Search Publications
Highly Structured Inner Planetary System Debris around the Intermediate Age Sun-like Star TYC 8830 410 1
Weinberger, Alycia J.; Song, Inseok; Olofsson, Johan +4 more
We present a detailed characterization of the extremely dusty main-sequence star TYC 8830 410 1. This system hosts inner planetary system dust (T dust ≈ 300 K) with a fractional infrared luminosity of ~1%. Mid-infrared spectroscopy reveals a strong, mildly crystalline solid-state emission feature. TYC 8830 410 1 (spectral type G9 V) has…
APOGEE-2 Discovery of a Large Population of Relatively High-metallicity Globular Cluster Debris
Bizyaev, Dmitry; Pan, Kaike; Majewski, Steven R. +13 more
We report the discovery of a new, chemically distinct population of relatively high-metallicity ([Fe/H] > -0.7) red giant stars with super-solar [N/Fe] (≳+0.75) identified within the bulge, disk, and halo of the Milky Way. This sample of stars was observed during the second phase of the Apache Point Observatory Galactic Evolution Experiment (AP…
Direct Measurements of Giant Star Effective Temperatures and Linear Radii: Calibration against Spectral Types and V - K Color
Ciardi, David R.; Clark, Catherine A.; van Belle, Gerard T. +8 more
We calculate directly determined values for effective temperature (T eff) and radius (R) for 191 giant stars based upon high-resolution angular size measurements from optical interferometry at the Palomar Testbed Interferometer. Narrow- to wideband photometry data for the giants are used to establish bolometric fluxes and luminosities t…
Random Walk and Trapping of Interplanetary Magnetic Field Lines: Global Simulation, Magnetic Connectivity, and Implications for Solar Energetic Particles
Matthaeus, William H.; Goldstein, Melvyn L.; Usmanov, Arcadi V. +4 more
The random walk of magnetic field lines is an important ingredient in understanding how the connectivity of the magnetic field affects the spatial transport and diffusion of charged particles. As solar energetic particles propagate away from near-solar sources, they interact with the fluctuating magnetic field, which modifies their distributions. …
Probing Current Sheet Instabilities from Flare Ribbon Dynamics
Matthews, Sarah A.; French, Ryan J.; Jonathan Rae, I. +1 more
The presence of current sheet instabilities, such as the tearing mode instability, are needed to account for the observed rate of energy release in solar flares. Insights into these current sheet dynamics can be revealed by the behavior of flare ribbon substructure, as magnetic reconnection accelerates particles down newly reconnected field lines …
On the Issue of the Origin of Type II Solar Radio Bursts
Chernov, Gennady; Fomichev, Valery
Type II solar radio bursts are among the most powerful events in the solar radio emission in the meter wavelength range. It is generally accepted that the agents generating type II radio bursts are magnetohydrodynamic shock waves. But the relationship between the shock waves and the other manifestations of the large-scale disturbances in the solar…
Deeply Buried Nuclei in the Infrared-luminous Galaxies NGC 4418 and Arp 220. I. ALMA Observations at λ = 1.4-0.4 mm and Continuum Analysis
Wilner, David J.; Aalto, Susanne; Martín, Sergio +4 more
We observed with Atacama Large Millimeter/submillimeter Array three deeply buried nuclei in two galaxies, NGC 4418 and Arp 220, at ~0.″2 resolution over a total bandwidth of 67 GHz in f rest = 215-697 GHz. Here we (1) introduce our program, (2) describe our data reduction method for wide-band, high-resolution imaging spectroscopy, (3) a…
Magnetohydrostatic Equilibrium Structure and Mass of Polytropic Filamentary Cloud Threaded by Lateral Magnetic Field
Tomisaka, Kohji; Kashiwagi, Raiga
Filamentary structures are recognized as a fundamental component of interstellar molecular clouds in observations made by the Herschel satellite. These filaments, especially massive filaments, often extend in a direction perpendicular to the interstellar magnetic field. Furthermore, the filaments sometimes have an apparently negative temperature g…
Multiwavelength Characterization of the High-mass X-Ray Binary Population of M31
Williams, Benjamin F.; Eracleous, Michael; Sasaki, Manami +7 more
We present our analysis of high-quality high-mass X-ray binary (HMXB) candidates in M31 selected from point-source optical counterpart candidates from the Chandra-PHAT survey catalog. We fit the spectral energy distributions of optical counterpart candidates using the Bayesian Extinction and Stellar Tool. We used the best-fit luminosity, effective…
Energy Supply by Low-frequency Break Sweeping for Heating the Fast Solar Wind from 0.3 to 4.8 au
He, Jiansen; Wang, Xin; Tu, Chuanyi +3 more
Solar wind protons undergo significant heating during the expansion of the solar wind and turbulence plays an important role in this process. It is believed that the energy is injected from the energy-containing range into the inertial range and then transferred to dissipate into heat eventually. However, the energy injection process in the helios…