Search Publications
Evolution of Barb Angle and Filament Eruption
Liu, Y.; Li, C.; Zhang, H. Q. +6 more
Hα observations of a quiescent U-shaped filament were obtained at Big Bear Solar Observatory and at Hida Observatory with the Flare Monitoring Telescope. The filament was located in the southern hemisphere on 1998 November 4. We study the evolution of the angle of a barb with respect to the axis of the filament and find the evolution can be divide…
Separating C Stars from Dust in the Central Region of the Seyfert 2 Galaxy NGC 1241
Díaz, Rubén J.; Dottori, Horacio; Carranza, Gustavo +2 more
The Seyfert 2 galaxy NGC 1241 presents a 1.5 kpc large circumnuclear ring (CNR) of star formation embracing a small bar plus leading arms. Those structures are Paα emitters but barely seen in Hα. It also presents stellar trailing arms inside the CNR. Gemini and HST imagery allow the construction of high-resolution (V-H) and (J-Ks) color…
Properties of the Solar Acoustic Source Inferred from Nonadiabatic Oscillation Spectra
Kosovichev, A. G.; Wachter, R.
Severino et al. suggested in 2001 that observed power and cross spectra of medium-degree p-modes in velocity and intensity can be described by splitting the solar background noise into correlated, coherent, and uncoherent components. We account for the nonadiabatic nature of solar oscillations by including the perturbations of the radiative energy…
Dust Morphology of Hidden Broad-Line Region and Non-Hidden Broad-Line Region Seyfert 2 Galaxies
Hwang, Chorng-Yuan; Yu, Po-Chieh
We investigate the nuclear dust properties of hidden broad-line region (HBLR) and non-HBLR Seyfert 2 galaxies. Optical images obtained from the Hubble Space Telescope for a selected sample of HBLR and non-HBLR Seyfert 2 galaxies are fitted with the Galfit package to probe the inner structures of these galaxies within the central 1 kpc regions. Mos…
The Discovery of Oxygen-rich Chromospheres in Two Massive DQ White Dwarfs
Provencal, J. L.; Shipman, H. L.; MacDonald, James
We present HST observations of the massive DQ white dwarfs G227-5 and G35-26 in which we find the first clear evidence of chromospheric activity in cool field white dwarfs. The chromospheric spectra, obtained over a very narrow wavelength range, show lines of the usually expected species O I, N I, C II, and possibly Si III and Mg II. The O I/C II …
The Disk Atmospheres of Three Herbig Ae/Be Stars
Woodward, Charles E.; Temi, Pasquale; Wooden, Diane H. +1 more
We present infrared (IR) spectrophotometry (R~=180) of three Herbig Ae/Be stars surrounded by possible protoplanetary disks: HD 150193, HD 100546, and HD 179218. We construct a mid-IR spectral energy distributions (SEDs) for each object by using 7.6-13.2 µm HIFOGS spectra, 2.4-45 µm spectrophotometry from the Infrared Space Observatory…
Optical Constraints on an X-ray Transient Source in M31
Williams, Benjamin F.; McClintock, Jeffrey E.; Murray, Stephen S. +2 more
We have detected a transient X-ray source in the M31 bulge through a continuing monitoring campaign with the Chandra ACIS-I camera. The source was detected at R.A.=00h42m33.428s+/-0.11", decl.=+41deg17'03.37"+/-0.11" in only a single observation taken 2004 May 23. Fortuitous optical HST ACS imaging of th…
The Impact of Sunspots on the Interpretation of Coronal Observations of the O VI Doublet
Morgan, H.; Habbal, S. Rifai
Due to their high intensity of emission in the O VI λλ1031.9 and 1037.6 lines, even small sunspots on the solar disk can strongly influence the intensity of the radiative scattering component of O VI lines in the corona. Observations of O VI disk spectra show a λ1032/λ1038 line intensity ratio of >2.6 in a sunspot, compared to quiet-disk values…
Hubble Space Telescope STIS Spectroscopy of the Lyα Emission Line in the Central Dominant Galaxies in A426, A1795, and A2597: Constraints on Clouds in the Intracluster Medium
Koekemoer, Anton M.; Baum, Stefi A.; Mack, Jennifer +2 more
We report on HST STIS spectra of the Lyα emission in the central dominant galaxies in three rich clusters of galaxies. We find evidence for a population of clouds in the intracluster medium. We detect 10 Lyα absorption systems toward the nucleus of NGC 1275 with columns of N(HI)~1012-1014 cm-2. These columns would …
A Chandra Observation of the Diffuse Emission Centered on the Low-Mass X-Ray Binary 4U 1755-33
McClintock, Jeffrey E.; Miller, Jon M.; Murray, Stephen S. +1 more
We present an analysis of a Chandra observation of the field surrounding the low-mass X-ray binary 4U 1755-33, which has been in quiescence since 1996. In 2003, Angelini & White reported the appearance of a narrow 7'-long jetlike feature centered on the position of 4U 1755-33 using the XMM-Newton telescope. Although the source and jet are not …