Three-Dimensional Properties of Coronal Mass Ejections from STEREO/SECCHI Observations

We identify 565 coronal mass ejections (CMEs) between January 2007 and December 2010 in observations from the twin STEREO/SECCHI/COR2 coronagraphs aboard the STEREO mission. Our list is in full agreement with the corresponding SOHO/LASCO CME Catalog ( http://cdaw.gsfc.nasa.gov/CME_list/ ) for events with angular widths of 45^° and up. The monthly event rates behave similarly to sunspot rates showing a three- to fourfold rise between September 2009 and March 2010. We select 51 events with well-defined white-light structure and model them as three-dimensional (3D) flux ropes using a forward-modeling technique developed by Thernisien, Howard and Vourlidas (Astrophys. J. 652, 763??C?773, 2006). We derive their 3D properties and identify their source regions. We find that the majority of the CME flux ropes (82?%) lie within 30^° of the solar equator. Also, 82?% of the events are displaced from their source region, to a lower latitude, by 25^° or less. These findings provide strong support for the deflection of CMEs towards the solar equator reported in earlier observations, e.g. by Cremades and Bothmer (Astron. Astrophys. 422, 307??C?322, 2004).     

RHESSI Data Analysis Software: Rationale and Methods

The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) performs imaging spectroscopy of the Sun with high spatial and spectral resolution from 3 keV to 17 MeV using indirect Fourier-transform techniques. We review the rationale behind the RHESSI data analysis software, and explain the underlying structure of the software tools. Our goal was to make the large data set available within weeks after the RHESSI launch, and to make it possible for any member of the scientific community to analyze it easily. This paper describes the requirements for the software and explores our decisions to use the SolarSoftWare and Interactive Data Language programming packages, to support both Windows and Unix platforms, and to use object-oriented programming. We also describe how the data are rapidly disseminated and how ancillary data sets are used to enhance the RHESSI science. Finally, we give a schematic overview of some of the data flow through the high-level analysis tools. More information on the data and analysis procedures can be found at the RHESSI Data Center website, http://hesperia.gsfc.nasa.gov/rhessidatacenter. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1022444531435     

The WMAP data and results

The Wilkinson Microwave Anisotropy Probe (WMAP) science team has released results from the first year of operation at the Earth–Sun L₂ Lagrange point. The maps are consistent with previous observations but have much better sensitivity and angular resolution than the COBE DMR maps, and much better calibration accuracy and sky coverage than ground-based and balloon-borne experiments. The angular power spectra from these ground-based and balloon-borne experiments are consistent within their systematic and statistical uncertainties with the WMAP results. WMAP detected the large angular-scale correlation between the temperature and polarization anisotropies of the CMB caused by electron scattering since the Universe became reionized after the “Dark Ages”, giving a value for the electron scattering optical depth of 0.17 ± 0.04. The simplest ΛCDM model with n=1 and Ω_tot=1 fixed provides an adequate fit to the WMAP data and gives parameters which are consistent with determinations of the Hubble constant and observations of the accelerating Universe using supernovae. The time-ordered data, maps, and power spectra from WMAP can be found at http://lambda.gsfc.nasa.gov along with 13 papers by the WMAP science team describing the results in detail.     

再探伽玛射线暴中能量与脉冲宽度的依赖关系

探索来源于BATSE(http://cossc:gsfc:nasa:gov/batse)的GRB(Gamma-Ray Burst,伽玛射线暴)观测数据的半峰宽度(FWHM)与能量之间的关系,基于64个用KRL函数模型(即,文[1]中的(22)式)能很好地拟合的FRDE(Fast Rise and Exponential Decay,快速上升指数下降)型脉冲样本。发现64个样本中有63个的半峰宽度(FWHM)与能量之间的关系属于平台—幂率—平台型结构或峰型结构。64个样本的半峰宽度(FWHM)与能量之间的关系在观测中可详细分为5种类型:a)有34个样本为幂率形式关系;b)18个样本为低能段平台关系;c)有7个样本为高能段平台关系;d)4个样本为峰型结构关系;e)另外有1个样本为其他结构。结果表明:GRB观测数据的半峰宽度(FWHM)与能量之间的确存在有幂率的关系。此结果进一步确认了文[2](Qin etal 2005)的观点,即半峰宽度(FWHM)与能量之间的关系是由于火球模型的多普勒效应(Doppler effect)导致的。     

Earth-Based Support for the Titan Saturn System Mission

The Titan Saturn System Mission (TSSM) concept is composed of a TSSM orbiter provided by NASA that would carry two Titan in situ elements provided by ESA: the montgolfière and the probe/lake lander. One overarching goal of TSSM is to explore in situ the atmosphere and surface of Titan. The mission has been prioritized as the second Outer Planets Flagship Mission, the first one being the Europa Jupiter System Mission (EJSM). TSSM would launch around 2023–2025 arriving at Saturn 9 years later followed by a 4-year science mission in the Saturn system. Following delivery of the in situ elements to Titan, the TSSM orbiter would explore the Saturn system via a 2-year tour that includes Enceladus and Titan flybys before entering into a dedicated orbit around Titan. The Titan montgolfière aerial vehicle under consideration will circumnavigate Titan at a latitude of ~20° and at altitudes of ~10 km for a minimum of 6 months. The probe/lake lander will descend through Titan’s atmosphere and land on the liquid surface of Kraken Mare (~75° north latitude). As for any planetary space science mission, and based on the Cassini–Huygens experience, Earth-based observations will be synergistic and enable scientific optimization of the return of such a mission. Some specific examples of how this can be achieved (through VLBI and Doppler tracking, continuous monitoring of atmospheric and surface features, and Direct-to-Earth transmission) are described in this paper.     

Mapping of the icy Saturnian satellites: First results from Cassini-ISS

Images of the icy Saturnian satellites Mimas, Enceladus, Tethys, Dione, Rhea, Iapetus, and Phoebe, derived by the Voyager and Cassini cameras are used to produce new local high-resolution image mosaics as well as global mosaics [http://ciclops.org, http://photojournal.jpl.nasa.gov]. These global mosaics are valuable both for scientific interpretation and for the planning of future flybys later in the ongoing Cassini orbital tour. Furthermore, these global mosaics can be extended to standard cartographic products.     

The EMIR Near-Infrared Multi-Object Spectrograph for GTC

EMIR is a near-infrared (NIR) multi-object spectrograph (MOS) proposed for first-generation common user instrument of the Gran Telescopio Canarias GTC. It has three observing modes: imaging, multiobject spectroscopy and integral-field spectroscopy, in the NIR Z, J, H and K bands. The design uses cryogenic multislit masks to allow simultaneous spectroscopy of up to approximately 50 objects. The spectral resolution R=5000 allows for effective "see through" the OH line forest that dominates the J and H sky backgrounds. EMIR addresses one of the fundamental goals of large telescopes, the spectroscopy of large quantities of faint sources. Science applications include young stellar objects embedded in molecular clouds, brown dwarfs, stellar clusters, resolved population in external galaxies and distant galaxies. EMIR is being designed by a consortium of Spanish, UK and French Institutes. Project updates and information will be posted at http://www.ucm.es/info/emir/. This revised version was published online in July 2006 with corrections to the Cover Date.     

High-resolution Atlases of Mimas, Tethys, and Iapetus derived from Cassini-ISS images

The Cassini Imaging Science Subsystem (ISS) acquired 282, 258, and 513 high-resolution images (<800 m/pixel) of Mimas, Tethys, and Iapetus, respectively, during two close flyby of Tethys and Iapetus and eight non-targeted flybys between 2004 and 2007. We combined these images with lower-resolution Cassini images and others taken by Voyager cameras to produce high-resolution semi-controlled mosaics of Mimas, Tethys, and Iapetus. These global mosaics are the baseline for high-resolution Mimas and Iapetus maps and a Tethys atlas. The nomenclature used in these maps was proposed by the Cassini imaging team and was approved by the International Astronomical Union (IAU). The two maps and the atlas are available to the public through the Imaging Team's website [http://ciclops.org/maps] and the Planetary Data System [http://pds.jpl.nasa.gov].     

Understanding the Internal Magnetic Field Configurations of ICMEs Using More than 20 Years of <Emphasis Type="Italic">Wind</Emphasis> Observations

The magnetic topology, structure, and geometry of the magnetic obstacles embedded within interplanetary coronal mass ejections (ICMEs) are not yet fully and consistently described by in situ models and reconstruction techniques. The main goal of this work is to better understand the status of the internal magnetic field of ICMEs and to explore in situ signatures to identify clues to develop a more accurate and reliable in situ analytical models. We take advantage of more than 20 years of Wind observations of transients at 1 AU to compile a comprehensive database of ICMEs through three solar cycles, from 1995 to 2015. The catalog is publicly available at wind.gsfc.nasa.gov and is fully described in this article. We identify and collect the properties of 337 ICMEs, of which 298 show organized magnetic field signatures. To allow for departures from idealized magnetic configurations, we introduce the term “magnetic obstacle” (MO) to signify the possibility of more complex configurations. To quantify the asymmetry of the magnetic field strength profile within these events, we introduce the distortion parameter (DiP) and calculate the expansion velocity within the magnetic obstacle. Circular-cylindrical geometry is assumed when the magnetic field strength displays a symmetric profile. We perform a statistical study of these two parameters and find that only 35% of the events show symmetric magnetic profiles and a low enough expansion velocity to be compatible with the assumption of an idealized cylindrical static flux rope, and that 41% of the events do not show the expected relationship between expansion and magnetic field compression in the front, with the maximum magnetic field closer to the first encounter of the spacecraft with the magnetic obstacle; 18% show contractions (i.e. apparent negative expansion velocity), and 30% show magnetic field compression in the back. We derive an empirical relation between DiP and expansion velocity that is the first step toward improving reconstructions with possible applications to space weather studies. In summary, our main results demonstrate that the assumed correlation between expanding structure and asymmetric magnetic field is not always valid. Although 59% of the cases could be described by circular-cylindrical geometry, with or without expansion, the remaining cases show significant in situ signatures of departures from circular-cylindrical geometry. These results will aid in the development of more accurate in situ models to reconcile image.     

The Kepler Mission: Astrophysics and Eclipsing Binaries

The Kepler Mission is a photometric space mission that will continuously observe a single 100 square degree field of view (FOV) of the sky of more than 100,000 stars in the Cygnus-Lyra region for four or more years with a precision of 14 parts per million (ppm) for a 6.5 hour integration including shot noise for a twelfth magnitude star. The primary goal of the mission is to detect Earth-size planets in the habitable zone of solar-like stars. In the process, many eclipsing binaries (EB) will also be detected. Prior to launch, the stellar characteristics will have been determined for all the stars in the FOV with K<14.5. As part of the verification process, stars with transits (about 5%) will need to have follow-up radial velocity observations performed to determine the component masses and thereby separate grazing eclipses caused by stellar companions from transits caused by planets. The result will be a rich database on EBs. The community will have access to the archive for uses such as for EB modeling of the high-precision light curves. A guest observer program is also planned for objects not already on the target list.     

Changes of solar magnetic asymmetry

The results of an analysis of the north–south asymmetry in solar activity and solar magnetic fields are reported. The analysis is based on solar mean magnetic field and solar polar magnetic field time series, 1975–2015 (http://wso.stanford.edu), and the Greenwich sunspot data, 1875–2015 (http://solarscience.msfc.nasa.gov/greenwch.shtml). A long-term cycle (small-scale magnetic fields, toroidal component) of ~140 years is identified in the north–south asymmetry in solar activity by analyzing the cumulative sum of the time series for the north–south asymmetry in the area of sunspots. A comparative analysis of the variations in the cumulative sums of the time series composed of the daily values of the sun’s global magnetic field and in the asymmetry of the daily sunspot data over the time interval 1975–2015 shows that the photospheric large-scale magnetic fields may also have a similar long-term cycle. The variations in the asymmetry of large-scale and small-scale solar magnetic fields (sunspot area) are in sync until 2005.5 and in antiphase since then.     

Science issues of the “Spektr-UF” project

The “Spektr-UF” project (“World Space Observatory-Ultraviolet” (WSO-UV)) will be the largest space observatory for observations in the UV band. In this paper we briefly outline the key science issues that the WSO-UV will address during its lifetime with the help of its instrumentation: spectrographs and a field camera unit. Of special interest are early Universe physics (reionization and search for baryonic matter), star formation, chemical evolution of galaxies, astrophysical accretion processes, stellar atmosphere physics, and planetary atmosphere studies.     

Venus Express science planning

Venus Express is the first European mission to the planet Venus. Its payload consists of seven instruments and will investigate the atmosphere, the plasma environment, and the surface of Venus from orbit. Science planning is a complex process that takes into account requests from all experiments and the operational constraints. The planning of the science operations is based on synergetic approach to provide good coverage of science themes derived from the main mission goals. Typical observations in a single orbit—so-called “science cases” are used to build the mission science activity plan. The nominal science mission (from June 4, 2006 till October 2, 2007) is divided in nine phases depending on observational conditions, occurrences of the solar and Earth occultation, and particular science goals. The observation timelines for each phase were developed in a coordinated way to optimize the payload activity, maximize the overall mission science return, and to fit into the available mission budgets.     

galev evolutionary synthesis models – I. Code, input physics and web interface

galev (GALaxy EVolution) evolutionary synthesis models describe the evolution of stellar populations in general, of star clusters as well as of galaxies, both in terms of resolved stellar populations and of integrated light properties over cosmological time-scales of ≥13 Gyr from the onset of star formation shortly after the big bang until today.
For galaxies, galev includes a simultaneous treatment of the chemical evolution of the gas and the spectral evolution of the stellar content, allowing for what we call a chemically consistent treatment: we use input physics (stellar evolutionary tracks, stellar yields and model atmospheres) for a large range of metallicities and consistently account for the increasing initial abundances of successive stellar generations.
Here we present the latest version of the galev evolutionary synthesis models that are now interactively available at http://www.galev.org . We review the currently used input physics, and also give details on how this physics is implemented in practice. We explain how to use the interactive web interface to generate models for user-defined parameters and also give a range of applications that can be studied using galev , ranging from star clusters, undisturbed galaxies of various types E–Sd to starburst and dwarf galaxies, both in the local and the high-redshift Universe.     

An Impacting Descent Probe for Europa and the Other Galilean Moons of Jupiter

We present a study of an impacting descent probe that increases the science return of spacecraft orbiting or passing an atmosphere-less planetary bodies of the solar system, such as the Galilean moons of Jupiter. The descent probe is a carry-on small spacecraft (<100 kg), to be deployed by the mother spacecraft, that brings itself onto a collisional trajectory with the targeted planetary body in a simple manner. A possible science payload includes instruments for surface imaging, characterisation of the neutral exosphere, and magnetic field and plasma measurement near the target body down to very low-altitudes (~1 km), during the probe’s fast (~km/s) descent to the surface until impact. The science goals and the concept of operation are discussed with particular reference to Europa, including options for flying through water plumes and after-impact retrieval of very-low altitude science data. All in all, it is demonstrated how the descent probe has the potential to provide a high science return to a mission at a low extra level of complexity, engineering effort, and risk. This study builds upon earlier studies for a Callisto Descent Probe for the former Europa-Jupiter System Mission of ESA and NASA, and extends them with a detailed assessment of a descent probe designed to be an additional science payload for the NASA Europa Mission.     

The effect of the prompt particle environment at L2 on optical CCDs for astronomy and astrophysics

The increasing number of probes carrying large focal planes consisting of many charge-coupled devices (CCDs), planned to be sent to the L2 Lagrangian point, 1.5 million kilometres from Earth in the next 15 years, implies that a detailed study of the effects of the prompt particle environment at L2 on CCDs is required. The focus of this study will be on CCDs for optical astronomy, astrometry and photometric applications. This study will be of particular interest to GAIA the European Space Agency's (ESA) cornerstone optical astronomy mission to further explore and map sections of our galaxy in greater detail. The results will also have implications for future X-ray astronomy missions like the X-ray Evolving Universe Spectroscopy Mission (XEUS). Both the above missions will require large area focal planes incorporating many CCD detectors.The sources of the instrument background are both solar and galactic and if a probe is launched around the peak in the next solar cycle (2010), the possible false detection rate or the amount of data that could be lost during a mission must be determined. This paper presents measured data for a spacecraft in a geostationary orbit, specifically Geosynchronous Operational Environmental Satellites (GOES) data, and makes predictions of the flux and energy of the particle environment at L2. The solar and galactic cosmic ray background was determined by using the Cosmic Ray Effects on Micro-Electronics or CREME96 code. A comparison was then made between the GOES data and the output from the CREME96 code in order to make predictions about the L2 environment.