Search Publications
The Long-Term Evolution of AR 7978: The Scalings of the Coronal Plasma Parameters with the Mean Photospheric Magnetic Field
Klimchuk, J. A.; Mandrini, C. H.; van Driel-Gesztelyi, L. +2 more
We analyze the evolution of the fluxes observed in X-rays and correlate them with the magnetic flux density in active region (AR) NOAA 7978 from its birth throughout its decay, for five solar rotations. We use Solar and Heliospheric Observatory Michelson Doppler Imager (MDI) data, together with Yohkoh Soft X-Ray Telescope (SXT) and Yohkoh Bragg Cr…
Improved Astrometry and Photometry for the Luyten Catalog. I. Bright Stars
Gould, Andrew; Salim, Samir
We outline the construction of a refined version of the New Luyten Two-Tenths (NLTT) catalog of high proper motion stars, which will contain improved astrometry and photometry for the vast majority of the ~59,000 stars in NLTT. The bright end is constructed by matching NLTT stars to Hipparcos, Tycho-2, and Starnet; the faint end by matching to USN…
Models of the Morphology, Kinematics, and Star Formation History of the Prototypical Collisional Starburst System NGC 7714/7715 = ARP 284
Struck, Curtis; Smith, Beverly J.
We present new N-body, hydrodynamical simulations of the interaction between the starburst galaxy NGC 7714 and its poststarburst companion NGC 7715, focusing on the formation of the collisional features, including (1) the gas-rich star-forming bridge, (2) the large gaseous loop (and stellar tails) to the west of the system, (3) the very extended H…
Global Parameter and Helioseismic Tests of Solar Variability Models
Guenther, D. B.; Demarque, P.; Basu, S. +3 more
We construct models of the structure and evolution of the Sun which include variable magnetic fields and turbulence. The magnetic effects are (1) magnetic pressure, (2) magnetic energy, and (3) magnetic modulation to turbulence. The effects of turbulence are (1) turbulent pressure, (2) turbulent kinetic energy, and (3) turbulent inhibition of the …
Flux Rope Acceleration and Enhanced Magnetic Reconnection Rate
Moon, Y. -J.; Choe, G. S.; Cheng, C. Z. +1 more
A physical mechanism of flares has emerged from our 2.5-dimensional resistive MHD simulations of the dynamical evolution of current sheet formation and magnetic reconnection and flux rope acceleration subject to the continuous, slow increase of magnetic shear in the arcade. With anomalous nonuniform resistivity in the current sheet the simulation …
Post-Asymptotic Giant Branch Evolution in the Large Magellanic Cloud: A Study of the Central Stars of Planetary Nebulae
Villaver, Eva; Shaw, Richard A.; Stanghellini, Letizia
We present medium- and broadband Hubble Space Telescope (HST) photometry of a sample of 35 central stars (CSs) of planetary nebulae (PNs) in the Large Magellanic Cloud (LMC). The observations were made with the Wide Field Planetary Camera 2 (WFPC2) and Space Telescope Imaging Spectrograph instruments on board the HST. By observing LMC objects, our…
A Luminous Recurrent Supersoft X-Ray Source in NGC 300
Kong, A. K. H.; Di Stefano, R.
We report the results of XMM-Newton observations for an especially luminous supersoft X-ray source (SSS) with a bolometric luminosity of 1039 ergs s-1 in the spiral galaxy NGC 300. The source was detected as an SSS in 1992 and disappeared in subsequent X-ray observations. The source was active again during recent XMM-Newton o…
The First Detection of Spatially Resolved Mid-Infrared Scattered Light from a Protoplanetary Disk
Duchêne, G.; Ghez, A. M.; McCabe, C.
We report spatially resolved 11.8 µm images, obtained at the W. M. Keck 10 m telescope, of the protoplanetary disk around the pre-main-sequence star HK Tau B. The mid-infrared morphology and astrometry of HK Tau B with respect to HK Tau A indicate that the flux observed in the mid-infrared from HK Tau B has been scattered off the upper surfa…
Far-Ultraviolet Emission from Elliptical Galaxies at z = 0.33
Ferguson, Henry C.; Brown, Thomas M.; Rich, R. Michael +4 more
We present far-UV images of the rich galaxy cluster ZwCl 1358.1+6245, taken with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope (HST). When combined with archival HST observations, our data provide a measurement of the UV-to-optical flux ratio in eight early-type galaxies at z=0.33. Because the UV flux originates in a…
A Far-Ultraviolet Survey of 47 Tucanae. II. The Long-Period Cataclysmic Variable AKO 9
Zurek, David R.; Gilliland, Ronald L.; Shara, Michael M. +2 more
We present time-resolved far-ultraviolet (FUV) spectroscopy and photometry of the 1.1 day eclipsing binary system AKO 9 in the globular cluster 47 Tucanae. The FUV spectrum of AKO 9 is blue and exhibits prominent C IV and H II emission lines. The spectrum broadly resembles that of long-period cataclysmic variables (CVs) in the Galactic field. Comb…