منابع مشابه
Abundance gradients in the outer galactic disk from planetary nebulae
Radial abundance gradients of the element ratios O/H, Ne/H, S/H, and Ar/H are determined on the basis of a sample of disk planetary nebulae. The behaviour of the gradients at large distances from the galactic centre, R > R0 = 7.6 kpc, is emphasized. It is concluded that the derived gradients are consistent with an approximately constant slope in the inner parts of the Galaxy, and some flattenin...
متن کاملThe galactic double – mode Cepheids
By considering the least–squares fits of the double–mode Cepheid light curves discussed in Paper I we defined their properties by their Fourier parameters and generalized phase differences G i,j. When plotting the latter quantities as a function of the respective order, the second order terms are confined in the region just below 3/2π; the third order terms have π/2 < G i,j < π, the fourth orde...
متن کاملStellar abundance gradients in galactic disks. I. Method and spectral line gradients
We describe the technique of absorption line imaging of galaxy disks using the Taurus Tunable Filter on the Anglo-Australian Telescope and demonstrate its sensitivity to the behaviour of spectral features associated with Mg and Fe. Radial profiles of Mg2 and Fe5270 line-strengths are presented for a sample of eight face-on spiral galaxies spanning a range of Hubble types. Signatures of phenomen...
متن کاملMultiplicity of Galactic Cepheids from long-baseline interferometry
Context. More than 60% of Cepheids are in binary or multiple systems. Studying such systems could lead to a better understanding of the age and evolution of Cepheids. These are also useful tools to estimate the mass of Cepheids, and constrain theoretical models of their pulsation and evolution. Aims. We aim at determining the masses of Cepheids in binary systems, as well as their geometric dist...
متن کاملGalactic Kinematics of Cepheids from Hipparcos Proper Motions
The Hipparcos proper motions of 220 galactic Cepheids, together with relevant groundbased photometry, have been analysed. The effects of galactic rotation are very clearly seen. Mean values of the Oort constants, A = 14.82 ± 0.84 km skpc, and B = −12.37 ± 0.64 km skpc, and of the angular velocity of circular rotation at the Sun, Ωo = 27.19 ± 0.87 km s kpc, are derived. Comparison of the value o...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2008
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361:200810192