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KiDS-450: tomographic cross-correlation of galaxy shear with Planck lensing
Hoekstra, Henk; Heymans, Catherine; Merten, Julian +15 more
We present the tomographic cross-correlation between galaxy lensing measured in the Kilo Degree Survey (KiDS-450) with overlapping lensing measurements of the cosmic microwave background (CMB), as detected by Planck 2015. We compare our joint probe measurement to the theoretical expectation for a flat Λ cold dark matter cosmology, assuming the bes…
Evolution of the magnetic field at comet 67P/Churyumov-Gerasimenko
Goetz, Charlotte; Richter, Ingo; Volwerk, Martin +1 more
The magnetic field at a comet is significantly influenced by the solar wind on one side and the outgassing rate on the other. There are no simple spatial models for the magnetic field direction, neither at a comet with low outgassing rates (∼1025 s-1) where ion gyroradius effects are non-negligible, nor at high outgassing rat…
Are we seeing accretion flows in a 250 kpc Lyα halo at z = 3?
Boulanger, F.; Humphrey, A.; Villar-Martín, M. +8 more
Using MUSE on the ESO-VLT, we obtained a four-hour exposure of the z = 3.12 radio galaxy MRC 0316-257. We detect features down to 10-19 erg s-1 cm-2 arcsec-2, with the highest surface brightness regions reaching more than a factor of 100 higher. We find Lyα emission out to 250 kpc in projection from the …
Dynamic molecular oxygen production in cometary comae
Yao, Yunxi; Giapis, Konstantinos P.
Abundant molecular oxygen was discovered in the coma of comet 67P/Churyumov-Gerasimenko. Its origin was ascribed to primordial gaseous O2 incorporated into the nucleus during the comet's formation. This thesis was put forward after discounting several O2 production mechanisms in comets, including photolysis and radiolysis of …
A Rogues’ Gallery of Andromeda's Dwarf Galaxies. I. A Predominance of Red Horizontal Branches
Lewis, Geraint F.; Dolphin, Andrew E.; Skillman, Evan D. +11 more
We present homogeneous, sub-horizontal branch photometry of 20 dwarf spheroidal satellite galaxies of M31 observed with the Hubble Space Telescope. Combining our new data for 16 systems with archival data in the same filters for another four, we show that Andromeda dwarf spheroidal galaxies favor strikingly red horizontal branches or red clumps do…
Relationship between turbulence energy and density variance in the solar neighbourhood molecular clouds
Federrath, C.; Kainulainen, J.
The relationship between turbulence energy and gas density variance is a fundamental prediction for turbulence-dominated media and is commonly used in analytic models of star formation. We determine this relationship for 15 molecular clouds in the solar neighbourhood. We use the line widths of the CO molecule as the probe of the turbulence energy …
The Small Magellanic Cloud Investigation of Dust and Gas Evolution (SMIDGE): The Dust Extinction Curve from Red Clump Stars
Dolphin, Andrew E.; Yanchulova Merica-Jones, Petia; Williams, Benjamin F. +6 more
We use Hubble Space Telescope (HST) observations of red clump stars taken as part of the Small Magellanic Cloud Investigation of Dust and Gas Evolution (SMIDGE) program to measure the average dust extinction curve in a ∼200 pc × 100 pc region in the southwest bar of the Small Magellanic Cloud (SMC). The rich information provided by our eight-band …
New outburst of the symbiotic nova AG Pegasi after 165 yr
Wolf, M.; Boyd, D.; Skopal, A. +13 more
Context. AG Peg is known as the slowest symbiotic nova, which experienced its nova-like outburst around 1850. After 165 yr, during June of 2015, it erupted again showing characteristics of the Z And-type outburst.
Aims: The primary objective is to determine basic characteristics, the nature and type of the 2015 outburst of AG Peg.
Method…
The Carbon and Nitrogen Abundance Ratio in the Broad Line Region of Tidal Disruption Events
Ferland, Gary J.; Zhou, Hongyan; Jiang, Ning +4 more
The rest-frame UV spectra of three recent tidal disruption events (TDEs), ASASSN-14li, PTF15af, and iPTF16fnl, display strong nitrogen emission lines but weak or undetectable carbon lines. In these three objects, the upper limits of the C III] λ 1908/N III] λ 1750 ratio are about two orders of magnitude lower than those of quasars, suggesting a hi…
The Secret Lives of Cepheids: δ Cep—The Prototype of a New Class of Pulsating X-Ray Variable Stars
Harper, Graham M.; Guinan, Edward F.; Engle, Scott G. +4 more
From our Secret Lives of Cepheids program, the prototype Classical Cepheid, δ Cep, is found to be an X-ray source with periodic pulsation-modulated X-ray variations. This finding complements our earlier reported phase-dependent FUV-UV emissions of the star that increase ∼10-20 times with highest fluxes at ∼ 0.90{--}0.95φ , just prior to maximum br…