3,828 research outputs found
A magnetically rotated electric arc air heater employing a strong magnetic field and copper electrodes
Magnetically rotated electric arc air heater using strong magnetic field and copper electrode
1,3,4,6-Tetramethyl-1,4-dihydro-1,2,4,5-tetrazine, C_6H_(12)N_4
M_r =140∙19, monoclinic, P2_1/n, a = 10∙612(3), b=6∙820(1), c= 10∙975 (2) Å, β=95∙31(2)°, V=790.9(5) Å^3, Z=4, D_m=1.13(5) (flotation), D_x = 1∙177 g cm^(-3), Mo Kα, λ = 0.71073 Å, μ= 0.848 cm^(-1), F(000) = 304, T= 295 K, R = 0∙077 for 704 observed reflections. This potentially antiaromatic or homoaromatic ring system has a flattened boat conformation with both N-methyls in equatorial positions. Bond angles and distances (excluding H's) predicted to be symmetry equivalent exhibit variations of 0.002-0.014 Å and 0.0-2.0°. Substantial delocalization of the electron lone pairs of N(1) and N(4) is found
Detecting Exomoons Via Doppler Monitoring of Directly Imaged Exoplanets
Recently, Teachey, Kipping, and Schmitt (2018) reported the detection of a
candidate exomoon, tentatively designated Kepler-1625b I, around a giant planet
in the Kepler field. The candidate exomoon would be about the size and mass of
Neptune, considerably larger than any moon in our Solar System, and if
confirmed, would be the first in a new class of giant moons or binary planets.
Motivated by the large mass ratio in the Kepler-1625b planet and satellite
system, we investigate the detectability of similarly massive exomoons around
directly imaged exoplanets via Doppler spectroscopy. The candidate moon around
Kepler-1625b would induce a radial velocity signal of about 200 m/s on its host
planet, large enough that similar moons around directly imaged planets orbiting
bright, nearby stars might be detected with current or next generation
instrumentation. In addition to searching for exomoons, a radial velocity
survey of directly imaged planets could reveal the orientations of the planets'
spin axes, making it possible to identify Uranus analogs.Comment: 15 pages, 8 figures, 2 tables. Accepted for publication in A
Feasibility study of transit photon correlation anemometer for Ames Research Center unitary wind tunnel plan
A laser transit anemometer measured a two-dimensional vector velocity, using the transit time of scattering particles between two focused and parallel laser beams. The objectives were: (1) the determination of the concentration levels and light scattering efficiencies of naturally occurring, submicron particles in the NASA/Ames unitary wind tunnel and (2) the evaluation based on these measured data of a laser transit anemometer with digital correlation processing for nonintrusive velocity measurement in this facility. The evaluation criteria were the speeds at which point velocity measurements could be realized with this technique (as determined from computer simulations) for given accuracy requirements
Effective pre-school, primary and secondary education 3-14 project (EPPSE 3-14) - Final report from the Key Stage 3 phase: influences on students' development from age 11 - 14
Two Small Planets Transiting HD 3167
We report the discovery of two super-Earth-sized planets transiting the
bright (V = 8.94, K = 7.07) nearby late G-dwarf HD 3167, using data collected
by the K2 mission. The inner planet, HD 3167 b, has a radius of 1.6 R_e and an
ultra-short orbital period of only 0.96 days. The outer planet, HD 3167 c, has
a radius of 2.9 R_e and orbits its host star every 29.85 days. At a distance of
just 45.8 +/- 2.2 pc, HD 3167 is one of the closest and brightest stars hosting
multiple transiting planets, making HD 3167 b and c well suited for follow-up
observations. The star is chromospherically inactive with low rotational
line-broadening, ideal for radial velocity observations to measure the planets'
masses. The outer planet is large enough that it likely has a thick gaseous
envelope which could be studied via transmission spectroscopy. Planets
transiting bright, nearby stars like HD 3167 are valuable objects to study
leading up to the launch of the James Webb Space Telescope.Comment: Accepted by ApJL. 6 pages, 1 figure, 2 table
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