Search Publications
On the line profile changes observed during the X2.2 class flare in the active region NOAA 11158
Raja Bayanna, Ankala; Kumar, Brajesh; Venkatakrishnan, Parameswaran +4 more
The solar active region NOAA 11158 produced a series of flares during its passage through the solar disk. The first major flare (of class X2.2) of the current solar cycle occurred in this active region on 2011 February 15 around 01:50 UT. We have analyzed the Dopplergrams and magnetograms obtained by the Helioseismic and Magnetic Imager (HMI) inst…
X-Ray Detection of the Cluster Containing the Cepheid S Mus
Schaefer, Gail H.; Bond, Howard E.; Evans, Nancy Remage +7 more
The galactic Cepheid S Muscae has recently been added to the important list of Cepheids linked to open clusters, in this case the sparse young cluster ASCC 69. Low-mass members of a young cluster are expected to have rapid rotation and X-ray activity, making X-ray emission an excellent way to discriminate them from old field stars. We have made an…
A Fourier-transformed Bremsstrahlung Flash Model for the Production of X-Ray Time Lags in Accreting Black Hole Sources
Becker, Peter A.; Kroon, John J.
Accreting black hole sources show a wide variety of rapid time variability, including the manifestation of time lags during X-ray transients, in which a delay (phase shift) is observed between the Fourier components of the hard and soft spectra. Despite a large body of observational evidence for time lags, no fundamental physical explanation for t…
The Interaction Between Coronal Mass Ejections and Streamers: A Statistical View over 15 Years (1996 - 2010)
Llebaria, A.; Lamy, P.; Floyd, O.
We report on the statistical analysis of the interaction between coronal mass ejections (CMEs) and streamers based on 15 years (from 1996 to 2010 inclusive) of observation of the solar corona with the LASCO-C2 coronagraph. We used synoptic maps and improved the method of analysis of past investigations by implementing an automatic detection of bot…
Dynamics of the correlation between polar cap radio absorption and solar energetic proton fluxes in the interplanetary medium
Donovan, E. F.; Kouznetsov, A.; Knudsen, D. J. +1 more
During solar energetic particle (SEP) events, large fluxes of energetic particles spreading throughout the interplanetary medium (IPM) have access to the upper polar atmosphere where they play important roles in physical and chemical processes. We examine the dynamics of the relation between solar energetic proton (SEP) fluxes detected outside the…
A ~100 mHz QPO in the X-ray emission from IGR J17361-4441
Ferrigno, C.; Papitto, A.; Belloni, T. M. +1 more
IGR J17361-4441 was discovered by INTEGRAL undergoing its first detectable X-ray outburst in 2011 and was initially classified as an accreting X-ray binary in the globular cluster NGC 6388. A reanalysis of the outburst data collected with INTEGRAL and Swift suggested that the enhanced X-ray emission from IGR J17361-4441 could have been caused by a…
Sparse point-source removal for full-sky CMB experiments: application to WMAP 9-year data
Starck, J. -L.; Bobin, J.; Rassat, A. +2 more
Missions such as WMAP or Planck measure full-sky fluctuations of the cosmic microwave background and foregrounds, among which bright compact source emissions cover a significant fraction of the sky. To accurately estimate the diffuse components, the point-source emissions need to be separated from the data, which requires a dedicated processing. W…
BV technique for investigating 1-D interfaces
Dorville, Nicolas; Belmont, Gérard; Rezeau, Laurence +2 more
To investigate the internal structure of the magnetopause with spacecraft data, it is crucial to be able to determine its normal direction and to convert the measured time series into spatial profiles. We propose here a new single-spacecraft method, called the BV method, to reach these two objectives. Its name indicates that the method uses a comb…
Extreme-ultraviolet Observations of Global Coronal Wave Rotation
Long, D. M.; van Driel-Gesztelyi, L.; Green, L. M. +2 more
We present evidence of global coronal wave rotation in EUV data from SOHO/EIT, STEREO/EUVI, and SDO/AIA. The sense of rotation is found to be consistent with the helicity of the source region (clockwise for positive helicity, anticlockwise for negative helicity), with the source regions hosting sigmoidal structures. We also study two coronal wave …
The kinetic Sunyaev-Zel'dovich effect from the diffuse gas in the Local Group
Loeb, Abraham; Rubin, Douglas
Since the Local Group (LG) of galaxies moves with a bulk velocity with respect to the cosmic microwave background radiation (CMB), free electrons in its gaseous halo should imprint large-scale non-primordial temperature shifts in the CMB via the kinetic Sunyaev-Zel'dovich (kSZ) effect. By modeling the distribution of gas in the LG halo and using i…