3,122 research outputs found
Recommended from our members
New data on carbon isotopic compositions of some ureilites
We have collected new C data from high resolution stepped combustion analyses of 5 ureilites to better constrain their relationships with O and mineralogical/petrographic groupings. This may help the future development of petrogenetic models
Recommended from our members
An integrated mineralogical, petrographic, light stable isotope and noble gas investigation of Sahara 99201 ureilite
New ureilite Sahara 99201 has been investigated to determine mineralogy, petrography, light stable isotopes and noble gases. The sample is a typical olivine pigeonite ureilite (Fo 78, Wo 10, En 72). C, N, O and Ar are consistent with other ureilites
Longitudinal Stability Characteristics of the Consolidated Vultee XFY-1 Airplane with Windmilling Propellers as Obtained from Flight of 0.133-Scale Rocket-Propelled Model at Mach Numbers from 0.70 to 1.13
A flight test has been conducted to determine the longitudinal stability and control characteristics of a 0.133-scale model of the Consolidated Vultee XFY-1 airplane with windmilling propellers for the Mach number range between 0.70 and 1.13. The variation of lift-curve slope C(sub L(sub alpha) with Mach number was gradual with a maximum value of 0.074 occurring at a Mach number of 0.97. Propellers had little effect upon the values of lift-curve slope or the linearity of lift coefficient with angle of attack. At lift coefficients between approximately 0.25 and 0.45 with an elevon angle of approximately -l0 deg, there was a region of neutral longitudinal stability at Mach numbers below 0.93 introduced by the addition of windmilling propellers. Below a lift coefficient of 0.10 and above a lift coefficient of 0.45, the model was longitudinally stable throughout the Mach number range of the test. There was a forward shift in the aerodynamic center of about 3-percent mean aerodynamic chord introduced by the addition of propellers. The aerodynamic center as determined at low lift moved gradually from a value of 28.5-percent mean aerodynamic chord at a Mach number of 0.75 to a value of 47-percent mean aerodynamic chord at a Mach number of 1.10. There was an abrupt decrease in pitch damping between Mach numbers of 0.88 and 0.99 followed by a rapid increase in damping to a Mach number of 1.06. The propellers had little effect upon the pitch damping characteristics . The transonic trim change was a large pitching-down tendency with and without windmilling propellers. The elevons were effective pitch controls throughout the speed range; however, their effectiveness was reduced about 50 percent at supersonic speeds. The propellers had no appreciable effect upon the control effectiveness
Potential Alteration of Analogue Regolith by X-Ray Computed Tomography
The Mars 2020 rover mission will collect and cache samples from the martian surface for possible retrieval and subsequent return to Earth. Mars Returned Samples may provide definitive information about the presence of organic compounds that could shed light on the existence of past or present life on Mars. Post-mission analyses will depend on the development of a set of reliable sample handling and analysis procedures that cover the full range of materials which may or may not contain evidence of past or present martian life [1]
Comparison of the Minimum Drag of Two Versions of a Modified Delta-wing Fighter as Obtained from Flight Tests of Rocket-boosted Models and Equivalent Bodies Between Mach Numbers of 0.80 and 1.64
The complex morphology of the young disk MWC 758: Spirals and dust clumps around a large cavity
We present Atacama Large Millimeter Array (ALMA) observations at an angular
resolution of 0.1-0.2" of the disk surrounding the young Herbig Ae star MWC
758. The data consist of images of the dust continuum emission recorded at 0.88
millimeter, as well as images of the 13CO and C18O J = 3-2 emission lines. The
dust continuum emission is characterized by a large cavity of roughly 40 au in
radius which might contain a mildly inner warped disk. The outer disk features
two bright emission clumps at radii of about 47 and 82 au that present
azimuthal extensions and form a double-ring structure. The comparison with
radiative transfer models indicates that these two maxima of emission
correspond to local increases in the dust surface density of about a factor 2.5
and 6.5 for the south and north clumps, respectively. The optically thick 13CO
peak emission, which traces the temperature, and the dust continuum emission,
which probes the disk midplane, additionally reveal two spirals previously
detected in near-IR at the disk surface. The spirals seen in the dust continuum
emission present, however, a slight shift of a few au towards larger radii and
one of the spirals crosses the south dust clump. Finally, we present different
scenarios in order to explain the complex structure of the disk.Comment: 15 pages, 11 figures. The paper has been published in ApJ. References
added and typos correcte
Recommended from our members
Were Presolar Grains Destroyed by the Nebular Process Responsible for the Volatile Element Fractionation?
We present SiC abundances from a number of CM and CR chondrites using NanoSIMS raster ion imaging of acid residues. We find higher SiC abundances for CRs than previously estimated based on noble gases
- …