Asymptotic Giant Branch Stars as Tracers of Star Formation Histories: the GAIA Context

We discuss a possible use of the asymptotic giant branch (AGB) stars for tracing star formation histories on the Galactic and extragalactic distance scales with the ESA's astrometric space mission GAIA. Extensive numerical simulations demonstrate that metallicities (Δ [M/H] ≲ 0.3) can be obtained for the AGB stars with GAIA up to the distances of ∼ 200 kpc, if no interstellar extinction is present. Reliable population ages can be also obtained from the AGB stars if their T _eff are constrained precisely. We show that precise effective temperatures can be obtained by fitting observed spectral energy distributions of the AGB stars with theoretical fluxes calculated from the synthetic spectra. A combination of the derived effective temperatures with the bolometric luminosities allows to derive precise population ages for a wide range of ages and metallicities over the large distance scales. This demonstrates that AGB stars can be employed very effectively for tracing star formation histories with GAIA, allowing to refine the global evolutionary scenarios of stellar populations in the Milky Way and the galaxies beyond. This revised version was published online in July 2006 with corrections to the Cover Date.     

Geologische und paragenetische Verhältnisse der Erzgänge des Jiblava-Jezdovicer Reviers

Ohne ZusammenfassungMit 18 Textabbildungen     

On the possible identification of ‘solid-state’ lines in T-Tauri stars

The possibility that the unidentified absorption lines observed in the spectrum of YY Orionis star S CrA can be attributed to the absorption features of irradiated amethyst is discussed.     

Tectonosedimentary Evolution of the Cheb Basin (NW Bohemia,Czech Republic) between Late Oligocene and Pliocene: A Preliminary Note

Studia Geophysica et Geodaetica -     

Exact Elastodynamic Green Functions for Simple Types of Anisotropy Derived from Higher-Order Ray Theory

Using higher-order ray theory, we derived exact elastodynamic Green functions for three simple types of homogeneous anisotropy. The first type displays an orthorhombic symmetry, the other two types display transverse isotropy. In all cases, the slowness surfaces of waves are either ellipsoids, spheroids or spheres. All three Green functions are expressed by a ray series with a finite number of terms. The Green functions can be written in explicit and elementary form similar to the Stokes solution for isotropy. In two Green functions, the higher-order ray approximations form a near-singularity term, which is significant near a kiss singularity. In the third Green function, the higher-order ray approximations also form a near-field term, which is significant near the point source. No effect connected with the line singularity was observed.     

Comparison of Solar and Geomagnetic Activity Effects on the Northern Hemisphere Weather Changes

The changes of pressure and temperature fields in the winter lower troposphere observed in association with changes in solar and/or geomagnetic activity are compared. It is shown that the fact whether it was solar or geomagnetic activity was not so important as whether the levels of the two activities were high or low. The differences between the effects of solar/geomagnetic activity, however, are revealed, the pressure and temperature data being stratified according to the QBO phase. The relationship obtained are discussed from the viewpoint of mechanisms resting upon both the planetary wave propagation and the changes of atmospheric air currents in the global electric circuit.     

The Kyoto Protocol Emission Allocations: Windfall Surpluses for Russia and Ukraine

The emission targets adopted in the Kyoto Protocol¹ far exceed thelikely level of emissions from Russia and Ukraine. These countries could selltheir surplus if the Protocol is followedand industrialized countries establish an international emission tradingsystem. Critics have condemned the potentialsale and dubbed the surplus hot air because it does not represent anyreduction in emissions below the level thatwould have occurred anyway. Using the most recent, comprehensive regionalscenarios² for the emissions of carbon dioxide from the energysystem, we estimate that during the Protocol's2008–2012 budget period the surplus will range from 9 MtC (milliontons of carbon) to 900 MtC for Russia andfrom 3 MtC to 200 MtC for Ukraine. Even scenarios with high economic growthand carbon-intensive technologies donot exhaust the surplus before the budget period. In the central (middlecourse) scenario, the total carbon surplusexceeds 1000 MtC and is worth 22 to 170 billion U.S. dollars (4 to 34 billionU.S. dollars per year). This flow ofrevenues, which could exceed Russian earnings from natural gas exports($10 billion in 1997³), is comparable with the projectedtotal investmentsof the Russian energy system for 2008–2012. If directed towardslow-carbon infrastructure investments (e.g., gaspipelines), surplus transfers could reinforce and partially lock-indecarbonization of the world energy system.     

Locations of Footpoints of Transequatorial Interconnecting Loops

We discuss footpoints of loops seen by Yohkoh in soft X-rays that connect active regions across the equator (transequatorial interconnecting loops – TILs). While most TILs are rooted in moderately strong fields at peripheries of active regions, there are also cases when these loops are anchored in very weak or very strong fields, ranging from < 30 G to several hundred gauss. Some have their footpoints near sunspot penumbrae, creating `X-ray fountains' in a combination with active region loops. But TILs are never rooted in sunspots. The most likely explanation is that magnetic field lines leave spots almost vertically so that TILs rooted in them extend high into the corona and density in them is below the limit of visibility in X-rays. The fact that in force-free modeling some TILs are rooted in sunspots is most probably due to the difference between field-line connections in `vacuum' and in the highly conductive plasma on the Sun. Some TILs end before they reach active regions which sometimes may indicate the real situation, but mostly this `gap' is probably due to a temperature decrease near the loop footpoints which makes them invisible in X-rays. In that case the fact that these cool lowest parts of TILs are never found in TRACE or SOHO EIT images indicates that plasma density in TILs must be very low. Still, the total absence of any counterparts of X-ray TILs in TRACE and EIT images is puzzling and, therefore, other possible interpretations of the `gap' origin are also briefly mentioned.