1,538 research outputs found
The mass of Kepler-93b and the composition of terrestrial planets
Get PDFKepler-93b is a 1.478 ± 0.019 R ⊕ planet with a 4.7 day period around a bright (V = 10.2), astroseismically characterized host star with a mass of 0.911 ± 0.033 M ☉ and a radius of 0.919 ± 0.011 R ☉. Based on 86 radial velocity observations obtained with the HARPS-N spectrograph on the Telescopio Nazionale Galileo and 32 archival Keck/HIRES observations, we present a precise mass estimate of 4.02 ± 0.68 M ⊕. The corresponding high density of 6.88 ± 1.18 g cm–3 is consistent with a rocky composition of primarily iron and magnesium silicate. We compare Kepler-93b to other dense planets with well-constrained parameters and find that between 1 and 6 M ⊕, all dense planets including the Earth and Venus are well-described by the same fixed ratio of iron to magnesium silicate. There are as of yet no examples of such planets with masses >6 M ⊕. All known planets in this mass regime have lower densities requiring significant fractions of volatiles or H/He gas. We also constrain the mass and period of the outer companion in the Kepler-93 system from the long-term radial velocity trend and archival adaptive optics images. As the sample of dense planets with well-constrained masses and radii continues to grow, we will be able to test whether the fixed compositional model found for the seven dense planets considered in this paper extends to the full population of 1-6 M ⊕ planets.Peer reviewe
HII 2407: an eclipsing binary revealed by K2 observations of the Pleiades
Get PDFThe material presented herein is based upon work supported in 2015 by the National Science Foundation Graduate Research Fellowship under grant No. DGE1144469. T.J.D. gratefully acknowledges support from France Córdova through the Neugebauer Scholarship. This research was partially supported by an appointment to the NASA Postdoctoral Program at the Ames Research Center, administered by Oak Ridge Associated Universities through a contract with NASA. Support for this work was provided by NASA via grant NNX15AV62G. C.B. acknowledges support from the Alfred P. Sloan Foundation. A.C.C. acknowledges support from STFC grant ST/M001296/1. Funding for WASP comes from consortium universities and from UKs Science and Technology Facilities Council.The star HII 2407 is a member of the relatively young Pleiades star cluster and was previously discovered to be a single-lined spectroscopic binary. It is newly identified here within Kepler/K2 photometric time series data as an eclipsing binary system. Mutual fitting of the radial velocity and photometric data leads to an orbital solution and constraints on fundamental stellar parameters. While the primary has arrived on the main sequence, the secondary is still pre-main sequence and we compare our results for the M/M⊙ and R/R⊙ values with stellar evolutionary models. We also demonstrate that the system is likely to be tidally synchronized. Follow-up infrared spectroscopy is likely to reveal the lines of the secondary, allowing for dynamically measured masses and elevating the system to benchmark eclipsing binary status.Peer reviewe
The kepler-10 planetary system revisited by harps-n : a hot rocky world and a solid neptune-mass planet
Get PDFKepler-10b was the first rocky planet detected by the Kepler satellite and confirmed with radial velocity follow-up observations from Keck-HIRES. The mass of the planet was measured with a precision of around 30%, which was insufficient to constrain models of its internal structure and composition in detail. In addition to Kepler-10b, a second planet transiting the same star with a period of 45 days was statistically validated, but the radial velocities were only good enough to set an upper limit of 20 M ⊕ for the mass of Kepler-10c. To improve the precision on the mass for planet b, the HARPS-N Collaboration decided to observe Kepler-10 intensively with the HARPS-N spectrograph on the Telescopio Nazionale Galileo on La Palma. In total, 148 high-quality radial-velocity measurements were obtained over two observing seasons. These new data allow us to improve the precision of the mass determination for Kepler-10b to 15%. With a mass of 3.33 ± 0.49 M ⊕ and an updated radius of R ⊕, Kepler-10b has a density of 5.8 ± 0.8 g cm–3, very close to the value predicted by models with the same internal structure and composition as the Earth. We were also able to determine a mass for the 45-day period planet Kepler-10c, with an even better precision of 11%. With a mass of 17.2 ± 1.9 M ⊕ and radius of R ⊕, Kepler-10c has a density of 7.1 ± 1.0 g cm–3. Kepler-10c appears to be the first strong evidence of a class of more massive solid planets with longer orbital periods
Distribution and evolution of starspots on the RS CVn binary II Pegasi in 2004
No full textThis work is supported by National Natural Science Foundation of China through grants Nos. 10373023, 10773027 and 11333006, Chinese Academy of Sciences through project KJCX2-YW-T24.We present Doppler images of RS CVn-type binary II Peg based on two data sets obtained in 2004 February and November. In order to improve signal-to-noise ratio and reliability,we apply least-squares deconvolution technique to calculate average profiles from 2032 photospheric absorption lines. Both of the resulting surface images show a wide latitude distribution of starspots. Most spots are concentrated at a high-latitude belt above 60° and a low-latitude belt near equator. The starspots evolved dramatically between two observing runs, which may indicate shorter time-scale evolution in this epoch, especially for low-latitude belt. There is no stable preferred active longitude that can be found in our images. We also find out a possible phenomenon that the intermediate-latitude spot migrated poleward and merged with the high-latitude spot to make it stronger, which may reveal a more complex behaviour of starspots on II Peg. A potential change of orbital ephemeris zero-point was detected. This may imply an orbital period change of II Peg like other active close binaries.Peer reviewe
Evaluating the Ecological Impacts of Cultivating Genetically Modified Herbicide Tolerant (GMHT) Oilseed Rape and Maize: (2007-B-DS-1-S1) STRIVE Report
No full textThis report is published as part of the Science, Technology, Research and Innovation for the
Environment (STRIVE) Programme 2007–2013.Author has checked copyrigh
The first Doppler images of the eclipsing binary SZ Piscium
Get PDFWe present the first Doppler images of the active eclipsing binary system SZ Psc, based on the high-resolution spectral data sets obtained in 2004 November and 2006 September-December. The least-squares deconvolution technique was applied to derive high signal-to-noise profiles from the observed spectra of SZ Psc. Absorption features contributed by a third component of the system were detected in the LSD profiles at all observed phases. We estimated the mass and period of the third component to be about 0.9 M⊙ and 1283 ± 10 d, respectively. After removing the contribution of the third body from the least-squares deconvolved profiles, we derived the surface maps of SZ Psc. The resulting Doppler images indicate significant star-spot activities on the surface of the K subgiant component. The distributions of star-spots are more complex than that revealed by previous photometric studies. The cooler K component exhibited pronounced high-latitude spots as well as numerous low- and intermediate-latitude spot groups during the entire observing seasons, but did not show any large, stable polar cap, different from many other active RS CVn-type binaries.Peer reviewe
Institutional reform in emerging securities markets
Get PDFIn the long run, sound, efficient securities markets can contribute to economic growth; in the short run, they play an important role in financial liberalization. The author provides a guide to issues involved in institutional and regulatory reform of securities markets - and a discussion of the practical implications of different policy options and sequencing decisions. He argues that establishing sound securities markets requires institutional development that is a substantial task for many developing countries. Prerequisities for the development of securities markets include: (a) a macroeconomic and fiscal environment conducive to the supply of quality securities; (b) a legal, regulatory, and institutional infrastructure that can support efficient operation of the securities market. Essentially such an infrastructure must provide four things: (a) certainty about property rights and contracts; (b) transparent trading and other procedures and public disclosure by companies of all information relevant to the value of their securities; (c) protection against unfair practices by insiders and intermediaries; and (d) protection against the financial failure of intermediaries and market institutions such as clearinghouses. The author also provides examples of the policy conflicts and uncertainties that are routine in securities market reform and development, and suggests approaches to managing them.Financial Intermediation,Environmental Economics&Policies,Insurance&Risk Mitigation,Banks&Banking Reform,Economic Theory&Research
Looking ahead optimally in allocating aid
Get PDFThe Collier-Dollar approach to aid allocation has been less than fully embraced by donors – even those focused on poverty reduction – and has come into conflict with a different approach based on the Millennium Development Goals. These two approaches are shown to be special cases of a more general model of optimal aid allocation, in which donors care about future as well as current poverty. The model is illustratively applied to data for developing regions. Adding a poverty decline adjustment to the allocation formulae now used by aid agencies would make these formulae more efficient and more acceptable.
Andrew B. Moore Letter and Clipping, MSS.2055
No full textAbstract: A newspaper clipping noting the gift of 15,000, payable in gold to A.B. Moore, then governor for the defense of Alabama. The clipping ends "More than 20 years have elapsed, the $15,000 went up in blood and smoke, the patriotic writer, and the no less patriotic Governor have gone the way of all flesh; but the bold letters conveying the gift, are as fresh and defiant appearing, as if the transaction were only yesterday."Biographical/Historical Note: Andrew B. Moore was born on March 7, 1807 in the Spartanburg District in South Carolina to Charles and Jane Moore. In 1823 Moore's father purchased land in Perry County, Alabama and moved the family there although Andrew remained in school in South Carolina until 1826.Moore study law and was admitted to the bar in 1833. He served as Justice of the Peace for Perry County for eight years. He was elected to the State House of Representatives in 1839 and reelected in 1842; he served four consecutive terms. He worked closely with Governor Benjamin Fitzpatrick in the liquidation of the State Bank and advocated the relocation of the state capital to Montgomery. He delivered the last speech in the old Hall of the House of Representatives in Tuscaloosa.In 1846 Moore resumed his law practice and was appointed by Governor Henry W. Collier to fill a vacancy on the circuit bench in 1851. He served in that capacity until 1857 when he was elected governor. After he left office in 1861, Moore was appointed special aide-de-camp by Governor John Gill Shorter where he worked to coordinate the procurement and transportation of supplies to General Albert Sidney Johnston in northern Alabama. Following the surrender of Lee at Appomattox, Moore was arrested by federal troops and imprisoned in Fort Pulaski, Savannah, Georgia, with other Confederate leaders. After his release in August 1865, he returned to Marion, Perry County, Alabama. He died in 1873
Advisory committee process and program design : low carbon fuel standards
No full textFinal Report -- Appendix A. Summary of Advisory Committee Input -- Appendix B. Lifecycle Analysis -- Appendix C. Infrastructure Cost Assumptions Memorandum -- Appendix D. Economic Analysis -- Appendix E. Comparable Economic Studies in Other States -- Appendix F. Compliance Scenario Documentation -- Appendix G. Indirect Land Use Change Comparative Analysis -- Appendix H. Fuels Assessment Discussion Paper -- Appendix I. Oregon Biomass Assessment -- Appendix J. Credit and Deficit Calculations -- Appendix K. Review of Biodiesel and Renewable Diesel Use Considerations.principal authors: Sue Langston, David Collier, Cory Ann Wind, Dave Nordberg, Carrie Ann Capp, Wendy Simons.Title from PDF cover (viewed on April 20, 2020)."11-AQ-004."This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Includes bibliographical references.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
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