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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…
Host galaxies and black hole masses of low- and high-luminosity radio-loud active nuclei
Treves, Aldo; Falomo, Renato; Carangelo, Nicoletta
We investigate the host galaxy luminosities of BL Lac objects (BLLs) and radio-loud quasars (RLQs) at z < 0.5, imaged with the Hubble Space Telescope (HST). From a homogeneous treatment of the data, we construct the host-galaxy luminosity functions (HGLFs) and find that RLQ hosts are ~0.5 mag brighter than those of BLLs: <MR>
Properties of high-latitude CME-driven disturbances during Ulysses second northern polar passage
St. Cyr, O. C.; Reisenfeld, D. B.; Forsyth, R. J. +2 more
Ulysses observed five coronal mass ejections (CMEs) and their associated disturbances while the spacecraft was immersed in the polar coronal hole (CH) flow above 70° N in late 2001. Of these CMEs, two were very fast (>850 km s-1) driving strong shocks in the wind ahead, and two others were over-expanding. The two fast CMEs were obser…
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 …
Discovery of narrow X-ray absorption features from the low-mass X-ray binary X 1254-690 with XMM-Newton
Parmar, A. N.; Boirin, L.
We report on two XMM-Newton observations of the low-mass X-ray binary X 1254-690. During an XMM-Newton observation of the low-mass X-ray binary in 2001 January a deep X-ray dip was seen while in a second observation one year later no dips were evident. The 0.5-10 keV EPIC spectra from both non-dipping intervals are very similar being modeled by a …
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 …
Are stellar coronae optically thin in X-rays?. A systematic investigation of opacity effects
Schmitt, J. H. M. M.; Mewe, R.; Audard, M. +2 more
The relevance of resonant scattering in the solar corona has always been discussed controversially. Ratios of emission lines from identical ions but different oscillator strengths have been used in order to estimate damping of resonance lines due to possible resonant scattering, i.e., absorption by photo-excitation and re-emission out of the line …
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…
Saturn's wayward shepherds: the peregrinations of Prometheus and Pandora
French, Richard G.; Dones, Luke; Lissauer, Jack J. +1 more
Saturn's narrow F ring is flanked by two nearby small satellites, Prometheus and Pandora, discovered in Voyager images taken in 1980 and 1981 (Synnott et al., 1983, Icarus 53, 156-158). Observations with the Hubble Space Telescope (HST) during the ring plane crossings (RPX) of 1995 led to the unexpected finding that Prometheus was ∼19° behind its …