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Observational Evidence Linking Interstellar UV Absorption to PAH Molecules
Behar, Ehud; Brosch, Noah; Tielens, Alexander G. G. M. +2 more
The 2175 Å UV extinction feature was discovered in the mid-1960s, yet its physical origin remains poorly understood. One suggestion is absorption by polycyclic aromatic hydrocarbon (PAH) molecules, which is supported by theoretical molecular structure computations and by laboratory experiments. PAHs are positively detected by their 3.3, 6.2, 7.7, …
Particle Radiation Sources, Propagation and Interactions in Deep Space, at Earth, the Moon, Mars, and Beyond: Examples of Radiation Interactions and Effects
Downs, Cooper; Riley, Pete; Kozarev, Kamen +13 more
Particle radiation has significant effects for astronauts, satellites and planetary bodies throughout the Solar System. Acute space radiation hazards pose risks to human and robotic exploration. This radiation also naturally weathers the exposed surface regolith of the Moon, the two moons of Mars, and other airless bodies, and contributes to chemi…
Identification of Faint Chandra X-Ray Sources in the Core-collapsed Globular Cluster NGC 6752
Anderson, Jay; Heinke, Craig O.; Cool, Adrienne M. +2 more
We have searched for optical identifications for 39 Chandra X-ray sources that lie within the 1.‧9 half-mass radius of the nearby (d=4.0 {kpc}), core-collapsed globular cluster, NGC 6752, using deep Hubble Space Telescope ACS/WFC imaging in B 435, {R}625, and Hα. Photometry of these images allows us to classify candidate coun…
Transit probabilities in secularly evolving planetary systems
Triaud, Amaury H. M. J.; Wyatt, Mark C.; Read, Matthew J.
This paper considers whether the population of known transiting exoplanets provides evidence for additional outer planets on inclined orbits, due to the perturbing effect of such planets on the orbits of inner planets. As such, we develop a semi-analytical method for calculating the probability that two mutually inclined planets are observed to tr…
Jupiter cloud morphology and zonal winds from ground-based observations before and during Juno's first perijove
Hueso, R.; Sánchez-Lavega, A.; Rojas, J. F. +8 more
We analyze Jupiter observations between December 2015 and August 2016 in the 0.38-1.7 µm wavelength range from the PlanetCam instrument at the 2.2 m telescope at Calar Alto Observatory and in the optical range by amateur observers contributing to the Planetary Virtual Observatory Laboratory. Over this time Jupiter was in a quiescent state wi…
No Neon, but Jets in the Remarkable Recurrent Nova M31N 2008-12a?—Hubble Space Telescope Spectroscopy of the 2015 Eruption
Ness, J. -U.; Henze, M.; Shafter, A. W. +14 more
The 2008 discovery of an eruption of M31N 2008-12a began a journey on which the true nature of this remarkable recurrent nova continues to be revealed. M31N 2008-12a contains a white dwarf (WD) close to the Chandrasekhar limit, accreting at a high rate from its companion, and undergoes thermonuclear eruptions that are observed yearly and may even …
Discovery of Two Small High-velocity Compact Clouds in the Central 10 pc of Our Galaxy
Oka, Tomoharu; Iwata, Yuhei; Nomura, Mariko +2 more
We discovered two small high-velocity compact clouds (HVCCs) in the HCN J = 4-3 and J = 3-2 maps of the central 20 pc of our Galaxy. Both HVCCs have broad velocity widths ({{Δ }}V≳ 40 km s-1) and compact sizes (d∼ 1 {pc}), and originate from the dense molecular clouds in the position-velocity space. One of them has a faint counterpart i…
Detection of Very Low-frequency, Quasi-periodic Oscillations in the 2015 Outburst of V404 Cygni
Kouveliotou, C.; Gehrels, N.; van der Klis, M. +12 more
In 2015 June, the black hole X-ray binary (BHXRB) V404 Cygni went into outburst for the first time since 1989. Here, we present a comprehensive search for quasi-periodic oscillations (QPOs) of V404 Cygni during its recent outburst, utilizing data from six instruments on board five different X-ray missions: Swift/XRT, Fermi/GBM, Chandra/ACIS, INTEG…
The properties, origin and evolution of stellar clusters in galaxy simulations and observations
Dale, D. A.; Calzetti, D.; Smith, L. J. +16 more
We investigate the properties and evolution of star particles in two simulations of isolated spiral galaxies, and two galaxies from cosmological simulations. Unlike previous numerical work, where typically each star particle represents one `cluster', for the isolated galaxies we are able to model features we term `clusters' with groups of particle…
The 1600 Å Emission Bump in Protoplanetary Disks: A Spectral Signature of H2O Dissociation
France, Kevin; Roueff, Evelyne; Abgrall, Hervé
The FUV continuum spectrum of many accreting pre-main sequence stars, Classical T Tauri Stars (CTTSs), does not continue smoothly from the well-studied Balmer continuum emission in the NUV, suggesting that additional processes contribute to the short-wavelength emission in these objects. The most notable spectral feature in the FUV continuum of so…