Search Publications
Keck Laser Guide Star Adaptive Optics Monitoring of 2MASS J15344984-2952274AB: First Dynamical Mass Determination of a Binary T Dwarf
Dupuy, Trent J.; Ireland, Michael J.; Liu, Michael C.
We present multiepoch imaging of the T5.0+T5.5 binary 2MASS J15344984-2952274AB obtained with the Keck laser guide star adaptive optics system. Combined with archival HST imaging, our total data span ~50% of the orbital period. We use a Markov chain Monte Carlo analysis to determine a period of 15.1+ 2.3-1.6 yr and a total ma…
Characterizing the Nonthermal Emission of Cassiopeia A
Vink, J.; Helder, E. A.
We report on our analysis of the 1 Ms Chandra observation of the supernova remnant Cas A in order to localize, characterize, and quantify the nonthermal X-ray emission. More specifically, we investigated whether the X-ray synchrotron emission from the inside of the remnant is from the outward shock, but projected toward the inner ring, or from the…
Observations of Active Region Loops with the EUV Imaging Spectrometer on Hinode
Warren, Harry P.; Doschek, George A.; Ugarte-Urra, Ignacio +2 more
Previous solar observations have shown that coronal loops near 1 MK are difficult to reconcile with simple heating models. These loops have lifetimes that are long relative to a radiative cooling time, suggesting quasi-steady heating. The electron densities in these loops, however, are too high to be consistent with thermodynamic equilibrium. Mode…
Molecular Gas in a Submillimeter Galaxy at z = 4.5: Evidence for a Major Merger at 1 Billion Years after the Big Bang
Smolčić, V.; Taniguchi, Y.; Yun, M. S. +8 more
We report the detection of CO molecular line emission in the z = 4.5 millimeter-detected galaxy COSMOS J100054+023436 (hereafter J1000+0234) using the IRAM Plateau de Bure interferometer (PdBI) and NRAO's Very Large Array (VLA). The 12CO(4-3) line as observed with PdBI has a full line width of ~1000 km s-1, an integrated line…
A Hubble and Spitzer Space Telescope Survey for Gravitationally Lensed Galaxies: Further Evidence for a Significant Population of Low-Luminosity Galaxies beyond z = 7
Richard, Johan; Smith, Graham P.; Stark, Daniel P. +4 more
We present the results of a systematic search for gravitationally lensed continuum Lyman break "dropouts" beyond a redshift 7 conducted via very deep imaging through six foreground clusters undertaken with the Hubble and Spitzer space telescopes. The survey has yielded 10 z-band and two J-band dropout candidates to photometric limits of J110<…
Formation of Solar Magnetic Flux Tubes with Kilogauss Field Strength Induced by Convective Instability
Tsuneta, Saku; Shimizu, Toshifumi; Lites, Bruce W. +11 more
Convective instability has been a mechanism used to explain the formation of solar photospheric flux tubes with kG field strength. However, the turbulence of the Earth's atmosphere has prevented ground-based observers from examining the hypothesis with precise polarimetric measurement on the subarcsecond scale flux tubes. Here we discuss observati…
Evaluating the Performance of Solar Flare Forecasting Methods
Leka, K. D.; Barnes, G.
The number of published approaches to solar flare forecasting using photospheric magnetic field observations has proliferated recently, with widely varying claims about how well each works. As different analysis techniques and data sets were used, it is essentially impossible to directly compare the results. A systematic comparison is presented he…
PAH Emission from Herbig Ae/Be Stars
Watson, D. M.; Chen, C. H.; Sargent, B. +10 more
We present spectra of a sample of Herbig Ae and Be (HAeBe) stars obtained with the Infrared Spectrograph on Spitzer. All but one of the Herbig stars show emission from PAHs, and seven of the spectra show PAH emission, but no silicate emission at 10 µm. The central wavelengths of the 6.2, 7.7-8.2, and 11.3 µm emission features decrease …
Discovery of the Radio and X-Ray Counterpart of TeV γ-Ray Source HESS J1731-347
Leahy, D. A.; Jiang, B.; Haverkorn, M. +1 more
We discover a faint shell-type radio and X-ray source, G353.6-0.7, associated with HESS J1731-347. G353.6-0.7 is likely an old supernova remnant (SNR), based on radio (0.8, 1.4, and 5 GHz), infrared (8 µm from the GLIMPSE Legacy Project and 21 µm from the Midcourse Space Experiment), and X-ray (0.1-2.4 keV from the ROSAT survey and 5-2…
Mid-Infrared Spectroscopy of Lensed Galaxies at 1 < z < 3: The Nature of Sources Near the MIPS Confusion Limit
Kneib, J. -P.; Rigby, J. R.; Papovich, C. +10 more
We present Spitzer IRS mid-infrared spectra for 15 gravitationally lensed, 24 µm-selected galaxies, and combine the results with four additional very faint galaxies with IRS spectra in the literature. The median intrinsic 24 µm flux density of the sample is 130 µJy, enabling a systematic survey of the spectral properties of the v…