Search Publications
Time Variation and Statistical Studies of Magnetic Helicity Injection in Solar Magnetic Regions
Sakurai, T.; Yamamoto, Tetsuya T.
In this study, we analyzed the helicity injection in solar active regions statistically with the method proposed by Kusano et al. We investigated the variation in helicity injection as an active region evolves and the statistical distribution of helicity injection against the magnetic flux (Φ) and the latitude. The temporal evolution of active reg…
Magnetic Structure of Umbral Dots Observed with the Hinode Solar Optical Telescope
Ichimoto, Kiyoshi; Katsukawa, Yukio; Kitai, Reizaburo +1 more
A high-resolution, seeing-free spectroscopic observation of a decaying sunspot was made with the Solar Optical Telescope aboard the Hinode satellite. The target was NOAA 10944, located in the west side of the solar surface from 2007 March 2 to March 4. The umbra included many umbral dots (UDs) with a size of ∼300 km in continuum light. We report o…
Comparison of HIPWAC and Mars Express SPICAM observations of ozone on Mars 2006-2008 and variation from 1993 IRHS observations
Lefèvre, Franck; Fast, Kelly E.; Sonnabend, Guido +5 more
Ozone is a tracer of photochemistry in the atmosphere of Mars and an observable used to test predictions of photochemical models. We present a comparison of retrieved ozone abundances on Mars using ground-based infrared heterodyne measurements by NASA Goddard Space Flight Center's Heterodyne Instrument for Planetary Wind And Composition (HIPWAC) a…
Acoustic-Power Maps of Solar Active Regions with Direction Filters and Phase-Velocity Filters
Liang, Zhi-Chao; Chou, Dean-Yi; Sun, Ming-Tsung +1 more
We study the properties of power maps of solar acoustic waves filtered with direction filters and phase-velocity filters. A direction filter is used to isolate acoustic waves propagating in a narrow range of directions. The acoustic-power map of the waves filtered with a direction filter shows extended reduced-power features behind magnetic region…
A New XMM-Newton Long Look of the Low-Luminosity Active Galactic Nucleus NGC 3226
Rothschild, R. E.; Markowitz, A.; Binder, B.
We present the results of a 99 ks XMM-Newton observation of NGC 3226, a low-luminosity active galactic nucleus. The long exposure has enabled us to critically test several models for the form of the 0.3-10 keV spectrum. We find the 0.3-10 keV spectrum is best fitted by a partial-covering model, consisting of a power-law continuum (Γ ≈ 1.87) absorb…
Initial mass function biases created by binning and unresolved systems
Maíz Apellániz, Jesús
I discuss two of the possible sources of biases in the determination of the stellar initial mass function: binning and the existence of unresolved components. The first source is important for clusters with a small number of stars detected in a given mass bin, while the second is relevant for all clusters located beyond the immediate solar neighbo…
Oxygen in dense interstellar gas. The oxygen abundance of the star forming core ρ Ophiuchi A
Liseau, R.; Justtanont, K.
Context: Oxygen is the third most abundant element in the universe, but its chemistry in the interstellar medium is still not understood well.
Aims: To critically examine the entire oxygen budget, we initially attempt to estimate the abundance of atomic oxygen, O, in the only region where molecular oxygen, O{2}, has been detected to date.
…
Huygens HASI servo accelerometer: A review and lessons learned
Leese, M. R.; Hathi, B.; Zarnecki, J. C. +6 more
The servo accelerometer constituted a vital part of the Huygens Atmospheric Structure Instrument (HASI): flown aboard the Huygens probe, it operated successfully during the probe's entry, descent, and landing on Titan, on 14th January 2005. This paper reviews the Servo accelerometer, starting from its development/assembly in the mid-1990s, to moni…
Interstellar heliospheric probe/heliospheric boundary explorer mission—a mission to the outermost boundaries of the solar system
Wimmer-Schweingruber, Robert F.; Valtonen, Eino; Wurz, Peter +4 more
The Sun, driving a supersonic solar wind, cuts out of the local interstellar medium a giant plasma bubble, the heliosphere. ESA, jointly with NASA, has had an important role in the development of our current understanding of the Suns immediate neighborhood. Ulysses is the only spacecraft exploring the third, out-of-ecliptic dimension, while SOHO h…
A new multivariate time series data analysis technique: Automated detection of flux transfer events using Cluster data
Lavraud, B.; Wang, Y.; Karimabadi, H. +2 more
A new data mining technique called MineTool-TS is introduced which captures the time-lapse information in multivariate time series data through extraction of global features and metafeatures. This technique is developed into a JAVA-based data mining software which automates all the steps in the model building to make it more accessible to nonexper…