32,423 research outputs found
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Derivation of globally averaged lunar heat flow from the local heat flow values and the Thorium distribution at the surface: expected improvement by the LUNAR-A Mission
The relationship between the Th abundance and the heat flow data of the Apollo sites and the LUANR-A sites, where the Th concentrations are in the wide range from 1 ppm to 6 ppm, will allow for a more precise estimation of the averaged heat flow value
Recommended from our members
Thermal in situ measurements in the Lunar Regolith using the LUNAR-A penetrators: an outline of data reduction methods
For determining the lunar heat flow two parameters need to be measured: The thermal gradient and the thermal conductivity of the regolith. Methods for inferring these quantities from in situ measurements using the LUNAR-A penetrators will be presented
Recommended from our members
In situ lunar heat flow experiment using the LUNAR-A penetrator
An in situ lunar heat flow measurement is planned using the Japanese Lunar-A penetrators. The temperature gradient of the regolith is expected to be obtained within 12% error
Constraints on the origin of the ultra-high energy cosmic-rays using cosmic diffuse neutrino flux limits: An analytical approach
Astrophysical neutrinos are expected to be produced in the interactions of
ultra-high energy cosmic-rays with surrounding photons. The fluxes of the
astrophysical neutrinos are highly dependent on the characteristics of the
cosmic-ray sources, such as their cosmological distributions. We study possible
constraints on the properties of cosmic-ray sources in a model-independent way
using experimentally obtained diffuse neutrino flux above 100 PeV. The
semi-analytic formula is derived to estimate the cosmogenic neutrino fluxes as
functions of source evolution parameter and source extension in redshift. The
obtained formula converts the upper-limits on the neutrino fluxes into the
constraints on the cosmic-ray sources. It is found that the recently obtained
upper-limit on the cosmogenic neutrinos by IceCube constrains the scenarios
with strongly evolving ultra-high energy cosmic-ray sources, and the future
limits from an 1 km^3 scale detector are able to further constrain the
ultra-high energy cosmic-rays sources with evolutions comparable to the cosmic
star formation rate.Comment: 9 pages, 3 figures and 1 table. Accepted by Phys. Rev.
Gallium concentration dependence of room-temperature near-bandedge luminescence in n-type ZnO:Ga
We investigated the optical properties of epitaxial \textit{n}-type ZnO films
grown on lattice-matched ScAlMgO substrates. As the Ga doping concentration
increased up to cm, the absorption edge showed a
systematic blueshift, consistent with the Burstein-Moss effect. A bright
near-bandedge photoluminescence (PL) could be observed even at room
temperature, the intensity of which increased monotonically as the doping
concentration was increased except for the highest doping level. It indicates
that nonradiative transitions dominate at a low doping density. Both a Stokes
shift and broadening in the PL band are monotonically increasing functions of
donor concentration, which was explained in terms of potential fluctuations
caused by the random distribution of donor impurities.Comment: accepted for publication for Applied Physics Letters 4 figure
Dense Molecular Gas In A Young Cluster Around MWC 1080 -- Rule Of The Massive Star
We present CS , CO , and CO , observations with the 10-element Berkeley Illinois Maryland Association
(BIMA) Array toward the young cluster around the Be star MWC 1080. These
observations reveal a biconical outflow cavity with size 0.3 and 0.05 pc
for the semimajor and semiminor axis and 45\arcdeg position angle.
These transitions trace the dense gas, which is likely the swept-up gas of the
outflow cavity, rather than the remaining natal gas or the outflow gas. The gas
is clumpy; thirty-two clumps are identified. The identified clumps are
approximately gravitationally bound and consistent with a standard isothermal
sphere density, which suggests that they are likely collapsing protostellar
cores. The gas kinematics suggests that there exists velocity gradients
implying effects from the inclination of the cavity and MWC 1080. The
kinematics of dense gas has also been affected by either outflows or stellar
winds from MWC 1080, and lower-mass clumps are possibly under stronger effects
from MWC 1080 than higher-mass clumps. In addition, low-mass cluster members
tend to be formed in the denser and more turbulent cores, compared to isolated
low-mass star-forming cores. This results from contributions of nearby forming
massive stars, such as outflows or stellar winds. Therefore, we conclude that
in clusters like the MWC 1080 system, effects from massive stars dominate the
star-forming environment in both the kinematics and dynamics of the natal cloud
and the formation of low-mass cluster members. This study provides insights
into the effects of MWC 1080 on its natal cloud, and suggests a different
low-mass star forming environment in clusters compared to isolated star
formation.Comment: 42 pages, 5 tables, and 13 figures, accepted for publication in Ap
Hamiltonian solutions of the 3-body problem in (2+1)-gravity
We present a full study of the 3-body problem in gravity in flat
(2+1)-dimensional space-time, and in the nonrelativistic limit of small
velocities. We provide an explicit form of the ADM Hamiltonian in a regular
coordinate system and we set up all the ingredients for canonical quantization.
We emphasize the role of a U(2) symmetry under which the Hamiltonian is
invariant and which should generalize to a U(N-1) symmetry for N bodies. This
symmetry seems to stem from a braid group structure in the operations of
looping of particles around each other, and guarantees the single-valuedness of
the Hamiltonian. Its role for the construction of single-valued energy
eigenfunctions is also discussed.Comment: 25 pages, no figure. v2: some calculation details removed to make the
paper more concise (see v1 for the longer version), minor correction in a
formula in the section on quantization, references added; results and
conclusions unchange
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