spectra of Comet C/1999 S4 (LINEAR) on July 22−28, 2002 |
| title_full |
On changes in the spectra of Comet C/1999 S4 (LINEAR) on July 22−28, 2002 |
| title_fullStr |
On changes in the spectra of Comet C/1999 S4 (LINEAR) on July 22−28, 2002 |
| title_full_unstemmed |
On changes in the spectra of Comet C/1999 S4 (LINEAR) on July 22−28, 2002 |
| title_sort |
on changes in the spectra of comet c/1999 s4 (linear) on july 22−28, 2002 |
| author |
Chubko, L.S. Churyumov, K.I. Lukyanyk, I.V. Kleshchonok, V.V. |
| author_facet |
Chubko, L.S. Churyumov, K.I. Lukyanyk, I.V. Kleshchonok, V.V. |
| topic |
MS5: Dynamics and Physics of Solar System Bodies |
| topic_facet |
MS5: Dynamics and Physics of Solar System Bodies |
| publishDate |
2005 |
| language |
English |
| container_title |
Кинематика и физика небесных тел |
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Головна астрономічна обсерваторія НАН України |
| format |
Article |
| description |
Some spectra of Comet C/1999 S4 (LINEAR) are obtained with the UAGS spectrograph (long slit and CCD) installed on the 1-m Zeiss reflector of the SAO RAS (the Northern Caucasus, Nizhny Arkhyz) on July 23/24, 26/27, and 27/28, 2000. Sophisticated identification of emission lines in the spectra of Comet C/1999 S4 (LINEAR) is made. Emission lines of the molecules C₂, C₃, CN, NH, CH, NH₂, CO⁺, H₂O⁺, and others were identified in the spectra of Comet C/1999 S4 (LINEAR) derived on July 22/23, 2000 before splitting the cometary nucleus. Analysis of the CCD spectra obtained on July 27/28, 2000 reveals very weak emission lines superposed on the solar reflection spectrum, unlike the case of spectra obtained with the same instrument on July 22/23. From analysis of the surface brightness profile of C₂ along the slit, the velocity of expansion of two secondary fragments (V = 10 km/hr) and energy of fragment expansion (E = 8.7 · 10¹⁵ erg) are estimated. The luminescence cometary continuum is detected by a level of 26% at 5000 Å in the spectra of the comet. Possible mechanisms of nucleus splitting are discussed.
|
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0233-7665 |
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https://nasplib.isofts.kiev.ua/handle/123456789/79710 |
| citation_txt |
On changes in the spectra of Comet C/1999 S4 (LINEAR) on July 22−28, 2002 / L.S. Chubko, K.I. Churyumov, I.V. Lukyanyk, V.V. Kleshchonok // Кинематика и физика небесных тел. — 2005. — Т. 21, № 5-додаток. — С. 504-508. — Бібліогр.: 8 назв. — англ. |
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| first_indexed |
2025-11-25T20:25:07Z |
| last_indexed |
2025-11-25T20:25:07Z |
| _version_ |
1850520941032898560 |
| fulltext |
ON CHANGES IN THE SPECTRA OF COMET C/1999 S4 (LINEAR)
ON JULY 22–28, 2002
L. S. Chubko, K. I. Churyumov, I. V. Lukyanyk, V. V. Kleshchonok
Astronomical Observatory, National Taras Shevchenko University of Kyiv
3 Observatorna Str., 04053 Kyiv, Ukraine
e-mail: chubko@observ.univ.kiev.ua
Some spectra of Comet C/1999 S4 (LINEAR) are obtained with the UAGS spectrograph (long slit
and CCD) installed on the 1-m Zeiss reflector of the SAO RAS (the Northern Caucasus, Nizhny
Arkhyz) on July 23/24, 26/27, and 27/28, 2000. Sophisticated identification of emission lines in
the spectra of Comet C/1999 S4 (LINEAR) is made. Emission lines of the molecules C2, C3,
CN, NH, CH, NH2, CO+, H2O+, and others were identified in the spectra of Comet C/1999 S4
(LINEAR) derived on July 22/23, 2000 before splitting the cometary nucleus. Analysis of the CCD
spectra obtained on July 27/28, 2000 reveals very weak emission lines superposed on the solar
reflection spectrum, unlike the case of spectra obtained with the same instrument on July 22/23.
From analysis of the surface brightness profile of C2 along the slit, the velocity of expansion of
two secondary fragments (V = 10 km/hr) and energy of fragment expansion (E = 8.7 · 1015 erg)
are estimated. The luminescence cometary continuum is detected by a level of 26% at 5000 Å in
the spectra of the comet. Possible mechanisms of nucleus splitting are discussed.
INTRODUCTION
Comet C/1999 S4 (LINEAR) belongs to a rare type of splitting comets. There are more than 30 comet
nuclei of which were destroyed by action of poorly understood or unknown physical mechanisms. The physical
mechanism of the unexpectedly destroyed nucleus of Comet C/1999 S4 (LINEAR) and its full disappearance
before observers’ eyes are one of the great riddles of comets. Therefore, every observation and especially
spectral ones, obtained during the comet splitting process, is of considerable importance in deriving important
information on physical and chemical properties of inner sheets of cometary icy nuclei and on early stages of
solar nebula if, how are thought, comets are primitive substance of the protosolar nebula.
OBSERVATIONS AND DATA REDUCTION
The spectra of Comet C/1999 S4 (LINEAR) were obtained with the UAGS spectrograph (long slit and CCD)
installed on the 1-m Zeiss reflector of the Special Astrophysical Observatory of the Russian Academy of Sci-
ences (SAO RAS) (the Northern Caucasus, Nizhny Arkhyz) on July 23/24, 26/27, and 27/28, 2000. Detailed
identification of emission lines in the spectra of Comet C/1999 S4 (LINEAR) was made. Emission lines of
the molecules C2, C3, CN, NH, CH, NH2, CO+, H2O+, and others were identified in the spectra of Comet
C/1999 S4 (LINEAR) obtained on July 22/23, 2000 before splitting of the cometary nucleus.
During three observational nights (July 23, 27, and 28, 2000) 12 spectra of Comet C/1999 S4 (LINEAR) were
obtained. Processing was made with the “Long” ESO-MIDAS. For calibration, the standard star BD+28 4211
was used. Figure 1 shows the spectra of the comet for three dates. Identification of the cometary emission
lines was made using the catalog of the spectral lines in Comet Brorsen–Metcalf [2]. For the spectra obtained
on July 23, typical cometary emission lines were found: C2, C3, CN, NH, CH, NH2, CO+, H2O+, and others.
The spectrum of the comet under investigation is a typical cometary spectrum with the spectral features which
are specific to many other comets.
PROCESSING AND DISCUSSION
Figure 1 shows that the intensity of the cometary emissions during July 23–27 decreased considerably and on
July 28 the cometary spectrum was practically completed by repeating reflected solar spectrum. One can see
from Fig. 1 that the intensity of the cometary emissions changed very fast during this time interval.
c© L. S. Chubko, K. I. Churyumov, I. V. Lukyanyk, V. V. Kleshchonok, 2004
504
Table 1. Instruments for observations of Comet C/1999 S4 (LINEAR) and their characteristics
Collimator Parabolic mirror, F/4 (F = 300 mm)
Camera Schmidt camera, F/0.9 (F = 110 mm)
Comparison spectrum He+Ne+Ar spectral lamp
Slit length 140 arcsec
Image scale 0.41 arcsec/pixel
Wavelength range 4000–6000 Å
Gratings 651(8) grooves/mm
Linear dispersion 3.1 Å/pixel
TV-guide field 3 arcmin
CCD detector ISD015A (“Electron” St.-Petersburg), 530×580 pixel
Pixel size 18×24 mkm
Readout noise 12 electron
Figure 1. Evolution of the spectra of Comet C/1999 S4 (LINEAR) from July 23 to July 28, 2000
505
Figure 2. Distribution of surface brightness along the slit for emission line C2 from July 23 to July 28, 2000
Rather sharp decrease of fluxes in the emission lines is confirmed by a noticeable decreasing of the comet
visual magnitude, which characterized the luminosity of the comet mainly in the C2 Swan bands. One of
the authors (Churyumov) observed Comet C/1999 S4 (LINEAR) in Kyiv with a binocular and estimated its
visual integral magnitudes on July 22.90 UT (m1 = 6.4m) and 23.90 UT (m1 = 6.3m).
The estimations of the integral visual magnitude made by M. Lehky (Czech Republic) on July 31.85 UT
(m1 = 8.5m) and D. Sergent (Australia) on August 2.35 UT (m1 = 9.0m) show that during July 22 – August 2,
2000 the comet magnitude decreased by 2.5m, and on August 9 the comet magnitude became less than 11–12m.
Noticeable changes took place in the profile of the comet brightness in some emission lines. Figure 2 shows
space profiles of the surface brightness of the C2 emission line along the slit on July 23, 27, and 28. On July 23
the space profile of the C2 emission line is quite smooth, asymmetric, elongated in the opposite side direction
from the Sun, that is to the tail, and has one maximum peak. Figure 2 also shows the profiles of brightness of
the emission line on July 27 and 28, 2000. We believed that two-peak profiles of C2 in the spectra of Comet
C/1999 S4 (LINEAR), obtained on July 27 and 28, 2000 could be explained by the existence of the secondary
maximum of brightness in the near-nucleus region of the comet tied presumably with any secondary fragments of
the nucleus. In this time the comet image have prolonged form without the evidence maximum of the brightness.
But at least 16 fragments were detected in images of Comet C/1999 S4 (LINEAR) taken on August 5, 2000
with the Hubble Space Telescope (HST) and on August 6 with the Very Large Telescope (VLT) [7].
Figure 2 shows that the distance between the brightness maxima on July 27 and 28 changed. Using the sizes
of the pixels on the image we estimated the velocity of fragments escaping in the near-nucleus region (10 km/hr).
It supports probably the fact that escaping fragments are monolithic (not gaseous) objects.
To estimate the size and possible mass of the cometary nucleus, we determined the absolute magnitude of
the comet H0. For this aim we built the light curve of Comet C/1999 S4 (LINEAR). To build the light curve and
to find its photometric parameters, the observations published in the International Comet Quarterly [1] were
used. After the exclusion of rough errors using Tompson’s rule, the data per day were averaged. The photometric
parameters were calculated by Orlov’s formula:
m = Hy + 5 logΔ + 2.5n log r, (1)
where Δ, r are the geo- and heliocentric distances, respectively.
Figure 3 represents light curves. Photometric parameters of Comet C/1999 S4 (LINEAR) before perihelion
are Hy = 8.79 ± 0.03 and n = 6.7 ± 0.1. To build the light curve, we used shorter intervals of the heliocentric
distances than Yoshida’s ones [http://www.aerith.net/comet/catalog/1999S4/1999S4.html]. Therefore,
the absolute magnitude of the comet obtained by us (H0 = 8.8m) differs from the absolute magnitude of
the comet deduced by Yoshida (H0 = 7.7m) approximately by 1m.
As shown by photographic observations of the comet made by T. Kryachko at Mount Pastukhov with
the 40-cm Zeiss astrograph and also from the analysis of the cometary light curve (Fig. 3), the intense destruction
of the cometary nucleus began probably on July 23, 2000. The light curve shows that the maximum brightness
of the comet occurred on July 23, 2000 or three days before the moment of the perihelion passage. Using
the absolute magnitude of the comet (H0 = 8.8m), we estimated approximately the cometary nucleus size by
506
Figure 3. Detection of fluorescent continuum in the spectrum of Comet C/1999 S4 (LINEAR) on July 23, 2000
Whipple’s formula [8] as R ≈ 1.7 km. Supposing that the average density of the matter of the comet icy
nucleus is close to 1 g/cm3, we estimated approximately minimal kinetic energy which is needed for escaping of
secondary fragments as E = 8.7 · 1015 erg.
What physical mechanism may explain splitting of Comet C/1999 S4 (LINEAR) nucleus? We can assume
that a high level of the solar activity influences the nucleus splitting. The cometary nucleus splitting was
developed at the time close to the phase of maximum of the 23rd cycle of the solar activity and more likely
the splitting of the cometary nucleus was initiated by a powerful ejection of the coronal matter (transient) on
July 14, 2000 which was detected by the SOHO satellite. As the result of the interaction of the coronal plasma of
the transient with the cometary nucleus ice electrolysis of the ice took place according to a physical mechanism
suggested by E. Drobyshevsky. As the result of electrolysis in the outer sheets of the cometary nucleus a mixture
of H2O2 was formed which exploded by the action of the next transient thrown from the solar corona. Solar
transients are formed very often during the maximum phase of the solar activity.
One of possible mechanisms of explosion may be Shulman’s mechanism according to which disintegration
of the ion-molecular clusters in the cometary icy nucleus may be a basic source of energy of the outburst.
The existence of solvate ions in Comet C/1999 S4 (LINEAR) nucleus is most likely because this comet belongs
to “new” comets in the Oort sense.
Explosion may be a result of heating of the icy cometary nucleus during its approaching to the Sun at
a distance of 0.76 AU. The heating led to formation numerous microcracks in the icy nucleus and later to
outburst escaping of gases from the nucleus caves.
It is possible that the decoding of the real reason of Comet C/1999 S4 (LINEAR) destruction and death
basing on the obtained observational data will allow one to solve the enigma of the possible destruction of
famous Comet Halley which happened on February 14, 1991, 14.3 AU away from the Sun. The analysis of CCD
images obtained with the 1.5-m telescope at the ESO in Chile shows that during the outburst from the Comet
Halley nucleus the dusty cloud erupted was 300 times as bright as a supposed dusty cloud for Comet Halley.
In the spectrum of Comet C/1999 S4 (LINEAR) we also detected the luminescence comet continuum which
has a non-solar origin. This effect was observed for a real number of comets and is caused by contribution
of luminescence of cometary dust [5]. For the first time this effect was detected in Comet Halley by [5, 6]
from decrease of the Fraunhofer lines contrast. According to the procedure from [5, 6] the optical depth τc of
the cometary atmosphere is determined by scattering of the solar light. It is a cometary characteristic which
is proportional to the ratio of the spectral intensities of the comet Ic and the Sun I�. In the presence of
luminescence the optical depth must be determined for this component by the formula:
τc(λ) =
R2�
4r2
c
Ic(λ) − If
c (λ)
I�(λ)
, (2)
where R� is the radius of the Sun, r is the heliocentric distance of the comet, and If
c (λ) is the intensity of
the comet dust luminescence.
The test of real determination of additional component If
c (λ) is the absence of traces of the Fraunhofer lines
in dependence τc(λ). For the given spectrum a level of the fluorescent continuum in the spectral region near
the wave length λ 5000 Å is equal to 26% of the comet continuum.
In [4], spectra of three comets are investigated to determine the real level of the non-solar-origin con-
tinuum in the spectral region from 350 to 500 nm. Spectra of three comets, 24P (Schaumasse), C/1989 Y1
507
(Scoritchenko–George), and C/1995 O1 (Hale–Bopp), were observed with the help of the 6-m BTA telescope
and the spectrograph with the long slit at the SAO RAS. Spectra of Comet Hale–Bopp (C/1995 O1) were also
obtained with the 1-m Zeiss telescope and echelle spectrometer of the SAO RAS.
Below are some results of processing of spectra of several comets.
1. For Comet Schaumasse (24P) on March 14–15, 1993, the level of the non-solar-origin continuum is equal
to 44% of the sum continuum level at 430 nm.
2. For Comet Scoritchenko–George (C/1989 Y1) on February 27, 1990, the level of the non-solar-origin
continuum is equal to 40% of the sum continuum level at 387 nm, 68% at 430 nm (max), and 23% at
480 nm.
3. For Comet Hale–Bopp (C/1995 O1) on April 17, 1997, the level of the non-solar-origin continuum is equal
to 32% of the sum continuum level at 397 nm and 77% at 438 nm (maximum).
Analysis of Comet C/1999 S4 (LINEAR) spectra also showed the presence of comet luminescence continuum
(non-solar origin) with its maximum at 5000 Å by a level of 26% of the sum continuum level. Similar position
of the maximum for luminescence continuum was detected in the spectrum of Comet C/2001 A2 (LINEAR).
The number of comets studied by us showed that this maximum is in the blue part of the comet spectra
(at 4300 Å). Possibly, this shift of the luminescence continuum maximum to the green part of the spectral
region close to 5000 Å is related to the presence (in the coma) of a special type of organic particles-luminofors
sublimated from the icy nucleus of Comet C/1999 S4 (LINEAR).
CONCLUSION
During three observational nights (July 23, 27, and 28, 2000) 12 middle resolution spectra of the splitting
of Comet C/1999 S4 (LINEAR) were obtained at the SAO RAS (the Northern Caucasus). Emission lines of
the molecules C2, C3, CN, NH, CH, NH2, CO+, H2O+, and others were identified in the spectra of Comet
C/1999 S4 (LINEAR) obtained on July 22/23, 2000 before splitting of the cometary nucleus. Analysis of
the CCD spectrum obtained on July 27/28, 2000 reveals very weak emission lines superposed on the solar
reflection spectrum, unlike the case of the spectra obtained with the same instrument on July 22/23. Changes
in the spectra and fast decrease of fluxes in the cometary emission lines are found and discussed. From analysis
of the surface brightness profile of C2 along the slit, the velocity of expansion of two secondary fragments
(V = 10 km/hr) and energy of fragments expansion (E = 8.7 · 1015 erg) are estimated. The luminescence
cometary continuum by a level of 26% of the sum continuum level at 5000 Å in the spectra of the comet is
detected. Possible mechanisms of nucleus splitting are discussed.
[1] International Comet Quarterly.–2000.–2. (1–4).
[2] Brown M. E., Bouches A. H., Spinrad H., Johns-Krull C. M. A High-resolution catalog of cometary emission
lines // Astrophys. J.–1996.–112, N 3.–P. 1197.
[3] Churyumov K. I., Kleshchonok V. V., Vlassyuk V. V. Spectral monitoring of the head of comet Hale–Bopp
(C/1995 O1) with the 6-meter BTA reflector // New Trends in Astronomy and Astrophysics: JENAM-97.–1997.–
P. 70.
[4] Churyumov K. I., Kleshchonok V. V. Detection of non-solar-origin continuum in spectra of comets 24P (Schau-
masse), C/1989 Y1 (Scoritchenko–George) and C/1995 O1 (Hale–Bopp) // JENAM-01, Astronomishe Gesellschaft.
Abstract Series.–Munich, 2001.–P. 257.
[5] Nazarchuk H. K. The luminescent dust particles in the comet Halley (1982i) atmosphere // Kometnyj Tsirkuliar.–
1987.–372.—P. 2.
[6] Nazarchuk H. K. Verification of the hypothesis about the luminescent dust particles in the comet Halley atmo-
sphere // Kometnyj Tsirkuliar.–1987.–377.–P. 2.
[7] Weaver H. A., Sekanina Z., Toth I., et al. HST and VLT Investigations of the Fragments of Comet C/1999 S4
(LINEAR) // Science.–2001.–292, N 5520.–P. 1329–1334.
[8] Whipple F. L. The cometary nucleus. Current concept // Astron. and Astrophys.–1987.–187.–P. 852–858.
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