Search Publications
Radius Inflation at Low Rossby Number in the Hyades Cluster
Stassun, Keivan G.; Somers, Garrett; Jaehnig, Karl
Radius inflation continues to be explored as a peculiar occurrence among magnetically active, low-mass stars. Recently, Somers & Stassun showed that radius inflation among low-mass stars in the young open cluster M45 (Pleiades Cluster) is correlated to the rotation rate: faster rotators are more inflated. Here we extend that work to a sample o…
The Dynamics, Structure, and Fate of a Young Cluster during Gas Dispersal: Hectoschelle, Chandra, Spitzer, and Gaia Observations of Cep OB3b
Jeffries, R. D.; Megeath, S. T.; Gutermuth, R. A. +5 more
We present a study of the kinematics and structure of the Cep OB3b cluster based on new spectra obtained with the Hectoschelle spectrograph on the MMT and data from Spitzer, Chandra, and Gaia. At a distance of 819 ± 16 pc, Cep OB3b is one of the closest examples of a young (∼3-5 Myr), large (∼3000 total members) cluster at the late stages of gas d…
Models of the Mass-ejection Histories of Pre-planetary Nebulae. III. The Shaping of Lobes by Post-AGB Winds
Frank, Adam; Balick, Bruce; Liu, Baowei
We develop a physical framework for interpreting high-resolution images and kinematics of pre-planetary nebulae (“prePNe”). We use hydrodynamical models to infer the historical properties of fast collimated nuclear flows (“jet”) that successfully form hollow, candle-shaped lobes over ≈103 yr, including the density, momenta, and geometry…
The Interplay of the Solar Wind Core and Suprathermal Electrons: A Quasilinear Approach for Firehose Instability
Lazar, M.; Poedts, S.; Yoon, P. H. +1 more
In the solar wind an equipartition of kinetic energy densities can be easily established between thermal and suprathermal electrons and the instability conditions are markedly altered by the interplay of these two populations. The new thresholds derived here for the periodic branch of firehose instability shape the limits of temperature anisotropy…
Transfer of Twists from a Mini-filament to Large-scale Loops by Magnetic Reconnection
Li, Ting; Xue, Zhike; Yan, Xiaoli +4 more
With high spatial and temporal resolution, Hα data from the New Vacuum Solar Telescope, X-ray images from the X-ray telescope on board Hinode and simultaneous observations from the Solar Dynamics Observatory, we present multiwavelength observations of the interaction between a mini-filament (MF) and its overlying large-scale active-region loops (A…
Spectral Evolution and Radial Dust Transport in the Prototype Young Eruptive System EX Lup
Carmona, A.; Ábrahám, P.; Chen, L. +7 more
EX Lup is the prototype of a class of pre-main-sequence eruptive stars defined by their repetitive outbursts lasting several months. In 2008 January-September EX Lup underwent its historically largest outburst, brightening by about 4 mag in visual light. In previous studies we discovered ongoing silicate crystal formation in the inner disk during …
Green Peas in X-Rays
Ehle, M.; Svoboda, J.; Orlitová, I. +1 more
Green Peas represent a population of compact, highly star-forming dwarf galaxies at redshifts z ∼ 0.2-0.3 that have recently been found to show signatures of ultraviolet ionizing radiation leakage. They are being considered as analogs to high-redshift star-forming galaxies, possibly responsible for cosmic reionization. Despite intensive studies of…
Where Do Quasar Hosts Lie with Respect to the Size-Mass Relation of Galaxies?
Kartaltepe, Jeyhan S.; Treu, Tommaso; Schramm, Malte +8 more
The evolution of the galaxy size-mass relation has been a puzzle for over a decade. High-redshift galaxies are significantly more compact than galaxies observed today at an equivalent mass, but how much of this apparent growth is driven by progenitor bias, minor mergers, secular processes, or feedback from active galactic nuclei (AGNs) is unclear.…
12,660 Spotted Stars toward the OGLE Galactic Bulge Fields
Soszyński, I.; Udalski, A.; Szymański, M. K. +12 more
We present the discovery and statistical analysis of 12,660 spotted variable stars toward and inside the Galactic bulge from the Optical Gravitational Lensing Experiment (OGLE) data that are over two decades long. We devise a new method of dereddening of individual stars toward the Galactic bulge where strong and highly nonuniform extinction is pr…
The Galactic Bulge Diffuse Emission in Broadband X-Rays with NuSTAR
Wik, Daniel R.; Krivonos, Roman; Perez, Kerstin
The diffuse hard X-ray emission that fills the Galactic center, bulge, and ridge is believed to arise from unresolved populations of X-ray binary systems. However, the identity of the dominant class of accreting objects in each region remains unclear. Recent studies of Fe line properties and the low-energy (<10 keV) X-ray continuum of the bulge…