Search Publications
An Analysis of ALMA Deep Fields and the Perceived Dearth of High-z Galaxies
Finkelstein, Steven L.; Casey, Caitlin M.; Zavala, Jorge A. +5 more
Deep, pencil-beam surveys from ALMA at 1.1-1.3 mm have uncovered an apparent absence of high-redshift dusty galaxies, with existing redshift distributions peaking around z ∼ 1.5-2.5. This has led to a perceived dearth of dusty systems at z ≳ 4 and the conclusion, according to some models, that the early universe was relatively dust-poor. In this p…
K2-141 b. A 5-M⊕ super-Earth transiting a K7 V star every 6.7 h
Deeg, H.; Erikson, A.; Fridlund, M. +32 more
We report on the discovery of K2-141 b (EPIC 246393474 b), an ultra-short-period super-Earth on a 6.7 h orbit transiting an active K7 V star based on data from K2 campaign 12. We confirmed the planet's existence and measured its mass with a series of follow-up observations: seeing-limited MuSCAT imaging, NESSI high-resolution speckle observations,…
Two Episodes of Magnetic Reconnections during a Confined Circular-ribbon Flare
Hou, Yijun; Li, Ting; Yang, Shuhong +2 more
We analyze a unique event with an M1.8 confined circular-ribbon flare on 2016 February 13, with successive formations of two circular ribbons at the same location. The flare had two distinct phases of UV and extreme ultraviolet emissions with an interval of about 270 s, of which the second peak was energetically more important. The first episode w…
CME-driven Shock and Type II Solar Radio Burst Band Splitting
Temmer, Manuela; Kontar, Eduard P.; Chrysaphi, Nicolina +1 more
Coronal mass ejections (CMEs) are believed to be effective in producing shocks in the solar corona and interplanetary space. One of the important signatures of shocks and shock acceleration are Type II solar radio bursts that drift with the shock speed and produce bands of fundamental and higher harmonic plasma radio emission. An intriguing aspect…
IRIS and SDO Observations of Solar Jetlets Resulting from Network-edge Flux Cancelation
Tiwari, Sanjiv K.; De Pontieu, Bart; Panesar, Navdeep K. +3 more
Recent observations show that the buildup and triggering of minifilament eruptions that drive coronal jets result from magnetic flux cancelation at the neutral line between merging majority- and minority-polarity magnetic flux patches. We investigate the magnetic setting of 10 on-disk small-scale UV/EUV jets (jetlets, smaller than coronal X-ray je…
Spatially resolved cold molecular outflows in ULIRGs
Rigopoulou, D.; Colina, L.; van der Werf, P. +11 more
We present new CO(2-1) observations of three low-z (d 350 Mpc) ultra-luminous infrared galaxy (ULIRG) systems (six nuclei) observed with the Atacama large millimeter/submillimeter array (ALMA) at high spatial resolution ( 500 pc). We detect massive cold molecular gas outflows in five out of six nuclei (Mout (0.3-5) × 108 M
Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals
Holmström, M.; Read, A. M.; Wing, S. +32 more
Both heliophysics and planetary physics seek to understand the complex nature of the solar wind's interaction with solar system obstacles like Earth's magnetosphere, the ionospheres of Venus and Mars, and comets. Studies with this objective are frequently conducted with the help of single or multipoint in situ electromagnetic field and particle ob…
The spiral structure of the Milky Way
Xu, Ye; Hou, Li-Gang; Wu, Yuan-Wei
The morphology and kinematics of the spiral structure of the Milky Way are long-standing problems in astrophysics. In this review we firstly summarize various methods with different tracers used to solve this puzzle. The astrometry of Galactic sources is gradually alleviating this difficult situation caused mainly by large distance uncertainties, …
Global-Mode Analysis of Full-Disk Data from the Michelson Doppler Imager and the Helioseismic and Magnetic Imager
Schou, Jesper; Larson, Timothy P.
Building upon our previous work, in which we analyzed smoothed and subsampled velocity data from the Michelson Doppler Imager (MDI), we extend our analysis to unsmoothed, full-resolution MDI data. We also present results from the Helioseismic and Magnetic Imager (HMI), in both full resolution and processed to be a proxy for the low-resolution MDI …
Statistical Analysis of Torus and Kink Instabilities in Solar Eruptions
Xu, Yan; Liu, Chang; Jing, Ju +4 more
A recent laboratory experiment of ideal magnetohydrodynamic instabilities revealed four distinct eruption regimes readily distinguished by the torus instability (TI) and helical kink instability (KI) parameters. To establish its observational counterpart, we collected 38 solar flares (stronger than GOES-class M5 in general) that took place within …