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The Variability of Solar Coronal Abundances in Active Regions and the Quiet Sun
Doschek, G. A.; Warren, H. P.
Measurements of elemental abundances hold important clues to how mass and energy flow through the solar atmosphere. Variations in abundances are organized by an element’s first ionization potential (FIP), and many previous studies have assumed that low FIP (less than 10 eV) elements are enriched by a factor of 3-4 in the corona. In this paper, we …
The Ultraviolet Detection of Diffuse Gas in Galaxy Groups
Danforth, Charles W.; Stocke, John T.; Jannuzi, Buell +5 more
A small survey of the UV-absorbing gas in 12 low-z galaxy groups has been conducted using the Cosmic Origins Spectrograph on board the Hubble Space Telescope. Targets were selected from a large, homogeneously selected sample of groups found in the Sloan Digital Sky Survey. A critical selection criterion excluded sight lines that pass close (<1.…
Optical Counterparts of ULXs and Their Host Environments in NGC 4490/4485
Balman, Şölen; Fabrika, Sergei; Akyuz, Aysun +6 more
We report the identification of the possible optical counterparts of five out of seven ultraluminous X-ray sources (ULXs) in the galaxy pair NGC 4490/4485. Using archival Hubble Space Telescope (HST) imaging data, we identified a single optical candidate for two ULXs (X-4 and X-7) and multiple optical candidates for the other three (X-2, X-3, and …
First measurements of Jupiter's zonal winds with visible imaging spectroscopy
Sato, Bun'ei; Rivet, Jean-Pierre; Guillot, Tristan +12 more
We present the first measurements of Jupiter's wind profile ever obtained with Doppler velocity measurements in the visible. Hitherto, knowledge about atmospheric dynamics has been obtained with cloud-tracking techniques, which consist of tracking visible features from images taken at different dates. However, cloud tracking indicates the motion o…
Mapping of shadows cast on a protoplanetary disk by a close binary system
van der Plas, G.; Avenhaus, H.; Girard, J. +47 more
For a comprehensive understanding of planetary formation and evolution, we need to investigate the environment in which planets form: circumstellar disks. Here we present high-contrast imaging observations of V4046 Sagittarii, a 20-Myr-old close binary known to host a circumbinary disk. We have discovered the presence of rotating shadows in the di…
S and VV Corona Australis: Spectroscopic Variability in Two Young Binary Star Systems
Edwards, Suzan; Schaefer, Gail H.; Prato, L. +2 more
We used high-resolution near-infrared spectroscopy from the NIRSPEC instrument on the Keck II telescope, taken over multiple epochs spanning five years, to examine two young binary T Tauri star systems, S Corona Australis and VV Corona Australis. The stars in these 1″-2″ separation systems have optically thick circumstellar disks and high extincti…
On the Possible Mechanism of GLE Initiation
Gan, W. Q.; Rodríguez-Pacheco, J.; Li, Y. P. +2 more
With the goal of understanding the initiations of solar energetic particle (SEP) (MeV) and ground-level enhancement (GLE) (GeV) particles, we have studied relative timings at approximately the Sun between temporal evolutions of the particles and some electromagnetic radiation components representing flares and shocks. Results show that GLE onsets …
Runaways and shells around the CMa OB1 association
Montmerle, T.; Gregorio-Hetem, J.; Santos-Silva, T. +1 more
Context. The origin of the arc-shaped Sh 2-296 nebula is still unclear. Mainly due to its morphology, the nebula has been suggested to be a 0.5 Myr old supernova remnant (SNR) that could be inducing star formation in the CMa OB1 association. This means that the region might be an excellent laboratory for investigating the influence of massive star…
Multi-waveband detection of quasi-periodic pulsations in a stellar flare on EK Draconis observed by XMM-Newton
Broomhall, A. -M.; Rosen, S. R.; Pye, J. P. +2 more
Context. Quasi-periodic pulsations (QPPs) are time variations in the energy emission during a flare that are observed on both the Sun and other stars and thus have the potential to link the physics of solar and stellar flares.
Aims: We characterise the QPPs detected in an X-ray flare on the solar analogue, EK Draconis, which was observed by X…
OGLE-2015-BLG-1670Lb: A Cold Neptune beyond the Snow Line in the Provisional WFIRST Microlensing Survey Field
Han, Cheongho; Udalski, Andrzej; Lee, Chung-Uk +56 more
We present the analysis of the microlensing event OGLE-2015-BLG-1670, detected in a high-extinction field very close to the Galactic plane. Due to the dust extinction along the line of sight, this event was too faint to be detected before it reached the peak of magnification. The microlensing light-curve models indicate a high-magnification event …