Search Publications
Infrared Fe II Emission in Narrow-Line Seyfert 1 Galaxies
Pastoriza, M. G.; Prato, L.; Rodríguez-Ardila, A. +1 more
We obtained 0.8-2.4 µm spectra at a resolution of 320 km s-1 of four narrow-line Seyfert 1 galaxies in order to study the near-infrared properties of these objects. We focus on the analysis of the Fe II emission in that region and the kinematics of the low-ionization broad lines. We show that the 1 µm Fe II lines (λ9997, λ10…
Multi-wavelength observations of an X-class flare without a coronal mass ejection.
van Driel-Gesztelyi, L.; Culhane, J. L.; Green, L. M. +2 more
Developments in our knowledge of coronal mass ejections (CMEs) have shown that many of these transients occur in association with solar flares. On the occasions when there is a common occurrence of the eruption and the flare, it is most likely that the flare is of high intensity and/or long-duration (Burkepile, Hundhausen, and Webb, 1994; Munro et…
A Far Ultraviolet Spectroscopic Explorer Survey of Interstellar O VI Absorption in the Small Magellanic Cloud
Hoopes, Charles G.; Sembach, Kenneth R.; Savage, Blair D. +2 more
We present the results of a Far Ultraviolet Spectroscopic Explorer (FUSE) survey of O VI λ1031.93 and λ1037.62 absorption toward 18 OB stars in the Small Magellanic Cloud (SMC). The FUSE data are of very high quality, allowing a detailed study of the coronal temperature gas in the SMC. We find that O VI is ubiquitous in the SMC, with a detection a…
Diffuse X-ray emission from the planetary nebula NGC 7009
Gruendl, R. A.; Chu, Y. -H.; Guerrero, M. A.
XMM-Newton EPIC observations of the planetary nebula (PN) NGC 7009, the Saturn Nebula, have detected extended X-ray emission in its central cavity. The diffuse X-ray emission must originate in the shocked fast stellar wind. The spectra show that the temperature of the hot gas is 1.8x 106 K. The rms density derived from the volume emissi…
Optical Slitless Spectroscopy of Large Magellanic Cloud Planetary Nebulae: A Study of the Emission Lines and Morphology
Mutchler, Max; Blades, J. Chris; Balick, Bruce +3 more
Hubble Space Telescope Space Telescope Imaging Spectrograph slitless spectroscopy of LMC planetary nebulae (PNs) is the ideal tool to study their morphology and their ionization structures at once. We present the results from a group of 29 PNs that have been spatially resolved, for the first time, in all the major optical lines. Images in the ligh…
A new, cleaner colour-magnitude diagram for the metal-rich globular cluster NGC 6528. Velocity dispersion in the Bulge, age and proper motion of NGC 6528
Feltzing, S.; Johnson, R. A.
Using two epochs of HST/WFPC2 images of the metal-rich globular cluster NGC 6528 we derive the proper motions of the stars and use them to separate the stars belonging to NGC 6528 from those of the Galactic bulge. The stellar sequences in the resulting colour-magnitude diagram for the cluster are significantly better determined than in previously …
The Luminosity Functions of Old and Intermediate-Age Globular Clusters in NGC 3610
Kundu, Arunav; Whitmore, Bradley C.; Schweizer, François +1 more
The Wide Field Planetary Camera 2 on board the Hubble Space Telescope (HST) has been used to obtain high-resolution images of NGC 3610, a dynamically young elliptical galaxy in a group environment. These observations supersede shorter, undithered HST observations in which an intermediate-age population of globular clusters was discovered. The new …
Discovery and Implications of a New Large-Scale Stellar Bar in NGC 5248
Laine, Seppo; Jogee, Shardha; Knapen, Johan H. +3 more
For decades, the grand-design SAB spiral galaxy NGC 5248 has been postulated to host a short bar of semimajor axis 22" (1.6 kpc). From dynamical and morphological arguments, however, we argue that its spiral structure is being driven by a large-scale bar whose corotation radius lies at ~115" (8.6 kpc). Our estimate is based partially on a deep R-b…
Hubble Space Telescope Imaging of a Peculiar Stellar Complex in NGC 6946
Elmegreen, Bruce G.; Hodge, Paul W.; Larsen, Søren S. +4 more
The stellar populations in a stellar complex in NGC 6946 are analyzed on images taken with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. The complex is peculiar because of its very high density of stars and clusters and semicircular shape. Its physical dimensions are about the same as for the local Gould Belt, but the stel…
April 2000 magnetic storm: Solar wind driver and magnetospheric response
Pulkkinen, Tuija I.; Palmroth, Minna; Pulkkinen, Antti +4 more
On 4 April 2000, a coronal mass ejection (CME) took place close to the western limb of the Sun. The shock front of the CME hit the Earth's magnetosphere on 6 April. A strong interplanetary southward BZ event in the sheath region caused a magnetic storm that was the second strongest in the year 2000 if quantified by the peak of the Dst i…