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ORFEUS spectroscopy of the O BT VI lines in symbiotic stars and the Raman scattering process
Schmutz, W.; Grewing, M.; Schild, H. +16 more
We present orfeus spectra of the O vi lambda lambda 1032,1038 emission lines in the symbiotic stars AG Dra, V1016 Cyg, RR Tel, CD-43(deg) 14304, AG Peg and Z And. The O vi emission lines can convert into broad and highly polarized emission lines at lambda 6825 and lambda 7082 in a Raman scattering process by neutral hydrogen. From a comparison of …
HUBBLE SPACE TELESCOPE Observations of the Local Group Dwarf Galaxy Leo I
Freedman, Wendy L.; Mateo, Mario; Stetson, Peter B. +10 more
We present deep HST F555W (V) and F814W (I) observations of a central field in the Local Group dwarf spheroidal (dSph) galaxy Leo I. The resulting color-magnitude diagram (CMD) reaches I~=26 and reveals the oldest ~=10-15 Gyr old turnoffs. Nevertheless, a horizontal branch is not obvious in the CMD. Given the low metallicity of the galaxy, this li…
Interstellar dust and magnetic field at the boundaries of the Local Bubble. Analysis of polarimetric data in the light of HIPPARCOS parallaxes
Leroy, J. L.
Hipparcos stellar parallaxes have been used to reanalyse existing interstellar polarization data. The main results are: The nearest interstellar dust patches are at about 70 pc in some directions, in others beyond 150 pc. Thus the region devoid of dust, commonly identified with the Local Hot Bubble, is irregular in shape. The interstellar magnetic…
Injection of>~10 MeV Protons in Association with a Coronal Moreton Wave
Torsti, Jarmo; Teittinen, Matti; Thompson, Barbara J. +1 more
We report extreme-UV observations of the coronal Moreton wave and concurrent observations of ~10-100 MeV protons. Observations are carried out with the Extreme-UV Imaging Telescope and the Energetic and Relativistic Nuclei and Electron instrument on board the SOHO spacecraft. We study the proton events associated with coronal mass ejections (CMEs)…
Changes of the boot-shaped coronal hole boundary during Whole Sun Month near sunspot minimum
Hoeksema, J. T.; Scherrer, P. H.; Zhao, X. P.
The August 27, 1996, boot-shaped coronal hole is shown to rotate nearly rigidly at a rate of 13.25°/day, greater than the equatorial rotation rate of bipolar magnetic regions such as active regions and plages. The day-to-day variation of the coronal hole border is determined by comparing the rigid rotation projection of the disk-center hole bounda…
ISOGAL survey of Baade's Windows in the mid-infrared
Alard, C.; Blommaert, J. A. D. L.; Ganesh, S. +6 more
The ISOGAL mid-infrared survey of areas close to the Galactic plane aims to determine the stellar content of those areas, and its possible bearing on the history of the Galaxy. The NGC 6522 and Sgr I Baade's Windows of low obscuration towards the inner parts of the Galactic bulge represent ideal places in which to calibrate and understand the ISOG…
Identification of moving groups and member selection using HIPPARCOS data
Aguilar, Luis A.; Hoogerwerf, Ronnie
A new method to identify coherent structures in velocity space - moving groups - in astrometric catalogues is presented: the Spaghetti method. It relies on positions, parallaxes and proper motions, and is ideally suited to searching for moving groups in the Hipparcos Catalogue. No radial-velocity information is required. The method has been tested…
The colour-magnitude relation of early-type galaxies in the Hubble Deep Field
Bell, Eric F.; Kodama, Tadayuki; Bower, Richard G.
We present the rest-frame colour-magnitude diagram for 35 early-type galaxies in the Hubble Deep Field with median redshift 0.9. Although they have considerable scatter, a red sequence that is well described by the passive evolution of an intrinsically old stellar population is observed. Comparison with the passively evolved colour-magnitude relat…
Two multiple-imaged Z = 4.05 galaxies in the cluster-lens Abell 2390
Smail, I.; Pelló, R.; Kneib, J. P. +8 more
We present the first results on the identification and study of very distant field galaxies in the core of cluster-lenses, using a selection criterium based on both lens modelling and photometric redshifts. We concentrate on two multiple-imaged sources at z = 4.05 in the cluster Abell 2390. The two objects presented in this paper, namely H3 (cusp …
Nonlinear Sunspot Transition Region Oscillations in NOAA 8378
Wilhelm, K.; Kjeldseth-Moe, O.; Brynildsen, N. +1 more
Observations obtained with the Solar and Heliospheric Observatory joint observing program for velocity fields in sunspot regions are used to study the 3 minute transition region oscillations above four sunspots. Here we report mainly on the results obtained for NOAA 8378, based on simultaneous recordings of the transition region lines O V λ629 and…