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η Carinae: The 1998 brightening and the smearing-out effect
Sterken, C.; van Genderen, A. M.
A comparison of broad-band photometry of the Homunculus (ground-based data) and of broad-band and narrow-band photometry of the central region (HST-based) from 1997 to 2003 reveals that, apart from the brightening in 1998, the Homunculus as well as the central star varied in a very similar way. This excludes smearing-out effects as an explanation …
Local Modulation of Solar Oscillations by Magnetic Fields
Thompson, M. J.; Rajaguru, S. P.; Nicholas, C. J.
The amplitudes of solar oscillations measured in Doppler velocity are modulated by the presence of a strong photospheric magnetic field. Here we show that the amount of modulation cannot be predicted solely on the local photospheric magnetic field strength. Qualitatively, magnetic fields of similar strength have similar effects on the oscillations…
Broadband Observations of the Transient X-ray Pulsar SAX J2103.5+4545
Sunyaev, R. A.; Lutovinov, A. A.; Revnivtsev, M. G. +5 more
We investigated the optical, X-ray, and gamma-ray variability of the pulsar SAX J2103.5+4545. Our timing and spectral analyses of the X-ray and gamma-ray emissions from the source using RXTE and INTEGRAL data show that the shape of its spectrum in the energy range 3-100 keV is virtually independent of its intensity and the orbital phase. Based on …
Relationship between horizontal flow velocity and cell lifetime for supergranulation from SOHO Dopplergrams
Singh, Jagdev; Paniveni, U.; Krishan, V. +1 more
A study of 50 supergranular cells obtained from Solar and Heliospheric Observatory (SOHO) Dopplergrams was undertaken in order to investigate the relationship between the lifetime (T) and the horizontal flow velocity (vh) of the cells. For this sample, we find that the two parameters are correlated with a relation vh~T1/…
The dispersion in the Cepheid period-luminosity relation and the consequences for the extragalactic distance scale
Shanks, Tom; Allen, Paul D.
Using published Hubble Space Telescope (HST) Cepheid data from 25 galaxies, we have found a correlation between the dispersion in the Cepheid period-luminosity (P-L) relation and host galaxy metallicity, which is significant at the ~3σ level in the V band. In the I band the correlation is less significant, although the tighter intrinsic dispersion…
Cassini/VIMS observation of an Io post-eclipse brightening event
Brown, R. H.; Baines, K. H.; Buratti, B. J. +10 more
During the Cassini-Jupiter flyby, VIMS observed Io at different phase angles, both in full sunlight and in eclipse. By using the sunlight measurements, we were able to produce phase curves in the visual through all the near infrared wavelengths covered by the VIMS instrument (0.85-5.1 µm). The phase angle spanned from ∼2° to ∼120°. The measu…
FUSE Observations of Highly Ionized Gas in the Vela Supernova Remnant
Blair, William P.; Nichols, Joy S.; Slavin, Jonathan D.
We present Far Ultraviolet Spectroscopic Explorer (FUSE) data on O VI absorption lines observed toward nine stars behind the Vela supernova remnant (SNR). The O VI observations are compared with International Ultraviolet Explorer (IUE) observations of C IV absorption toward the same stars. All of these stars are B stars, which generally have compl…
Global control of merging by the interplanetary magnetic field: Cluster observations of dawnside flank magnetopause reconnection
Balogh, A.; RèMe, H.; André, M. +7 more
Detailed Cluster observations of flank magnetopause reconnection are presented for two events on the Northern and the Southern Hemispheric dawnside flanks when the interplanetary magnetic field (IMF) clock angle ? = arctan(By/Bz) is within ∼45° of the equatorial plane. The event selection is based on the relative proximity be…
Evidence for the Same Hot Plasma after Coronal Mass Ejection Events, in Both Remote and In Situ Observations
Poletto, G.; Ko, Y. -K.; Bemporad, Alessandro +4 more
We present here evidence for highly ionized Fe observed both in the corona, in the aftermath of a coronal mass ejection, and, after propagation, in situ. The apparent source temperature is greater than 6 MK. To our knowledge, this is the first time that such an unambiguous identification has been made. This detection complements studies correlatin…
A serendipitous survey for galaxy clusters by the XMM-Newton Survey Science Center
Elvis, M.; Watson, M. G.; Lamer, G. +6 more
We describe the initial results of a programme to detect and identify extended X-ray sources found serendipitously in XMM-Newton observations. We have analyzed 186 EPIC-PN images at high galactic latitude with a limiting flux of 1 × 10 -14 erg cm -2 s -1 and found 62 cluster candidates. Thanks to the enhanced sensi…