5,127 research outputs found
A Search for Binary Stars at Low Metallicity
We present initial results measuring the companion fraction of metal-poor
stars ([Fe/H]2.0). We are employing the Lick Observatory planet-finding
system to make high-precision Doppler observations of these objects. The binary
fraction of metal-poor stars provides important constraints on star formation
in the early Galaxy (Carney et al. 2003). Although it has been shown that a
majority of solar metallicity stars are in binaries, it is not clear if this is
the case for metal-poor stars. Is there a metallicity floor below which binary
systems do not form or become rare? To test this we are determining binary
fractions at metallicities below [Fe/H]. Our measurments are not as
precise as the planet finders', but we are still finding errors of only 50 to
300 m/s, depending on the signal-to-noise of a spectrum and stellar atmosphere
of the star. At this precision we can be much more complete than previous
studies in our search for stellar companions.Comment: To appear in conference proceedings,"First Stars III", eds. B.
O'Shea, A. Heger & T. Abel. 3 pages, 5 figure
Black Family Life: An African American parenting magazine
Abstract only availableParenting magazines geared toward strengthening the traditional northern European family have been around for decades. Yet, they have not focused on the different family types or the needs of African American families. African American parenting has unique features and qualities that are deeply rooted in their past ancestry. Black families are so diverse and are made up of so many unique backgrounds, so it is necessary to have a parenting magazine geared toward their different needs. A scripture often lamented in the black community is "train up a child in the way he should go, and when he is old he will not depart." The meaning behind the phrase is to raise children in a manner that they will succeed from, so that when they are adults they will stay true to their roots. Though this scripture is very popular it is not being properly applied to the upbringing of African American children. One solution to these issues is "Black Family Life" magazine. This magazine will enhance the mentality and skills of the modern black parent by providing alternative tips on raising their children from specialists and ordinary people who have experienced similar situations. The magazine will also encourage black parents to better prepare their children for challenges in the world ahead by providing advice on effective discipline, techniques to assist children in developing study skills, college preparation methods(both academically and financially) and much more.Emerge Summer Undergraduate Research Internshi
Chemical Abundances For Evolved Stars In M5: Lithium Through Thorium
We present analysis of high-resolution spectra of a sample of stars in the globular cluster M5 (NGC 5904). The sample includes stars from the red giant branch (RGB; seven stars), the red horizontal branch (two stars), and the asymptotic giant branch (AGB; eight stars), with effective temperatures ranging from 4000 K to 6100 K. Spectra were obtained with the HIRES spectrometer on the Keck I telescope, with a wavelength coverage from 3700 angstrom to 7950 angstrom for the HB and AGB sample, and 5300 angstrom to 7600 angstrom for the majority of the RGB sample. We find offsets of some abundance ratios between the AGB and the RGB branches. However, these discrepancies appear to be due to analysis effects, and indicate that caution must be exerted when directly comparing abundance ratios between different evolutionary branches. We find the expected signatures of pollution from material enriched in the products of the hot hydrogen burning cycles such as the CNO, Ne-Na, and Mg-Al cycles, but no significant differences within these signatures among the three stellar evolutionary branches especially when considering the analysis offsets. We are also able to measure an assortment of neutron-capture element abundances, from Sr to Th, in the cluster. We find that the neutron-capture signature for all stars is the same, and shows a predominately r-process origin. However, we also see evidence of a small but consistent extra s-process signature that is not tied to the light-element variations, pointing to a pre-enrichment of this material in the protocluster gas.National Science Foundation AST-0802292NSF AST-0406988, AST-0607770, AST-0607482DFGW. M. Keck FoundationAstronom
Carbon and Strontium Abundances of Metal-Poor Stars
We present carbon and strontium abundances for 100 metal-poor stars measured
from R7000 spectra obtained with the Echellette Spectrograph and Imager
at the Keck Observatory. Using spectral synthesis of the G-band region, we have
derived carbon abundances for stars ranging from [Fe/H] to
[Fe/H]. The formal errors are dex in [C/Fe]. The strontium
abundance in these stars was measured using spectral synthesis of the resonance
line at 4215 {\AA}. Using these two abundance measurments along with the barium
abundances from our previous study of these stars, we show it is possible to
identify neutron-capture-rich stars with our spectra. We find, as in other
studies, a large scatter in [C/Fe] below [Fe/H]. Of the stars with
[Fe/H], 94% can be classified as carbon-rich metal-poor stars. The Sr
and Ba abundances show that three of the carbon-rich stars are
neutron-capture-rich, while two have normal Ba and Sr. This fraction of carbon
enhanced stars is consistent with other studies that include this metallicity
range.Comment: ApJ, Accepte
Interviews with Charlie Bruntzle, Eugene Campbell, Jeanne Marie Latas, Elva Jean Latas, and Doris J. Sassman
Interviews with Charlie Bruntzle, Eugene Campbell, Jeanne Marie Latas, Elva Jean Latas, and Doris J. Sassman 00:00:05 - Charlie Bruntzel, Song, Rip Van Winkle Was a Lucky Man 00:02:56 - Song, Deep Down in My Heart 00:05:31 - Song, Back In Western Kansas Where I Was Born 00:10:00 - Jeanne Marie Latas reciting jump rope rhymes, Teddy Bear, Teddy Bear 00:10:22 - Cinderella 00:10:33 - Andy Pandy 00:11:08 - Johnny 00:11:26 - Cups and Saucers 00:11:36 - Fruit cake, cupcake 00:12:02 - Teacher, teacher 00:12:15 - Cinderella 00:12:28 - Ice Cream Soda 00:13:46 - One two, buckle my shoe 00:14:18 - 1, 2, 3, 4, 5, Once I caught a fish alive 00:14:44 - A, B, C, D, twirl with me 00:15:20 - Nursery game, Making Cake 00:16:48 - Nursery rhyme, This little piggy 00:17:13 - ABC\u27s from a teacher\u27s manual 00:18:29 - Rhyme about the months of the year 00:19:52 - Rhyme about writing numbers 00:21:35 - Introduction, Doris J. Sassman of Garden City, KS 00:22:02 - Story about the ghost of a train engineer 00:22:52 - Song, Charles Guiteau unidentified man 00:24:17 - Flatt and Scruggs recording, banjo and vocal, Mrs. McKinleyhttps://scholars.fhsu.edu/sackett/1126/thumbnail.jp
Early classroom reading environment moderates influences on reading comprehension in adolescence
BACKGROUND. Reading is important for children’s success in school and beyond yet many adolescents fail to reach expected levels of proficiency. This highlights the need to better understand the factors that influence reading effectiveness over time, including genes and environment. Greater expression of genetic influence on first and second grade reading fluency has been observed in higher quality classroom reading environments. To what degree this early environment continues to influence genetic and other environmental influences on later reading is unknown and was tested in this study. METHODS. The quality of the early classroom reading environment was approximated by gains in oral reading fluency (ORF) across the school year among first- or second-grade classmates of 546 MZ and 1,016 DZ twin children (mean age = 7.13 years; SD = 0.45) who had reading comprehension scores from a state-wide mandatory test in school year 2013–14 when most twin pairs were in seventh to tenth grade (mean age = 14.41; SD = 1.13) in a variable called Class ORF Gain. Biometrical models were fit to the data to assess whether Class ORF Gain moderated the genetic, shared environmental, and/or non-shared environmental variance associated with adolescent reading comprehension. RESULTS. Class ORF Gain moderated shared environmental influences on reading comprehension 6–9 years later. When early classroom reading gains were poor, variability in reading comprehension in adolescence was high and was associated largely with shared environmental influences. When early classroom reading gains were good, overall and shared environmentally influenced variability in adolescent reading comprehension was lower so that genetic influences were most relevant in explaining that variability. CONCLUSIONS. Our findings suggested that classroom reading environment experienced when children were learning to read had a lasting influence on the factors underlying variability in later reading effectiveness
Results of 2018–2019 assessment of Thuja occidentalis populations at the Fox River Fen
â–·Collected seed from mature individuals of Thuja occidentalis at Trout Park and Chicago Junior School, as well as 3 control sites for comparison
â–·Measured seed set, seed weight, and seed morphology to determine site variability
â–·Conducted germination trials in growth chambers under incremental salt concentrations to determine the effect of salt on seed germination
â–·Conducted periodic soil samples over the span of 1 year to assess salt levels at Trout Park and Chicago Junior School
â–·Found differences between Trout Park and Chicago Junior School for reproductive metrics and soil salt levels, but not for germinationIllinois State Toll Highway Authorityunpublishednot peer reviewedOpe
Noxious and Selected Invasive Plant Populations along Illinois Toll Highway Rights-of-Way
• Repeated a 2010 survey for selected invasive species and listed noxious weeds throughout the ISTHA corridor.
• Mapped 1345 populations of invasive species.
• Found the ISTHA corridor to be heavily populated by invasive species throughout the length of each roadway.
• Most frequently found species were Canada Thistle (Cirsium arvense) and Cut-leaf Teasel (Dipsacus laciniatus).
• Recommend management specific to each of 8 species or groups of species found during the survey.Illinois State Toll Highway Authorityunpublishednot peer reviewedOpe
A Puzzle Involving Galactic Bulge Microlensing Events
We study a sample of 16 microlensed Galactic bulge main sequence turnoff
region stars for which high dispersion spectra have been obtained with detailed
abundance analyses. We demonstrate that there is a very strong and highly
statistically significant correlation between the maximum magnification of the
microlensed bulge star and the value of the [Fe/H] deduced from the high
resolution spectrum of each object. Physics demands that this correlation,
assuming it to be real, be the result of some sample bias. We suggest several
possible explanations, but are forced to reject them all,and are left puzzled.
To obtain a reliable metallicity distribution in the Galactic bulge based on
microlensed dwarf stars it will be necessary to resolve this issue through the
course of additional observations.Comment: Submitted to ApJL, table 2 (quite long) will only appear in the
on-line version of ApJ
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