Astron. Astrophys. 351, 752-758 (1999)

4. Relationship between the meteoroids of the 14P/Wolf and D/1892 T1 streams

The number of similar (mutually identified) theoretical and actual orbits at consecutive periods (outputs from numerical integration of orbits of modelled particles), from 0 to , can be seen in Table 1 for comet 14P/Wolf. From the 2-nd to 4-th columns, there are numbers of meteors in the orbits from the IAU MDC database, which are similar to at least one orbit of the modelled particles. Three values correspond to the identification at three models with , 0.001, and 0.002. Hereinafter, we refer to these meteors as associated with comet 14P/Wolf. Their numbers are variable but significant. First modelled particles are moved to orbits similar to that of observed meteors after period equal to ( for ). The value 0.001 of the free parameter seems to be the most appropriate from the three values considered. For , the number of identified meteors is relatively low. On the other hand, increasing this parameter to 0.002 does not result in a significant increase in the number of identified meteors either.

Table 1. The numbers of actually observed meteors associated with the `old' orbit (before 1922) of comet 14P/Wolf, which are identified with the modelled particles released by this comet. The numbers are given by 11 consecutive equidistant intervals beginning on May 3.56978, 1905 and ending on June 28.70888, 1987. is the number of orbits from the IAU Meteor Data Center Catalogue, which are similar to at least one of the orbits of modelled particles, is number of modelled-particle orbits which come within AU of the orbit of the Earth at the end of the given period. Three values of as well as correspond to the three values, 0.0005, 0.001, and 0.002, of the parameter (see text Sect. 2, point 2) used to model three individual theoretical streams. is the initial (catalogue) orbital period of 14P/Wolf.

The identification of each meteor from the IAU MDC database with every modelled particles can seem to be unusual. However, we modelled only the central part of the theoretical stream and the IAU MDC database contains the data on a very small number of all meteors which have appeared in the Earth's atmosphere. Therefore, one meteor in our study, observed as modelled, is a representative of an entire "beam" of meteors, which should have been modelled (if we knew the way how to create an exact model and had sufficient computational facilities) or have existed, respectively. An indication that the procedure used is far from leading to random identification, comes from the fact that no meteor could been identified for 7 comets (in the preliminary analysis of 77 comets mentioned in Sect. 1) in spite of the particles of their streams approached the Earth's orbit closer than AU. An extreme example are the particles of the comet 37P/Forbes stream, where as much as 52% of these approached the Earth's orbit below AU, but none could be identified with any observed meteor. There occurs to be a sufficiently distinct boundary between the positive and negative cases.

In the last three columns in Table 1, there are numbers of modelled particles in the orbits within AU of the orbit of the Earth. The maximum of such orbits is obtained for .

The appropriate associated stream is modelled on May 3.61, 1905. After 1922, the comet finished contributing to that part of stream which approached the Earth's orbit: an analogous modelling in the case of new orbit, after 1922, shows that no modelled particle approaches the Earth's orbit and can be identified with any orbit of actually observed meteor. It is obvious seeing the large difference between the old and new orbits of the comet (Table 4).

In Table 2, there are analogous numbers of meteor orbits as in Table 1, but for comet D/1892 T1 (the meteors associated with D/1892 T1). Here, the first modelled particles are moved to the orbits similar to that of observed meteors after a period equal to . The numbers of identified actual observed meteors are less than analogous numbers for 14P/Wolf, but not zero in contrast to those for the first known Capricornids parent body, comet 45P/Honda-Mrkos-Pajdusáková, for (Neslusan 1999, Table 3), for example. The choice of value of free parameter was not a significant influence on the number of identified meteors in this case: the number is almost the same for , 0.001 and 0.002.

Table 2. The numbers of observed meteors associated with the orbit of comet D/1892 T1 (Barnard 3) which are identified with the modelled particles released by this comet. The structure of table and used notation is the same as in Table 1. Here, is the initial (catalogue) orbital period of D/1892 T1 and the entire analysed period begins on December 11.17421, 1892 and ends on February 23.43521, 1958.

The mean orbital elements of observed meteors identified with the modelled particles associated with comets 14P/Wolf, D/1892 T1, as well as 45P/Honda-Mrkos-Pajdusáková are given in Table 3. (The angular elements as well as coordinates of radiants are, hereinafter, referred to the same equinox as the angular elements and radiant coordinates in the utilized photographic database, i.e. equinox 1950.0.) For a comparison, the mean orbital elements of the Capricornids meteor shower are attached. The mean parameters of the shower are determined in the same way as in our previous paper (Neslusan et al. 1995) except for considering the limiting value instead of . The elements of an individual meteor belonging to the given stream are considered as many times in the calculation of the mean elements as were identified with modelled particles at the outputs of particle-orbit integration (the sum of all 3 terms of in Table 5 in the case of comet D/1892 T1). In other words, the number of identifications of a given meteor represents its weight in the calculation.

Table 3. The mean orbital elements of meteors identified with the modelled particles of theoretical streams associated with a given parent body (its name is given in the first column) as well as mean orbital elements of the Capricornids meteor shower. - perihelion distance (in AU), - eccentricity, - argument of perihelion, - longitude of ascending node, - inclination to the ecliptic (, , and are given in degrees).

Analyzing the radiants of individual meteors (see Sect. 5), it is convenient to divide the stream associated with 14P/Wolf into two strands: the upper corresponding to the stream of D/1892 T1 and the lower corresponding to the Capricornids meteor shower (or the stream associated with 45P/Honda-Mrkos-Pajdusáková). Consequently, there are two sets of mean elements of 14P/Wolf stream in Table 3.

Now, let us analyze the relationship between the orbits of meteors associated with D/1892 T1 (Barnard 3) and those associated with 14P/Wolf. Both the comets had similar orbits before 1922 as is clear from their elements (compare lines 1 and 3 in Table 4). The nucleus of comet D/1892 T1 was probably a fragment of 14P/Wolf, separating sometime before 1892, which belonged to the common stream. Therefore, a coincidence of their streams can be expected. Actually, such coincidence is already observable comparing the mean orbital elements of upper strand of 14P/Wolf stream and D/1892 T1 stream (the first and second lines in Table 3).

Table 4. The orbits of comets 14P/Wolf (before and after 1922) and D/1892 T1 (Barnard 3) referred to epoch (Marsden 1989). q - perihelion distance (in AU), e - eccentricity, , , i - argument of perihelion, longitude of ascending node, and inclination, respectively (in degrees).

Another proof of the coincidence can be seen in the list of the meteors associated with comet D/1892 T1 given in Table 5. At each meteor, there are presented the numbers of identifications of the meteor with the modelled stream at the integration outputs. Three terms correspond to the numbers for , 0.001, and 0.002, respectively. We can see that 19 of 22 meteors (86%) associated with comet D/1892 T1 are meteors which can also be associated with comet 14P/Wolf. Two (9%) meteors of these can perhaps be associated with comet 45P/Honda-Mrkos-Pajdusáková. Only 3 () meteors are associated exclusively with D/1892 T1.

Table 5. The observed meteors (contained in the IAU Meteor Data Center database) associated with comet D/1892 T1 (Barnard 3) and their relationship to comets 14P/Wolf and 45P/Honda-Mrkos-Pajdusáková. - date of meteor detection, its publication serial number, and author or station code as presented in the IAU MDC database; , , - number of identifications of given meteor with the modelled particles at individual outputs of particle-orbit integration (from to - see text and Table 1) in the case of comet D/1892 T1, 14P, and 45P, respectively. Three terms represent the numbers for , 0.001, and 0.002.

Seeing Table 5, the stream of D/1892 T1 was active from the end of September to the end of October.

© European Southern Observatory (ESO) 1999

Online publication: November 3, 1999
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