Search Publications
Migration of Zonal Flows Detected Using Michelson Doppler Imager F-Mode Frequency Splittings
Schou, J.
The small-scale zonal flows in the outer part of the solar convection zone were recently detected by Kosovichev & Schou using f-mode frequency splittings. Results from five 72 day time series (Schou et al.) show a slight drift of the pattern toward the equator in a manner similar to that seen in the so-called torsional oscillation observed usi…
Comparison of Two Coronal Mass Ejections Observed by EIT and LASCO with a Model of an Erupting Magnetic Flux Rope
Chen, J.; Howard, R. A.; Wood, B. E. +3 more
We present observations of two coronal mass ejections (CMEs) observed by the LASCO and EIT instruments on board the Solar and Heliospheric Observatory. One was observed on 1997 April 30 and the other on 1997 February 23. The latter CME is accompanied by a spectacular prominence eruption and reaches velocities of about 900 km s-1, while …
Carbon in Spiral Galaxies from Hubble Space Telescope Spectroscopy
Terlevich, E.; Garnett, D. R.; Skillman, E. D. +5 more
We present measurements of the gas-phase abundance ratio C/O in six H II regions in the spiral galaxies M101 and NGC 2403, based on ultraviolet spectroscopy using the Faint Object Spectrograph on the Hubble Space Telescope. The ratios of C to O increase systematically with O/H in both galaxies, from log C/O~-0.8 at log O/H=-4.0 to log C/O~-0.1 at …
Blue Straggler Stars: The Spectacular Population in M80
Ferraro, Francesco R.; Paltrinieri, Barbara; Dorman, Ben +1 more
Using Hubble Space Telescope WFPC2 observations in two ultraviolet (UV) filters (F225W and F336W) of the central region of the high-density Galactic globular cluster (GGC) M80, we have identified 305 blue straggler stars (BSS), which represents the largest and most concentrated population of BSS ever observed in a GGC. We also identify the largest…
The Double Nucleus and Central Black Hole of M31
Kormendy, John; Bender, Ralf
New spectroscopy of M31 supports Tremaine's model in which both nuclei are parts of a single eccentric disk of stars orbiting the black hole (BH). The kinematics and Hubble Space Telescope photometry are used to measure the offset of the BH from the center of mass. This confirms that the BH mass is ~3×107 Msolar by a techniqu…
Discovery of an Extremely Young Accreting Protostar in Taurus
Motte, F.; André, P.; Bacmann, A.
We report the discovery of a new, very young accreting class 0 protostar in the southern part of the Taurus molecular cloud. This object, designated by IRAM 04191+1522, coincides with a cold (T~12 K) dust continuum condensation found at 1.3 mm with the IRAM 30 m telescope ~1' southwest of the class I infrared source IRAS 04191+1523. Although IRAM …
A Candidate Substellar Companion to CD -33°7795 (TWA 5)
Schneider, Glenn; Hines, Dean C.; Terrile, Richard J. +12 more
We present the discovery of a candidate substellar object in a survey of young stars in the solar vicinity using the sensitivity and spatial resolution afforded by the NICMOS coronagraph on the Hubble Space Telescope. The H=12.1 mag object was discovered approximately 2" from the TW Hydrae association member CD -33°7795 (TWA 5), and the photometry…
Hubble Space Telescope Imaging of the CFRS and LDSS Redshift Surveys. III. Field Elliptical Galaxies at 0.2<z<1.0
Brinchmann, Jarle; Broadhurst, Tom; Glazebrook, K. +9 more
Two-dimensional surface photometry has been performed on a magnitude-limited sample of 46 field galaxies that are classified as ellipticals based on two-dimensional fitting of their luminosity profiles using Hubble Space Telescope imaging. These galaxies are described well by a de Vaucouleurs R1/4 profile. The sample was selected from t…
Semiempirical Two-dimensional MagnetoHydrodynamic Model of the Solar Corona and Interplanetary Medium
Guhathakurta, Madhulika; Sittler, Edward C., Jr.
We have developed a two-dimensional semiempirical MHD model of the solar corona and solar wind. The model uses empirically derived electron density profiles from white-light coronagraph data measured during the Skylab period and an empirically derived model of the magnetic field which is fitted to observed streamer topologies, which also come from…
Dust in an Extremely Metal-Poor Galaxy: Mid-infrared Observations ofSBS 0335-052
Sauvage, Marc; Madden, Suzanne; Thuan, Trinh X.
The metal-deficient (Z=Zsolar/41) blue compact dwarf galaxy SBS 0335-052 was observed with ISOCAM between 5 and 17 µm. With an L12µm/LB ratio of 2.15, the galaxy is unexpectedly bright in the mid-infrared for such a low-metallicity object. The mid-infrared spectrum shows no sign of the unidentified infr…