Search Publications
The Metallicity Gradient and Complex Formation History of the Outermost Halo of the Milky Way
Yoon, Jinmi; Beers, Timothy C.; Placco, Vinicius M. +1 more
We present an examination of the metallicity distribution function of the outermost stellar halo of the Galaxy based on an analysis of both local (within 4 kpc of the Sun, ∼16,500 stars) and non-local (∼21,700 stars) samples. These samples were compiled using spectroscopic metallicities from the Sloan Digital Sky Survey and photometric metalliciti…
The SOFIA Massive (SOMA) Star Formation Survey. III. From Intermediate- to High-mass Protostars
Yang, Yao-Lun; Tanaka, Kei E. I.; Zhang, Yichen +9 more
We present $\sim 10\mbox{--}40\,\mu {\rm{m}}$ SOFIA-FORCAST images of 14 intermediate-mass protostar candidates as part of the SOFIA Massive (SOMA) Star Formation Survey. We build spectral energy distributions, also using archival Spitzer, Herschel, and IRAS data. We then fit the spectral energy distributions with radiative transfer models of Zhan…
Heating at the Remote Footpoints as a Brake on Jet Flows along Loops in the Solar Atmosphere
Fu, Hui; Li, Bo; Xia, Lidong +3 more
We report on observations of a solar jet propagating along coronal loops taken by the Solar Dynamics Observatory, the Interface Region Imaging Spectrograph, and the 1 m New Vacuum Solar Telescope. The ejecta of the jet consist of multithermal components and propagate with a speed greater than 100 km s-1. Brightenings are found in the re…
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…