Search Publications
X-Ray Spectroscopy of η Carinae with XMM-Newton
Ramsay, Gavin; Leutenegger, Maurice A.; Kahn, Steven M.
We present XMM-Newton observations of the luminous star η Carinae, including a high-resolution soft X-ray spectrum of the surrounding nebula obtained with the Reflection Grating Spectrometer (RGS). The European Photon Imaging Camera (EPIC) image of the field around η Car shows many early-type stars and diffuse emission from hot, shocked gas. The E…
Does the Sun Shrink with Increasing Magnetic Activity?
Antia, H. M.
It has been demonstrated that frequencies of f-modes can be used to estimate the solar radius to a good accuracy. These frequencies have been used to study temporal variations in the solar radius with conflicting results. The variation in f-mode frequencies is more complicated than what is assumed in these studies. If a careful analysis is perform…
An Icy, Bipolar Proto-Planetary Nebula with Knotty Jets: IRAS 22036+5306
Sahai, R.; Sánchez Contreras, C.; Zijlstra, A. +1 more
Using the Hubble Space Telescope's Wide Field Planetary Camera 2, we have discovered that the proto-planetary nebula (PPN) IRAS 22036+5306 (I22036) is an extended (5.7"×1.3") bipolar nebula. A dark, (partial) ringlike band defines the nebular waist region and probably results from a tilted, geometrically thick disk that obscures the central star. …
Detection of X-Ray Emission from the Eastern Radio Lobe of Pictor A
Guainazzi, Matteo; Morganti, Raffaella; Tavecchio, Fabrizio +5 more
The XMM-Newton satellite has revealed extended X-ray emission from the eastern radio lobe of the Fanaroff-Riley II radio galaxy Pictor A. The X-ray spectrum, accumulated on a region covering about half the entire radio lobe, is well described by both a thermal (kT=5+9-2 keV) model and a power law with an energy index αX<…
Acceleration and Enrichment of 3He in Impulsive Solar Flares by Electron Firehose Waves
Benz, A. O.; Kallenbach, R.; Paesold, G.
A new mechanism for acceleration and enrichment of 3He during impulsive solar flares is presented. Low-frequency electromagnetic plasma waves excited by the electron firehose instability (EFI) can account for the acceleration of ions up to 1 MeV amu-1 energies as a single-stage process. The EFI arises as a direct consequence …
The Dynamical Morphologies of Flares Associated with the Two Types of Solar Coronal Mass Ejections
Golub, Leon; Zhang, Mei
In this paper we study the high-cadence TRACE observations of a sample of 28 X- and M-class flares, with particular focus on the relation between flare morphology and the two types (fast and slow) of solar coronal mass ejections (CMEs). Among the 28 flares studied, 10 are associated with fast CMEs, 10 are associated with slow CMEs, and 8 are loose…
An XMM-Newton Observation of Nova LMC 1995: A Bright Supersoft X-Ray Source
Orio, Marina; Greiner, Jochen; Still, Martin +1 more
Nova LMC 1995, previously detected during 1995-1998 with ROSAT, was observed again as a luminous supersoft X-ray source with XMM-Newton in 2000 December. This nova offers the possibility to observe the spectrum of a hot white dwarf, burning hydrogen in a shell and not obscured by a wind or nebular emission as in other supersoft X-ray sources. Notw…
Star Formation History and Other Properties of the Northern Hubble Deep Field
Thompson, Rodger I.
The original analysis of the star formation history in the NICMOS deep images of the northern Hubble Deep Field (NHDF) is extended to the entire NHDF utilizing NICMOS and WFPC2 archival data. The roughly constant star formation rate from redshifts 1-6 found in this study is consistent with the original results. Star formation rates from this study…
Spatial Separation of the 3.29 Micron Emission Feature and Associated 2 Micron Continuum in NGC 7023
Sellgren, K.; An, Jin H.
We present a new 0.9" resolution 3.29 µm narrowband image of the reflection nebula NGC 7023. We find that the 3.29 µm infrared emission feature (IEF) in NGC 7023 is brightest in narrow filaments northwest of the illuminating star HD 200775. These filaments have been previously seen in images of extended red emission, K', near-infrared …
SOHO-Ulysses Spring 2000 Quadrature: Coronal Diagnostic Spectrometer and SUMER Results
Parenti, S.; Landi, E.; Bromage, B. J. I.
We present results from SOHO/CDS and SOHO/SUMER coordinated observations of coronal streamers made during the spring 2000 quadrature of SOHO, the Sun, and Ulysses. These observations form part of the JOP 112, which is primarily aimed at investigating the composition of the regions of the corona and the solar wind observed by both SOHO and Ulysses.…