Search Publications
Missions
Journals
Publication Years
Statistics of superimposed flares in the Taurus molecular cloud
Audard, M.; Güdel, M.; Telleschi, A. +2 more
Context: Stochastically occurring flares provide a possible mechanism of coronal heating in magnetically active stars such as T Tauri objects in star-forming regions.
Aims: We investigate the statistics of stellar X-ray light curves from the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST).
Methods: To this end, the light cu…
Study of the fast X-ray transient XTE J1901+014 based on INTEGRAL, RXTE, and ROSAT data
Lutovinov, A. A.; Karasev, D. I.; Grebenev, S. A.
The source XTE J1901+014 discovered by the RXTE observatory during an intense outburst of hard radiation and classified as a fast X-ray transient is studied. The source’s spectral characteristics in the quiescent state have been investigated for the first time both in the soft X-ray energy range (3 20 keV) based on ROSAT and RXTE data and in the h…
Statistical Correlations between Parameters of Photospheric Magnetic Fields and Coronal Soft X-Ray Brightness
Jing, Ju; Wang, Haimin; Song, Hui +4 more
Using observations of more than 160 active regions, we investigate the relationship between the coronal X-ray brightness, LB, and five parameters derived from the photospheric magnetic fields. The coronal X-ray brightness and the magnetic measures were obtained from co-aligned SFD composite images from the Yohkoh SXT and full-disk magne…
Discovery of 13 Nova Candidates in M87
Ferguson, Henry C.; Livio, Mario; Sparks, William B. +2 more
We have made 13 positive identifications of near-ultraviolet (NUV) transient sources in the giant elliptical galaxy M87 using the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). We give a representative sample of the light curves that we derive for these transients, and based on their characteristics we ident…
Soft and Hard X-Ray Excess Emission in Abell 3112 Observed with Chandra
Bonamente, Massimiliano; Lieu, Richard; Nevalainen, Jukka
Chandra ACIS-S observations of the galaxy cluster Abell 3112 feature the presence of an excess of X-ray emission above the contribution from the diffuse hot gas, which can be equally well modeled with an additional nonthermal power-law model or with a low-temperature thermal model of low metal abundance. We show that the excess emission cannot be …
High-Energy Protons Associated with Liftoff of a Coronal Mass Ejection
Riihonen, E.; Torsti, J.; Klein, K. -L. +7 more
Large solar energetic particle (SEP) events occur in association with fast coronal mass ejections (CMEs) and flares. We have studied in detail the rise phase of the SEP event of 1998 May 2 observed with the particle telescope ERNE aboard the Solar and Heliospheric Observatory (SOHO) spacecraft and ground-based neutron monitors. Using the ERNE data…
Contributions to the cross shock electric field at a quasiperpendicular collisionless shock
Eastwood, J. P.; Bale, S. D.; Mozer, F. S. +1 more
The normal electric field structure of a supercritical (M ms = 5.2), quasiperpendicular (theta Bn = 70°) collisionless shock is examined using Cluster four-spacecraft observations of the terrestrial bow shock. Comparing the observed electric field with magnetic field and plasma observations, two different techniques find that the J × B/ne term in …
Hα Dimming Associated With the Eruption of a Coronal Sigmoid in the Quiet Sun
Yang, Liheng; Shen, Yuandeng; Chen, Huadong +2 more
We report on the occurrence of Hα dimming associated with a sigmoid eruption in a quiet-sun region on 14 August 2001. The coronal sigmoid in soft X-ray images from the Yohkoh Soft X-ray Telescope was located over an Hα filament channel. Its eruption was accompanied by a flare of GOES X-ray class C2.3 and possibly associated with a halo coronal mas…
A U-band survey of brown dwarfs in the Taurus molecular cloud with the XMM-Newton optical/UV monitor
Audard, M.; Güdel, M.; Grosso, N. +2 more
Aims:We aim to characterize the U-band variability of young brown dwarfs in the Taurus Molecular Cloud and discuss its origin.
Methods: We used the XMM-Newton Extended Survey of the Taurus Molecular Cloud, where a sample of 11 young bona fide brown dwarfs (spectral type later than M 6) were observed simultaneously in X-rays with XMM-Newton and…
A New Explanation for the Origin of Trans-equatorial Loops based on a Dynamo Model
Wang, Jingxiu; Jiang, Jie; Choudhuri, Arnab Rai
Trans-equatorial loops (TLs) are one of the distinct magnetic structures in the solar corona and have a close relationship to solar activity. We present a systematic study of the origin of TLs linking with the Babcock - Leighton dynamo process based on the model of Chatterjee, Nandy, and Choudhuri (Astron. Astrophys.427, 1019, 2004). We propose th…