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The galactic surface density derived from K giants
Author(s) -
Brosche P.,
Schwarz O.
Publication year - 2007
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200610716
Subject(s) - galactic plane , physics , astrophysics , amplitude , superposition principle , plane (geometry) , galaxy , population , dark matter , surface (topology) , astronomy , geometry , optics , demography , mathematics , quantum mechanics , sociology
We compare the W velocity dispersions of Brosche, Schwan & Schwarz (2001) with more recent results. The increase with the distance | z | from the galactic plane is confirmed, although perhaps with reduced amplitude. This could be interpreted either as one homogenous population or as a superposition of (at least) two populations with two constant dispersions and two scale heights. For each of the possibilities we propose a simple model. Combined with two observational variants for the velocity variation, we obtain surface densities up to | z | = 250 pc ranging from 5 to 44 M ⊙ pc –2 . Thus the case for considerable dark matter in the neighbourhood of the galactic plane is not supported