Search Publications
Constraints on Cosmic-ray Acceleration Efficiency in Balmer Shocks of Two Young Type Ia Supernova Remnants in the Large Magellanic Cloud
Hughes, John P.; Pandya, Viraj; McCully, Curtis +2 more
We present results from an optical study of two young Balmer-dominated remnants of SNIa in the Large Magellanic Cloud, 0509-67.5 and 0519-69.0, in an attempt to search for signatures of efficient cosmic-ray (CR) acceleration. We combine proper motion measurements with corresponding optical spectroscopic measurements of the Hα line at multiple rim …
On the Apparent Absence of Wolf-Rayet+Neutron Star Systems: The Curious Case of WR124
Hamann, W. -R.; Chu, Y. -H.; Guerrero, M. A. +8 more
Among the different types of massive stars in advanced evolutionary stages is the enigmatic WN8h type. There are only a few Wolf-Rayet (WR) stars with this spectral type in our Galaxy. It has long been suggested that WN8h-type stars are the products of binary evolution that may harbor neutron stars (NS). One of the most intriguing WN8h stars is th…
Star Cluster Ages in the Gaia Era
Choi, Jieun; Conroy, Charlie; Ting, Yuan-Sen +3 more
We use the framework developed as part of the MESA Isochrones and Stellar Tracks (MIST) project to assess the utility of several types of observables in jointly measuring the age and 1D stellar model parameters in star clusters. We begin with a pedagogical overview summarizing the effects of stellar model parameters, such as the helium abundance, …
The Triggering of the 2014 March 29 Filament Eruption
Harra, Louise K.; Matthews, Sarah A.; Kusano, Kanya +3 more
The X1 flare and associated filament eruption occurring in NOAA Active Region 12017 on SOL2014-03-29 has been a source of intense study. In this work, we analyze the results of a series of nonlinear force-free field extrapolations of the flare’s pre- and post-flare periods. In combination with observational data provided by the IRIS, Hinode, and S…
Stellar Populations in the Outer Disk and Halo of the Spiral Galaxy M101
Mihos, J. Christopher; Harding, Paul; Durrell, Patrick R. +2 more
We use deep Hubble Space Telescope imaging in the outskirts of the nearby spiral M101 to study stellar populations in the galaxy’s outer disk and halo. Our Advanced Camera for Surveys (ACS) field lies 17.‧6 (36 kpc) from the center of M101 and targets the blue “NE Plume” of M101's outer disk, while the parallel Wide Field Camera 3 (WFC3) field lie…
A Late-type L Dwarf at 11 pc Hiding in the Galactic Plane Characterized Using Gaia DR2
Gonzales, Eileen C.; Burgasser, Adam J.; Marocco, Federico +4 more
We report on the characterization of a nearby (d={11.20}-0.08+0.09 pc) ultracool L dwarf (WISE J192512.78+070038.8; hereafter W1925) identified as a faint (G = 20.038 ± 0.009) object with high proper motion (219.834 ± 1.843 mas yr-1)in the Gaia Data Releases 1 and 2. A Palomar/TripleSpec near-infrared spectrum of W…
Late Bloomer Galaxies: Growing Up in Cosmic Autumn
Kelson, Daniel D.; Dressler, Alan; Abramson, Louis E.
Late bloomers (LBs) are massive ({M}* > {10}10 {\text{}}{M}⊙ ) galaxies at z < 1 that formed the majority of their stars within ∼2 Gyr of the epoch of observation. Our improved methodology for deriving star formation histories (SFHs) of galaxies at redshifts 0.45 < z < 0.75 from the Carnegie-Spitzer-IMA…
Density Fluctuations in a Polar Coronal Hole
Hahn, Michael; D'Huys, Elke; Savin, Daniel Wolf
We have measured the root-mean-square (rms) amplitude of intensity fluctuations, ΔI, in plume and interplume regions of a polar coronal hole. These intensity fluctuations correspond to density fluctuations. Using data from the Sun Watcher using the Active Pixel System detector and Image Processing on the Project for Onboard Autonomy (Proba2), our …
High Spectral Resolution SOFIA/EXES Observations of C2H2 toward Orion IRc2
Le Gal, Romane; Herbst, Eric; Acharyya, Kinsuk +8 more
We present high spectral resolution observations from 12.96 to 13.33 microns toward Orion IRc2 using the mid-infrared spectrograph, Echelon-Cross-Echelle Spectrograph (EXES), at Stratospheric Observatory for Infrared Astronomy (SOFIA). These observations probe the physical and chemical conditions of the Orion hot core, which is sampled by a bright…
Resolving the Inner Arcsecond of the RY Tau Jet with HST
Skinner, Stephen L.; Güdel, Manuel; Audard, Marc +1 more
Faint X-ray emission from hot plasma (T x > 106 K) has been detected extending outward a few arcseconds along the optically delineated jets of some classical T Tauri stars including RY Tau. The mechanism and location where the jets are heated to X-ray temperatures are unknown. We present high spatial resolution Hubble Sp…