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Energetics and Propagation of Coronal Mass Ejections in Different Plasma Environments
Lin, Jun
Based on previous work, we investigate the propagation of CMEs in a more realistic plasma environment than the isothermal atmosphere, and find that it is a slightly faster reconnection for flux ropes to break free. The average Alfvén Mach number MA for the inflow into the reconnection site has to be at least 0.013 in order to give a pla…
Coronal White-Light Jets near Sunspot Maximum
Sheeley, N. R., Jr.; Wang, Y. -M.
During the 1996-1997 activity minimum, the Large Angle and Spectrometric Coronagraph (LASCO) on the Solar and Heliospheric Observatory (SOHO) recorded numerous jetlike ejections above the Sun's polar regions. In a previous study, we showed that these white-light ejections were the outward extensions of extreme-ultraviolet (EUV) jets, which in turn…
XMM-Newton Observations of the Neutron Star X-Ray Transient KS 1731-260 in Quiescence
Guainazzi, Matteo; Wijnands, Rudy; Méndez, Mariano +1 more
We report on XMM-Newton observations performed on 2001 September 13-14 of the neutron star X-ray transient KS 1731-260 in quiescence. The source was detected at an unabsorbed 0.5-10 keV flux of only (4-8)×10-14 ergs cm-2 s-1, depending on the model used to fit the data, which for a distance of 7 kpc implies a 0.5-1…
The percentage of stellar light re-radiated by dust in late-type Virgo Cluster galaxies
Tuffs, Richard J.; Popescu, Cristina C.
We show that the mean percentage of stellar light re-radiated by dust is ~30 per cent for the Virgo Cluster late-spirals measured with ISOPHOT by Tuffs et al. A strong dependence of this ratio with morphological type was found, ranging from typical values of ~15 per cent for early spirals to up to ~50 per cent for some late spirals. The extreme BC…
Tomography of the Solar Corona. II. Robust, Regularized, Positive Estimation of the Three-dimensional Electron Density Distribution from LASCO-C2 Polarized White-Light Images
Frazin, Richard A.; Janzen, Paul
Solar rotational tomography is used to determine the three-dimensional electron density distribution of the solar corona from 2.4 to 6.0 Rsolar. The robust, regularized, positive estimation method, described in a previous paper, is demonstrated on test cases and on LASCO-C2 data. Because the solar rotational pole is inclined to the plan…
Lyα Absorption around Nearby Galaxies
Bowen, David V.; Pettini, Max; Blades, J. Chris
We have used the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope to search for Lyα absorption lines in the outer regions of eight nearby galaxies using background quasars and AGNs as probes. Lyα lines are detected within a few hundred kilometers per second of the systemic velocity of the galaxy in all cases. We conclu…
Far-Infrared Photometry of a Statistical Sample of Late-Type Virgo Cluster Galaxies
Tuffs, Richard J.; Popescu, Cristina C.; Pierini, Daniele +6 more
We present deep diffraction-limited far-infrared (FIR) strip maps of a sample of 63 galaxies later than S0 and brighter than BT=16.8, selected from the Virgo Cluster Catalogue of Binggeli, Sandage, & Tammann. The ISOPHOT instrument on board the Infrared Space Observatory was used to achieve sensitivities typically an order of magnit…
Radial Velocity Studies of Close Binary Stars. VI.
Rucinski, Slavek M.; Capobianco, Christopher C.; Lu, Wenxian +5 more
Radial velocity measurements and sine-curve fits to the orbital velocity variations are presented for the sixth set of 10 close binary systems: SV Cam, EE Cet, KR Com, V410 Cyg, GM Dra, V972 Her, ET Leo, FS Leo, V2388 Oph, and II UMa. All systems except FS Leo are double-lined spectroscopic binaries. The type of FS Leo is unknown, while SV Cam is …
Are Starburst Galaxies the Hosts of Gamma-Ray Bursts?
Chary, R.; Armus, L.; Becklin, E. E.
We present deep 2.2 µm imaging of 12 gamma-ray burst host galaxies. Template spectral energy distributions are fitted to the multiband photometry between visible and near-infrared wavelengths to derive a better constraint on the stellar mass of these galaxies. The internal extinction in the host galaxies is estimated using the rest-frame ult…
ISOCAM Observations of Galactic Globular Clusters: Mass Loss along the Red Giant Branch
Ferraro, Francesco R.; Origlia, Livia; Fusi Pecci, Flavio +1 more
Deep images in the 10 µm spectral region have been obtained for five massive Galactic globular clusters, NGC 104 (=47 Tuc), NGC 362, NGC 5139 (=ω Cen), NGC 6388, NGC 7078 (=M15), and NGC 6715 (=M54) in the Sagittarius Dwarf Spheroidal using the ISOCAM on board the Infrared Space Observatory in 1997. A significant sample of bright giants have…