Science Archives Publication System

Physical Conditions in the O⁺⁺ Zone from ISO and HST Data: NGC 6543 Revisited

DOI: 10.1086/374942 Bibcode: 2003AJ....125.3196L

Luridiana, V.; Cerviño, M.; Pérez, E.

We revise the physical conditions in the O⁺⁺ zone of the planetary nebula NGC 6543, obtaining two different estimates of the electron temperature (T_e) and one estimate of the electron density (N_e). The electron temperature is computed by means of two independent methods, the nebular-to-auroral ratio [O III] λ5007/λ…

2003 • The Astronomical Journal

ISO eHST 5

A comparison between the CaII(k₃), H_alpha, SOHO/MDI and radio-enhanced temperature regions of the Sun

DOI: 10.1051/0004-6361:20030221 Bibcode: 2003A&A...402.1103R

Pohjolainen, S.; Valtaoja, E.; Riehokainen, A.

We present a comparison of the enhanced temperature regions (ETRs) in the radio emission of the Sun with other manifestations of solar activity over 5 days. The radio observations at 87 GHz were observed with the Metsähovi Radio Telescope (Finland). We superposed the intensity contours of the full-disk radio maps on the Meudon spectroheliograph Ca…

2003 • Astronomy and Astrophysics

SOHO 4

Introduction to a Further Examination of the Hipparcos Data

DOI: 10.1023/A:1026278631277 Bibcode: 2003SSRv..108..447V

van Leeuwen, Floor; Fantino, Elena

We present an introduction to four papers on further analysis of the raw Hipparcos data. This analysis has lead to the recognition of how orbit, radiation and temperature conditions did or didn't affect the scientific results of the Hipparcos mission. It also led the way to a new reduction of the scientific data that shows from its initial results…

2003 • Space Science Reviews

Hipparcos 4

X-ray spectra of XMM-Newton AXIS serendipitous sources

DOI: 10.1002/asna.200310013 Bibcode: 2003AN....324...48M

Barcons, X.; Carrera, F. J.; Mateos, S. +2 more

We have carried out a broad-band spectral analysis of X-ray sources detected serendipitously with the EPIC-pn instrument onboard XMM-Newton in AXIS fields. Our total catalogue contains 1837 X-ray sources detected in the energy band 0.5-4.5 keV down to a flux of ~ 3x 10^-15 erg cm^-2 s^-1. Optical identifications are a…

2003 • Astronomische Nachrichten

XMM-Newton 4

Peak proton intensities and composition variations of heavy ions during large solar energetic particle events: Uleis observations

DOI: 10.1016/S0273-1177(03)00355-7 Bibcode: 2003AdSpR..32..561H

Gold, R. E.; Roelof, E. C.; Ho, G. C. +2 more

We have examined low energy proton and heavy ion intensities in large solar energetic particle (SEP) events from 1997 to the end of 2001 using the ULEIS instrument on ACE spacecraft. We selected 33 events that are isolated and show clear onsets at 1 AU. The optical and radio signatures for all of our events are identified and where data are availa…

2003 • Advances in Space Research

SOHO 4

Improving the spatial resolution of XMM-Newton EPIC images by direct demodulation technique}

DOI: 10.1051/0004-6361:20030324 Bibcode: 2003A&A...402.1151F

Feng, Hua; Zhang, S. N.; Lu, F. J. +2 more

We have applied the direct demodulation technique to XMM-Newton EPIC images to achieve a higher spatial resolution; the restored images are compared with Chandra images. With the improved images we can extract spectra of fine structures in XMM-Newton data.

2003 • Astronomy and Astrophysics

XMM-Newton 4

On the XMM-Newton spectra of soft X-ray selected QSOs

DOI: 10.1051/0004-6361:20030395 Bibcode: 2003A&A...403..869A

Georgantopoulos, I.; Barcons, X.; Akylas, A.

We study the XMM-Newton spectra of a sample of 32 soft X-ray selected QSOs. Our goal is to check, using the spectra of moderate redshift (z ~ 1.5), faint (f_0.2-8 keV>5x 10^-15 erg cm^-2 s^-1) broad-line QSOs, previous claims for either significant intrinsic absorption or spectral hardening at high energi…

2003 • Astronomy and Astrophysics

XMM-Newton 4

A search for O VI in the winds of B-type stars

DOI: 10.1051/0004-6361:20030601 Bibcode: 2003A&A...405.1043Z

Massa, D.; Fullerton, A. W.; Lehner, N. +1 more

We have conducted a survey of FUSE spectra of 235 Galactic B-type stars in order to determine the boundaries in the H-R diagram for the production of the superion {O Vi} in their winds. By comparing the locations and morphology of otherwise unidentified absorption features in the vicinity of the {O Vi} resonance doublet with the bona fide wind pro…

2003 • Astronomy and Astrophysics

IUE 4

The Energy Equation in the Lower Solar Convection Zone

DOI: 10.1023/A:1027324825877 Bibcode: 2003SoPh..217....1D

Durney, Bernard R.

As a consequence of the Taylor-Proudman balance, a balance between the pressure, Coriolis and buoyancy forces in the radial and latitudinal momentum equations (that is expected to be amply satisfied in the lower solar convection zone), the superadiabatic gradient is determined by the rotation law and by an unspecified function of r, say, S'_Ω<…

2003 • Solar Physics

SOHO 4

Flare stars in the TW Hydrae association: the HIP 57269 syste

DOI: 10.1002/asna.200310166 Bibcode: 2003AN....324..516K

Neuhäuser, R.; Guenther, E. W.; Hambaryan, V. +1 more

We discuss a new member candidate of the TW Hydrae association (TWA) among the stars of the Gershberg et al. ( te{gershberg}) flare star catalog. TWA is one of the closest known associations of young stars at about 60 pc. Three supposedly young flare stars are located in the same region of the sky as TWA. One of them (HIP 57269)…

2003 • Astronomische Nachrichten

Hipparcos 4