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Extreme-Ultraviolet Sunspot Plumes Observed with SOHO
Kjeldseth-Moe, O.; Haugan, S. V. H.; Brekke, P. +4 more
Bright EUV sunspot plumes have been observed in five out of nine sunspot regions with the Coronal Diagnostic Spectrometer on the Solar and Heliospheric Observatory. In the other four regions, the brightest line emissions may appear inside the sunspot but are mainly concentrated in small regions outside the sunspot areas. These results are in contr…
Particle acceleration at corotating interaction regions in the three-dimensional heliosphere
Balogh, A.; Forsyth, R. J.; Desai, M. I. +3 more
We have investigated the relationship between the energetic (~1MeV) proton intensity (J) and the magnetic compression ratio (C) measured at the trailing edges of corotating interaction regions observed at Ulysses. In general, our results show that the proton intensity was well correlated with the compression ratio, provided that the seed intensity…
The Hubble Space Telescope Medium Deep Survey Cluster Sample: Methodology and Data
Nichol, R. C.; Griffiths, R. E.; Ostrander, E. J. +1 more
We present a new, objectively selected, sample of galaxy overdensities detected in the Hubble Space Telescope Medium Deep Survey (MDS). These clusters/groups were found using an automated procedure that involved searching for statistically significant galaxy overdensities. The contrast of the clusters against the field galaxy population is increas…
HST mid-ultraviolet spectroscopy of comet 46P/Wirtanen during its approach to perihelion in 1996-1997
Parker, Joel Wm.; Bertaux, Jean-Loup; Stern, S. Alan +6 more
We have used the Hubble Space Telescope Faint Object Spectrograph to observe the mid-UV spectrum of the ROSETTA mission target comet, 46P/Wirtanen, on three dates during the comet's apparition in 1996 and early 1997. During this time the comet moved inward from a heliocentric distance near 2.7 AU to 1.3 AU. The first measurement (22.7 July 1996) d…
The Ages and Distances of Globular Clusters with the Luminosity Function Method: The Case of M5 and M55
Jimenez, Raul; Padoan, Paolo
We present new age and distance determinations for the Galactic globular clusters M55 and M5, using the luminosity function (LF) method of Padoan & Jimenez. Using the set of stellar tracks computed by Jimenez & MacDonald and taking into account a value of [α/Fe] = 0.4, we find an age of 12.5 +/- 1.0 Gyr for M55 and 10.6 +/- 0.8 Gyr for M5.…
Boron Abundances and Internal Mixing in Stars. I. The Hyades Giants
Pinsonneault, Marc H.; Peterson, Ruth C.; Duncan, Douglas K. +1 more
The boron abundances of two giants and one turnoff star in the Hyades, and the field K0 III giant β Gem, have been measured from spectra obtained with the Hubble Space Telescope in the vicinity of the B I lines near 2500 Å. This provides a test of the dilution of giant envelopes predicted by standard stellar evolutionary models: since B is destroy…
Absolute magnitudes of carbon stars from HIPPARCOS parallaxes
Eglitis, I.; Alksnis, A.; Balklavs, A. +1 more
Hipparcos trigonometric parallaxes and photometric data for about 40 bright carbon stars have been analysed. Individual absolute visual and bolometric magnitudes, normal color indices (B-V)_0, absorption values and distance moduli were determined. By comparison with stellar evolutionary tracks for initial mass 1<= M/M_⊙<=4 it is found that t…
SOHO Observations of the Connection Between Line Profile Parameters in Active and Quiet Regions and the Net Red Shift in EUV Emission Lines
Harrison, R. A.; Wilhelm, K.; Fredvik, T. +5 more
We present high spatial and spectral resolution observations of one active and one quiet-Sun region, obtained with CDS and SUMER on SOHO. The connections between the line profile parameters are studied and a systematic wavelength shift towards the red with increasing peak line intensity (line broadening) is detected. The large scatter in the data …
The mass of (1) Ceres from its gravitational perturbations on the orbits of 9 asteroids
Viateau, B.; Rapaport, M.
The mass of (1) Ceres is about half of the total mass of the main asteroid belt, and its long-term perturbations on the orbits of many solar system objects are important. For this reason, a very good knowledge of this mass is necessary. Although many determinations of the mass of Ceres have been made until now, the uncertainty remaining on its val…
A multiwavelength study of the early evolution of the classical nova LMC 1988 1
Sonneborn, G.; Baron, E.; Hauschildt, Peter H. +3 more
LMC 1988 1 was a moderately fast, CO, dust-forming classical nova. It was observed extensively in many different wavelength regions during its early evolution. The UV, optical and infrared light curves of LMC 1988 1 are very similar to those of the Galactic Nova V1668 Cyg 1978. As in V1668 Cyg, LMC 1988 1 showed the presence of an optically thin d…