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Fast photospheric flows and magnetic fields in a flaring active region
Meunier, N.; Kosovichev, A.
We present new results from the coordinated observations between the THEMIS telescope (in the multi-line spectropolarimetric mode) and Michelson Doppler Imager (MDI) on SOHO obtained in November 2000 for active region NOAA 9236 which was the source of several X-class flares. The goal of these observations was twofold: to verify MDI measurements of…
The Remarkable Alternating Spectra of the Of?p Star HD 191612
Walborn, Nolan R.; Howarth, Ian D.; Herrero, Artemio +1 more
The spectrum of HD 191612 has been found to display large, recurrent variations between two highly reproducible, peculiar states; at least four transformations have occurred since 1950. In one state, the spectral type is O6-O7, with C III λ4650 emission comparable to N III λ4640 (the definition of the Of?p category) and P Cygni profiles at He II λ…
INTEGRAL and XMM-Newton Observations of the Weak Gamma-Ray Burst GRB 030227
Tiengo, A.; Götz, D.; Mereghetti, S. +16 more
We present International Gamma-Ray Astrophysical Laboratory (INTEGRAL) and XMM-Newton observations of the prompt γ-ray emission and the X-ray afterglow of GRB 030227, the first gamma-ray burst for which the quick localization obtained with the INTEGRAL Burst Alert System has led to the discovery of X-ray and optical afterglows. GRB 030227 had a du…
Magnetoacoustic Waves in Sunspots
Bellot Rubio, L. R.; Collados, M.; Khomenko, E. V.
Observed variations of the magnetic field strength in sunspot umbrae consist of intrinsic oscillations and ``false'' oscillations due to time-dependent opacity effects. Here we present an approach intended for the separation of these components. We develop a mathematical formalism based on the analytical solution of the MHD equations including gra…
The planetary nebula K 1-2 and its binary central star VW Pyx
Exter, K. M.; Pollacco, D. L.; Bell, S. A.
New data are presented of the post-common-envelope binary VW Pyx and its associated planetary nebula (PN), K 1-2. The central star is found to be a single-lined (and possibly double-lined) spectroscopic binary and is a good candidate for a system in which the main-sequence secondary star is more massive than the subdwarf primary star. The old PN h…
The XMM-Newton/2dF survey - I. X-ray properties of normal galaxies
Georgakakis, A.; Georgantopoulos, I.; Shanks, T. +2 more
This paper explores the X-ray properties of `normal' galaxies using a shallow (2-10 ks) XMM-Newton survey covering an area of ~1.5 deg2. The X-ray survey overlaps with the 2dF Galaxy Redshift Survey. Compared with previous studies this has the advantage that high-quality spectra and spectral classifications (early-, late-type) exist for…
The First Two Host Galaxies of X-Ray Flashes: XRF 011030 and XRF 020427
Berger, E.; Bloom, J. S.; Djorgovski, S. G. +4 more
Given the paucity of empirical constraints, the nature of the newly recognized phenomena called X-ray flashes (XRFs) has been an open question. However, with the recent detections of radio and X-ray afterglow it is finally possible to study the large- and small-scale environments of XRFs. We present Chandra, Hubble Space Telescope (HST), and Keck …
The Multiphase Absorption Systems toward PG 1206+459
Charlton, Jane C.; Churchill, Christopher W.; Palma, Christopher +1 more
A high-resolution (R=30,000) ultraviolet spectrum is presented, which covers Lyα and many low-, intermediate-, and high-ionization transitions in the three Mg II-selected absorption systems toward the quasar PG 1206+459. Three systems (A, B, and C), which are clustered within 1500 km s-1 at z~0.93, were originally identified in a spectr…
On the Size Difference between Red and Blue Globular Clusters
Brodie, Jean P.; Larsen, Søren S.
Several recent studies have reported a mean size difference of about 20% between the metal-rich and metal-poor subpopulations of globular clusters (GCs) in a variety of galaxies. In this paper, we investigate the possibility that the size difference might be a projection effect, resulting from a correlation between cluster size and galactocentric …
High resolution spectroscopy and emission line imaging of DEM L 71 with XMM-Newton
Kaastra, J. S.; Vink, J.; Bleeker, J. A. M. +1 more
The X-ray emission from the supernova remnant DEM L 71 is measured and analysed using the high-resolution cameras and spectrometers on board XMM-Newton. The spectrum from the outer shell is reproduced very well by two plasma components of kTe = 0.3 and 0.8 keV. The abundance value from this shell is consistent with the average LMC value…