6,606 research outputs found
UV observations of blue stragglers and population 2 K dwarfs
Blue stragglers are stars, found usually in either open or globular clusters, that appear to lie on the main sequence, but are brighter and bluer than the cluster turn-off. Currently, two rival models are invoked to explain this apparently pathological behavior: internal mixing (so that fresh fuel is brought into the stellar core); and mass transfer (by which a normal main sequence star acquires mass from an evolving nearby companion and so moves up the main sequence). The latter model predicts that in the absence of complete mass transfer (i.e., coalescence), blue stragglers should be binary systems with the fainter star in a post-main sequence evolutionary state. It is important to ascertain the cause of this phenomenon since stellar evolution models of main sequence stars play such a vital role in astronomy. If mass transfer is involved, one may easily exclude binaries from age determinations of clusters, but if mixing is the cause, our age determinations will be much less accurate unless we can determine whether all stars or only some mix, and what causes the mixing to occur at all
Investigation of a liquid-fed water resistojet plume
Measurements of mass flux and flow angle were taken throughout the forward flow region of the exhaust of a liquid-fed water resistojet using a quartz crystal microbalance (QCM). The resistojet operated at a mass flow rate of 0.1 g/s with a power input of 330 Watts. Measured values were compared to theoretical predictions obtained by employing a source flow approximation. Excellent agreement between predicted and measured mass flux values was attained; however, this agreement was highly dependent on knowledge of nozzle flow conditions. Measurements of the temperature at which the exhaust condensed on the QCM were obtained as a function of incident mass flux
Recommended from our members
Method of treating endothelial dysfunction comprising administration of a thrombin peptide derivative
Endothelial dysfunction (ED) is associated with a number of diseases and disorders. Agonists of the non-proteolytically activated thrombin receptor can be used in methods to treat ED or ED-related diseases and disorders.Board of Regents, University of Texas Syste
An Undersea Radioisotope Power Supply
The results and current status of an Aerojet sponsored program to develop a product line of low power radioisotope thermoelectric generators for marine applications are discussed. A 1-watt ( e) Undersea Radioisotope Power Supply (URIPS) has been designed, fabricated, and tested Extensive parametric studies were performed to select optimum design characteristics; typical parameters investigated were radioisotope and chemical fuel form, thermoelectric material, fuel capsule L/D ratio, shield material and geometry, and operating conditions . The design emphasizes high reliability and low cost, but considerable emphasis was placed on adaptability to meet a wide spectrum of user requirements . URIPS is designed to provide a steady power output for a minimum of five years at ocean depths up to 20 , 000 feet
Recommended from our members
Methods of therapy with thrombin derived peptides
The present invention relates to a method for promoting cardiac tissue repair comprising administering to the cardiac tissue a therapeutically effective amount of an angiogenic thrombin derivative peptide and/or inhibiting or reducing vascular occlusion or restenosis. The invention also relates to methods of stimulating revascularization. In yet another embodiment, the invention relates to the use of thrombin derivative peptides in the manufacture of a medicament for the methods described herein.Board of Regents, University of Texas Syste
Kinematics of Nearby Subdwarf Stars
We present an analysis of the space motions of 742 subdwarf stars based on
the sample of Carney et al. (1994, CLLA). Hipparcos parallaxes, TYC2+HIP proper
motions and Tycho2 proper motions were combined with radial velocities and
metallicities from CLLA. The kinematical behavior is discussed in particular in
relation to their metallicities. The majority of these sample stars have metal
abundances of [Fe/H] >-1 and represent the thick disk population. The halo
component, with [Fe/H] <-1.6, is characterized by a low mean rotation velocity
and a radially elongated velocity ellipsoid. In the intermediate metallicity
range (-1.6 < [Fe/H] <-1), we find a significant number of subdwarfs with
disklike kinematics. We interpret this population of stars as a metal-weak
thick disk population.Comment: 6 pages, 7 figures, accepted by Astronomy & Astrophysic
Recommended from our members
Stimulation of bone growth with thrombin peptide derivatives
Disclosed is a method of stimulating bone growth at a site in a subject in need of osteoinduction. The method comprises the step of administering a therapeutically effective amount of an agonist of the non-proteolytically activated thrombin receptor to the site.Board of Regents, University of Texas Syste
Categorizing, Coding, and Manipulating Qualitative Data Using the WordPerfect® Word Processor
In this paper, we present a method of categorizing, coding, and sorting/manipulating qualitative (descriptive) data using the capabilities of a commonly-used word processor: WordPerfect®. We explain the process and its development in simple terms for the person who may be familiar with qualitative research and data, but not with computer and/or word processor manipulation of that data. Although we developed the process to suit our methods, it can easily be adapted/evolved to fit different research situations where a method of rapidly handling large amounts of descriptive data is desirable
Speckle Interferometry of Metal-Poor Stars in the Solar Neighborhood. I
We report the results of speckle-interferometric observations of 109 high
proper-motion metal-poor stars made with the 6-m telescope of the Special
Astrophysical Observatory of the Russian Academy of Sciences. We resolve eight
objects -- G102-20, G191-55, BD+19~1185A, G89-14, G87-45, G87-47,
G111-38, and G114-25 -- into individual components and we are the first to
astrometrically resolve seven of these stars. New resolved systems included two
triple (G111-38, G87-47) and one quadruple (G89-14) star. The ratio of
single-to-binary-to-triple-to-quadruple systems among the stars of our sample
is equal to 71:28:6:1.Comment: 8 pages, 4 figures, accepted to Astrophysical Bulleti
- …