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Parent Star (parent + star)
Selected AbstractsParent stars of extrasolar planets , VIII.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2007Chemical abundances for 18 elements in 31 stars ABSTRACT We present the results of detailed spectroscopic abundance analyses for 18 elements in 31 nearby stars with planets (SWPs). The resulting abundances are combined with other similar studies of nearby SWPs and compared to a sample of nearby stars without detected planets. We find some evidence for abundance differences between these two samples for Al, Si and Ti. Some of our results are in conflict with a recent study of SWPs in the SPOCS data base. We encourage continued study of the abundance patterns of SWPs to resolve these discrepancies. [source] A model-independent test of the spatial variations of the Newtonian gravitational constant in some extrasolar planetary systemsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007Lorenzo Iorio ABSTRACT In this paper, we directly constrain possible spatial variations of the Newtonian gravitational constant G over the range , 0.01,5 au in various extrasolar multiplanet systems. Using the third Kepler law, we determine the quantity ,XY=GX/GY for each couple of planets X and Y located at different distances from their parent star; deviations of the measured values of , from unity would signal variations of G. The obtained results for ,= 1 ,, are found to be very compatible with zero within the experimental errors (,/,,, 0.2,0.3). We make a comparison with an analogous test previously performed in our Solar system. [source] Metallicity, planetary formation and migrationMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2003Mario Livio ABSTRACT Recent observations show a clear correlation between the probability of hosting a planet and the metallicity of the parent star. As radial velocity surveys are biased, however, towards detecting planets with short orbital periods, the probability,metallicity correlation could merely reflect a dependence of migration rates on metallicity. We investigated the possibility, but find no basis to suggest that the migration process is sensitive to the metallicity. The indication is, therefore, that a higher metallicity results in a higher probability for planet formation. [source] A method for the direct determination of the surface gravities of transiting extrasolar planetsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2007John Southworth ABSTRACT We show that the surface gravity of a transiting extrasolar planet can be calculated from only the spectroscopic orbit of its parent star and the analysis of its transit light curve. This does not require additional constraints, such as are often inferred from theoretical stellar models or model atmospheres. The surface gravity of the planet can therefore be measured precisely and from only directly observable quantities. We outline the method and apply it to the case of the first known transiting extrasolar planet, HD 209458b. We find a surface gravity of gp= 9.28 ± 0.15 m s,2, which is an order of magnitude more precise than the best available measurements of its mass, radius and density. This confirms that the planet has a much lower surface gravity than that predicted by published theoretical models of gas giant planets. We apply our method to all 14 known transiting extrasolar planets and find a significant correlation between surface gravity and orbital period, which is related to the known correlation between mass and period. This correlation may be the underlying effect as surface gravity is a fundamental parameter in the evaporation of planetary atmospheres. [source] Planetary transit observations at the University Observatory Jena: TrES-2,ASTRONOMISCHE NACHRICHTEN, Issue 5 2009St. Raetz Abstract We report on observations of several transit events of the transiting planet TrES-2 obtained with the Cassegrain-Teleskop-Kamera at the University Observatory Jena. Between March 2007 and November 2008 ten different transits and almost a complete orbital period were observed. Overall, in 40 nights of observation 4291 exposures (in total 71.52 h of observation) of the TrES-2 parent star were taken. With the transit timings for TrES-2 from the 34 events published by the TrES-network, the Transit Light Curve project and the Exoplanet Transit Database plus our own ten transits, we find that the orbital period is P = (2.470614 ± 0.000001) d, a slight change by ,0.6 s compared to the previously published period. We present new ephemeris for this transiting planet. Furthermore, we found a second dip after the transit which could either be due to a blended variable star or occultation of a second star or even an additional object in the system. Our observations will be useful for future investigations of timing variations caused by additional perturbing planets and/or stellar spots and/or moons (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Titanium isotopic compositions of well-characterized silicon carbide grains from Orgueil (CI): Implications for s-process nucleosynthesisMETEORITICS & PLANETARY SCIENCE, Issue 7-8 2007Gary R. Huss Using the 16 most-precise measurements, we estimate the relative contributions of stellar nucleosynthesis during the asymptotic giant branch (AGB) phase and the initial compositions of the parent stars to the compositions of the grains. To do this, we compare our data to the results of several published stellar models that employ different values for some important parameters. Our analysis confirms that s -process synthesis during the AGB phase only slightly modified the titanium compositions in the envelopes of the stars where mainstream silicon carbide grains formed, as it did for silicon. Our analysis suggests that the parent stars of the >1 ,m silicon carbide grains that we measured were generally somewhat more massive than the Sun (2,3 M,) and had metallicities similar to or slightly higher than solar. Here we differ slightly from results of previous studies, which indicated masses at the lower end of the range 1.5,3 M, and metallicities near solar. We also conclude that models using a standard 13C pocket, which produces a good match for the main component of s -process elements in the solar system, overestimate the contribution of the 13C pocket to s -process nucleosynthesis of titanium found in silicon carbide grains. Although previous studies have suggested that the solar system has a significantly different titanium isotopic composition than the parent stars of silicon carbide grains, we find no compelling evidence that the Sun falls off of the array defined by those stars. We also conclude that the Sun does lie on the low-metallicity end of the silicon and titanium arrays defined by mainstream silicon carbide grains. [source] | ||||||||||