544 research outputs found

    A Biography of Francis J. Cercopuly

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    Francis Juan Cercopuly was born on March 15, 1805 in St. Augustine, Florida, the son of Greek and Spanish immigrants. He came to Savannah while a young man and worked on the small barges and boats traveling along the Savannah River. He became a captain on the steamers “Ida” and “Beauregard,” both of which played important roles in Savannah’s history during the Civil War. He died on July 26, 1869 and was buried in Cathedral Cemetery in Savannah.https://digitalcommons.georgiasouthern.edu/sav-bios-lane/1032/thumbnail.jp

    Kepler planet occurrence rates for mid-type M dwarfs as a function of spectral type

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    Previous studies of planet occurrence rates largely relied on photometric stellar characterizations. In this paper, we present planet occurrence rates for mid-type M dwarfs using spectroscopy, parallaxes, and photometry to determine stellar characteristics. Our spectroscopic observations have allowed us to constrain spectral type, temperatures, and, in some cases, metallicities for 337 out of 561 probable mid-type M dwarfs in the primary Kepler field. We use a random forest classifier to assign a spectral type to the remaining 224 stars. Combining our data with Gaia parallaxes, we compute precise (~3%) stellar radii and masses, which we use to update planet parameters and occurrence rates for Kepler mid-type M dwarfs. Within the Kepler field, there are seven M3 V to M5 V stars that host 13 confirmed planets between 0.5 and 2.5 Earth radii and at orbital periods between 0.5 and 10 days. For this population, we compute a planet occurrence rate of 1.190.49+0.70{1.19}_{-0.49}^{+0.70} planets per star. For M3 V, M4 V, and M5 V, we compute planet occurrence rates of 0.860.68+1.32{0.86}_{-0.68}^{+1.32}, 1.361.02+2.30{1.36}_{-1.02}^{+2.30}, and 3.072.49+5.49{3.07}_{-2.49}^{+5.49} planets per star, respectively.Published versio

    Spatial characteristics of the remotely-sensed surface urban heat island in Baton Rouge, LA: 1988-2003

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    Our understanding of urban effects on local climate remains unsatisfactory due to several difficulties: 1) the inherent complexity of the city-atmosphere system, 2) lack of a clear conceptual theoretical framework for inquiry, and 3) the high expense and enormous difficulties of acquiring a sufficient quantity of high-quality, high-resolution (both spatially and temporally) observations in cities. Using remotely-sensed data, this study analyzes urban heat islands (UHI) that are manifested through an elevation in the surface thermal emissions within urban regions known as surface heat islands (SHI). The study area for this research endeavor is Baton Rouge, Louisiana. Whereas the surface air temperature-derived UHI did not portray an accurate representation of distinct changes in surface temperature across the study area, the remotely-sensed surface temperature-derived SHI proved to reveal microscale differences that the surface air temperature-derived UHI was unable to depict. This study also provided verification that altering amounts of vegetation within a given land cover over time can reveal changes in surface temperature values, thus providing a means to reconstruct and predict future SHIs. This was achieved through regression equations predicting surface temperatures from known NDVI values. Finally, the moist static energy parameter was evaluated to test for a better indicator of the UHI over time throughout the study area. A decreasing temporal trend in MSE was identified throughout the study period (1988 - 2003) whereas no significant linear trend occurred in air temperature. This is supported by change detection rates generated from a comparison of the 1988 and 2003 LANDSAT data sets, as well as the range in 1988 and 2003 predicted surface temperatures (as a function of land cover)

    Use of Auto-Germ to Model Germination Timing in the Sagebrush-Steppe

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    Germination timing has a strong influence on direct seeding efforts, and therefore is a closely tracked demographic stage in a wide variety of wildland and agricultural settings. Predictive seed germination models, based on soil moisture and temperature data in the seed zone are an efficient method of estimating germination timing. We utilized Visual Basic for Applications (VBA) to create Auto‐Germ, which is an Excel workbook that allows a user to estimate field germination timing based on wet‐thermal accumulation models and field temperature and soil moisture data. To demonstrate the capabilities of Auto‐Germ, we calculated various germination indices and modeled germination timing for 11 different species, across 6 years, and 10 Artemisia‐steppe sites in the Great Basin of North America to identify the planting date required for 50% or more of the simulated population to germinate in spring (1 March or later), which is when conditions are predicted to be more conducive for plant establishment. Both between and within the species, germination models indicated that there was high temporal and spatial variability in the planting date required for spring germination to occur. However, some general trends were identified, with species falling roughly into three categories, where seeds could be planted on average in either fall (Artemisia tridentata ssp. wyomingensis and Leymus cinereus), early winter (Festuca idahoensis, Poa secunda, Elymus lanceolatus, Elymus elymoides, and Linum lewisii), or mid‐winter (Achillea millefolium, Elymus wawawaiensis, and Pseudoroegneria spicata) and still not run the risk of germination during winter. These predictions made through Auto‐Germ demonstrate that fall may not be an optimal time period for sowing seeds for most non‐dormant species if the desired goal is to have seeds germinate in spring

    Peer Mentoring: Effects on Ninth Grade Student Achievement

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    The purpose of this study was to examine the potential academic impact that a trained peer mentor, would have on first time ninth grade students. Specifically, the study was aimed to measure the academic performance of ninth grade students by focusing on the interim assessment, which is a summative pre and post- test aligned to End of Course Test content weights and is used to assess students at the end of each term or semester. The study addressed whether there is a difference in post-test interim assessment scores, passing rates, and numerical averages in Integrated Algebra I by examining first time ninth grade students who receive assistance from a trained mentors (Group 1) and first time ninth grade students who did not receive peer mentoring assistance

    Characterizing mid-type M dwarfs in the Kepler field with the Discovery Channel Telescope and WIYN

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    Planet occurrence rates increase with decreasing stellar mass (later spectral types); therefore, M dwarf systems are our most promising targets in the search for exoplanets. The identification and characterization of stars in the original Kepler field was accomplished using photometry alone, resulting in large uncertainties for late-type stars like M dwarfs. In order to more accurately compute the planet occurrence rate around mid- type M dwarfs, we need to better constrain their stellar radii and masses, properties which strongly correlate with other stellar parameters such as temperature and metallicity. These measurements need to be performed on a statistically significant population of stars including systems with and without planets. Therefore, we have begun to spectroscopically characterize the properties of the 559 probable mid-type M dwarfs in the Kepler field using red optical spectra obtained with the DeVeny Spectrograph on the Discovery Channel Telescope (DCT) and Hydra on the WIYN telescope in order to constrain the planet occurrence rate for such stars. We will be presenting initial results from our DCT and WIYN observations, including new temperature, radius, and mass estimates which we can use in occurrence rate calculations.http://adsabs.harvard.edu/abs/2017AAS...22912608HPublished versio

    Scaling K2. I. Revised Parameters for 222,088 K2 Stars and a K2 Planet Radius Valley at 1.9 R_⊕

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    Previous measurements of stellar properties for K2 stars in the Ecliptic Plane Input Catalog largely relied on photometry and proper motion measurements, with some added information from available spectra and parallaxes. Combining Gaia DR2 distances with spectroscopic measurements of effective temperatures, surface gravities, and metallicities from the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) DR5, we computed updated stellar radii and masses for 26,838 K2 stars. For 195,250 targets without a LAMOST spectrum, we derived stellar parameters using random forest regression on photometric colors trained on the LAMOST sample. In total, we measured spectral types, effective temperatures, surface gravities, metallicities, radii, and masses for 222,088 A, F, G, K, and M-type K2 stars. With these new stellar radii, we performed a simple reanalysis of 299 confirmed and 517 candidate K2 planet radii from Campaigns 1–13, elucidating a distinct planet radius valley around 1.9 R_⊕, a feature thus far only conclusively identified with Kepler planets, and tentatively identified with K2 planets. These updated stellar parameters are a crucial step in the process toward computing K2 planet occurrence rates
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