منابع مشابه
Observations of Intrahour Variable Quasars: Scattering in our Galactic Neighbourhood
Interstellar scintillation (ISS) has been established as the cause of the random variations seen at centimetre wavelengths in many compact radio sources on timescales of a day or less. Observations of ISS can be used to probe structure both in the ionized insterstellar medium of the Galaxy, and in the extragalactic sources themselves, down to μas scales. A few quasars have been found to show la...
متن کاملThe Neighbourhood Polynomial of some Nanostructures
The neighbourhood polynomial G , is generating function for the number of faces of each cardinality in the neighbourhood complex of a graph. In other word $N(G,x)=sum_{Uin N(G)} x^{|U|}$, where N(G) is neighbourhood complex of a graph, whose vertices are the vertices of the graph and faces are subsets of vertices that have a common neighbour. In this paper we compute this polynomial for some na...
متن کاملLetter to the Editor Evidence for a signature of the galactic bar in the solar neighbourhood
Using available kinematical data for a subsample of NLTT stars from the HIPPARCOS mission we confirm the existence of a previously reported local anomaly in the (u, v) plane: the mean motion u for old disc stars, with v < −30 km s−1, is largely positive (+19 ± 9 km s−1 w.r.t. the Galactic Center). With the use of the newest global self-consistent numerical models of our Galaxy (Fux 1997), we sh...
متن کاملAstronomy and Astrophysics Evidence for a Signature of the Galactic Bar in the Solar Neighbourhood ⋆
Using available kinematical data for a sub-sample of NLTT stars from the HIPPARCOS mission we confirm the existence of a previously reported local anomaly in the (u, v) plane: the mean motion u for our sample is largely positive (+20 km s −1). With the use of the newest global self-consistent numerical models of our Galaxy (Fux 1997), we show that a bar could be responsible for this observed ve...
متن کاملEffect of Different Stellar Galactic Environments on Planetary Discs I: The Solar Neighbourhood and the Birth Cloud of the Sun
We have computed trajectories, distances and times of closest approaches to the Sun by stars in the solar neighbourhood with known position, radial velocity and proper motions. For this purpose, we have used a full potential model of the Galaxy that reproduces the local z-force, the Oort constants, the local escape velocity and the rotation curve of the Galaxy. From our sample, we constructed i...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1978
ISSN: 0074-1809
DOI: 10.1017/s0074180900144262