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Luminosity Functions for Globular Clusters
D'Antona, Francesca; Ventura, Paolo; Silvestri, Fabio +1 more
We present theoretical mass-luminosity relations and luminosity functions (LFs) for globular cluster stars, from luminosities above the horizontal branch down to the minimum luminosity of hydrogen-burning stars. The LFs are available for metal mass fraction Z from Z = 10-4 to Z = 4 × 10-3, in the Johnson V band and in the Bes…
The Geometric Spreading of Coronal Plumes and Coronal Holes
Wu, S. T.; Poletto, G.; Suess, S. T. +2 more
The geometric spreading in plumes and in the interplume region in coronal holes is calculated, using analytic and numerical theoretical models, between 1.0 and 5.0 R⊙. We apply a two-scale approximation that permits the rapid local spreading at the base of plumes (fl) to be evaluated separately from the global spreading (f
High-Velocity Lyα Emission from SNR 1987A
Pun, Chun S. J.; Sonneborn, George; Borkowski, Kazimierz J. +2 more
The high-velocity Lyα emission from SN 1987A observed with the Space Telescope Imaging Spectrograph (STIS) evidently comes from a reverse shock formed where the outer envelope of SN 1987A strikes ionized gas inside the inner circumstellar ring. The observations can be explained by a simple kinematic model, in which the Lyα emission comes from hydr…
Global Context of the Galileo-E6 Observations of Jupiter's White Ovals
Simon, Amy A.; Belton, Michael J. S.; Gierasch, Peter J. +3 more
Galileo Solid State Imaging (SSI) data taken during the E6 orbit on February 19, 1997 offer a brief, high-resolution glimpse of Jupiter's White Ovals. These data can be used to infer relative cloud heights and systematic rotations over a small area of latitude and longitude (approximately 20° by 30°) around the White Ovals. To fully understand the…
First-year continuous solar EUV irradiance from SOHO by the CELIAS/SEM during 1996 solar minimum
Galvin, A. B.; Judge, D. L.; Ogawa, H. S. +2 more
The CELIAS/SEM photodiode spectrometer aboard SOHO continuously monitors the full-disk EUV solar irradiance in an 8-nm wavelength band centered at 30.4 nm (first order), and in a broad wavelength band between 0.1 and 77 nm (central order). We present the absolute solar EUV irradiances for the 1996 solar EUV minimum year at 1 AU. The uncertainty in…
Monitoring Lyα Emission from the Blazar 3C 279
Urry, C. Megan; Koratkar, Anuradha; Pian, Elena +1 more
The blazar 3C 279 is well studied and shows frequent large continuum flares from radio to γ-ray wavelengths. There have been a number of multiwavelength observations of 3C 279, and hence there are extensive ultraviolet data for this object available in the UV archives. In this paper we present Lyα emission line measurements for 3C 279 using all th…
Resonance scattering of Lyman alpha from interstellar hydrogen
Brasken, Mats; Kyrola, Erkki
We derive a set of new line-of-sight (LOS) integrals and phase functions for the resonance scattering of unpolarized Lyman alpha light in the optically thin medium limit. To explicitly show the approximations done, and to indicate the range of validity of previously published formulas, we start by treating the general theory of resonance scatterin…
Coronal C+3 in the Large Magellanic Cloud: Evidence for a Hot Halo
Chu, You-Hua; Wakker, Bart; Points, Sean D. +2 more
Based on the detection of C IV absorption in five Large Magellanic Cloud (LMC) stars observed with the Goddard High-Resolution Spectrograph on the Hubble Space Telescope, we present the first unambiguous evidence that C+3 exists in the LMC away from regions where it could have been locally produced. We can exclude that this C+3
The Acoustic Moat and Thermal Transport in the Neighborhoods of Sunspots
Braun, D. C.; Lindsey, C.
Helioseismic holography of sunspots shows a remarkable acoustic anomaly surrounding the sunspot, which we call an ``acoustic moat.'' We used Solar and Heliospheric Observatory (SOHO) Michelson Doppler Imager observations of NOAA Active Region 7973 to render acoustic images of a typical sunspot. These images show a conspicuous halo, 70,000 km in di…
High resolution spectroscopy of symbiotic stars. IV. BX Monocerotis: orbital and stellar parameters
Schmutz, W.; Nussbaumer, H.; Shore, S. N. +4 more
We investigate the orbit and the components of the symbiotic BX Mon system with new high resolution spectroscopy, IUE spectra, published photographic magnitudes, and brightness estimates from the RASNZ. We review the available photometry and deduce a new binary period of 1401 days. We also find evidence in the IUE data that BX Mon is an eclipsing …