Search Publications
A Ulysses Detection of Secondary Helium Neutrals
Wood, Brian E.; Müller, Hans-Reinhard; Witte, Manfred
The Interstellar Boundary EXplorer (IBEX) mission has recently studied the flow of interstellar neutral He atoms through the solar system and discovered the existence of a secondary He flow that likely originates in the outer heliosheath. We find evidence for this secondary component in Ulysses data. By coadding hundreds of Ulysses He beam maps to…
Masses of the Planetary Nebula Central Stars in the Galactic Globular Cluster System from HST Imaging and Spectroscopy
Bond, Howard E.; De Marco, Orsola; Lanz, Thierry +4 more
The globular cluster (GC) system of our Galaxy contains four planetary nebulae (PNe): K 648 (or Ps 1) in M15, IRAS 18333-2357 in M22, JaFu 1 in Pal 6, and JaFu 2 in NGC 6441. Because single-star evolution at the low stellar mass of present-epoch GCs was considered incapable of producing visible PNe, their origin presented a puzzle. We imaged the P…
The Solar Flare Complex Network
Safari, Hossein; Gheibi, Akbar; Javaherian, Mohsen
We investigate the characteristics of the solar flare complex network. The limited predictability, nonlinearity, and self-organized criticality of the flares allow us to study systems of flares in the field of the complex systems. Both the occurrence time and the location of flares detected from 2006 January 1 to 2016 July 21 are used to design th…
Evidence for Reduced Specific Star Formation Rates in the Centers of Massive Galaxies at z = 4
Papovich, Casey; Finkelstein, Steven L.; Dickinson, Mark +11 more
We perform the first spatially resolved stellar population study of galaxies in the early universe (z = 3.5-6.5), utilizing the Hubble Space Telescope Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey imaging data set over the GOODS-S field. We select a sample of 418 bright and extended galaxies at z = 3.5-6.5 from a parent sample of …
Hot Molecular Gas in the Circumnuclear Disk
Togi, Aditya; Mills, Elisabeth A. C.; Kaufman, Michael
We present an analysis of archival Infrared Space Observatory observations of H2 for three 14\prime\prime × 20\prime\prime pointings in the central 3 pc of the Galaxy: toward the southwest region and northeast region of the Galactic center circumnuclear disk (CND), and toward the supermassive black hole Sgr A*. We …
A Multiwavelength Study of Nearby Millisecond Pulsar PSR J1400-1431: Improved Astrometry and an Optical Detection of Its Cool White Dwarf Companion
Ray, P. S.; Kaplan, D. L.; Lorimer, D. R. +16 more
In 2012, five high-school students involved in the Pulsar Search Collaboratory discovered the millisecond pulsar (MSP) PSR J1400-1431, and initial timing parameters were published in Rosen et al. a year later. Since then, we have obtained a phase-connected timing solution spanning five years, resolving a significant position discrepancy and measur…
A Statistical Comparison between Photospheric Vector Magnetograms Obtained by SDO/HMI and Hinode/SP
Sainz Dalda, Alberto
Since 2010 May 1, we have been able to study (almost) continuously the vector magnetic field in the Sun, thanks to two space-based observatories: the Solar Dynamics Observatory (SDO) and Hinode. Both are equipped with instruments able to measure the Stokes parameters of Zeeman-induced polarization of photospheric line radiation. But the observatio…
Solar Flare Termination Shock and Synthetic Emission Line Profiles of the Fe xxi 1354.08 Å Line
Li, Gang; Raymond, John; Guo, Lijia +1 more
Solar flares are among the most energetic phenomena that occur in the solar system. In the standard solar flare model, a fast mode shock, often referred to as the flare termination shock (TS), can exist above the loop-top source of hard X-ray emissions. The existence of the TS has been recently related to spectral hardening of a flare’s hard X-ray…
Little Blue Dots in the Hubble Space Telescope Frontier Fields: Precursors to Globular Clusters?
Elmegreen, Bruce G.; Elmegreen, Debra Meloy
Galaxies with stellar masses < {10}7.4 {M}⊙ and specific star formation rates {sSFR}> {10}-7.4 yr-1 were examined on images of the Hubble Space Telescope Frontier Field Parallels for Abell 2744 and MACS J0416.1-02403. They appear as unresolved “Little Blue Dots” (LBDs). They are less massive and h…
NuSTAR and XMM-Newton Observations of the 2015 Outburst Decay of GX 339-4
Stiele, H.; Kong, A. K. H.
The extent of the accretion disk in the low/hard state of stellar mass black hole X-ray binaries remains an open question. There is some evidence suggesting that the inner accretion disk is truncated and replaced by a hot flow, while the detection of relativistic broadened iron emission lines seems to require an accretion disk extending fully to t…