Search Publications
A Precise Proper Motion for the Crab Pulsar, and the Difficulty of Testing Spin-Kick Alignment for Young Neutron Stars
Anderson, J.; Chatterjee, S.; Kaplan, D. L. +1 more
We present a detailed analysis of archival Hubble Space Telescope data that we use to measure the proper motion of the Crab pulsar, with the primary goal of comparing the direction of its proper motion with the projected axis of its pulsar wind nebula (the projected spin axis of the pulsar). We demonstrate that our measurement, using 47 observatio…
Effects of Dust Geometry in Lyα Galaxies at z = 4.4
Finkelstein, Steven L.; Malhotra, Sangeeta; Grogin, Norman +2 more
Equivalent widths (EWs) observed in high-redshift Lyα galaxies could be stronger than the EW intrinsic to the stellar population if dust is present residing in clumps in the interstellar medium (ISM). In this scenario, continuum photons could be extinguished, while the Lyα photons would be resonantly scattered by the clumps, eventually escaping th…
Hinode, TRACE, SOHO, and Ground-based Observations of a Quiescent Prominence
Heinzel, P.; Anzer, U.; Golub, L. +10 more
A quiescent prominence was observed by several instruments on 2007 April 25. The temporal evolution was recorded in Hα by the Hinode SOT, in X-rays by the Hinode XRT, and in the 195 Å channel by TRACE. Moreover, ground-based observatories (GBOs) provided calibrated Hα intensities. Simultaneous extreme-UV (EUV) data were also taken by the Hinode EI…
A Population of Massive and Evolved Galaxies at z gtrsim 5
Panagia, N.; Dickinson, M.; Ferguson, H. C. +4 more
We report results from a search for massive and evolved galaxies at z gtrsim 5 in the GOODS southern field. Combining HST ACS, VLT ISAAC, and Spitzer IRAC broadband photometric data, we develop a color selection technique to identify candidates for being evolved galaxies at high redshifts. The color selection is primarily based on locating the Bal…
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…