Search Publications
Seeds and sequences of element abundances in solar energetic particle events
Reames, Donald V.
Solar energetic particles (SEPs) in the small "impulsive" events, primarily accelerated during magnetic reconnection in solar jets, have strong enhancements of the abundances of increasingly heavy elements. In contrast, the shock acceleration of ambient coronal plasma in most large "gradual" SEP events produces flat or decreasing abundances vs. el…
Chandra X-Ray Observations of PSR J1849-0001, Its Pulsar Wind Nebula, and the TeV Source HESS J1849-000
Kargaltsev, Oleg; Klingler, Noel; Yang, Hui +4 more
We obtained a 108 ks Chandra X-ray Observatory (CXO) observation of PSR J1849-0001 and its pulsar wind nebula (PWN) coincident with the TeV source HESS J1849-000. By analyzing the new and old (archival) CXO data, we resolved the pulsar from the PWN, explored the PWN morphology on arcsecond and arcminute scales, and measured the spectra of differen…
HD 222237 b: a long-period super-Jupiter around a nearby star revealed by radial-velocity and Hipparcos-Gaia astrometry
Butler, R. Paul; Rice, Malena; Wittenmyer, Robert A. +16 more
Giant planets on long-period orbits around the nearest stars are among the easiest to directly image. Unfortunately these planets are difficult to fully constrain by indirect methods, e.g. transit and radial velocity (RV). In this study, we present the discovery of a super-Jupiter, HD 222237 b, orbiting a star located
Probing the energy and luminosity-dependent spectro-timing properties of RX J0440.9+4431 with AstroSat
Paul, Biswajit; Ratheesh, Ajay; Sharma, Rahul +3 more
The Be/X-ray binary pulsar RX J0440.9+4431 went through a giant outburst in December 2022 with a peak flux of
Atmospheric Abundances and Bulk Properties of the Binary Brown Dwarf Gliese 229Bab from JWST/MIRI Spectroscopy
Zhang, Yapeng; Perrin, Marshall D.; Knutson, Heather A. +8 more
We present JWST/Mid Infrared Instrument (MIRI) low-resolution spectroscopy (4.75–14 µm) of the first known substellar companion, Gliese 229Bab, which was recently resolved into a tight binary brown dwarf. Previous atmospheric retrieval studies modeling Gliese 229B as a single brown dwarf have reported anomalously high carbon-to-oxygen ratios…
Cassini's CDA observes a variety of dust populations just outside Saturn's main rings
Postberg, Frank; Hillier, Jon K.; Srama, Ralf +5 more
Before the end of its mission, the Cassini spacecraft orbited Saturn in a series of highly inclined elliptical 'Ring-Grazing' orbits (RGO). During the RGO, the spacecraft passed repeatedly through the ring plane outside the F ring, near the orbits of Janus and Epimetheus, at an average relative speed of ~20 km s-1. For the first time, C…
Ulysses spacecraft in situ detections of cometary dust trails
Krüger, Harald; Grün, Eberhard; Strub, Peter
The Ulysses spacecraft was launched in 1990 and, after a Jupiter swing-by in 1992, became the first interplanetary spacecraft orbiting the Sun on a highly inclined trajectory with an inclination of 79 ∘ . The spacecraft was equipped with an impact ionization dust detector which provided 17 years of in situ dust measurements in interplan…
The chemical diversity of the metal-poor Milky Way
Hawkins, Keith; Jofré, Paula; Yates, Robert M. +2 more
We present a detailed study of the chemical diversity of the metal-poor Milky Way using data from the GALAH DR3 survey. Considering 17 chemical abundances relative to iron ([X/Fe]) for 9923 stars, we employ principal component analysis (PCA) and extreme deconvolution (XD) to identify 10 distinct stellar groups. This approach, free from chemical or…
Undersampling effects on observed periods of coronal oscillations
Gao, Yuhang; Van Doorsselaere, Tom; Lim, Daye +3 more
Context. Recent observations of decayless transverse oscillations have revealed two branches in the relationship between period and loop length. One is a linear relationship, interpreted as a standing mode, while the other shows almost no correlation and has not yet been interpreted conclusively. Aims. We investigated the undersampling effect on o…
The Polstar UV spectropolarimetry mission
Ignace, R.; Scowen, P.
The Polstar small explorer concept is for an ultraviolet (UV) spectropolarimetry space telescope mission with a focus on massive star astrophysics. The instrument waveband will be from 115 nm to 286 nm for spectroscopy, and from 122 nm to 286 nm for polarimetry. All four Stokes parameters, I, Q, U, and V , will be measured at a resolving power of …