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An abundance study of red-giant-branch stars in the Hercules dwarf spheroidal galaxy
red-giant-branch stars the Hercules dwarf spheroidal galaxy
2011/1/11
Using high-resolution spectroscopy, we provide a determination of [Fe/H] and [Ca/H] for confirmed red-giant branch member stars of the Hercules dwarf spheroidal galaxy. Based on this we explore the ag...
Project Icarus: A Review of Local Interstellar Medium Properties of Relevance for Space Missions to the Nearest Stars
Project Icarus Local Interstellar Medium Properties
2011/1/10
I review those properties of the interstellar medium within 15 light-years of the Sun which will be relevant for the planning of future rapid ($v /ge 0.1c$) interstellar space missions to the nearest ...
Pasta Structures of Quark-Hadron Phase Transition in Proto-Neutron Stars
Pasta Structures Quark-Hadron Phase Transition
2011/1/11
We study the quark-hadron mixed phase in proto-neutron stars with the finite-size effects. In the calculations of pasta structures appeared in the mixed phase, the Gibbs conditions require the pressur...
The rapid rotation (P=0.44 d) of the M dwarf V374Peg (M4) along with its intense magnetic field point toward magneto-centrifugal acceleration of a coronal wind. In this work, we investigate the struct...
The chemical abundances of metal-poor stars are an excellent test bed by which to set new constraints on models of neutron-capture processes at low metallicity. Some r-process-rich (hereafter r-rich) ...
Holographically smeared Fermi surface: Quantum oscillations and Luttinger count in electron stars
Holographically smeared Fermi surface Quantum oscillations
2010/12/23
We apply a small magnetic field to strongly interacting matter with a gravity dual description as an electron star. These systems are both metallic and quantum critical at low energies. The resulting ...
We present results of a survey of post-asymptotic giant branch stars (post-AGBs) at high galactic latitude. To date, few post-AGB stars are known throughout the Galaxy and the number of known members ...
Effects of rotation and magnetic fields on the lithium abundance and asteroseismic properties of exoplanet-host stars
magnetic fields the lithium abundance asteroseismic properties
2011/1/11
Aims: The effects of rotation and magnetic fields on the surface abundances of solar-type stars are studied in order to investigate whether the reported difference in lithium content of exoplanet-host...
Central Stars of Planetary Nebulae: New spectral classifications and catalogue
Central Stars Planetary Nebulae spectral classifications
2011/1/11
Context. There are more than 3000 true and probable known Galactic Planetary Nebulae (PNe), but only for 13% of them there is central star spectroscopic information available. Aims. To contribute to t...
We present an overview of a few spectroscopic diagnostics of massive stars. We explore the following wavelength ranges: UV (1000 to 2000 A), optical (4000--7000 A) and near-infrared (mainly H and K ba...
There is much debate on how high-mass star formation varies with environment, and whether the sparsest star-forming environments are capable of forming massive stars. To address this issue, we have ob...
Rotation and differential rotation in rapidly rotating field stars
differential rotation rapidly rotating field stars
2011/1/13
We continue our studies on stellar latitudinal differential rotation. The presented work is a sequel of the work of Reiners et al. who studied the spectral line broadening profile of hundreds of stars...
The connection between missing AGB stars and extended horizontal branches
missing AGB stars extended horizontal branches
2011/1/13
Recent surveys confirm early results about a deficiency or even absence of CN-strong stars on the asymptotic giant branch (AGB) of globular clusters (GCs), although with quite large cluster-to-cluster...
The chemical composition of the Orion star-forming region: II. Stars, gas, and dust: the abundance discrepancy conundrum
the Orion star-forming region II. Stars
2011/1/13
We re-examine the recombination/collisional emission line (RL/CEL) nebular abundance discrepancy problem in the light of recent high-quality abundance determinations in young stars in the Orion star-f...
The spin parameter of uniformly rotating compact stars
spin parameter of uniformly compact stars
2010/12/21
We study the dimensionless spin parameter j (= cJ/(GM2)) of uniformly rotating neutron stars
and quark stars in general relativity. We show numerically that the maximum value of the spin
parameter o...