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Host Star (host + star)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

The dynamical stability of a Kuiper Belt-like region

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2007
A. Celletti
ABSTRACT The dynamics of the Kuiper Belt region between 33 and 63 au is investigated just taking into account the gravitational influence of Neptune. Indeed the aim is to analyse the information which can be drawn from the actual exoplanetary systems, where typically physical and orbital data of just one or two planets are available. Under this perspective we start our investigation using the simplest three-body model (with Sun and Neptune as primaries), adding at a later stage the eccentricity of Neptune and the inclinations of the orbital planes to evaluate their effects on the Kuiper Belt dynamics. Afterwards we remove the assumption that the orbit of Neptune is Keplerian by adding the effect of Uranus through the Lagrange,Laplace solution or through a suitable resonant normal form. Finally, different values of the mass ratios of the primary to the host star are considered in order to perform a preliminary analysis of the behaviour of exoplanetary systems. In all cases, the stability is investigated by means of classical tools borrowed from dynamical system theory, like Poincaré mappings and Lyapunov exponents. [source]

On the nature of the purported common proper motion companions to the exoplanet host star 51 Peg

ASTRONOMISCHE NACHRICHTEN, Issue 7 2010
E.E. MamajekArticle first published online: 21 JUL 2010
Abstract Greaves (2006) proposed that three red, high proper motion stars within 10° of 51 Peg (NLTT 54007, 54064, and 55547) are co-moving companions to this famous exoplanet host star. While the stars clearly have proper motions similar to 51 Peg, the inferred kinematic parallaxes for these stars produce extremely inconsistent color-magnitude positions 2 to 4 magnitudes below the main sequence. All three stars are likely to be background stars unrelated to 51 Peg (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

New constraints from the H, line for the temperature of the transiting planet host star OGLE-TR-10,

ASTRONOMISCHE NACHRICHTEN, Issue 6 2008
M. Ammler-von Eiff
Abstract The spectroscopic analysis of systems with transiting planets gives strong constraints on planetary masses and radii as well as the chemical composition of the systems. The properties of the system OGLE-TR-10 are not well-constrained, partly due to the discrepancy of previous measurements of the effective temperature of the host star. This work, which is fully independent from previous works in terms of data reduction and analysis, uses the H, profile in order to get an additional constraint on the effective temperature. We take previously published UVES observations which have the highest available signal-to-noise ratio for OGLE-TR-10. A proper normalization to the relative continuum is done using intermediate data products of the reduction pipeline of the UVES spectrograph. The effective temperature then is determined by fitting synthetic H, profiles to the observed spectrum. With a result of Teff = 6020 ± 140 K, the H, profile clearly favours one of the previous measurements. The H, line is further consistent with dwarf-like surface gravities as well as solar and super-solar metallicities previously derived for OGLE-TR-10. The H, line could not be used to its full potential, partly because of the varying shape of the UVES échelle orders after flat field correction. We suggest to improve this feature when constructing future spectrographs. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Earth-like planets: one hot and rocky, one wet

ASTRONOMY & GEOPHYSICS, Issue 1 2010
Article first published online: 14 JAN 2010
European astronomers have found a planet like a bigger Earth, made mostly of water ice and orbiting a nearby star. It was found by detection of its transit across the face of its host star. [source]

Pulsations and planets: The asteroseismology-extrasolar-planet connection

ASTRONOMISCHE NACHRICHTEN, Issue 5 2010
S. Schuh
Abstract The disciplines of asteroseismology and extrasolar planet science overlap methodically in the branch of high-precision photometric time series observations. Light curves are, amongst others, useful to measure intrinsic stellar variability due to oscillations, as well as to discover and characterize those extrasolar planets that transit in front of their host stars, periodically causing shallow dips in the observed brightness. Both fields ultimately derive fundamental parameters of stellar and planetary objects, allowing to study for example the physics of various classes of pulsating stars, or the variety of planetary systems, in the overall context of stellar and planetary system formation and evolution. Both methods typically also require extensive spectroscopic follow-up to fully explore the dynamic characteristics of the processes under investigation. In particularly interesting cases, a combination of observed pulsations and signatures of a planet allows to characterize a system's components to a very high degree of completeness by combining complementary information. The planning of the relevant space missions has consequently converged with respect to science cases, where at the outset there was primarily a coincidence in instrumentation and techniques. Whether space- or ground-based, a specific type of stellar pulsations can themselves be used in an innovative way to search for extrasolar planets. Results from this additional method at the interface of stellar pulsation studies and exoplanet hunts in a beyond-mainstream area are presented (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]