Search Publications
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 …
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…
Transition Region Downflows in the Impulsive Phase of Solar Flares
Brooks, D. H.; Kurokawa, H.; Kamio, S. +2 more
We present observations of four flares that occurred during coordinated observations between the Coronal Diagnostic Spectrometer (CDS) on board SOHO and the Domeless Solar Telescope (DST) at Hida Observatory. We studied the evolution of relative Doppler velocities in the flare kernels by using He I (3.5×104 K), O V (2.2×105 K…
Observations of Hα Intensity Oscillations in a Flare Ribbon
Gallagher, Peter T.; Mathioudakis, Mihalis; Bloomfield, D. Shaun +6 more
High-cadence Hα blue wing observations of a C9.6 solar flare obtained at Big Bear Solar Observatory using the Rapid Dual Imager are presented. Wavelet and time-distance methods were used to study oscillatory power along the ribbon, finding periods of 40-80 s during the impulsive phase of the flare. A parametric study found statistically significan…
Transient Coronal Holes as Seen in the He I 1083 nm MLSO Observations
de Toma, G.; Holzer, T. E.; Burkepile, J. T. +1 more
Observations from Yohkoh SXT and SOHO EIT have shown that dimming regions often appear on the solar disk near the location of a coronal mass ejection (CME). We now can see brightenings in He I 1083 nm observations made at the Mauna Loa Solar Observatory (MLSO) that form at the same time and are cospatial with the EUV intensity dimmings observed fr…
Recovery of the Orbital Parameters and Pulse Evolution of V0332+53 during a Huge Outburst
Torres, Diego F.; Zhang, Shu; Qu, Jin-Lu +1 more
The high-mass X-ray binary V0332+53 became active at the end of 2004, and the outburst was observed in hard X-rays by RXTE and INTEGRAL. Based on these hard X-ray observations, we measure the orbital parameters by fitting the Doppler-shifted spin periods. The derived orbital period and eccentricity are consistent with those obtained by Stella et a…
Physical Conditions in the Narrow-Line Region of Markarian 3. I. Observational Results
Collins, Nicholas R.; Crenshaw, D. Michael; Bruhweiler, Frederick C. +3 more
We use Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) long-slit low-resolution spectroscopy from 1150 to 10300 Å to study the physical conditions in the narrow-line region (NLR) of the Seyfert 2 galaxy Markarian 3. We find from the He II λ1640/λ4686 line ratio and the Balmer decrement that the extinction within Mrk 3 along the …
Discovery of Photospheric Germanium in Hot DA White Dwarfs
Vennes, Stéphane; Chayer, Pierre; Dupuis, Jean
We report the identification of Ge IV resonance lines in ultraviolet spectra of the hot DA white dwarfs Feige 24, G191-B2B, and GD 246. The lines originate in the stellar photosphere, and we measure low Ge/H abundance ratios ranging between -8.0 and -8.7. We also tentatively identify a resonance line of Sn IV blended with an Fe V line in the spect…
Supernova Remnants in the Magellanic Clouds. VI. The DEM L316 Supernova Remnants
Chu, Y. -H.; Williams, R. M.
The DEM L316 system contains two shells, both with the characteristic signatures of supernova remnants (SNRs). We analyze Chandra and XMM-Newton data for DEM L316, investigating its spatial and spectral X-ray features. Our Chandra observations resolve the structure of the northeastern SNR (shell A) as a bright inner ring and a set of ``arcs'' surr…
Evidence for Gravitational Infall of Matter onto the Supermassive Black Hole in the Quasar PG 1211+143?
Turner, T. J.; Uttley, P.; Kraemer, S. +5 more
We report the detection of redshifted iron Kα absorption lines in the Chandra LETG spectrum of the narrow-line quasar PG 1211+143. The absorption lines are observed at 4.22 and 4.93 keV in the quasar spectrum, corresponding to 4.56 and 5.33 keV in the rest frame of PG 1211+143. From Monte Carlo simulations, the chance probability of both lines bei…