Search Publications
Discovery of Ubiquitous Fast-Propagating Intensity Disturbances by the Chromospheric Lyman Alpha Spectropolarimeter (CLASP)
Auchère, F.; Giono, G.; Kubo, M. +25 more
High-cadence observations by the slit-jaw (SJ) optics system of the sounding rocket experiment known as the Chromospheric Lyman Alpha Spectropolarimeter (CLASP) reveal ubiquitous intensity disturbances that recurrently propagate in either the chromosphere or the transition region or both at a speed much higher than the speed of sound. The CLASP/SJ…
An Investigation of the Sources of Earth-directed Solar Wind during Carrington Rotation 2053
van Driel-Gesztelyi, L.; Fazakerley, A. N.; Harra, L. K.
In this work we analyze multiple sources of solar wind through a full Carrington Rotation (CR 2053) by analyzing the solar data through spectroscopic observations of the plasma upflow regions and the in situ data of the wind itself. Following earlier authors, we link solar and in situ observations by a combination of ballistic backmapping and pote…
The Dimensionless Age of the Universe: A Riddle for Our Time
Kirshner, Robert P.; Avelino, Arturo
We present the interesting coincidence of cosmology and astrophysics that points toward a dimensionless age of the Universe H 0 t 0 that is close to one. Despite cosmic deceleration for 9 Gyr and acceleration since then, we find H 0 t 0 = 0.96 ± 0.01 for the ΛCDM model that fits SN Ia data from Pan-STARR…
Sodium Absorption Systems toward SN Ia 2014J Originate on Interstellar Scales
Foley, R. J.; Sato, B.; Tanaka, M. +21 more
Na I D absorbing systems toward Type Ia supernovae (SNe Ia) have been intensively studied over the last decade with the aim of finding circumstellar material (CSM), which is an indirect probe of the progenitor system. However, it is difficult to deconvolve CSM components from non-variable, and often dominant, components created by interstellar mat…
The Discovery of Lensed Radio and X-Ray Sources behind the Frontier Fields Cluster MACS J0717.5+3745 with the JVLA and Chandra
Churazov, E.; Zitrin, A.; Rosati, P. +24 more
We report on high-resolution JVLA and Chandra observations of the Hubble Space Telescope (HST) Frontier Cluster MACS J0717.5+3745. MACS J0717.5+3745 offers the largest contiguous magnified area of any known cluster, making it a promising target to search for lensed radio and X-ray sources. With the high-resolution 1.0-6.5 GHz JVLA imaging in A and…
On the Origin of Inner Coma Structures Observed by Rosetta during a Diurnal Rotation of Comet 67P/Churyumov--Gerasimenko.
Kramer, Tobias; Noack, Matthias
The Rosetta probe around comet 67P/Churyumov-Gerasimenko (67P) reveals an anisotropic dust distribution of the inner coma with jet-like structures. The physical processes leading to jet formation are under debate, with most models for cometary activity focusing on localized emission sources, such as cliffs or terraced regions. Here we suggest, by …
Bayesian Analysis of Two Stellar Populations in Galactic Globular Clusters. I. Statistical and Computational Methods
Stenning, D. C.; Wagner-Kaiser, R.; Robinson, E. +4 more
We develop a Bayesian model for globular clusters composed of multiple stellar populations, extending earlier statistical models for open clusters composed of simple (single) stellar populations. Specifically, we model globular clusters with two populations that differ in helium abundance. Our model assumes a hierarchical structuring of the parame…
Weighing Stars: The Identification of an Evolved Blue Straggler Star in the Globular Cluster 47 Tucanae
Dalessandro, E.; Massari, D.; Mucciarelli, A. +4 more
Globular clusters are known to host peculiar objects named blue straggler stars (BSSs), significantly heavier than the normal stellar population. While these stars can be easily identified during their core hydrogen-burning phase, they are photometrically indistinguishable from their low-mass sisters in advanced stages of the subsequent evolution.…
Simulations of Alfvén and Kink Wave Driving of the Solar Chromosphere: Efficient Heating and Spicule Launching
Arber, T. D.; Brady, C. S.
Two of the central problems in our understanding of the solar chromosphere are how the upper chromosphere is heated and what drives spicules. Estimates of the required chromospheric heating, based on radiative and conductive losses, suggest a rate of ∼0.1 erg cm-3 s-1 in the lower chromosphere and drops to ∼10-3 er…
The Gigaelectronvolt Counterpart of VER J2019+407 in the Northern Shell of the Supernova Remnant G78.2+2.1 (γ Cygni)
Fraija, N.; Araya, M.
Analysis of gamma-ray emission from the supernova remnant G78.2+2.1 (γ Cygni) with 7.2 years of cumulative data from the Fermi Large Area Telescope shows a distinct hard, bright, and extended component to the north of the shell coincident with the known teraelectronvolt source VER J2019+407. In the gigaelectronvolt to teraelectronvolt (GeV-TeV) en…