Search Publications
Investigating Possible Binarity for GJ 229B
Mandell, Avi M.; McElwain, Michael W.; Howe, Alex R.
GJ 229B, the first type-T brown dwarf to be discovered, has presented a tension between comparisons with evolutionary models and the larger-than-expected mass and radius values derived from spectroscopic and astrometric observations. We examine the hypothesis that GJ 229B is actually a binary substellar object by using two grid-based fits using ev…
Connection between Polytropic Index and Heating
McComas, D. J.; Livadiotis, G.
The paper derives the one-to-one connecting relationships between plasma heating and its polytropic index, and addresses the consequences through the transport equation of temperature. Thermodynamic polytropic processes are classified in accordance to their polytropic index, the exponent of the power-law relationship of thermal pressure expressed …
Deep Search for Gamma-Ray Emission from the Accreting X-Ray Pulsar 1A 0535+262
Torres, D. F.; Li, J.; Ji, L. +2 more
Binary systems are a well-established subclass of gamma-ray sources. The high mass X-ray binary pulsar 1A 0535+262 has been considered to be a possible gamma-ray emitter for a long time, although former gamma-ray searches using the Fermi Large Area Telescope (LAT) and VERITAS data resulted in upper limits only. We aim at a deep search for gamma-ra…
The Origin of Dust Polarization in the Orion Bar
Soam, Archana; Hoang, Thiem; Le Gouellec, Valentin J. M. +8 more
The linear polarization of thermal dust emission provides a powerful tool to probe interstellar and circumstellar magnetic fields, because aspherical grains tend to align themselves with magnetic field lines. While the Radiative Alignment Torque (RAT) mechanism provides a theoretical framework for this phenomenon, some aspects of this alignment me…
Probability Distribution Functions of Sunspot Magnetic Flux
Toriumi, Shin; Sakurai, Takashi
We investigated the probability distributions of sunspot area and magnetic flux by using data from the Royal Greenwich Observatory and USAF/NOAA. We constructed a sample of 2995 regions with maximum-development areas ≥500 MSH (millionths of solar hemisphere), covering 146.7 yr (1874-2020). The data were fitted by a power-law distribution and four …
Harnessing the Hubble Space Telescope Archives: A Catalog of 21,926 Interacting Galaxies
Mantha, Kameswara Bharadwaj; Simmons, Brooke D.; Merín, Bruno +13 more
Mergers play a complex role in galaxy formation and evolution. Continuing to improve our understanding of these systems requires ever larger samples, which can be difficult (even impossible) to select from individual surveys. We use the new platform ESA Datalabs to assemble a catalog of interacting galaxies from the Hubble Space Telescope science …
Morphology of Star-forming Clumps in Ram-pressure Stripped Galaxies as Seen by HST
Scarlata, Claudia; Calzetti, Daniela; Vulcani, Benedetta +9 more
We characterize the morphological properties of a statistically relevant sample of Hα and UV young star-forming clumps and optical complexes, observed with the Hubble Space Telescope in six galaxies of the GASP sample undergoing ram pressure stripping. The catalogs comprise 2406 (323 in the tails) Hα clumps, 3750 (899) UV clumps, and 424 tail opti…
HH 80/81: Structure and Kinematics of the Fastest Protostellar Outflow
Bally, John; Reipurth, Bo
Hubble Space Telescope (HST) images obtained in 2018 are combined with archival HST data taken in 1995 to detect changes and measure proper motions in the HH 80/81 shock complex, which is powered by the fastest known jet driven by a forming star, the massive object IRAS 18162-2048. Some persistent features close to the radio jet axis have proper m…
Variability of Magnetic Hot Stars from the TESS Observations
Li, Gang; Zhang, Yu; Fu, Jian-Ning +7 more
Magnetic hot stars refer to stars that have effective temperatures approximately in the range from 7000-50,000 K, and with large-scale globally organized magnetic fields. These magnetic fields exhibit strengths ranging from tens of Gauss to tens of kilo-Gauss. They are key in understanding the effects caused by magnetic fields in the stellar evolu…
Caught in the Act: A Metal-rich High-velocity Cloud in the Inner Galaxy
Jenkins, Edward B.; Fox, Andrew J.; Wakker, Bart P. +7 more
We characterize the chemical and physical conditions in an outflowing high-velocity cloud (HVC) in the inner Galaxy. We report a supersolar metallicity of [O/H] = +0.36 ± 0.12 for the HVC at v LSR = 125.6 km s-1 toward the star HD 156359 (l = 328.°7, b = -14.°5, d = 9 kpc, z = -2.3 kpc). Using archival observations from the F…