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The R-Process Alliance: Discovery of a Low-α, r-process-enhanced Metal-poor Star in the Galactic Halo
Grebel, Eva K.; Steinmetz, Matthias; Beers, Timothy C. +24 more
A new moderately r-process-enhanced metal-poor star, RAVE J093730.5-062655, has been identified in the Milky Way halo as part of an ongoing survey by the R-Process Alliance. The temperature and surface gravity indicate that J0937-0626 is likely a horizontal branch star. At [Fe/H] = -1.86, J0937-0626 is found to have subsolar [X/Fe] ratios for near…
Determining mass limits around HD 163296 through SPHERE direct imaging data
Barbieri, M.; Rouan, D.; Henning, T. +33 more
HD 163296 is a Herbig Ae/Be star known to host a protoplanetary disc with a ringed structure. To explain the disc features, previous works proposed the presence of planets embedded into the disc. We have observed HD 163296 with the near-infrared (NIR) branch of SPHERE composed by IRDIS (InfraRed Dual-band Imager and Spectrograph) and IFS (integral…
Extreme resonance line profile variations in the ultraviolet spectra of NGC 1624-2: probing the giant magnetosphere of the most strongly magnetized known O-type star
Martins, F.; Owocki, S. P.; Wade, G. A. +12 more
In this paper, we present high-resolution HST/COS observations of the extreme magnetic O star NGC 1624-2. These represent the first ultraviolet spectra of this archetypal object. We examine the variability of its wind-sensitive resonance lines, comparing it to that of other known magnetic O stars. In particular, the observed variations in the prof…
On the observational behaviour of the highly polarized Type IIn supernova SN 2017hcc
Eswaraiah, Chakali; Pandey, S. B.; Kumar, Brajesh +10 more
We present the results based on photometric (Swift UVOT), broad-band polarimetric (V and Rbands) and optical spectroscopic observations of the Type IIn supernova (SN) 2017hcc. Our study is supplemented with spectropolarimetric data available in literature for this event. The post-peak light-curve evolution is slow (∼0.2 mag 100 d-1 in b…
Bidirectional Reconnection Outflows in an Active Region
Aulanier, Guillaume; Schmieder, Brigitte; Masson, Sophie +4 more
We report on bidirectional coronal reconnection outflows reaching ±200 km s-1 as observed in an active region with the Si IV and C II spectra of the Interface Region Imaging Spectrograph (IRIS). The evolution of the active region with an emerging flux, a failed filament eruption, and a jet is followed in Solar Dynamical Observatory (SDO…
The metal-rich halo tail extended in |z|: a characterization with Gaia DR2 and APOGEE
Beers, Timothy C.; Chiappini, Cristina; Recio-Blanco, Alejandra +12 more
We report an analysis of the metal-rich tail ([Fe/H] > -0.75) of stars located at distances from the Galactic plane up to |z| ∼ 10 kpc, observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE). We examine the chemistry, kinematics, and dynamics of this metal-rich sample using chemical abundances and radial velocities prov…
Activity and rotation of the X-ray emitting Kepler stars
Belfiore, A.; Marelli, M.; Poretti, E. +6 more
The relation between magnetic activity and rotation in late-type stars provides fundamental information on stellar dynamos and angular momentum evolution. Rotation-activity studies found in the literature suffer from inhomogeneity in the measurement of activity indexes and rotation periods. We overcome this limitation with a study of the X-ray emi…
The Disappearing Solar Filament of 2013 September 29 and Its Large Associated Proton Event: Implications for Particle Acceleration at the Sun
Kahler, S. W.; Shimojo, M.; Cliver, E. W. +1 more
We present observations of a notable example of a disappearing solar filament (DSF) on 2013 September 29 that was associated with a large solar proton event (SPE) and discuss this event in the context of four recent studies that compare flare and SPE size parameters. The DSF-associated flare was characterized by weak radio and soft X-ray emissions…
High-resolution Spectroscopic Analysis of a Large Sample of Li-rich Giants Found By LAMOST
Shi, Jianrong; Zhao, Gang; Blanco-Cuaresma, S. +6 more
The discovery of Li-rich giants has introduced a new challenge for standard stellar evolution models. To resolve this issue, the number of this type of object has been rapidly increased through the development of worldwide surveys. Taking advantage of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope survey, 44 new Li-rich giants are r…
Modelling accretion disc emission with generalized temperature profile and its effect on AGN spectral energy distribution
Jin, Chichuan; Yuan, Weimin; Liu, He-Yang +3 more
The broad-band spectral energy distribution (SED) of active galactic nuclei (AGNs) is investigated for a well-selected sample composed of 23 Seyfert 1 galaxies observed simultaneously in the optical/ultraviolet (UV) and X-ray bands with the Neil Gehrels Swift Observatory. The optical to UV continuum spectra are modelled, for the first time, with e…