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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…
Detection of short-term variations in Mira-type variables from HIPPARCOS photometry
de Laverny, P.; Mignard, F.; Mennessier, M. O. +1 more
The Hipparcos photometric observations carried out over 37 months have been investigated in detail for ~ 250 Miras. This leads to an unexpected by-product of the mission that we already suspected from ESOC real-time reductions: the first detection from space of photometric short-term brightness variations in Mira-type variables. Altogether, 51 eve…
Diffuse ionized gas toward beta Canis Majoris
Gry, Cecile; Dupin, Olivier
This paper presents the study of the interstellar medium toward beta CMa, a disk sight-line known for its low neutral gas density. This study uses high and medium resolution HST-GHRS spectra including lines from the following species: H i, D i, N i, O i, S ii, S iii, Si ii, Si iii, Si iv, Al ii, Al iii, Fe ii, Mg i, Mg ii, Mn ii, C ii and C iv. Th…
The Theory of Anomalous Cosmic Rays
Giacalone, J.; Jokipii, J. R.
Anomalous cosmic rays are a heliospheric phenomenon in which interstellar neutral atoms stream into the heliosphere, are ionized by either solar radiation or the solar wind, and are subsequently accelerated to very high energies, greater than 1 GeV. Current thinking has the bulk of the acceleration to very-high energies taking place, by the mechan…
The Solar Minimum Active Region 7978, Its X2.6/1B Flare, CME, and Interplanetary Shock Propagation of 9 July 1996
Michels, D. J.; Paswaters, S. E.; Koomen, M. J. +21 more
The first X-class flare in four years occurred on 9 July 1996. This X2.6/1B flare reached its maximum at 09:11 UT and was located in active region 7978 (S10° W30°) which was an old-cycle sunspot polarity group. We report the SOHO LASCO/EIT/MDI and SOONSPOT observations before and after this event together with Yohkoh SXT images of the flare, radio…