《自然》[Nature]13年1月3日出版pdf全文

nero1981

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Giant spiral galaxies are assembled from smaller
( p# u/ k* e% ]* g$ wsystems through a process known as hierarchical clustering. In orbit around
8 |9 r' V# I% I1 T) ]8 Othese giants are dwarf galaxies, which are presumably remnants of the galactic
" p4 o( d, J& ]& j. H; k3 S0 ~) g9 ^% Lprogenitors. Recent studies of the dwarf galaxies of the Milky Way have lead * ?: }8 p/ N# d8 |
some astronomers to suspect that their orbits are not randomly distributed. This # R# ?5 u" i: R: h+ z$ Y, E) i6 d
suspicion, which challenges current theories of galaxy formation, is now
; }4 n& y5 x) {4 x; o* @bolstered by the discovery of a plane of dwarf galaxies corotating as a coherent
$ _- m% ]- Q5 |7 `/ L. k0 E9 |0 epancake-like structure around the Andromeda galaxy, the Milky Way’s close
5 k- W: h, T& J' i1 B3 Hneighbour and in many respects its ‘twin’. The structure is extremely thin yet
& z- v1 W# g' F9 t- M) P* icontains about half of the dwarf galaxies in the Andromeda system. The authors
0 ?' t) n. {' S3 J. ~report that 13 of the 15 satellites in the plane share the same sense of / v0 j) n$ z2 d# ~
rotation. On the cover, a true colour image of the Andromeda galaxy, with two " j5 }. A) T7 a" f
satellite galaxies visible, by Jean-Charles Cuillandre (CFHT) and Giovanni
9 d+ l& K: M; A- wAnselmi (Coelum Astronomia)., z/ |8 ~/ e8 @' o  z/ ~8 L3 U" j
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