Search Publications
CANDELS Meets GSWLC: Evolution of the Relationship between Morphology and Star Formation Since z = 2
Faber, S. M.; Tacchella, Sandro; Salim, Samir +7 more
Galaxy morphology and its evolution over the cosmic epoch hold important clues for understanding the regulation of star formation (SF). However, studying the relationship between morphology and SF has been hindered by the availability of consistent data at different redshifts. Our sample, combining CANDELS (0.8 < z < 2.5) and the GALEX-SDSS-…
Can Subphotospheric Magnetic Reconnection Change the Elemental Composition in the Solar Corona?
Long, David M.; Brooks, David H.; Baker, Deborah +6 more
Within the coronae of stars, abundances of those elements with low first ionization potential (FIP) often differ from their photospheric values. The coronae of the Sun and solar-type stars mostly show enhancements of low-FIP elements (the FIP effect) while more active stars such as M dwarfs have coronae generally characterized by the inverse-FIP e…
Electron Temperature Anisotropy and Electron Beam Constraints from Electron Kinetic Instabilities in the Solar Wind
Xie, Huasheng; Wu, Dejin; Sun, Heyu +2 more
Electron temperature anisotropies and electron beams are nonthermal features of the observed nonequilibrium electron velocity distributions in the solar wind. In collision-poor plasmas these nonequilibrium distributions are expected to be regulated by kinetic instabilities through wave-particle interactions. This study considers electron instabili…
Helium Line Emissivities in the Solar Corona
Andretta, V.; Del Zanna, G.; Storey, P. J. +1 more
We present new collisional-radiative models (CRMs) for helium in the quiescent solar corona and predict the emissivities of the He and He+ lines to be observed by DKIST, Solar Orbiter, and Proba-3. We discuss in detail the rates we selected for these models, highlighting several shortcomings we have found in previous work. As no previou…
On the Diversity of Jet Production Efficiency in Swift/BAT AGNs
Sikora, Marek; Gupta, Maitrayee; Rusinek, Katarzyna +1 more
We address the very large diversity of jet production efficiency in active galactic nuclei (AGNs) by using data on low-redshift AGNs selected from the Swift/BAT catalog and having black hole (BH) masses larger than 108.5 M⊙. Most of these AGNs accrete at intermediate rates and have bolometric luminosities dominated by mid-IR …
The Extreme Red Excess in Blazar Ultraviolet Broad Emission Lines
Berton, Marco; Punsly, Brian; Marziani, Paola +1 more
We present a study of quasars with very redward asymmetric (RA) ultraviolet (UV) broad emission lines (BELs). An excess of redshifted emission has been previously shown to occur in the BELs of radio-loud quasars and is most extreme in certain blazars. Paradoxically, blazars are objects that are characterized by a highly relativistic blueshifted ou…
ALMA Observations of Young Eruptive Stars: Continuum Disk Sizes and Molecular Outflows
Hales, Antonio S.; Pérez, Sebastián; Gonzalez-Ruilova, Camilo +7 more
We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm observations of four young, eruptive star-disk systems at 0"4 resolution: two FUors (V582 Aur and V900 Mon), one EXor (UZ Tau E), and one source with an ambiguous FU/EXor classification (GM Cha). The disks around GM Cha, V900 Mon, and UZ Tau E are resolved. These observations in…
On the Ratios of Si IV Lines (λ1394/λ1403) in an Emerging Flux Region
Isobe, Hiroaki; Tripathi, Durgesh; Nived, V. N. +1 more
The resonance lines of Si IV formed at λ1394 and 1403 Å are the most critical for the diagnostics of the solar transition region in the observations of the Interface Region Imaging Spectrograph (IRIS). Studying the intensity ratios of these lines (1394 Å/1403 Å), which under optically thin conditions is predicted to be two, helps us to diagnose th…
The Extreme CNO-enhanced Composition of the Primitive Iron-poor Dwarf Star J0815+4729
Burgasser, Adam J.; Aguado, David S.; Allende Prieto, Carlos +2 more
We present an analysis of high-resolution Keck/HIRES spectroscopic observations of J0815+4729, an extremely carbon-enhanced, iron-poor dwarf star. These high-quality data allow us to derive a metallicity of [Fe/H] = -5.49 ± 0.14 from the three strongest Fe I lines and to measure a high [Ca/Fe] = 0.75 ± 0.14. The large carbon abundance of A(C) = 7.…
A Habitable-zone Earth-sized Planet Rescued from False Positive Status
Vanderburg, Andrew; Bryson, Steve; Latham, David W. +9 more
We report the discovery of an Earth-sized planet in the habitable zone of a low-mass star called Kepler-1649. The planet, Kepler-1649 c, is 1.06 ${}_{-0.10}^{+0.15}$ times the size of Earth and transits its 0.1977 ± 0.0051 ${M}_{\odot }$ "mid" M-dwarf host star every 19.5 days. It receives 74% ± 3% the incident flux of Earth, giving it an equilibr…