Search Publications
Solar Wind Density and Core Temperature Derived from the PSP Quasi-thermal Noise Measurements
Liu, Mingzhe; Liu, Kaijun; Pierrard, Viviane +6 more
Quasi-thermal noise (QTN) spectroscopy is a valuable method to deduce important parameters in space plasma, such as plasma density and temperature, especially when direct particle measurements are not available. The present study develops a new fitting method to fit the QTN spectra observed by the Parker Solar Probe (PSP) with a comprehensive theo…
Nitrogen Abundance Distribution in the Inner Milky Way
Gong, Yan; Menten, Karl M.; Anderson, L. D. +9 more
We combine a new Galactic plane survey of hydrogen radio recombination lines (RRLs) with far-infrared surveys of ionized nitrogen, N+, to determine nitrogen abundance across Galactic radius. RRLs were observed with the NASA Deep Space Network Station 43 70 m antenna and the Green Bank Telescope in 108 lines of sight spanning ‑135°< l…
Binary Yellow Supergiants in the Magellanic Clouds. I. Photometric Candidate Identification
Drout, Maria R.; O'Grady, Anna J. G.; Gaensler, B. M. +3 more
Recent works have constrained the binary fraction of evolved populations of massive stars in local galaxies such as red supergiants and Wolf–Rayet stars, but the binary fraction of yellow supergiants (YSGs) in the Hertzsprung gap remains unconstrained. Binary evolution theory predicts that the Hertzsprung gap is home to multiple populations of bin…
Modeling Cassini UVIS Interplanetary Hydrogen Lyα Observations from 1999 to 2017
Pryor, Wayne R.; Esposito, Larry W.; Gladstone, G. Randall +3 more
The Cassini Orbiter Ultraviolet Imaging Spectrograph (UVIS) obtained interplanetary hydrogen Lyα observations from 1999 to 2017, with mid-2004 to 2017 observations obtained from Saturn orbit. During its Saturn orbital phase, the spacecraft moved from mostly downwind and sidewind in the heliosphere to upwind. We analyze the full set of observations…
Coevolution and Nuclear Structure in the Dwarf Galaxy POX 52 Studied by Multiwavelength Data from Radio to X-Ray
Kawamuro, Taiki; Ricci, Claudio; Noda, Hirofumi +4 more
The nearby dwarf galaxy POX 52 at z = 0.021 hosts an active galactic nucleus (AGN) with a black hole (BH) mass of M BH ~ 105-6 M ⊙ and an Eddington ratio of ~0.1-1. This object provides the rare opportunity to study both AGN and host-galaxy properties in a low-mass highly accreting system. To do so, we collected it…
The Densities in Diffuse and Translucent Molecular Clouds: Estimates from Observations of C2 and from Three-dimensional Extinction Maps
Caselli, Paola; Welty, Daniel E.; Edenhofer, Gordian +7 more
Newly computed collisional rate coefficients for the excitation of C2 in collisions with H2, presented recently by Najar & Kalugina, are significantly larger than the values adopted previously in models for the excitation of the C2 molecule, a widely used probe of the interstellar gas density. With these new ra…
Vortex Fiber Nulling for Exoplanet Observations: First Direct Detection of M Dwarf Companions around HIP 21543, HIP 94666, and HIP 50319
Monnier, John D.; Schaefer, Gail H.; Lanthermann, Cyprien +35 more
Vortex fiber nulling (VFN) is a technique for detecting and characterizing faint companions at small separations from their host star. A near-infrared (∼2.3 µm) VFN demonstrator mode was deployed on the Keck Planet Imager and Characterizer (KPIC) instrument at the Keck Observatory and presented earlier. In this Letter, we present the first V…
A Radio Counterpart to a Jupiter-mass Binary Object in Orion
Zapata, Luis A.; Rodríguez, Luis F.; Loinard, Laurent
Using James Webb Space Telescope near-infrared data of the inner Orion Nebula, Pearson & McCaughrean detected 40 Jupiter-mass binary objects (JuMBOs). These systems are not associated with stars and their components have masses of giant Jupiter-like planets and separations in the plane of the sky of order ~100 au. The existence of these wide f…
Role of Polycyclic Aromatic Hydrocarbons with Edge Defects in Explaining Astronomical Infrared Emission Observations
Boersma, C.; Peeters, E.; Maragkoudakis, A. +2 more
A systematic study was performed on the spectral properties of polycyclic aromatic hydrocarbons (PAHs) with edge defects using harmonic density functional theory calculations. Their potential astronomical relevance was assessed through direct comparison with NIRSpec and MIRI-MRS spectra of the atomic photodissociation region of the Orion Bar from …
zoomies: A Tool to Infer Stellar Age from Vertical Action in Gaia Data
Hogg, David W.; Angus, Ruth; Price-Whelan, Adrian M. +3 more
Stellar age measurements are fundamental to understanding a wide range of astronomical processes, including Galactic dynamics, stellar evolution, and planetary system formation. However, extracting age information from main-sequence stars is complicated, with techniques often relying on age proxies in the absence of direct measurements. The Gaia d…