Search Publications
Can the Excess in the Fe XXVI Lyγ Line from the Galactic Center Provide Evidence for 17 keV Sterile Neutrinos?
Silk, Joseph; Prokhorov, Dmitry
Sterile neutrinos (or right-handed neutrinos) are a plausible warm dark matter candidate. We find that the excess of the intensity in the 8.7 keV line (at the energy of the Fe XXVI Lyγ line) in the spectrum of the Galactic center observed by Suzaku cannot be explained by standard ionization and recombination processes. We suggest that the origin o…
A Flux Rope Eruption Triggered by Jets
Guo, Juan; Zhang, Hongqi; Liu, Yu +3 more
We present an observation of a filament eruption caused by recurrent chromospheric plasma injections (surges/jets) on 2006 July 6. The filament eruption was associated with an M2.5 two-ribbon flare and a coronal mass ejection (CME). There was a light bridge in the umbra of the main sunspot of NOAA 10898; one end of the filament was terminated at t…
Nonlinear Force-free Modeling of Magnetic Fields in a Solar Filament
Xu, Yan; Jing, Ju; Wang, Haimin +3 more
We present a striking filament pattern in the nonlinear force-free (NLFF) chromospheric magnetic field of the active region NOAA 10956. The NLFF chromospheric field is extrapolated from the Hinode high-resolution photospheric vector magnetogram using the weighted optimization method. The modeled structure is characterized by a highly sheared field…
Testing Accretion Disk Structure with Suzaku Data of LMC X-3
Done, Chris; Dotani, Tadayasu; Ueda, Yoshihiro +3 more
The Suzaku observation of LMC X-3 gives the best data to date on the shape of the accretion disk spectrum. This is due to the combination of very low absorbing column density along this line of sight, which allows the shape of the disk emission to be constrained at low energies by the CCDs while the tail can be simultaneously determined up to 30 k…
Solar Rotation Rate During the Cycle 24 Minimum in Activity
Basu, Sarbani; Antia, H. M.
The minimum of solar cycle 24 is significantly different from most other minima in terms of its duration as well as its abnormally low levels of activity. Using available helioseismic data that cover epochs from the minimum of cycle 23 to now, we study the differences in the nature of the solar rotation between the minima of cycles 23 and 24. We f…
A Change of Rotation Profile in the Envelope in the HH 111 Protostellar System: A Transition to a Disk?
Lee, Chin-Fei
The HH 111 protostellar system consists of two Class I sources (VLA 1 and 2) with putative disks deeply embedded in a flattened envelope at a distance of 400 pc. A follow-up study of this system in C18O (J = 2-1), SO (NJ = 56-45), and 1.33 mm continuum at ~1'' (400 AU) resolution is performed, and it may…
X-ray Observational Signature of a Black Hole Accretion Disk in an Active Galactic Nucleus RX J1633+4718
Wang, T. G.; Yuan, W.; Liu, B. F. +1 more
We report the discovery of a luminous ultra-soft X-ray excess in a radio-loud narrow-line Seyfert 1 galaxy, RX J1633+4718, from archival ROSAT observations. The thermal temperature of this emission, when fitted with a blackbody, is as low as 32.5+8.0 -6.0 eV. This is in remarkable contrast to the canonical temperatures of ~0.…
Patterns of Flows in an Intermediate Prominence Observed by Hinode
Cao, Wenda; Chae, Jongchul; Ahn, Kwangsu +1 more
The investigation of plasma flows in filaments/prominences gives us clues to understanding their magnetic structures. We studied the patterns of flows in an intermediate prominence observed by Hinode/SOT. By examining a time series of Hα images and Ca II H images, we have found horizontal flows in the spine and vertical flows in the barb. Both of …
Could the Planets Around HR 8799 be Brown Dwarfs?
Rieke, George H.; Moro-Martín, Amaya; Su, Kate Y. L.
We consider the limiting case for orbital stability of the companions to HR 8799. This case is only consistent with ages for the system of ~100 Myr, not with the 1 Gyr age proposed from asteroseismology. The discrepancy probably arises because the inclination of the star is smaller than assumed in analyzing the asteroseismology data. Given this yo…
Re-flaring of a Post-flare Loop System Driven by Flux Rope Emergence and Twisting
Cheng, X.; Ding, M. D.; Zhang, J. +3 more
In this Letter, we study in detail the evolution of the post-flare loops on 2005 January 15 that occurred between two consecutive solar eruption events, both of which generated a fast halo coronal mass ejection (CME) and a major flare. The post-flare loop system, formed after the first CME/flare eruption, evolved rapidly, as manifested by the unus…