Search Publications
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…
A Possible Detection of M31* with Chandra
Williams, Benjamin F.; Kong, Albert K. H.; Barmby, Pauline +5 more
Two independent sets of Chandra and HST images of the nuclear region of M31 allow registration of X-ray and optical images to ~0.1". This registration shows that none of the bright (~1037 ergs s-1) X-ray sources near the nucleus is coincident with the central supermassive black hole, M31*. A 50 ks Chandra HRC image shows 2.5 …
Deep Near-Infrared Imaging and Photometry of the Antennae Galaxies with WIRC
Hayward, T. L.; Houck, J. R.; Brandl, B. R. +6 more
We present deep near-infrared images of the Antennae galaxies, taken with the Palomar Wide-Field Infrared Camera (WIRC). The images cover a 4.33 arcmin ×4.33 arcmin (24.7×24.7 kpc) area around the galaxy interaction zone. We derive J- and Ks-band photometric fluxes for 172 infrared star clusters and discuss details of the two galactic n…
Effect of a Converging Flow at the Streamer Cusp on the Genesis of the Slow Solar Wind
Lapenta, Giovanni; Knoll, D. A.
The observation by the Large Angle and Spectrometric Coronagraph (LASCO) instrument on the Solar and Heliospheric Observatory of blobs of plasma generated near the cusp region of the streamer belt has sparked the hope of gaining new insight into the genesis of the slow solar wind. The observations suggest that open and closed field lines reconnect…
A Statistical Study of the Correlation between Magnetic Helicity Injection and Soft X-Ray Activity in Solar Active Regions
Kusano, K.; Sakurai, T.; Yokoyama, T. +1 more
The correlation between magnetic helicity injection across the photosphere and soft X-ray activity in the solar corona is statistically investigated for seven active regions appearing in the years 1997-2000. The magnetic helicity flux into the solar corona is analyzed by the induction equation method, using magnetograms observed by the Michelson D…