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Global Solar Corona Revealed by Time Series Observations
Raymond, J. C.; Li, Jing; Kuhn, J. +2 more
Time series observations at UV (Extreme Ultraviolet Imaging Telescope/Solar and Heliospheric Observatory) and X-ray (Soft X-Ray Telescope/Yohkoh) wavelengths reveal properties of the global solar corona that are not easily identified in a single image. A median-filtering technique that rejects features varying with time is used to isolate backgrou…
Comparing Tycho-2 Astrometry with UCAC1
Zacharias, N.; Urban, S. E.; Zacharias, M. I. +1 more
The Tycho-2 Catalogue, released in February 2000, is based on the ESA Hipparcos space mission data and various ground-based catalogs for proper motions. An external comparison of the Tycho-2 astrometry is presented here using the first US Naval Observatory CCD Astrograph Catalog (UCAC1). The UCAC1 data were obtained from observations performed at …
Determination of the abundance of aluminum in the solar wind with SOHO/CELIAS/MTOF
Bochsler, Peter; Wurz, Peter; Weygand, James M. +2 more
The Al/Mg abundance ratio provides an excellent test case for investigating possible fractionation processes among low First Ionization Potential (FIP) elements in the solar wind. Al and Mg are refractory elements; their abundance ratio has been well determined in solar system materials and inferences for the abundance ratio in the solar atmospher…
A combined approach for object detection and deconvolution
Valtchanov, I.; Starck, J. -L.; Bijaoui, A. +1 more
The Multiscale Vision Model is a recent object detection method, based on the wavelet transform. It allows us to extract all objects contained in an image, whatever their size or their shape. From each extracted object, information concerning flux or shape can easily be determined. We show that such an approach can be combined with deconvolution, …
The bright 175 mu m knots of the Andromeda galaxy
Lemke, D.; Haas, M.; Schmidtobreick, L.
Discrete far-infrared (FIR) sources of M 31 are identified in the ISO 175 mu m map and characterized via their FIR colours, luminosities and masses in order to reveal the nature of these knots. With our spatial resolution of 300 pc at M 31's distance, the FIR knots are clearly seen as extended objects with a mean size of about 800 pc. Since this a…
Light-Element Abundance Patterns in the Orion Association. I.Hubble Space Telescope Observations of Boron in G Dwarfs
Cunha, Katia; Smith, Verne V.; Lambert, David L. +1 more
The boron abundances for two young solar-type members of the Orion association, BD -6°1250 and HD 294297, are derived from Hubble Space Telescope STIS spectra of the B I transition at 2496.771 Å. The best-fit boron abundances for the target stars are 0.13 and 0.44 dex lower than the solar meteoritic value of logɛ(B)=2.78. An anticorrelation of bor…
In-Flight Determination of the Plate Scale of the Extreme-Ultraviolet Imaging Telescope
Auchère, F.; Artzner, G.; DeForest, C. E.
Using simultaneous observations of the Michelson Doppler Imager and Extreme-Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory spacecraft, we determined in flight the plate scale of the EIT. We found a value of 2.629"+/-0.001" pixel-1, in fair agreement with the 2.627"+/-0.001" pixel-1 value d…
Hubble Space Telescope Observations of M Subdwarfs
Gizis, John E.; Reid, I. Neill
We present the results of a Hubble Space Telescope snapshot program to search for very low mass stellar companions to nearby M subdwarfs. None of our nine targetted metal-poor primaries has companions more massive than the hydrogen burning limit, implying that the halo binary fraction is equal to or less than the Galactic disk binary fraction belo…
Decaying post-flare loops system observed by SOHO/CDS and Yohkoh/SXT
Heinzel, P.; Fludra, A.; Varady, M.
The results of an analysis of joint SOHO/CDS and Yohkoh/SXT observations of a decaying post-flare loops system with a rapid time evolution are presented. The loop system was a remnant of a small single loop flare (GOES class C2.9). Using the CDS raster taken in several EUV lines with different formation temperatures and a temperature sensitive lin…
Optical Observations of the Binary Pulsar System PSR B1718-19: Implications for Tidal Circularization
Kulkarni, S. R.; van Kerkwijk, M. H.; Lyne, A. G. +3 more
We report on Keck and Hubble Space Telescope optical observations of the eclipsing binary pulsar system PSR B1718-19, in the direction of the globular cluster NGC 6342. These reveal a faint star (mF702W=25.21+/-0.07 Vega system) within the pulsar's 0.5" radius positional error circle. This may be the companion. If it is a main-sequence …