Search Publications
In Search of the Solar Cycle Variations of p-Mode Frequencies Generated by Perturbations in the Solar Interior
Chou, Dean-Yi; Serebryanskiy, Alexander
Observations show that the solar p-mode frequencies change with the solar cycle. The horizontal phase velocity dependence of the relative frequency change, scaled by mode mass, provides depth information on the perturbation in the solar interior. Our model study suggests that variations of smoothed, scaled relative frequency change versus horizont…
Keck HIRES Spectroscopy of Four Candidate Solar Twins
King, Jeremy R.; Boesgaard, Ann M.; Schuler, Simon C.
We use high signal-to-noise ratio, high-resolution Keck HIRES spectroscopy of four solar twin candidates (HIP 71813, 76114, 77718, and 78399) pulled from our Hipparcos-based Ca II H and K survey to carry out parameter and abundance analyses of these objects. Our spectroscopic Teff estimates are ~100 K hotter than the photometric scale of the recen…
O/H in the Local Bubble
Chayer, Pierre; Dupuis, Jean; Oliveira, Cristina M. +1 more
We present new measurements of the oxygen gas-phase abundance along four sight lines probing gas inside the Local Bubble, using data obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) and the Hubble Space Telescope (HST). Combining these with seven previously published N(O I) and N(H I) measurements, we determine a mean O/H ratio for …
Titan interaction with Saturn's magnetosphere: Voyager 1 results revisited
Johnson, R. E.; Hartle, R. E.; Sittler, E. C. +3 more
We investigate the details of Titan's interaction with Saturn's magnetosphere, which includes formation and location of an ionopause, mass loading via ion pickup, and the effects of finite gyroradii. We present new interpretations of the Voyager 1 plasma instrument measurements not addressed by Hartle et al. (1982). Pickup ions H+ and H…
Discovery of the INTEGRAL X/γ-ray transient IGR J00291+5934: A Comptonised accreting ms pulsar?
Rodriguez, J.; Walter, R.; Eckert, D. +8 more
We report the discovery of a high-energy transient with the IBIS/ISGRI detector on board the INTEGRAL observatory. The source, namely
A survey of flux transfer events observed by Cluster during strongly northward IMF
Fazakerley, A. N.; Owen, C. J.; Lucek, E. A. +1 more
During Cluster's annual dayside seasons (November-June) the four spacecraft cross the magnetopause at high latitudes near local noon, and at lower latitudes further along the flanks. During these crossings, observations of flux transfer events (FTEs), a signature of transient or variable-rate magnetopause merging, are often made. We have compiled …
XMM-Newton observations of two transient millisecond X-ray pulsars in quiescence
Campana, S.; Stella, L.; Israel, G. L. +1 more
We report on XMM-Newton observations of two X-ray transient millisecond pulsars (XRTMSPs). We detected XTE J0929-314 with an unabsorbed luminosity of ∼ 7× 1031 erg s-1 (0.5-10 keV) at a fiducial distance of 10 kpc. The quiescent spectrum is consistent with a simple power law spectrum. The upper limit on the flux from a coolin…
Cool Customers in the Stellar Graveyard. II. Limits to Substellar Objects around Nearby DAZ White Dwarfs
Debes, John H.; Woodgate, Bruce E.; Sigurdsson, Steinn
Results from a concerted Hubble Space Telescope (HST) survey of nearby white dwarfs for substellar objects are presented. A total of seven DAZ white dwarfs with distances of <50 pc had high-contrast and high spatial resolution NICMOS coronagraphic images taken to search for candidate substellar objects at separations <~10" away. Limits to un…
The Far-Ultraviolet Spectrum of Z Camelopardalis in Quiescence and Standstill
Long, Knox S.; Drew, Janet E.; Froning, Cynthia S. +1 more
We have obtained FUSE (905-1187 Å) spectra of the nonmagnetic cataclysmic variable Z Cam during a period of quiescence. The spectrum resembles that of a hot (57,000 K) metal-enriched white dwarf. A high effective temperature is consistent with the expectation that dwarf nova systems that show standstills, as Z Cam does, have higher than normal tim…
The late merging phase of a galaxy cluster: XMM EPIC observations of A 3266
Pratt, G. W.; Belsole, E.; Sauvageot, J. L.
We present a mosaic of five XMM-Newton observations of the nearby (z=0.0594) merging galaxy cluster Abell 3266. We use the spectro-imaging capabilities of XMM-Newton to build precise (projected) temperature, entropy, pressure and Fe abundance maps. The temperature map exhibits a curved, large-scale hot region, associated with elevated entropy leve…