Search Publications
Galactic Globular and Open Clusters in the Sloan Digital Sky Survey. II. Test of Theoretical Stellar Isochrones
Beers, Timothy C.; Masseron, Thomas; Pinsonneault, Marc H. +6 more
We perform an extensive test of theoretical stellar models for main-sequence (MS) stars in ugriz, using cluster fiducial sequences obtained in the previous paper of this series. We generate a set of isochrones using the Yale Rotating Evolutionary Code with updated input physics, and derive magnitudes and colors in ugriz from MARCS model atmosphere…
Statistical Assessment of Photospheric Magnetic Features in Imminent Solar Flare Predictions
Jing, Ju; Wang, Haimin; Yurchyshyn, Vasyl +3 more
In this study we use the ordinal logistic regression method to establish a prediction model, which estimates the probability for each solar active region to produce X-, M-, or C-class flares during the next 1-day time period. The three predictive parameters are (1) the total unsigned magnetic flux Tflux, which is a measure of an active …
AGN-starburst connection in NGC7582: Gemini near-infrared spectrograph integral field unit observations
Storchi-Bergmann, Thaisa; Riffel, Rogemar A.; Winge, Cláudia +1 more
We analyse two-dimensional near-infrared K-band spectra from the inner 660 × 315pc2 of the Seyfert galaxy NGC7582 obtained with the Gemini near-infrared spectrograph integral field unit at a spatial resolution of ~50pc and spectral resolving power R ~ 5900. The nucleus harbours an unresolved source well reproduced by a blackbody of temp…
An Intriguing Chromospheric Jet Observed by Hinode: Fine Structure Kinematics and Evidence of Unwinding Twists
Liu, Wei; Berger, Thomas E.; Tarbell, Theodore D. +1 more
We report a chromospheric jet lasting for more than 1 hr observed by the Hinode Solar Optical Telescope in unprecedented detail. The ejection occurred in three episodes separated by 12-14 minutes, with the amount and velocity of material decreasing with time. The upward velocities range from 438 to 33 km\nolimits s\nolimits ^{-1}, while the downwa…
High-Redshift Starbursting Dwarf Galaxies Revealed by γ-Ray Burst Afterglows
Pettini, Max; Chen, Hsiao-Wen; Perley, Daniel A. +7 more
We present a study of 15 long-duration γ-ray burst (GRB) host galaxies at z > 2. The GRBs are selected with available early-time afterglow spectra in order to compare interstellar medium (ISM) absorption-line properties with stellar properties of the host galaxies. In addition to five previously studied hosts, we consider new detections for the…
Evidence for an Intermediate-mass Black Hole in NGC 5408 X-1
Mushotzky, Richard F.; Strohmayer, Tod E.
We report the discovery with XMM-Newton of correlated spectral and timing behavior in the ultraluminous X-ray source (ULX) NGC 5408 X-1. An ≈100 ks pointing with XMM/Newton obtained in 2008 January reveals a strong 10 mHz quasi-periodic oscillation (QPO) in the >1 keV flux, as well as flat-topped, band-limited noise breaking to a power law. The…
Discovery of the Largest Known Lensed Images Formed by a Critically Convergent Lensing Cluster
Broadhurst, Tom; Zitrin, Adi
We identify the largest known lensed images of a single spiral galaxy, lying close to the center of the distant cluster MACS J1149.5+2223 (z = 0.544). These images cover a total area of ≃ 150'' and are magnified ≃200 times. Unusually, there is very little image distortion, implying that the central mass distribution is almost uniform over a wide a…
Propagating Slow Magnetoacoustic Waves in Coronal Loops Observed by Hinode/EIS
Wang, T. J.; Davila, J. M.; Ofman, L.
We present the first Hinode/EUV Imaging Spectrometer observations of 5 minute quasi-periodic oscillations detected in a transition-region line (He II) and five coronal lines (Fe X, Fe XII, Fe XIII, Fe XIV, and Fe XV) at the footpoint of a coronal loop. The oscillations exist throughout the whole observation, characterized by a series of wave packe…
The interstellar Ca II distance scale
Krełowski, J.; Galazutdinov, G. A.; Strobel, A. +1 more
Aims: We attempt to extend the relation between the strengths of the interstellar Ca II lines and the distances to early-type stars to objects beyond 1 kiloparsec, with the line saturation taken into account.
Methods: We measure the Ca II K and Ca II H equivalent widths, and compute Ca II column densities for 262 lines of sight towards early-t…
The Extension of the Transition Temperature Plasma into the Lower Galactic Halo
Savage, Blair D.; Wakker, Bart P.
Column densities for H I, Al III, Si IV, C IV, and O VI toward 109 stars and 30 extragalactic objects have been assembled to study the extensions of these species away from the Galactic plane into the Galactic halo. H I and Al III mostly trace the warm neutral and warm ionized medium, respectively, while Si IV, C IV, and O VI trace a combination o…