Search Publications
Effects of Solar Magnetic Activity on the Charge States of Minor Ions of Solar Wind
Wurz, Peter; Klecker, Berndt; Wang, Xuyu
We present an investigation of the effects of solar magnetic activity on the charge states of minor ions (Fe, Si, Mg, Ne, O, C) in the solar wind using ACE solar wind data, the "current sheet source surface" (CSSS) model of the corona, and SOHO MDI data during the 23rd solar cycle. We find that the mean charge states indicate a clear trend of incr…
Radio Continuum Observations of the Candidate Supermassive Black Hole in the Dwarf Elliptical VCC 128
Pasquali, Anna; Seth, Anil; Debattista, Victor P. +4 more
The presence of black holes (BHs) at the centers of dwarf elliptical galaxies (dEs) has been argued both theoretically and observationally. Using archival HST WFPC2 data, we found the Virgo cluster dwarf elliptical galaxy VCC 128 to harbor a binary nucleus, a feature that is usually interpreted as the observable signature of a stellar disk orbitin…
Time-Resolved FUSE Spectroscopy of the LMC WC + O Binaries Br 22 and Br 32
Moffat, Anthony F. J.; St-Louis, Nicole; Marchenko, Sergey V. +1 more
Using the Far Ultraviolet Spectroscopic Explorer satellite, we obtained series of spectra for two of the three known WC + O binaries in the LMC, Br 22, and Br 32 (HD 36521). Compared to Br 22, we detect a higher ratio of C IV to He II lines in Br 32, which could indicate a more advanced evolutionary stage for the latter. The orbit of the O star in…
Ice Emission and the Redshifts of Submillimeter Sources
Maloney, P. R.; Imanishi, M.; Dudley, C. C.
Observations at submillimeter wavelengths have revealed a population of sources thought to be at relatively large redshifts. The position of the 850 µm passband on the Rayleigh-Jeans portion of the Planck function leads to a maximum redshift estimate of z ~ 4.5, since sources will not retain their redshift-independent brightness close to the…
Erratum: "Probing Elemental Abundances in SNR 1987A using XMM-Newton" (ApJ, 676, 361 [2008])
Haberl, Frank; Heng, Kevin; Hasinger, Günther +1 more
Could We Have Forecast "The Day the Solar Wind Died"?
McIntosh, Scott W.; Leamon, Robert J.
In 1999 May an interval of unusually slow (<300 km s-1) and rarefied (<1 cm-3) solar wind was observed upstream of Earth by the ACE spacecraft. The event has been dubbed "The Day the Solar Wind Died." We apply our solar wind forecast model to the interval in question, to ask whether we could have predicted the phenomeno…
Star Formation in AEGIS Field Galaxies since z=1.1: The Dominance of Gradually Declining Star Formation, and the Main Sequence of Star-forming Galaxies
Le Floc'h, E.; Barmby, P.; Cooper, M. C. +26 more
We analyze star formation (SF) as a function of stellar mass (M*) and redshift z in the All-Wavelength Extended Groth Strip International Survey. For 2905 field galaxies, complete to 1010(1010.8) Msolar at z<0.7(1), with Keck spectroscopic redshifts out to z=1.1, we compile SF rates (SFRs) from emissi…
New Hubble Space Telescope Discoveries of Type Ia Supernovae at z >= 1: Narrowing Constraints on the Early Behavior of Dark Energy
Dickinson, Mark; Ferguson, Henry C.; Casertano, Stefano +18 more
We have discovered 21 new Type Ia supernovae (SNe Ia) with the Hubble Space Telescope (HST) and have used them to trace the history of cosmic expansion over the last 10 billion yr. These objects, which include 13 spectroscopically confirmed SNe Ia at z>=1, were discovered during 14 epochs of reimaging of the GOODS fields North and South over 2 …
Galaxy Luminosity Functions to z~1 from DEEP2 and COMBO-17: Implications for Red Galaxy Formation
Im, M.; Cooper, M. C.; Wolf, C. +31 more
The DEEP2 and COMBO-17 surveys are compared to study luminosity functions of red and blue galaxies to z~1. The two surveys have different methods and sensitivities, but nevertheless results agree. After z~1, M*B has dimmed by 1.2-1.3 mag for all colors of galaxies, φ* for blue galaxies has hardly changed, and φ
The Calibration of Mid-Infrared Star Formation Rate Indicators
Moustakas, J.; Roussel, H.; Leitherer, C. +25 more
With the goal of investigating the degree to which the MIR emission traces the SFR, we analyze Spitzer 8 and 24 µm data of star-forming regions in a sample of 33 nearby galaxies with available HST NICMOS images in the Paα (1.8756 µm) emission line. The galaxies are drawn from the SINGS sample and cover a range of morphologies and a fac…