Academy Newspaper Saturday 20th May 1876
Observations at
Toulouse
This observatory, which was placed under the direction of M.
Tisserand in 1874, has recently been supplied with a large reflector of thirty-two
inches aperture, which has been at once devoted to an examination of the great
nebula in Orion and of the 155 stars which Otto Sttuve has observed in it.
Among these stars are many which are supposed by M. Struve to be variable, and
M. Tisserand has found that several of these are now invisible, while he has
observed thirty-two new stars which M. Struve had not recorded, though fifteen
of them appear in Bond’s catalogue.
Of the remaining
seventeen the majority are extremely faint, but there are two of the thirteenth
magnitude which Struve could hardly have overlooked if they had then been as
bright as they are now. On the whole, M. Tisserand’s observations strongly
support the view that many of the stars in this nebula, and most probably
physically connected with it, are
undergoing change, an import an important
point in its bearing on the nebular theory and the evolution of
planetary systems.
M. Tisserand has also
observed the satellites of Uranus and some phenomena of Jupiter’s satellites.
Since, for the eclipses of the latter, the
observation consists in noting the disappearance of the last minute portion of the satellite
or of the reappearance of the first faint trace, much will depend on the size
of the telescope, and therefore observations
with such a large instrument as the Toulouse reflector will possess a
peculiar value, as giving a much closer
approximation to the true time of the phenomenon than could be possible with
small telescopes. M. Tisserand's observations are given in recent numbers of
the Comptes Rendus.
www.theramblingastronomer.co.uk
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