Search Publications
First simultaneous observations of flux transfer events at the high-latitude magnetopause by the Cluster spacecraft and pulsed radar signatures in the conjugate ionosphere by the CUTLASS and EISCAT radars
Balogh, A.; Davies, J. A.; Wild, J. A. +9 more
Cluster magnetic field data are studied during an outbound pass through the post-noon high-latitude magnetopause region on 14 February 2001. The onset of several minute perturbations in the magnetospheric field was observed in conjunction with a southward turn of the interplanetary magnetic field observed upstream by the ACE spacecraft and lagged …
Hubble Space Telescope NICMOS Detection of a Partially Embedded, Intermediate-Mass, Pre-Main-Sequence Population in the 30 Doradus Nebula
Walborn, Nolan R.; Grebel, Eva K.; Brandner, Wolfgang +2 more
We present the detection of an intermediate-mass, pre-main-sequence population embedded in the nebular filaments surrounding the 30 Doradus region in the Large Magellanic Cloud (LMC) using HST/NICMOS. In addition to four previously known luminous Class I infrared ``protostars,'' the NICMOS data reveal 20 new sources with intrinsic infrared excess …
Hard X-Radiation from a Fast Coronal Ejection
Hudson, H. S.; Nitta, N. V.; Shimojo, M. +1 more
We have observed a high-speed coronal ejection in hard X-rays, detectable to an altitude of some 2×105 km in the Yohkoh 23-53 keV energy bands. Simultaneous imaging at 17 and 34 GHz from the Nobeyama radioheliograph shows complex moving features simultaneous with the ejection, including a compact source that we identify with the rapid X…
The Stellar Population and Star Clusters in the Unusual Local Group Galaxy IC 10
Hunter, Deidre A.
We present an analysis of Hubble Space Telescope U, V, I, and Hα images of the peculiar Local Group irregular galaxy IC 10. The images are used to determine the nature of the stellar products in a portion of the recent starburst in this galaxy. We identified 13 stellar associations and clusters, two of which are probably old (>=350 Myr) and the…
Ion distributions in large magnetic holes in the fast solar wind
Smith, E. J.; Goldstein, B. E.; Neugebauer, M. +3 more
Magnetic holes are isolated localized depressions in the magnitude of the interplanetary magnetic field. Six examples of long-duration (9 to 30 min) magnetic holes observed by the Ulysses spacecraft at high heliographic latitudes near 3 AU are studied in detail. Each of the holes was in pressure balance with its surroundings. The proton-proton and…
Multiwavelength Monitoring of the Narrow-Line Seyfert 1 Galaxy Arakelian 564. III. Optical Observations and the Optical-UV-X-Ray Connection
Filippenko, A. V.; Martini, P.; Turner, T. J. +36 more
We present the results of a 2 yr long optical monitoring program of the narrow-line Seyfert 1 galaxy Ark 564. The majority of this monitoring project was also covered by X-ray observations (RXTE), and for a period of ~50 days, we observed the galaxy in UV (HST) and X-rays (RXTE and ASCA) simultaneously with the ground-based observations. Rapid and…
Optical and Near-Infrared Imaging of Infrared-Excess Palomar-Green Quasars
Sanders, D. B.; Evans, A. S.; Surace, Jason A.
Ground-based high spatial resolution (FWHM<0.3"-0.8") optical and near-infrared imaging (0.4-2.2 µm) is presented for a complete sample of optically selected Palomar-Green QSOs with far-infrared excesses at least as great as those of ``warm'' AGN-like ultraluminous infrared galaxies (Lir/LBBB>0.46). In all cases, …
NICMOS Observations of Low-Redshift Quasar Host Galaxies
McLeod, K. K.; McLeod, B. A.
We have obtained Near-Infrared Camera and Multi-Object Spectrometer images of 16 radio-quiet quasars observed as part of a project to investigate the ``luminosity/host-mass limit.'' The limit results were presented in a paper by McLeod, Rieke, & Storrie-Lombardi. In this paper, we present the images themselves, along with one- and two-dimensio…
Sustaining the Sun's Magnetic Network with Emerging Bipoles
Title, A. M.; Simon, G. W.; Weiss, N. O.
The Michelson Doppler Imager experiment on SOHO has revealed a ``magnetic carpet'' dominated by the emergence of bipolar magnetic flux in ephemeral active regions, which subsequently split into small flux elements that drift into the magnetic network. The effects of granular and supergranular convection on these flux elements are represented here …
Transition region oscillations above sunspots
Fludra, A.
We present observations of three sunspots made in the EUV wavelength range with the Coronal Diagnostic Spectrometer (CDS) on SOHO. We examine time series of line intensities obtained with a 15-s cadence and calculate their Fourier power spectra and the wavelet transforms. We find oscillations in the chromosphere and transition region above sunspot…