Search Publications
X-ray pulsations from the region of the supergiant fast X-ray transient IGR J17544-2619
Hill, A. B.; Bird, A. J.; McBride, V. A. +5 more
Phase-targeted RXTE observations have allowed us to detect a transient 71.49 ± 0.02 s signal that is most likely to be originating from the supergiant fast X-ray transient IGR J17544-2619. The phase-folded light curve shows a possible double-peaked structure with a pulsed flux of ~4.8 × 10-12 erg cm-2 s-1 (3-10 keV…
Principal component analysis of background and sunspot magnetic field variations during solar cycles 21-23
Zharkova, V. V.; Shepherd, S. J.; Zharkov, S. I.
The aim of this paper is to derive the principal components (PCs) in variations of (i) the solar background magnetic field (SBMF), measured by the Wilcox Solar Observatory with low spatial resolution for solar cycles 21-23, and (ii) the sunspot magnetic field (SMF) in cycle 23, obtained by SOHO/MDI. For reduction of the component dimensions, princ…
The Faint-end Slope of the Redshift 5.7 Lyα Luminosity Function
Martin, Crystal L.; Sawicki, Marcin; Dressler, Alan +2 more
Using new Keck DEIMOS spectroscopy, we examine the origin of the steep number counts of ultra-faint emission-line galaxies recently reported by Dressler et al. We confirm six Lyα emitters (LAEs), three of which have significant asymmetric line profiles with prominent wings extending 300-400 km s-1 redward of the peak emission. With thes…
The role of electrons during chorus intensification: Energy source and energy loss
Zong, Q. -G.; Cao, J. B.; Huang, S. Y. +4 more
The role of electrons during the shock-induced chorus intensification observed by THEMIS D on 19 November 2007 is investigated in detail. First, the electrons are accelerated through the local betatron acceleration and radial diffusion, which are primarily in the perpendicular direction and result in the positive anisotropy (T⊥>T
Two short mass-loss events that unveil the binary heart of Minkowski's Butterfly Nebula
Bachiller, R.; Chesneau, O.; Bujarrabal, V. +3 more
Context. Studying the appearance and properties of bipolar winds is critical to understand the stellar evolution from the AGB to the planetary nebula (PN) phase. Many uncertainties exist regarding the presence and role of binary stellar systems, mainly due to the deficit of conclusive observational evidences.
Aims: We investigate the extended…
Modeling Extragalactic Foregrounds and Secondaries for Unbiased Estimation of Cosmological Parameters from Primary Cosmic Microwave Background Anisotropy
Doré, O.; Dudley, J.; Knox, L. +5 more
Using the latest physical modeling and constrained by the most recent data, we develop a phenomenological parameterized model of the contributions to intensity and polarization maps at millimeter wavelengths from external galaxies and Sunyaev-Zeldovich effects. We find such modeling to be necessary for estimation of cosmological parameters from Pl…
The Orbit of Charon is Circular
Buie, Marc W.; Grundy, William M.; Tholen, David J.
We present a detailed analysis of the orbit of Charon where we show its orbit to be circular. This analysis explores the effects of surface albedo variations on the astrometry and the resulting errors in the orbital elements. We present two new epochs of data from the Hubble Space Telescope taken in 2008 and 2010 and combine that with a re-analysi…
Locations of thin liquid water layers on present-day Mars
Kereszturi, Akos; Rivera-Valentin, Edgard G.
CRISM indicates the presence of water ice patches in Richardson crater, located on Mars’ southern polar region at the area of the seasonal ice cap. Numerical simulations suggest that the maximum daytime temperature of the ice at these locations is between 195 and 220 K during local spring. Previous studies suggest that at these temperatures liquid…
Characterizing CO Fourth Positive Emission in Young Circumstellar Disks
Herczeg, Gregory J.; Valenti, Jeff A.; Brown, Alexander +5 more
Carbon monoxide is a commonly used IR/submillimeter tracer of gas in protoplanetary disks. We present an analysis of ultraviolet CO emission in Hubble Space Telescope Cosmic Origins Spectrograph spectra for 12 Classical T Tauri stars (CTTSs). Several ro-vibrational bands of the CO A 1Π-X 1Σ+ (Fourth Positive) elect…
Cosmic Origins Spectrograph Observations of Warm Intervening Gas at z ~ 0.325 toward 3C 263
Savage, Blair D.; Wakker, Bart P.; Narayanan, Anand
We present HST/COS high-S/N observations of the z = 0.32566 multiphase absorber toward 3C 263. The Cosmic Origins Spectrograph (COS) data show absorption from H I (Lyα to Lyθ), O VI, C III, N III, Si III, and C II. The Ne VIII in this absorber is detected in the FUSE spectrum along with O III, O IV, and N IV. The low and intermediate ions are kine…