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Irradiance models
Solanki, S. K.; Krivova, N. A.; Wenzler, T.
Measurements of solar irradiance have revealed variations at all the sampled time scales (ranging from minutes to the length of the solar cycle). One important task of models is to identify the causes of the observed (total and spectral) irradiance variations. Another major aim is to reconstruct irradiance over time scales longer than sampled by d…
INTEGRAL observations of five sources in the Galactic Center region
Sunyaev, R.; Revnivtsev, M.; Lutovinov, A. +1 more
A number of new X-ray sources (IGR J17091-3624, IGR/XTE J17391-3021, IGR J17464-3213 (=XTE J17464-3213 = H 1743-322), IGR J17597-2201, SAX/IGR J18027-2017) have been observed with the INTEGRAL observatory during ultra deep exposure of the Galactic Center region in August-September 2003. Most of them were permanently visible by INTEGRAL at energies…
Time series study of EUV spicules observed by SUMER/SoHO
Doyle, J. G.; Xia, L. D.; Popescu, M. D. +1 more
Here we study the dynamic properties of EUV spicules seen at the solar limb. The selected data were obtained as time series in polar coronal holes by SUMER/SoHO. The short exposure time and the almost fixed position of the spectrometer's slit allow the analysis of spicule properties such as occurrence, lifetime and Doppler velocity. Our data revea…
Variability of Fe II Emission Features in the Seyfert 1 Galaxy NGC 5548
Peterson, Bradley M.; Vestergaard, Marianne
We study the low-contrast Fe II emission blends in the ultraviolet (1250-2200 Å) and optical (4000-6000 Å) spectra of the Seyfert 1 galaxy NGC 5548 and show that these features vary in flux and that these variations are correlated with those of the optical continuum. The amplitude of variability of the optical Fe II emission is 50%-75% that of Hβ,…
Reevaluation of the Magnetic Structure and Evolution Associated with the Bastille Day Flare on 2000 July 14
Zhang, Hongqi; Liu, Chang; Wang, Haimin +1 more
The Bastille Day flare on 2000 July 14 was well observed by several space- and ground-based observatories and studied extensively by many researchers. Recently, we discovered that a large fraction of X-class flares are associated with a very interesting evolutionary pattern in δ sunspots: part of the outer δ spot structure decays rapidly after maj…
The early stage of a cosmic collision? XMM-Newton unveils two obscured AGN in the galaxy pair ESO509-IG066
Guainazzi, M.; Jiménez-Bailón, E.; Piconcelli, E. +1 more
We report the XMM-Newton discovery of a X-ray bright AGN pair in the interacting galaxy system ESO509-IG066. Both galaxies host an X-ray luminous (LX ∼ 1043 erg s-1) obscured nucleus with column densities NH ≃ 7 × 1022 cm-2 and NH ≃ 5 × 1021 cm-2. Th…
How Prometheus creates structure in Saturn's F ring
Porco, Carolyn C.; Burns, Joseph A.; Murray, Carl D. +4 more
Images of Saturn's narrow and contorted F ring returned by the Cassini spacecraft have revealed phenomena not previously detected in any planetary ring system. The perturbing effect of the inner shepherding satellite, Prometheus, seems to introduce channels through the F ring and a `streamer'-a line of particles that link the ring to the satellite…
XMM-Newton Observation of an X-Ray Trail between the Spiral Galaxy NGC 6872 and the Central Elliptical Galaxy NGC 6876 in the Pavo Group
Jones, Christine; Forman, William R.; Nulsen, Paul +2 more
We present XMM-Newton observations of a trail of enhanced X-ray emission extending along the full 8.7 arcmin ×4' region between the large spiral galaxy NGC 6872 and the dominant elliptical galaxy NGC 6876 in the Pavo group, the first known X-ray trail associated with a spiral galaxy in a poor galaxy group and, with a projected length of…
An XMM-Newton Observation of the Drifting Pulsar B0943+10
Pavlov, George G.; Zhang, Bing; Sanwal, Divas
Radio pulsar subpulse drifting has been interpreted as rotation of subbeams (sparks) of pair plasma produced by intermittent breakdowns of an inner vacuum gap above the pulsar polar cap. This model also predicts strong thermal X-ray emission from the polar cap caused by inflowing particles created in spark discharges. We have observed the best-stu…
Flares observed with XMM-Newton and the VLA
Audard, M.; Güdel, M.; Smith, K.
We present lightcurves obtained in X-ray by the XMM-Newton EPIC cameras and simultaneous radio lightcurves obtained with the VLA for five active M-type flare stars. A number of flare events were observed, and by comparing radio with X-ray data, we consider various possible flare mechanisms. In cases where there seems to be a clear correlation betw…