G.A.T. - Gruppo Astrofili Tradatese
in collaborazione con la
S.A.S. - Stazione Astronomica di Sozzago
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materiale del G.A.T.. Si tratta di un archivio di immagini cometarie
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Segue il testo originale così come inviato dagli autori
F.Manzini, R.Crippa e C.Guaita.
Sunward jets from Comet Hale-Bopp
Images of Comet Hale-Bopp were taken with 33,5 cm reflector of SAS
Observatory (near Milano, Italy), equipped by a CCD camera ( chip
Thomson 7895 M) without any filter.
We applied Larson-Sekanina algoritm to elaborate some sets of CCD pictures
taken on May 28.00 U.T. (cumulative exposition of 300 seconds), on July
25.00 U.T., on July 30.9 U.T. and July 31.9 U.T. (cumulative exposition
of 600 seconds)
Together with a well defined antisolar tail more than 6' long, it was
surprising to observe almost three principal linear jets (at p.a.=40¡,
145¡ and 270¡) and two other secondary jets coming from the nuclear region
toward solar direction too. The angolar position of the jets seems costant
during last week of July. Images taken on August 16, show a great
increase in the number and complexity of sunward jets, but olso a clear
modification of the tail ( that now appears as dubble) (see very well the
last images inclosed).
On May 28 the jets were very faint. Now, at the end of July, luminosity of
tail and of linear jets don't appear very different.
The jets are linear up to 60Ó- 80" from the nucleus and don't show any
tendency to bend in fountain shape. This is quite surprising if compared
with a large number of fountain jets we observed from Hyalutake nuclear
region on March and April '96, by the same equipment and after the same
kind of elaboration.
We interpret the difference between Hyakutake and Hale-Bopp jets as linked
to the different distance from the Sun. Probably, Hale-Bopp is now so far
from the sun ( 3.6 A.U.) that solar wind is not able to bend its jets
toward antisolar direction. Anyhow, the discovery of so bright jets is an
other clear indication that Hale-Bopp is an intrinsecally bright comet.
Our Group is part of a Consortium between italian Institutes, created by
Prof. C.B.Cosmovici, to coordiante studies about SL9, Hyakutake and
We would appreciate very much any comments, suggestions and information
about some other similar observation.
Enclosed you can find some Hale-Bopp elaborated pictures and a Hyakutake
picture taken on March 28 (we elaborated on the some way).
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