The galactic abundance gradient
نویسندگان
چکیده
منابع مشابه
On the Abundance Gradient of the Galactic Disk
Estimates of the gas temperature in planetary nebulae obtained from the [O III] emission line ratio and from the Balmer discontinuity indicate differences reaching up to 6000 K (Liu and Danziger 1993). The [O III] temperature is commonly used to obtain the ionic fractions of highly ionized ions, particularly the O and Ne ions when using the empirical method to calculate the elemental abundances...
متن کاملOn the Galactic Disk Metallicity Distribution from Open Clusters I. New Catalogues and Abundance Gradient
In this paper we have compiled two new open cluster catalogues. In the first one, there are 119 objects with ages, distances and metallicities available, while in the second one, 144 objects have both absolute proper motion and radial velocity data, of which 45 clusters also with metallicity data available. Taking advantages of the large number of objects included in our sample, we present an i...
متن کاملReionization and the Abundance of Galactic Satellites
One of the main challenges facing standard hierarchical structure formation models is that the predicted abundance of galactic subhalos with circular velocities vc ∼ 10−30 km s −1 is an order of magnitude higher than the number of satellites actually observed within the Local Group. Using a simple model for the formation and evolution of dark halos, based on the extended Press-Schechter formali...
متن کاملThe ISO⋆ Galactic Metallicity Gradient Revisited
Two independent groups (Giveon et al. 2002; Mart́ın-Hernández et al. 2002) have recently investigated the Galactic metallicty gradient as probed by ISO observations of mid-infrared emission-lines from HII regions. We show that the different gradients inferred by the two groups are due to differing source selection and differing extinction corrections. We show that both data sets in fact provide ...
متن کاملAbundance Ratios and Galactic Chemical Evolution
The metallicity of stars in the Galaxy ranges from [Fe/H]=−4 to +0.5 dex, and the solar iron abundance is (Fe)= 7.51± 0.01 dex. The average values of [Fe/H] in the solar neighborhood, the halo, and Galactic bulge are−0.2,−1.6, and−0.2
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1983
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/204.1.53