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Exciting dark matter and the INTEGRAL/SPI 511keV signal
Finkbeiner, Douglas P.; Weiner, Neal
We propose a dark matter candidate with an “excited state” 1 2 MeV above the ground state, which may be collisionally excited and deexcites by e+e- pair emission. By converting its kinetic energy into pairs, such a particle could produce a substantial fraction of the 511 keV line observed by the International Gamma-Ray Astrop…
Hubble Space Telescope Fine Guidance Sensor Parallaxes of Galactic Cepheid Variable Stars: Period-Luminosity Relations
Freedman, Wendy L.; Harrison, Thomas E.; Bean, Jacob L. +6 more
We present new absolute trigonometric parallaxes and relative proper motions for nine Galactic Cepheid variable stars: ell Car, ζ Gem, β Dor, W Sgr, X Sgr, Y Sgr, FF Aql, T Vul, and RT Aur. We obtain these results with astrometric data from Fine Guidance Sensor 1r, a white-light interferometer on the Hubble Space Telescope. We find absolute parall…
The high-resolution stereo camera (HRSC) experiment on Mars Express: Instrument aspects and experiment conduct from interplanetary cruise through the nominal mission
Jaumann, R.; Stephan, K.; Oberst, J. +24 more
ESA's Mars Express has successfully completed its nominal mission of one Martian year covering about 25% of the surface in stereo and color with resolutions up to 10 m/pixel by its high-resolution stereo camera (HRSC). Mars Express is now in its extended mission phase, during which much of the remaining part of the Martian surface is envisaged to …
What Do We Learn from IRAC Observations of Galaxies at 2 < z < 3.5?
van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo +9 more
We analyze very deep HST, VLT, and Spitzer photometry of galaxies at 2<z<3.5 in the Hubble Deep Field-South. The sample is selected from the deepest public K-band imaging currently available. We show that the rest-frame U-V versus V-J color-color diagram is a powerful diagnostic of the stellar populations of distant galaxies. Galaxies with r…
Electron acceleration in the Van Allen radiation belts by fast magnetosonic waves
Meredith, Nigel P.; Horne, Richard B.; Glauert, Sarah A. +3 more
Local acceleration is required to explain electron flux increases in the outer Van Allen radiation belt during magnetic storms. Here we show that fast magnetosonic waves, detected by Cluster 3, can accelerate electrons between ∼10 keV and a few MeV inside the outer radiation belt. Acceleration occurs via electron Landau resonance, and not Doppler …
Coronal Transverse Magnetohydrodynamic Waves in a Solar Prominence
Lites, B. W.; Ichimoto, K.; Shibata, K. +10 more
Solar prominences are cool 104 kelvin plasma clouds supported in the surrounding 106 kelvin coronal plasma by as-yet-undetermined mechanisms. Observations from Hinode show fine-scale threadlike structures oscillating in the plane of the sky with periods of several minutes. We suggest that these represent Alfvén waves propagat…
Rosina Rosetta Orbiter Spectrometer for Ion and Neutral Analysis
Livi, S.; Wurz, P.; Bochsler, P. +47 more
The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) will answer important questions posed by the mission’s main objectives. After Giotto, this will be the first time the volatile part of a comet will be analyzed in situ. This is a very important investigation, as comets, in contrast to meteorites, have maintained most of the vol…
The XMM-Newton extended survey of the Taurus molecular cloud (XEST)
Audard, M.; Güdel, M.; Grosso, N. +18 more
Context: The Taurus Molecular Cloud (TMC) is the nearest large star-forming region, prototypical for the distributed mode of low-mass star formation. Pre-main sequence stars are luminous X-ray sources, probably mostly owing to magnetic energy release.
Aims: The XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST) presented in this p…
Ion chemistry and N-containing molecules in Titan's upper atmosphere
Yelle, R. V.; Vuitton, V.; McEwan, M. J.
High-energy photons, electrons, and ions initiate ion-neutral chemistry in Titan's upper atmosphere by ionizing the major neutral species (nitrogen and methane). The Ion and Neutral Mass Spectrometer (INMS) onboard the Cassini spacecraft performed the first composition measurements of Titan's ionosphere. INMS revealed that Titan has the most compo…
Tip of the Red Giant Branch Distances. II. Zero-Point Calibration
Dolphin, Andrew E.; Shaya, Edward J.; Tully, R. Brent +4 more
The luminosity of the tip of the red giant branch (TRGB) provides an excellent measure of galaxy distances and is easily determined in the resolved images of nearby galaxies observed with Hubble Space Telescope. There is now a large amount of archival data that are relevant to the TRGB methodology and offer comparisons with other distance estimato…