bluuebunny/crossref_metadata_2025 huggingface dataset:
Special Session 4: Astronomy Education between Past and Future
Authors: de Greve Jean-Pierre
Published: October 2010

The special session aims at discussing an integrated approach of the different efforts to increase and promote the teaching and learning of astronomy in the world, with emphasis on developing countries. To this end, attention will be given to research on education, specifically in the field of physics, to best practices of the use of astronomy in educational systems (specifically in developing countries), and to innovative learning initiatives other than formal education. The Special Session aims also at creating a universal perspective wherein modern (post-Copernican) astronomy will presented as an intellectual cumulus. The objective of the session is to disseminate best practices in teaching and learning activities of astronomy and to give an opportunity to learn about initiatives in different cultural and socio-economic settings. The special session also wants to give food-for-thought and proposals for reflection for an integrative approach, and for optimization processes, to enhance the interest in astronomy and its role as a trigger towards science education in the educational systems, with emphasis on the developing countries. The outcome should be a sensitization of teachers and students alike to the concept of a universal history of astronomy and creation of some reliable source material which can be used as a teaching aid in a culture-specific context. The outcome could be a set of recommendations for future integrated actions, and eventually recommendations on new initiatives, framed into the new decadal policy plan.
The great oxidation of Earth's atmosphere
Authors: Musielak Zdzislaw E. , Cuntz Manfred , Roy Dipanjan
Published: October 2010

A simplified model of the Earth's atmosphere consisting of three nonlinear differential equations with a driving force was developed by Goldblatt et al. (2006). They found a steady-state solution that exhibits bistability and identified its upper value with the great oxidation of the Earth's atmosphere. Noting that the driving force in their study was a step function, it is the main goal of this paper to investigate the stability of the model by considering two different more realistic driving forces. The stability analysis is performed by using Lyapunov exponents. Our results show that the model remains stable and it does not exhibit any chaotic behavior.
Selection of most promising CoRoT candidates for radial-velocity follow-up
Authors: Da Silva Ronaldo , Silva-Valio Adriana
Published: October 2010

We used the method of Silva & Cruz (2006), which distinguishes between planetary and stellar companions by fitting transit light curves, to select the most promising CoRoT candidates to be monitored with radial-velocity measurements. Testing this method on the light curves of confirmed CoRoT exoplanetary systems shows that the estimated radius for such planets is smaller than 2 RJup, while for most of the light curves in which no planet has been detected, the secondary companion has an estimated radius larger than 2 RJup. We present preliminary results concerning other light curves for which no planet has been detected yet.
Detecting planetary signals with Bayesian methods
Authors: Kotiranta Samuli , Tuomi Mikko
Published: October 2010

In this paper we present an application of Bayesian model comparison to the radial velocity measurements of suspected extra-solar planetary system host star.
Modelling extrasolar planetary atmospheres
Authors: Allard France
Published: October 2010

The atmospheres of close-in Extrasolar Giant Planets (EGPs) experience important stellar radiation, raising the question of the heat redistribution around the planetary surface and of the importance of photochemistry effects for their spectral properties. They experience mass loss via quasi-thermal escape of their lightest elements. They rotate and experience tidal effects. Model atmospheres struggle to include even part of this complexity. Some address the dynamics of the atmospheres as a whole (3D) as subjected to rotation, or as patches of the surface (wind studies), compromising on the details of the composition and radiative/convective properties. Others solve the composition and radiative/convective properties, compromising on dynamical effects such as rotation. In this paper, we review existing model atmospheres for EGPs, and present the first high spatial resolution local (as opposed to global) 2/3D radiation hydrodynamic simulations of EGP atmospheres including dust cloud formation.
The discovery of glycolaldehyde in a star forming region
Authors: Beltràn Maria T. , Codella Claudio , Viti Serena , Neri Roberto , Cesaroni Riccardo
Published: October 2010

Glycolaldehyde is the simplest of the monosaccharide sugars and is directly linked to the origins of life. We report on the detection of glycolaldehyde (CH2OHCHO) towards the hot molecular core G31.41+0.31 through observations with the IRAM PdBI (Plateau de Bure Interferomter) at 1.4, 2.1, and 2.9 mm.
The “Living with a Red Dwarf” program: XUV radiation and plasma environments of hosted planets and impacts on habitability
Authors: Guinan Edward F. , Engle Scott G. , Mizusawa Trisha , McCook George P. , Wolfe A. , Coughlin Jeffrey
Published: October 2010

We describe the LWARD program on dM stars and habitability in their environment.
The SEE-COAST concept
Authors: Boccaletti Anthony , Sozzetti Alessandro , Schneider Jean , Baudoz Pierre , Tinetti Giovanna , Stam Daphne
Published: October 2010

The SEE COAST concept is designed with the objective to characterize extrasolar planets and possibly Super Earths via spectro-polarimetric imaging in reflected light. A space mission complementary to ground-based near IR planet finders is a first secure step towards the characterization of planets with mass and atmosphere comparable to that of the Earth. The accessibility to the Visible spectrum is unique and with important scientific returns.
Accretion Disks in the Sub-Stellar Realm: Properties and Evolution
Authors: Jayawardhana Ray
Published: October 2010

It is now well established that young brown dwarfs harbor accretion disks –and thus undergo a T Tauri phase– similar to their low-mass stellar counterparts. The supporting evidence includes infrared and millimeter observations of the dust component as well as optical and infrared spectra with signatures of gas accretion and outflow. Recent findings suggest that disks are common even around young planetary mass objects. The ubiquity of circum-sub-stellar disks not only hints at a common formation scenario for PMOs, brown dwarfs and stars, but also offers a new regime for investigating processes such as episodic accretion, grain growth and disk clearing.
Evolution of protoplanetary disks
Authors: Dullemond Cornelis P.
Published: October 2010

In this review I gave an overview of the structure and evolution of protoplanetary disks, and how the evolution of dust affects this. This is an important topic because these determine the conditions under which planets are formed, or were formed in our solar system 4.5 billion years ago.
High-energy radiation and particles in the environments of young stellar objects
Authors: Güdel Manuel
Published: October 2010

High-energy radiation and particles profoundly affect circumstellar disk gas and solids. We discuss stellar high-energy sources and summarize their effects on circumstellar disks.
Protoplanetary disks and hard X-rays
Authors: Feigelson Eric D. , Armitage Philip J. , Getman Konstantin V.
Published: October 2010

The physics of protoplanetary disks and the early stages of planet formation is strongly affected by the level of ionization of the largely-neutral gas (Armitage 2009; Balbus 2009). Where the ionization fraction is above some limit around ~ 10−12, the magnetorotational instability (MRI) will ensue and the gas will become turbulent. The presence or absence of disk turbulence at various locations and times has profound implications for viscosity, accretion, dust settling, protoplanet migration and other physical processes. The dominant source of ionization is very likely X-rays from the host star (Glassgold et al. 2000). X-ray emission is elevated in all pre-main sequence stars primarily due to the magnetic reconnection flares similar to, but much more powerful and frequent than, flares on the surface of the contemporary Sun (Feigelson et al. 2007).
Circumstellar disks in high-mass star environments: the early solar system
Authors: Montmerle Thierry , Gounelle Matthieu , Meynet Georges
Published: October 2010

The early solar system represents the only case we have of a circumstellar disk that can be investigated “in situ” -albeit 4.6 Gyr after its formation. Meteorites studies give mounting evidence for an intense irradiation phase of the young circumsolar disk by energetic particles, and also for contamination by products of high-mass stellar and/or explosive nucleosynthesis. We thus discuss the conditions of the birth of the solar system in a high-mass star environment.
Warm and hot circumstellar gas in V1647 Ori during the 2008-2009 outburst
Authors: Carmona A. , Audard M. , van den Ancker M. , van der Plas G. , Goto M. , Fedele D.
Published: October 2010

The pre-main sequence star V1647 Ori started a new outburst in August 2008. From October 2008 to February 2009 we monitored V1647 Ori, obtaining quasi-simultaneous VLT-CRIRES near-IR spectroscopy, VLT-VISIR mid-IR spectroscopy and VLT-FORS2 optical spectroscopy. We studied the evolution of H2 and CO emission from hot and warm gas and Hα and forbidden line-emission during the initial outburst phase of V1647 Ori. Hα is observed in emission displaying P-Cygni profiles with blue-shifted absorption up to –700 km/s, suggesting the presence of a high velocity wind (Fig. 1a). [OI] emission at 6300 Å is observed displaying a blue-shifted emission shoulder, indicating the presence of material moving away from the star (Fig. 1b). We detect H2 1-0 S(1) and CO (P4 to P14 and P30-P38) ro-vibrational lines centered at the velocity of the star at all epochs (Fig. 1c & d). This strongly suggests that the H2 and CO emission originates from a disk and not from a warm outflow. The H2 1–0 S(0) and 2-1 S(1) ro-vibrational lines at 2.22 and 2.24 μm and the pure-rotational H2 0–0 S(1) and 0–0 S(2) lines at 17 and 12 μm were not detected in our spectra. Changes in the Hα and [OI] profiles and the H2 and CO emission observed do not correlate. We modeled the H2 and CO line profiles assuming emission from a flat disk in keplerian rotation with line intensity decreasing with radius (I ~ I0(R/Rmin)−α). We found that the disk of V1647 Ori is observed nearly face-on and that the line emission is produced within a fraction of an AU of the star (Fig. 1d).
Stellar rotation at young ages: new results from Corot's monitoring NGC 2264
Authors: Favata F. , Micela G. , Alencar S. , Aigrain S. , Zwintz K.
Published: October 2010

Stellar rotation at young ages: new results from Corot's Angular momentum is one of the driving forces in the early evolution of stars. Issues such as the coupling between the star and the accretion disk (the so-called disk regulation paradigm), are traced by the evolution of rotational momentum, but affect the star-forming process as a whole. One of the features observed in star-forming regions (e.g. ONC and NGC 2264) of age between 1 and few Myr, for masses above 0.25 solar masses, is a bimodality of the rotational period distribution, with a peak around 1 day and the other at around 4 to 7 days. This bimodality has been interpreted as the smoking gun of the disk-locking mechanism (with the fast rotators having lost their disk and the slow ones still being regulated by their disks).
The early evolution of low mass stars and brown dwarfs
Authors: Baraffe Isabelle
Published: October 2010

My talk will focus on the early evolution of low mass objects. I will discuss the main uncertainties on current evolutionary models and the effects of rotation, magnetic field and early accretion history on young object's structure. I will also present possible solutions to the well known spread in HRD observed in star formation regions for objects of a few Myr old.
Observations of low mass companions to massive stars
Authors: Zinnecker H.
Published: October 2010

Massive stars are known to be multiple systems, often in tight, short-period OB stars binaries (SB1 and SB2, found by spectroscopic monitoring). However, little is known about low-mass companions to massive stars, such as A, F, and G stars with masses in the range of 1 to 3 solar masses. Yet systems of massive stars with wide low-mass companions (of the order of a few AU) must exist, for these are the progenitors of LMXB and HMXB (low-mass and high-mass X-ray binaries).
Dynamical masses for the nearest brown dwarf binary: ε Indi Ba,b
Authors: Cardoso C. V. , McCaughrean M. J. , King R. R. , Close L. M. , Scholz R.-D. , Lenzen R. , Brandner W. , Lodieu N. , Zinnecker H. , Koehler R. , Konopacky Q. M.
Published: October 2010

Binary brown dwarfs are important because their dynamical masses can be determined in a model-independent way. If a main sequence star is also involved, the age and metallicity for the system can be determined, making it possible to break the sub-stellar mass-age degeneracy. The most suitable benchmark system for intermediate age T dwarfs is ε Indi Ba,b, two T dwarfs (spectral types T1 and T6; McCaughrean et al. (2004)) orbiting a K4.5V star, ε Indi A, at a projected separation of 1460AU. At a distance of 3.6224pc (HIPPARCOS distance to ε Indi A; van Leeuwen (2007)), these are the closest brown dwarfs to the Earth, and thus both components are bright and the system is well-resolved. The system has been monitored astrometrically with NACO and FORS2 on the VLT since June 2004 and August 2005, respectively, in order to determine the system and individual masses independent of evolutionary models. We have obtained a preliminary system mass of 121±1MJup. We have also analysed optical/near-IR spectra (0.6-5.0μm at a resolution up to R~5000; King et al. (2009)) allowing us to determine bolometric luminosities, compare and calibrate evolutionary and atmospheric models of T dwarfs at an age of 4-8Gyr.
Prospects for planet formation in multiple stellar systems
Authors: Duchêne Gaspard
Published: October 2010

As I review here, planet formation in multiple stellar systems is far from exceptional. However, it appears that binaries with projected separation in the 5–100 AU range have different initial conditions and end result properties than wider systems, probably because they undergo different physical processes. In addition, very tight binaries, with projected separation less than a few AU, seem to fulfill all the known requirements to form planetary systems, suggesting that circumbinary planets are very likely to exist.
The Role of Multiplicity in Protoplanetary Disk Evolution
Authors: Kraus Adam L. , Ireland Michael J.
Published: October 2010

Interactions with close stellar or planetary companions can significantly influence the evolution and lifetime of protoplanetary disks. It has recently become possible to search for these companions, directly studying the role of multiplicity in protoplanetary disk evolution. We have described an ongoing survey to directly detect these stellar and planetary companions in nearby star-forming regions. Our program uses adaptive optics and sparse aperture mask interferometry to achieve typical contrast limits of Δ K=5-6 at the diffraction limit (5–8 MJup at 5–30 AU), while also detecting similar-flux binary companions at separations as low as 15 mas (2.5 AU). In most cases, our survey has found no evidence of companions (planetary or binary) among the well-known “transitional disk” systems; if the inner clearings are due to planet formation, as has been previously suggested, then this paucity places an upper limit on the mass of any resulting planet. Our survey also has uncovered many new binary systems, with the majority falling among the diskless (WTTS) population. This disparity suggests that disk evolution for close (5–30 AU) binary systems is very different from that for single stars. As we show in Figure 1, most circumbinary disks are cleared by ages of 1–2 Myr, while most circumstellar disks are not. These diskless binary systems have biased the disk frequency downward in previous studies. If we remove our new systems from those samples, we find that the disk fraction for single stars could be higher than was previously suggested.
Muti-technique observations and modelling of the gas and dust phases of protoplanetary disks
Authors: Pinte C. , Ménard F. , Duchěne G. , Augereau J. C.
Published: October 2010

A wide range of high-quality data is becoming available for protoplanetary disks. From these data sets many issues have already been addressed, such as constraining the large scale geometry of disks, finding evidence of dust grain evolution, as well as constraining the kinematics and physico-chemical conditions of the gas phase. Most of these results are based on models that emphasise fitting observations of either the dust component (SEDs or scattered light images or, more recently, interferometric visibilities), or the gas phase (resolved maps in molecular lines). In this contribution, we present a more global approach which aims at interpreting consistently the increasing amount of observational data in the framework of a single model, in order to to better characterize both the dust population and the gas disk properties, as well as their interactions. We present results of such modeling applied to a few disks (e.g. IM Lup, see Figure) with large observational data-sets available (scattered light images, polarisation maps, IR spectroscopy, X-ray spectrum, CO maps). These kinds of multi-wavelengths studies will become very powerful in the context of forthcoming instruments such as Herschel and ALMA.
First results from XILO: XMM-Newton Investigations in the Lambda Orionis star forming region
Authors: Stelzer B. , Barrado y Navascues D. , Huelamo N. , Morales-Calderon M. , Bayo A.
Published: October 2010

The λ Orionis star formation region (1-6 Myr, 400 pc) is a complex of star-forming clouds surrounded by a molecular ring with ~ 5° radius which was probably formed by a supernova explosion (Dolan & Mathieu 2002). For a complete picture of star formation, believed to be determined by the supernova blast, the large-scale distribution of the pre-main sequence population in λ Ori needs to be examined. We have embarked on a multi-wavelength study (XMM-Newton/X-ray, CFHT/optical, Spitzer/IR) of selected areas within this intriguing star-forming complex that enables us to identify young stars and brown dwarfs. Our study comprises various areas within the cloud complex as shown in Fig.1. This data set is among the most extended X-ray surveys carried out with XMM-Newton in a coherent star-forming environment. The XMM-Newton observations combined with optical and IR data reveal the low-mass stellar population down to ~ 0.4 M⊙. For this mass-limited sample, our preliminary analysis confirms the anomalously low disk-fraction of the central star cluster Coll 69, the Eastern extension of its low-mass population pointing towards B 35, and the concentration of young stars in front of B 35. The analysis of the ‘on-cloud field' of B 35 (white in the figure) will show if the cloud is currently forming stars. This will be crucial for determining the star-forming history in the whole λ Ori region.
Stellar and brown dwarf properties from numerical simulations
Authors: Bate Matthew R.
Published: October 2010

We review the statistical properties of stars and brown dwarfs obtained from the first hydrodynamical simulation of star cluster formation to produce more than a thousand stars and brown dwarfs while simultaneously resolving the lowest mass brown dwarfs (those with masses set by the opacity limit for fragmentation), binaries with separations down to ~ 1 AU, and discs with radii greater than ~ 10 AU. In particular, we present the eccentricity distribution of the calculation's very-low-mass and brown dwarf binaries which has not been previously published.
The formation of discs in clusters
Authors: Clark Paul C.
Published: October 2010

We review the properties of the discs that form around ‘sink particles’ in smoothed particle hydrodynamics (SPH) simulations of cluster formation, similar to those of Bate et al. (2003) and Bonnell et al. (2004), and compare them to the observed properties of discs in nearby star-forming regions. Contrary to previous suggestions, discs can form and survive in such an environment, despite the chaotic effects of competitive accretion. We find the discs are typically massive, with ratios of disc mass to central object mass of around 0.1, or higher, being typical. Naturally, the evolution of these discs is dominated by gravitational torques, and the more massive examples exhibit strong m=2 spiral modes. We also find that they can continuously grow over a period of 100,000 years, provided the central object is a single sink particle and the local density of sink particles is low. Discs that form around sink particles in the very centres of clusters tend to be shorter lived, but a single star can lose and gain a disc several times during the main accretion phase. However due to the nature of the turbulence in the cluster, the disc orientation can change dramatically over this time period, since disc-sink systems can accrete from counter-rotating envelopes. Since the competitive accretion process brings in material from large distances, the associated angular momentum can be higher than one would expect for an isolated star formation model. As such, we find that the discs are typically several hundred of AUs in extent, with the largest keplerian structures having radii of ~ 2000AU.
New and old roles for narrowband Hα
Authors: Drew Janet E.
Published: October 2010

Until recently, Hα has been seen as the tracer of ionized gas, picking out both star formation and the late stages of stellar evolution. This has been reaffirmed, spectacularly, by the recent WHAM and SHS surveys. But the advent of large-area digital detectors creates a new role for narrowband Hα as a direct, simultaneous, measure of intrinsic stellar colour and reddening when e.g. r'-Hα is combined with a nearby broad band colour e.g. r'- i'. This new capability has been clearly demonstrated by the nearly-complete IPHAS survey.
Billions of stars: the near infrared view of the Plane with UKIDSS and VISTA
Authors: Lucas Philip W. , Samuel David
Published: October 2010

The UKIDSS Galactic Plane Survey (GPS) is surveying the northern and equatorial plane in the J, H and K bands. Here we report initial results from searches for new clusters and star formation regions. 248 clusters have been detected by our Bayesian search, of which 127 are new. A visual inspection of the images is also proving successful. A cross match with Spitzer-GLIMPSE to find clusters of Young Stellar Objects is being attempted. No new globular clusters are detected except for two likely candidates already detected by Mercer et al. in GLIMPSE.
ATLASGAL, the APEX Telescope Large Area Survey of the Galaxy
Authors: Schuller F. , Menten K. M. , Wyrowski F. , Beuther H. , Bontemps S. , Bronfman L. , Contreras Y. , Henning T. , Motte F. , Schilke P. , Walmsley M. , Zavagno A.
Published: October 2010

Submillimeter continuum emission traces high molecular column densities and, thus, dense cloud regions in which new stars are forming. Surveys of the Galactic plane in such emission have the potential of delivering an unbiased view of high-mass star formation throughout the Milky Way. Here we present the scope, current status and first results of ATLASGAL, an ongoing survey of the Galactic plane using the Large APEX Bolometer Camera (LABOCA) on the Atacama Pathfinder Experiment (APEX) telescope at the Chajnantor plateau in Chile. Aimed at mapping 360 square degrees at 870 μm, with a uniform sensitivity of 50 mJy/beam, this survey will provide the first unbiased sample of cold dusty clumps in the Galaxy at submillimeter wavelengths. These will be targets for molecular line follow-up observations and high resolution studies with ALMA and the EVLA.
Exploring Extinction and Structure in the Milky Way Disk With 2MASS and Spitzer
Authors: Zasowski G. , Majewski S. R. , Nidever D. L. , Indebetouw R.
Published: October 2010

We present new maps of the distribution of both dust and stars across the Galactic disk, based largely on an improved analysis of 2MASS and Spitzer-IRAC data. The infrared extinction law is rederived throughout the disk and we found strong longitudinal variations in both diffuse and dense environments that we incorporate in our analysis.
The Near-IR Extinction Law
Authors: Stead Joseph J. , Hoare Melvin G.
Published: October 2010

We show that the power-law slope of the near-IR extinction law is significantly steeper than previously thought. Simulated colour-colour diagrams including a stellar population synthesis, realistic extinction distribution along the line-of-sight and synthesis through the filter profiles are compared to data from the UKIDSS Galactic Plane Survey. The slope of extinction with wavelength is found to be 2.14 ± 0.05 for total visual extinctions up to about 25 magnitudes and for a number of locations.
Unveiling the Unseen: The Mid-IR Galactic Disk
Authors: Churchwell Ed
Published: October 2010

The Spitzer mid-infrared (MIR) surveys, Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) and MIPSGAL have revealed a new view of the disk of the Milky Way. Hallmarks of the Galactic disk at MIR wavelengths with spatial resolution <2″ are bubbles/HII regions, infrared dark clouds, young stellar objects (YSOs)/star formation regions, diffuse dust and extended polycyclic aromatic hydrocarbons (PAHs), and more than 100 million publically available archived stars with measured flux densities at 7 wavelengths and positions accurate to 0.1″. At mid-IR wavelengths, the cool components in the Galaxy are preferentially bright and highlight physical processes that are not obvious at other wavelength regimes.
Evolution of abundance gradients for galactic plane PNe
Authors: Kholtygin A.F. , Milanova Yu.V. , Akimkin V.V.
Published: October 2010

The modern observations of planetary nebulae (PNe) are used to recalculate the element abundances for more than 150 PNe of the Milky Way and Magellanic Clouds. Basing on our data, we study the evolution of the abundance gradients for PNe in the thin disk and in the bulge.
The Star Formation Activity of Molecular Clouds in the Galactic Plane
Authors: Mottram Joseph C. , Brunt Christopher M.
Published: October 2010

It is well known that star formation takes place within molecular clouds. However, current observational surveys and investigations usually start by selecting a sample of sites where star formation is ongoing, thus biasing against those clouds and regions with little or no current formation activity. In an attempt to identify samples of clouds both with and without star formation, and to investigate their properties, we present an automated method for associating clouds identified in new 3D CO data with far-IR/sub-mm sources. Given the large number of surveys of the galactic plane currently planned, ongoing or being released, the methods used here may prove instructive in understanding how, where and under what conditions star formation takes place throughout our Galaxy. In addition, this will allow exploration of the properties of star forming regions on a range of spatial scales.
Massive Star Formation Throughout the Galactic Disk
Authors: Kurtz Stan
Published: October 2010

High-mass star formation is manifestly a phenomenon of the Galactic Plane. The process begins with pre-stellar cores, evolves to proto-stellar objects, and culminates in massive main-sequence stars. Because massive young stellar objects are deeply embedded, the radio, sub-mm, and far/mid-infrared spectral windows are the most revealing. Galactic plane surveys at these wavelengths trace hot and cold molecular gas, interstellar masers, warm dust, and ionized gas that are present during star formation.
Massive Star Forming Regions in the Galactic Plane: A Comparative Study Using BGPS, Spitzer, & Optical/Near-IR Surveys
Authors: Stringfellow Guy S. ,   & the BGPS team
Published: October 2010

The Bolocam Galactic Plane Survey (BGPS) is a 1.1 mm continuum survey that has detected more than 8300 clumps over a 170 square degree survey area in the Galactic plane. The full power of these data is realised only when considering the full complement of data spanning millimetre through x-ray wavelengths.
Galactic plane structure in hard X-rays
Authors: Lutovinov A. , Revnivtsev M. , Krivonos R.
Published: October 2010

We study the structure of the Galaxy in the hard X-ray energy band (¿20 keV) using data from the INTEGRAL observatory. The increased sensitivity of the survey and the very deep observations performed during six years of the observatory operation allow us to detect about a hundred new sources. This significantly enlarges the sample of hard X-ray sources in the Galactic disk and bulge in a comparison with the previous studies.
Broad view on hard X-ray background emission of the Galaxy
Authors: Krivonos Roman , Revnivtsev Mikhail , Tsygankov Sergey , Churazov Eugene , Sunyaev Rashid
Published: October 2010

The nature of the Galactic Ridge X-Ray Emission (GRXE) has been under scientific debate since its discovery more than 30 years ago. It is observed as extended emission along the Galactic disk. The question was: is GRXE truly diffuse or is it composed from a large number of unresolved point sources? Using near-infrared Galaxy maps measured with the DIRBE experiment and data from the INTEGRAL observatory, we show that the galactic background in the energy range 20-60 keV originates from the stellar population of the Galaxy, which is in contrast to the diffuse nature believed before (Krivonos et al., 2007). Here we show preliminary results of studying the transition region from hard X-rays to gamma diffuse background of the Galaxy, revealing the broad band picture of Galactic Background emission.
Long Period Variables as tracers of Galactic Structure
Authors: Groenewegen Martin A. T.
Published: October 2010

Distances to a large sample of long period variables are derived using a PL-relation and a 3D model for the reddening. Their use as a tracer of galactic structure is discussed.
IPHAS A-type Stars with Mid-IR Excesses in Spitzer Surveys
Authors: Hales Antonio S. , Barlow Michael J. , Drew Janet E. , Unruh Yvonne C. , Greimel Robert , Irwin Michael J. , González-Solares Eduardo
Published: October 2010

The Isaac Newton Photometric H-Alpha Survey (IPHAS) provides (r′-Hα)-(r′-i′) colors, which can be used to select AV0-5 Main Sequence star candidates (age~20-200 Myr). By combining a sample of 23050 IPHAS-selected A-type stars with 2MASS, GLIMPSE and MIPSGAL photometry we searched for mid-infrared excesses attributable to dusty circumstellar disks. Positional cross-correlation yielded a sample of 2692 A-type stars, of which 0.6% were found to have 8-μm excesses above the expected photospheric values. The low fraction of main sequence stars with mid-IR excesses found in this work indicates that dust disks in the terrestrial planet zone of Main Sequence intermediate mass stars are rare. Dissipation mechanisms such as photo-evaporation, grain growth, collisional grinding or planet formation could possibly explain the depletion of dust detected in the inner regions of these disks.
Gaia: A Stereoscopic Census of Our Galaxy
Authors: Prusti T.
Published: October 2010

Gaia is a space astrometry mission, a broad survey project following the measurement and operational principles of Hipparcos. It will help solving one of the most difficult yet deeply fundamental challenges in modern astronomy: to create an extraordinarily precise three-dimensional map of about one billion stars throughout our Galaxy and beyond. In the process, it will map their three-dimensional motions, which encode the origin and subsequent evolution of the Galaxy. Through comprehensive photometric and spectroscopic classification, it will provide the detailed physical properties of each star observed: characterising their luminosity, temperature, gravity, and elemental composition. This massive stellar census will provide the basic observational data to tackle an enormous range of important problems related to the origin, structure, and evolutionary history of our Galaxy.
GASKAP: The Galactic ASKAP Survey
Authors: Stanimirovič Snežana , Dickey John M. , Gibson Steven J. , Gómez José F. , Imai Hiroshi , Jones Paul A. , van Loon Jacco Th.
Published: October 2010

The Galactic Australian SKA Pathfinder (GASKAP) survey is one of several key science projects with ASKAP, a new radio telescope being built in Australia as a technology demonstrator for the Square Kilometer Array (SKA). GASKAP aims to survey about 12,779 square degrees of the Galaxy and the Magellanic System, at high spectral resolution (0.2 km s−1) and using several wavelengths: the λ21-cm HI line, the λ18-cm OH lines, and the comb of recombination lines around λ18-cm. The area covered by GASKAP includes all of the Galactic plane south of declination +40° with |b| < 10°, selected areas at higher latitudes covering important interstellar clouds in the disk and halo, the Large and Small Magellanic Clouds, and the Magellanic Bridge and Stream. Compared with previous surveys, GASKAP will achieve an order of magnitude or greater improvement in brightness sensitivity and resolution in various combinations of beam size and mapping speed matched to the astrophysical objectives.
Marking the 400th Anniversary of Kepler's Astronomia nova
Authors: Mahoney T. J.
Published: October 2010

Special Session 9 of the XXVII General Assembly (11–14 August 2009, Rio de Janeiro) was devoted to the topic “Marking the 400th Anniversary of Kepler's Astronomia nova”. During the two-and-a-half day meeting (spread over four days), there were nine invited and three contributed talks, a round-table discussion on the future of Kepler studies and an open session to propose the setting up of a Johannes Kepler Working Group under the aegis of the IAU.
Design of the magnet structure for the Advanced Photon Source superconducting undulator
Authors: Trakhtenberg E. , Ivanyushenkov Y. , Doose C. , Kasa M.
Published: October 2010

A superconducting planar undulator with 9.5 mm pole gap, 16 mm period and required peak field 0.64 T is at present under development at the Advanced Photon Source. Magnet structure precision is a key component of the project. The current design of the magnet structure is based on the assembled jaws with individual poles, while previous designs utilized solid cores with machined coil grooves. Each jaw has a core with pole grooves and separate precise poles inserted in these grooves and fixed with small screws. This approach allows achieving a uniformity of the poles thickness to within 15 µm, improving the surface finish, as well as using magnetic poles with non-magnetic cores. Several 42-pole jaws have already been produced, wound and tested. Magnetic measurements of the first structure have confirmed the mechanical precision of the assemblies. Details of the magnet structure design and jaw assembly, and changes made from the first prototype system to the production unit, are presented here.
Determining the key drivers of magnetospheric Pc5 wave power
Authors: Simms L. E. , Pilipenko V. A. , Engebretson M. J.
Published: October 2010

Long‐period ground ULF waves may be controlled by the mean values of solar wind and interplanetary magnetic field (IMF) parameters (velocity, density, and North‐South IMF component Bz). We investigated the influence of these parameters on ground ULF power in the Pc5 range (2–7 mHz) during periods of quiet and during coronal mass ejection (CME) and corotating interaction region (CIR) storms from 1991 to 2004. With multiple regression and path analysis, we studied the influence of these hourly parameters as a set rather than individually. This allowed us to determine which factors were most influential and which were only correlated with influential factors. By using multiple regression, we have explained more variation in Pc5 power than has been achieved in previous studies. In both storm types (CME and CIR) and during all storm phases (initial, main phase, recovery, and a 48 h period after recovery) as well as during quiet periods, solar wind velocity and IMF Bz influenced ground Pc5 power directly. These two variables also acted on the ULF Pc5 indirectly through the intermediate parameters of Dst, and the variations in number density and IMF, although at a weaker level. Ground Pc5 power was greater during CME storms during the main phase and recovery but larger during CIR storms in the period after recovery. In addition, the effect of certain independent variables differed depending on storm type. A model such as this offers the possibility of nowcasting Pc5 power by inserting current levels of solar wind and IMF variables as predictors into the regression equation.
Investigations on direct and indirect effect of nitrate on temperature and precipitation in China using a regional climate chemistry modeling system
Authors: Wang Tijian , Li Shu , Shen Yi , Deng Junjun , Xie Min
Published: October 2010

The tropospheric atmosphere chemistry model (TACM), including a condensed gaseous chemical mechanism and an inorganic aerosol thermodynamic equilibrium submodel, was coupled with the regional climate model (RegCM3) to build a Regional Climate Chemistry Modeling System (RegCCMS), which was applied to investigate the spatial and temporal distribution of anthropogenic nitrate aerosol, radiative forcing, and also its climatic effect over China. Modeling results show that the annual average surface concentration and column burden of nitrate are 2.19 μg/m3 and 5.05 mg/m2, respectively. The countrywide annual average direct radiative forcing, first indirect radiative forcing, and total radiative forcing at the top of atmosphere induced by nitrate are −0.88 W/m2, −2.47 W/m2, and −2.52 W/m2, respectively. Numerical experiments indicate that surface air temperature decreases and precipitation reduces when nitrate aerosol is included in the coupled modeling system. Changes in annual surface air temperature due to direct effect, first indirect effect, second indirect effect, and combined effect are −0.04°C, −0.11°C, −0.68°C and −0.78°C, respectively. The corresponding precipitation reduction is −0.05 mm/d, −0.10 mm/d, −0.42 mm/d, and −0.52 mm/d. Variations of surface temperature and precipitation due to the combined effect are less than the sum of individual direct, first indirect, and second indirect effect, showing a strong nonlinearity between radiative forcing and climate change. The indirect effect of nitrate is stronger than its direct effect. These preliminary results suggest that nitrate aerosol has unignorable effect on regional climate in China compared to sulfate and carbonaceous aerosols.
Lidar observations of Kasatochi volcano aerosols in the troposphere and stratosphere
Authors: Bitar L. , Duck T. J. , Kristiansen N. I. , Stohl A. , Beauchamp S.
Published: October 2010

The eruption of Kasatochi volcano on 7–8 August 2008 injected material into the troposphere and lower stratosphere of the northern midlatitudes during a period of low stratospheric aerosol background concentrations. Aerosols from the volcanic plume were detected with a lidar in Halifax, Nova Scotia (44.64°N, 63.59°W) 1 week after the eruption and for the next 4 months thereafter. The volcanic origin of the plume is established using the FLEXPART Lagrangian particle transport model for both the stratosphere and troposphere. The stratospheric plume descended 47.1 ± 2.8 m/d on average as it dispersed, corresponding to a cooling rate of 0.60 ± 0.07 K/d. The descent rate was the same for the tropopause (within statistical uncertainties). The top of the plume remained steady at about 18 km altitude and was likely sustained by vertical eddy diffusion from large‐scale horizontal mixing. The lower boundary of the plume descended with the tropopause. The integrated aerosol backscatter between 15 and 19 km altitude was relatively constant at about 8 × 10−5 sr−1 for 532 nm wavelength. Observations and modeling of Kasatochi aerosols in the middle and lower troposphere indicate a possible ground impact. The volcanic contribution to surface PM2.5 did not exceed 5 μg/m3 at the measurement site.
Improving snow processes in the Noah land model
Authors: Wang Zhuo , Zeng Xubin , Decker Mark
Published: October 2010

Snow is one of the most crucial land surface processes over middle and high latitudes. A widely known deficiency of the Noah land model as used in the National Centers for Environmental Prediction (NCEP) operational models and the Weather Research and Forecasting model (WRF) at the National Center for Atmospheric Research is that snowmelt occurs much too early. Through detailed diagnostics of the Noah output over the high‐altitude Niwot Ridge forest site (40.03°N, 105.55°W) and a boreal forest site (53.9°N, 104.7°W), six deficiencies in Noah model physics are identified along with improved formulations that (1) consider the vegetation shading effect on snow sublimation and snowmelt; (2) consider under‐canopy resistance; (3) revise the ground heat flux computation when snow is deep; (4) revise the momentum roughness length computation when snow is present; (5) revise the snow density computation near 0°C; and (6) increase the maximum iteration number from five to 30 in the turbulence computation. These revisions significantly improve Noah simulations of all snow processes such as snow water equivalent (SWE), snow depth, and sensible and latent heat fluxes over these two forest sites. The revisions were also evaluated (without tunings) with an independent forest site and a grassland site, further confirming the robust and positive impacts of these revisions on Noah snow simulations. These modifications maintain the Noah model structure and do not introduce new prognostic variables, allowing easy implementation into NCEP operational models and into WRF. Furthermore, they are found to be as good as, or slightly better than, a much more complicated land model in the snow simulation over the three forest sites.
A short‐duration cooling event around the tropical tropopause and its effect on water vapor
Authors: Takashima Hisahiro , Eguchi Nawo , Read William
Published: October 2010

For the 2008/2009 winter, extremely low temperatures near the tropical tropopause (∼83 hPa) were observed at the beginning of February 2009 by COSMIC over the western Pacific and over eastern Pacific‐South America in association with a wave response to the tropical heat source. At the same time, the water vapor field at 83 hPa detected from Aura MLS recorded a minimum, with a higher frequency of cirrus cloud observed by CALIOP. Although the temperature minima rapidly disappeared after the event, one possible interpretation is that the low water‐vapor concentration remained at this level and spread gradually over the entire tropics, finally impacting on the cold phase of the atmospheric tape recorder. However, further study is required to establish a link between the large‐scale reduction in water vapor and the dehydration that occurred during the cold event in early February.
Statistical maps of geomagnetic perturbations as a function of the interplanetary magnetic field
Authors: Weimer D. R. , Clauer C. R. , Engebretson M. J. , Hansen T. L. , Gleisner H. , Mann I. , Yumoto K.
Published: October 2010

Mappings of geomagnetic perturbations are shown for different combinations of the solar wind velocity, interplanetary magnetic field (IMF), and dipole tilt angle (season). Average maps were derived separately for the northward, eastward, and vertical (downward) components of the geomagnetic disturbances, using spherical cap harmonics in least error fits of sorted measurements. The source data are obtained from 104 ground‐based magnetometer stations in the Northern Hemisphere at geomagnetic latitudes over 40° during the years 1998 through 2001. Contour maps of statistical fits are shown along‐side scatter plots of individual measurements in corrected geomagnetic apex coordinates. The patterns are consistent with previous mappings of ionospheric electric potential. Interestingly, the vertical component of the magnetic perturbations closely resembles maps of the overhead, field‐aligned currents, including the Northward IMF configuration. The maximum and minimum values from the statistical mappings are graphed to show their changes as a function of southward IMF magnitude, solar wind velocity, and seasons. It is expected that this work will lead to better advance predictions of the geomagnetic perturbations that are based on real‐time IMF measurements.
The color of sea level: Importance of spatial variations in spectral shape for assessing the significance of trends
Authors: Hughes Chris W. , Williams Simon D. P.
Published: October 2010

We investigate spatial variations in the shape of the spectrum of sea level variability based on a homogeneously sampled 12 year gridded altimeter data set. We present a method of plotting spectral information as color, focusing on periods between 2 and 24 weeks, which shows that significant spatial variations in the spectral shape exist and contain useful dynamical information. Using the Bayesian Information Criterion, we determine that, typically, a fifth‐order autoregressive model is needed to capture the structure in the spectrum. Using this model, we show that statistical errors in fitted local trends range between less than 1 and more than 5 times of what would be calculated assuming “white” noise and that the time needed to detect a 1 mm/yr trend ranges between about 5 years and many decades. For global mean sea level, the statistical error reduces to 0.1 mm/yr over 12 years, with only 2 years needed to detect a 1 mm/yr trend. We find significant regional differences in trend from the global mean. The patterns of these regional differences are indicative of a sea level trend dominated by dynamical ocean processes over this period.
A comparison of shortwave reflectance over the East Antarctic Plateau observed by CERES to that estimated from surface reflectance observations
Authors: Hudson Stephen R. , Warren Stephen G. , Kato Seiji
Published: October 2010

Spectral albedo and bidirectional reflectance of snow were measured at Dome C on the East Antarctic Plateau for wavelengths of 350–2400 nm and solar zenith angles of 52°–87°. A parameterization of bidirectional reflectance, based on those measurements, is used as the lower boundary condition in the atmospheric radiation model SBDART to calculate radiance and flux at the top of the atmosphere (TOA). The model's atmospheric profile is based on radiosoundings at Dome C and ozonesoundings at the South Pole. Computed TOA radiances are integrated over wavelength for comparison with the Clouds and the Earth's Radiant Energy System (CERES) shortwave channel. CERES radiance observations and flux estimates from four clear days in January 2004 and January 2005 from within 200 km of Dome C are compared with the TOA radiances and fluxes computed for the same solar zenith angle and viewing geometry, providing 11,000 comparisons. The measured radiance and flux are lower than the computed values. The median difference is about 7% for CERES on Terra, and 9% on Aqua. Sources of uncertainty in the model and observations are examined in detail and suggest that the measured values should be less than the computed values, but only by 1.7% ± 4%. The source of the discrepancy of about 6% cannot be identified here; however, the modeled values do agree with observations from another satellite instrument (Multiangle Imaging Spectroradiometer), suggesting that the CERES calibration must be considered a possible source of the discrepancy.