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Variable Stars in Local Group Galaxies. III. And VII, NGC 147, and NGC 185: Insight into the Building Blocks of the M31 Halo
Stetson, P. B.; Bono, G.; Fiorentino, G. +5 more
We present the discovery of 1568 RR Lyrae stars in three of the most luminous M31 satellites: And VII (573), NGC 147 (177), and NGC 185 (818). We use their properties to study the formation history of Local Group spiral haloes, and in particular, to infer about the nature of their possible building blocks by comparison with available data for RR L…
The substorm cycle as reproduced by global MHD models
Gordeev, E.; Sergeev, V.; Tsyganenko, N. +7 more
Recently, Gordeev et al. (2015) suggested a method to test global MHD models against statistical empirical data. They showed that four community-available global MHD models supported by the Community Coordinated Modeling Center (CCMC) produce a reasonable agreement with reality for those key parameters (the magnetospheric size, magnetic field, and…
Ejection of large particles from cometary nuclei in the shape of prolate ellipsoids
Wesołowski, M.; Gronkowski, P.
The ejection of cometary grains from comets is examined. It is assumed that cometary grains are chunks of ice-dust material. We focus on cometary nuclei in the shape of prolate ellipsoids. Two mechanisms are considered. The first one is the drag acting on the motionless grains lying on the surface of a comet's nucleus. It is a consequence of the c…
Comparison of acoustic travel-time measurements of solar meridional circulation from SDO/HMI and SOHO/MDI
Gizon, Laurent; Liang, Zhi-Chao; Birch, Aaron C. +2 more
Context. Time-distance helioseismology is one of the primary tools for studying the solar meridional circulation, especially in the lower convection zone. However, travel-time measurements of the subsurface meridional flow suffer from a variety of systematic errors, such as a center-to-limb variation and an offset due to the position angle (P-angl…
Discovery of a radio relic in the low mass, merging galaxy cluster PLCK G200.9-28.2
Wik, Daniel R.; Giacintucci, Simona; Venturi, Tiziana +5 more
Radio relics at the peripheries of galaxy clusters are tracers of the elusive cluster merger shocks. We report the discovery of a single radio relic in the galaxy cluster PLCK G200.9-28.2 (z = 0.22, M500 = 2.7 ± 0.2 × 1014 M⊙) using the Giant Metrewave Radio Telescope at 235 and 610 MHz and the Karl G. Jansky Very …
The Molecular Cloud S242: Physical Environment and Star-formation Activities
Dewangan, L. K.; Ojha, D. K.; Janardhan, P. +3 more
We present a multi-wavelength study to probe the star-formation (SF) processes on a larger scale (∼ 1\buildrel{\circ}\over{.} 05× 0\buildrel{\circ}\over{.} 56) around the S242 site. The S242 molecular cloud is depicted in a velocity range from -3.25 to 4.55 km s-1 and has a spatially elongated appearance. Based on the virial analysis, t…
Determining Empirical Stellar Masses and Radii from Transits and Gaia Parallaxes as Illustrated by Spitzer Observations of KELT-11b
Pepper, Joshua; Stassun, Keivan G.; Siverd, Robert J. +8 more
Using the Spitzer Space Telescope, we observed a transit at 3.6 µm of KELT-11b. We also observed three partial planetary transits from the ground. We simultaneously fit these observations, ground-based photometry from Pepper et al., radial velocity data from Pepper et al., and a spectral energy distribution (SED) model using catalog magnitud…
Electron temperature anisotropy regulation by whistler instability
Yoon, P. H.; Hwang, J.; Kim, H. P. +1 more
The solar wind electron temperature anisotropy is regulated by a number of physical processes, which include adiabatic expansion, electron Coulomb collisions, and microinstabilities. In the collisionless limit, the measured electron temperature anisotropy is constrained by the marginal threshold conditions for whistler (electromagnetic electron cy…
New ALMA constraints on the star-forming interstellar medium at low metallicity: a 50 pc view of the blue compact dwarf galaxy SBS 0335-052
Lebouteiller, V.; Madden, S. C.; Galliano, F. +8 more
Properties of the cold interstellar medium of low-metallicity galaxies are not well known due to the faintness and extremely small scale on which emission is expected. We present deep ALMA band 6 (230 GHz) observations of the nearby, low-metallicity (12 + log (O/H) = 7.25) blue compact dwarf galaxy SBS 0335-052 at an unprecedented resolution of 0.…
Robust predictions for an oscillatory bispectrum in Planck 2015 data from transient reductions in the speed of sound of the inflaton
Hu, Bin; Torrado, Jesús; Achúcarro, Ana
We update the search for features in the cosmic microwave background (CMB) power spectrum due to transient reductions in the speed of sound, using Planck 2015 CMB temperature and polarization data. We enlarge the parameter space to much higher oscillatory frequencies of the feature, and define a robust prior independent of the ansatz for the reduc…