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HD 150382: A Lithium-rich Star at the Early-AGB Stage?
Pereira, C. B.; Holanda, N.; Drake, N. A.
We report the discovery of a lithium-rich giant, HD 150382, a post-red-giant-branch clump star. The atmospheric parameters, the chemical abundances for 17 elements, and the isotopic ratio 12C/13C were determined using the equivalent width and the spectral synthesis methods. The lithium abundance was determined via spectral sy…
Lyman continuum leakage in faint star-forming galaxies at redshift z = 3-3.5 probed by gamma-ray bursts
Covino, S.; Campana, S.; Salvaterra, R. +23 more
Context. The identification of the sources that reionized the Universe and their specific contribution to this process are key missing pieces of our knowledge of the early Universe. Faint star-forming galaxies may be the main contributors to the ionizing photon budget during the epoch of reionization, but their escaping photons cannot be detected …
The chemical composition of impact craters on Titan. I. Implications for exogenic processing
Drossart, P.; Witasse, O.; Altobelli, N. +12 more
We investigate the spectral behavior of nine Titan impact craters in order to constrain their composition. Past studies that have examined the chemical composition of impact craters on Titan have either used qualitative comparisons between craters or combined all craters into a single unit, rather than separating them by geographic location and/or…
CO-driven activity constrains the origin of comets
Blum, J.; Fulle, M.; Rotundi, A.
Context. An open question in the study of comets is the so-called cohesion bottleneck, that is, how dust particles detach from the nucleus.
Aims: We test whether the CO pressure buildup inside the pebbles of which cometary nuclei consist can overcome this cohesion bottleneck.
Methods: A recently developed pebble-diffusion model was appli…
Search for traversable wormholes in active galactic nuclei using x-ray data
Tripathi, Ashutosh; Zhou, Biao; Abdikamalov, Askar B. +2 more
In a previous paper, one of us calculated iron K α line profiles emitted from possible accretion disks around traversable wormholes as a first step to use x-ray reflection spectroscopy to search for astrophysical wormholes in active galactic nuclei. In the present paper, we extend that work and construct an XSPEC model for the whole relativistic r…
Galaxy classification: deep learning on the OTELO and COSMOS databases
Bland-Hawthorn, Joss; Gallego, Jesús; Sánchez-Portal, Miguel +19 more
Context. The accurate classification of hundreds of thousands of galaxies observed in modern deep surveys is imperative if we want to understand the universe and its evolution.
Aims: Here, we report the use of machine learning techniques to classify early- and late-type galaxies in the OTELO and COSMOS databases using optical and infrared pho…
Multiscale MHD-Kinetic PIC Study of Energy Fluxes Caused by Reconnection
Lapenta, Giovanni; Berchem, Jean; Walker, Raymond +1 more
We present an analysis of the energy partitioning in the magnetotail during a substorm at 03:58:00 UT on 7 February 2009. The analysis employs a multiscale approach where we use a state from a global magnetohydrodynamics (MHD) model to spawn a kinetic particle-in-cell (PIC) simulation of a large portion of the tail. We directly investigate the ene…
New ultracool dwarf neighbours within 20 pc from Gaia DR2
Scholz, R. -D.
Aims: The Gaia data release 2 (DR2) contains > 6000 objects with parallaxes (Plx + 3 × e_Plx) > 50 mas, placing them within 20 pc from the Sun. Because the expected numbers based on extrapolating the well-known 10 pc census are much lower, nearby Gaia stars need a quality assessment. The 20 pc sample of white dwarfs (WDs) has been verif…
A Tale of Two Transition Disks: ALMA Long-baseline Observations of ISO-Oph 2 Reveal Two Closely Packed Nonaxisymmetric Rings and a ∼2 au Cavity
Flock, Mario; Herczeg, Gregory J.; Pinilla, Paola +12 more
ISO-Oph 2 is a wide-separation (240 au) binary system where the primary star harbors a massive (Mdust ∼ 40 M⊕) ring-like disk with a dust cavity ∼50 au in radius and the secondary hosts a much lighter (Mdust ∼ 0.8 M⊕) disk. As part of the high-resolution follow-up of the "Ophiuchus Disk Survey Employing …
A hyper luminous starburst at z = 4.72 magnified by a lensing galaxy pair at z = 1.48
Daddi, E.; Elbaz, D.; Ilbert, O. +23 more
We serendipitously discovered in the Herschel Reference Survey an extremely bright infrared source with S500 ∼ 120 mJy in the line of sight of the Virgo cluster which we name Red Virgo 4 (RV4). Based on IRAM/EMIR and IRAM/NOEMA detections of the CO(5-4), CO(4-3), and [CI] lines, RV4 is located at a redshift of 4.724, yielding a total ob…