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The 2dF Galaxy Redshift Survey: the bJ -band galaxy luminosity function and survey selection function
Peder Norberg Shaun Cole Carlton M. Baugh Carlos S. Frenk Ivan Baldry Joss Bland-Hawthorn Terry Bridges Russell Cannon Matthew Colless Chris Collins Warrick Couch Nicholas J. G. Cross Gavin Dalton Roberto De Propris Simon P. Driver George Efstathiou Richard S. Ellis Karl Glazebrook Carole Jackson Ofer Lahav Ian Lewis Stuart Lumsden Steve Maddox Darren Madgwick John A. Peacock Bruce A. Peterson Will Sutherland Keith Taylor 《Monthly notices of the Royal Astronomical Society》2002,336(3):907-931
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R. G.Smith † R. D.Blum † D. E.Quinn K.Sellgren D. C. B.Whittet † 《Monthly notices of the Royal Astronomical Society》2002,330(4):837-843
To better understand the conditions under which ice mantles form on grains in molecular clouds, three globules in the Southern Coalsack have been searched for the presence of H2 O ice. Given the total lack of star formation in the Coalsack, it is an ideal site for studying unprocessed icy molecular mantles. In our sample of eight field stars lying behind the Coalsack we detect strong H2 O ice absorption in the lines of sight to two stars and possible weak absorption in four others. We estimate H2 O ice column densities or upper limits for these lines of sight. Compared to dark clouds such as Taurus, the Coalsack H2 O ice column densities are lower than expected given the quiescent nature of the Coalsack region. It is possible that the chemical evolution of the Coalsack may simply be at too early a stage for significant ice mantles to appear on the grains, except perhaps in the densest parts of some of the globules. Alternatively, the presence or absence of ice absorption may be related to the distribution of dust along each line of sight, specifically, the relative contributions of dense globules and a more extended diffuse component. For example, our observations are consistent with an ice threshold extinction similar to that observed in the Taurus dark cloud if extinction amounting to A V ∼5 towards Globules 2 and 3 arises in the extended component. Globule 1 appears to have no extended component. 相似文献
997.
We present R-band galaxy luminosity functions (GLFs) from aspectroscopic sample of six nearby rich galaxy clusters. In addition
to individual cluster GLFs, extending to, in one case, M
R=–14, we also present composite GLFs for cluster and field galaxies toM
R=–17. All six cluster samples are consistent with the composite GLF, but there is evidence that the GLF of the quiescent population
in clusters is not universal. Furthermore, the GLF of quiescent galaxies is significantly steeper in clusters than in the
field. The overall GLF in clusters is consistent with that of field galaxies, except for the luminous tip, which is enhanced
in clusters versus the field.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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