bluuebunny/crossref_metadata_2025 huggingface dataset:
The breaking of the Equivalence Principle in theories with varying α
Authors: Kraiselburd Lucila , Vucetich Héctor
Published: October 2010

The Standard Model and General Relativity provide a good description of phenomena at low energy. These theories, which agree very well with the experiment, contain a set of parameters called “fundamental constants”, that are assumed invariant under changes in location and reference system. However, their possible variation has been studied since Dirac made the large numbers hypothesis (LNH). Moreover, unified field theory and extra dimensions theories such as Kaluza-Klein or Superstring theories, state not only the variation of these constants, but also the simultaneity of the variations.

The Eötvös effect is one of the most sensitive indicators of changes in fundamental constants. Bekenstein (2002) showed that in his theory, using a classical static particle model of matter, there is no Eötvös effect and therefore met the Universality of Free Fall and the Principle of Equivalence.

We present different results than those obtained by Bekenstein, Kraiselburd, Vucetich (2009). Modifying his theory, taking more realistic models of matter and using the model THεμ techniques (Ligtman-Lee (1975) and Haugan (1979), not used before to analyze this model), very small but measurable effects have been found.
Cosmological models and the brightness profile of distant galaxies
Authors: Olivares-Salaverri I. , Ribeiro Marcelo B.
Published: October 2010

This work aims to determine the feasibility of an assumed cosmological model by means of a detailed analysis of the brightness profiles of distant galaxies. Starting from the theory of Ellis & Perry (1979) connecting the angular diameter distance obtained from a relativistic cosmological model and the detailed photometry of galaxies, we assume the presently most accepted cosmology with Λ ¬ = 0 and seek to predict the brightness profile of a galaxy in a given redshift z. To do so, we have to make assumptions concerning the galactic brightness structure and evolution, assuming a scenario where the specific emitted surface brightness Be,νe can be characterized as, Be,νe (r,z) = B0(z)J(νe,z)f[r(z)/a(z)]. Here r is the intrinsic galactic radius, νe the emitted frequency, B0(z) the central surface brightness, J(νe,z) the spectral energy distribution (SED), f[r(z)/a(z)] characterizes the shape of the surface profile distribution and a(z) is the scaling radius. The dependence on z is due to the galactic evolution. As spacetime curvature affects the received surface brightness, the reciprocity theorem (Ellis 1971) allows us to predict the theoretical received surface brightness. So, we are able to compare the theoretical surface brightness with its equivalent observational data already available for high redshift galaxies in order to test the consistency of the assumed cosmological model. The function f[r(z)/a(z)] is represented in the literature by various different shapes, like the Hubble, Hubble-Oemler and Abell-Mihalas single parameter profiles, characterizing the galactic surface brightness quite well when the disk or bulge dependence is dominant. Sérsic and core-Sérsic profiles use two or more parameters and reproduce the galactic profile almost exactly (Trujillo et al. 2004). If we consider all wavelengths, the theory tells us that the total intensity is equal to the surface brightness, so the chosen bandwidth should include most of the SED. In order to analyze only the effect of the cosmological model in the surface brightness and minimize evolutionary effects, we assume that there exists a homogeneous class of objects, whose properties are similar in all redshifts, allowing us to carry out comparisons at different values of z. Studying the parameters that affect the galactic evolution, as well as in others geometrical tests, we will be able to infer some possible galaxy evolution which could reproduce a theoretical surface brightness profile, in order to compare with the observational data and reach conclusions about the observational feasibility of the underlying cosmological model.
Calibration issues in Δα/α
Authors: Centurión Miriam , Molaro Paolo , Levshakov Sergei
Published: October 2010

Laser Comb Wavelength calibration shows ThAr one locally unreliable with deviations up to 100 m s−1 (or Δα/α ≈ 7 · 10−6 for a Fe ii-Mg ii pair) while delivering an overall 1 m s−1 accuracy. Comparison of line shifts of the 5 Fe ii lines with identical sensitivity to Δα/α offers a clean way to test local wavelength calibration errors of whatever origin.
Joint Discussion 10: 3D views on cool stellar atmospheres – theory meets observation
Authors: Nagendra K.N. , Bonifacio P. , Ludwig H.-G.
Published: October 2010

Much of what we know about the chemical composition of the Universe actually stems from the chemical composition of stars, which is often deciphered from the spectra emerging from their atmospheres. Cool, low-mass and long-living stars allow to study the evolution of the Universe's chemistry from a time shortly after the big bang until today. The observation and interpretation of stellar spectra is a classical field in astronomy but is still undergoing vivid developments. The enormous increase in available computational resources opened-up possibilities which led to a revolution in the degree of realism to which modelers can mimic Nature. High-resolution, high-stability, high-efficiency spectrographs are now routinely providing stellar spectra whose full information content can only be exploited if a very much refined description of a stellar atmosphere is at hand.
How surface magnetism affects helioseismic waves
Authors: Cally Paul S.
Published: October 2010

It has been known for two decades that sunspots both absorb and advance the phase of solar f and p-modes. More recently, Time-Distance and other local helioseismic techniques have been used to probe active regions by exploring phase shifts which are interpreted as travel-time perturbations. Although absorption is an intrinsically magnetic effect, phase shifts may be produced by both thermal and magnetic effects (and of course flows, though these can be factored out by averaging travel times in opposite directions). We will show how these two effects alter wave phase, and conclude that phase shifts in umbrae are predominantly thermal, whilst those in highly inclined field characteristic of penumbrae are essentially magnetic. The two effects are generally not additive.
The future of helioseismology
Authors: Kosovichev Alexander G.
Published: October 2010

Helioseismology has provided us with the unique knowledge of the interior structure and dynamics of the Sun, and the variations with the solar cycle. However, the basic mechanisms of solar magnetic activity, formation of sunspots and active regions are still unknown. Determining the physical properties of the solar dynamo, detecting emerging active regions and observing the subsurface dynamics of sunspots are among the most important and challenging problems. The current status and perspectives of helioseismology are briefly discussed.
Numerical simulation of propagation of the MHD waves in sunspots
Authors: Parchevsky K. , Kosovichev A. , Khomenko E. , Olshevsky V. , Collados M.
Published: October 2010

We present results of numerical 3D simulation of propagation of MHD waves in sunspots. We used two self consistent magnetohydrostatic background models of sunspots. There are two main differences between these models: (i) the topology of the magnetic field and (ii) dependence of the horizontal profile of the sound speed on depth. The model with convex shape of the magnetic field lines near the photosphere has non-zero horizorntal perturbations of the sound speed up to the depth of 7.5 Mm (deep model). In the model with concave shape of the magnetic field lines near the photosphere Δ c/c is close to zero everywhere below 2 Mm (shallow model). Strong Alfven wave is generated at the wave source location in the deep model. This wave is almost unnoticeable in the shallow model. Using filtering technique we separated magnetoacoustic and magnetogravity waves. It is shown, that inside the sunspot magnetoacoustic and magnetogravity waves are not spatially separated unlike the case of the horizontally uniform background model. The sunspot causes anisotropy of the amplitude distribution along the wavefront and changes the shape of the wavefront. The amplitude of the waves is reduced inside the sunspot. This effect is stronger for the magnetogravity waves than for magnetoacoustic waves. The shape of the wavefront of the magnetogravity waves is distorted stronger as well. The deep model causes bigger anisotropy for both mgnetoacoustic and magneto gravity waves than the shallow model.
New advances in asteroseismology of pulsating hot subdwarf stars
Authors: Charpinet S. , Van Grootel V. , Randall S.K. , Green E.M. , Fontaine G. , Brassard P. , Chayer P.
Published: October 2010

Hot subdwarf stars (of the sdB and sdO type) host three known classes of nonradial pulsators. Two of them feature short period (P ~ 60 - 600 s) accoustic mode oscillations, while the third group is characterized by slow g-mode deformations with periods of ~ 1 - 2h. These pulsations offer favorable grounds to infer some of the internal properties of these objects through asteroseismology. This has been exploited for the rapid p-mode sdB pulsators and the present contribution reviews some of the recent advances in this field. The long period g-mode pulsators, whose vibrations probe much deeper inside the star, are also of high interest. With the advent of space observations using CoRoT and KEPLER, the asteroseismology of these slower oscillators will also become a possibility, and likely contribute to significant breakthroughs in our understanding of these hot and compact stars.
Magnetoacoustic oscillations in Ap stars
Authors: Cunha Margarida S.
Published: October 2010

In this paper I briefly summarize a number of robust results derived from observational and theoretical studies of roAp stars over the past three decades.
Complex asteroseismology of the B-type main sequence pulsators
Authors: Daszyńska-Daszkiewicz Jadwiga , Walczak Przemysław
Published: October 2010

We present examples of an extended asteroseismic modelling in which we aim at fitting not only pulsational frequencies but also certain complex parameter related to each frequency. This kind of studies, called complex asteroseismology, has been successfully applied to a few main sequence B-type pulsators and provided, in particular, plausible constraints on stellar opacities. Here, we briefly describe our results for three early B-type stars.
Application of the Rayleigh-Ritz variational technique for coronal loop oscillations
Authors: Fathalian Narges , Safari Hossein , Nasiri Sadollah
Published: October 2010

We studied the fast kink modes of a cylindrical model of coronal loops, in coronal conditions, stratified density and low-β plasma. The mode frequencies and profiles are calculated.
Testing new models of M dwarfs
Authors: Baran A. , Kawaler S.D. , Krzesinski J.
Published: October 2010

We present our new observing project searching for pulsations in M dwarfs.
Hot DQ white dwarfs: a pulsational test of the mixing scenario for their formation
Authors: Romero A. , Córsico A. H. , Althaus L. G. , García-Berro E.
Published: October 2010

Hot DQ white dwarfs constitute a new class of white dwarf stars, uncovered recently within the framework of SDSS project. There exist nine of them, out of a total of several thousands white dwarfs spectroscopically identified. Recently, three hot DQ white dwarfs have been reported to exhibit photometric variability with periods compatible with pulsation g-modes. In this contribution, we presented the results of a non-adiabatic pulsation analysis of the recently discovered carbon-rich hot DQ white dwarf stars. Our study relies on the full evolutionary models of hot DQ white dwarfs recently developed by Althaus et al. (2009), that consistently cover the whole evolution from the born-again stage to the white dwarf cooling track. Specifically, we performed a stability analysis on white dwarf models from stages before the blue edge of the DBV instability strip (Teff ≈ 30000 K) until the domain of the hot DQ white dwarfs (18000-24000 K), including the transition DB→hot DQ white dwarf. We explore evolutionary models with M*= 0.585M⊙ and M* = 0.87M⊙, and two values of thickness of the He-rich envelope (MHe = 2 × 10−7M* and MHe = 10−8M*).
JD13 – Eta Carinae in the Context of the Most Massive Stars
Authors: Gull Theodore R. , Damineli Augusto
Published: October 2010

Eta Car, with its historical outbursts, visible ejecta and massive, variable winds, continues to challenge both observers and modelers. In just the past five years over 100 papers have been published on this fascinating object. We now know it to be a massive binary system with a 5.54-year period. In January 2009, η Car underwent one of its periodic low-states, associated with periastron passage of the two massive stars. This event was monitored by an intensive multi-wavelength campaign ranging from γ-rays to radio. A large amount of data was collected to test a number of evolving models including 3-D models of the massive interacting winds. August 2009 was an excellent time for observers and theorists to come together and review the accumulated studies, as have occurred in four meetings since 1998 devoted to Eta Car. Indeed, η Car behaved both predictably and unpredictably during this most recent periastron, spurring timely discussions.
Warm molecular gas in the M17 SW nebula
Authors: Pérez-Beaupuits J. P. , Spaans M. , Hogerheijde M. , Güsten R.
Published: October 2010

High resolution maps of the 12CO J = 6 → 5 line and the [C I]3P2 →3P1 (370 μm) fine-structure transition in the Galactic nebula M17 SW are presented. The maps were obtained using the dual color multiple pixel receiver CHAMP+ on the APEX† telescope.
Spitzer reveals what's behind Orion's Bar
Authors: Rubin Robert H.
Published: October 2010

We present Spitzer Space Telescope observations of 11 regions in the Orion Nebula all southeast of the Bright Bar. Our Cycle 5 program obtained deep spectra with both the IRS short-high (SH) and long-high (LH) modules with aperture grid patterns chosen to very closely match the same area in the nebula. Previous IR missions observed only the inner few arcmin (the ‘Huygens’ region). The extreme sensitivity of Spitzer in the 10-37 μm spectral range permitted us to measure many lines of interest to much larger distances from the exciting star θ1 Ori C.
Solenoidal versus compressive turbulence forcing
Authors: Federrath C. , Duval J. , Klessen R. S. , Schmidt W. , Low M.-M. Mac
Published: October 2010

We analyze the statistics and star formation rate obtained in high-resolution numerical experiments of forced supersonic turbulence, and compare with observations. We concentrate on a systematic comparison of solenoidal (divergence-free) and compressive (curl-free) forcing (Federrath et al. 2009 a, b), which are two limiting cases of turbulence driving. Our results show that for the same RMS Mach number, compressive forcing produces a three times larger standard deviation of the density probability distribution. When self-gravity is included in the models, the star formation rate is more than one order of magnitude higher for compressive forcing than for solenoidal forcing.
Search for High-Extinction Regions in the Small Magellanic Cloud
Authors: Lee M.-Y. , Stanimirović S. , Ott J. , van Loon J. Th. , Bolatto A. D. , Jones P. A. , Cunningham M. R. , Devine K. E. , Oliveira J. M.
Published: October 2010

We have applied the unsharp-masking technique to the 24 μm image of the SMC, obtained with the Spitzer, to search for high-extinction regions. Fifty-five candidate regions of high-extincion (namely high-contrast regions, HCRs) have been identified from the decremental contrast image. HCRs have a size of 8 - 14 pc and a peak contrast at 24 μm of 2 - 2.5%. To constrain physical properties of HCRs, we have performed observations of NH3, N2H+, HNC, HCO+, and HCN toward one of the HCRs, HCR LIRS36–east, using the ATCA and the Mopra telescope. No molecular line emission detected, but upper limits to column densities of molecular species suggest that HCRs are moderately dense with n ~ 103 cm−3. Two interesting properties of HCRs are shown below.
NRO Legacy Project: Survey of Giant Molecular Clouds in M33
Authors: Kuno N. , Tosaki T. , Onodera S. , Muraoka K. , Kaneko H. , Sawada T. , Nakanishi K. , Komugi S. , Tamura Y. , Kohno K. , Kawabe R. , Arimoto N. , Okamoto S.
Published: October 2010

As the Nobeyama Radio Observatory Legacy Project: Survey of Giant Molecular Clouds in M33, we have been mapping M33 in CO(1-0) with the multi-beam receiver BEARS equipped on the 45-m telescope using the OTF mapping technique since 2007. The purpose of this project is to investigate the physical properties of GMCs and understand the evolutionary process from GMC formation to star formation in GMCs by comparing with various data such as CO(3-2), 1.1 mm continuum obtained with ASTE10m telescope at Atacama and the optical data obtained with SUBARU. We identified 87 GMCs using the first year data of CO(1-0) and observed 28 GMCs among them in CO(3-2) with ASTE (Onodera 2009, PhD thesis, University of Tokyo). From the comparison of these lines, it was shown that the CO(3-2)/CO(1-0) ratio increases with star forming activity in the GMCs. Furthermore, we found that more massive GMCs tend to have higher CO(3-2)/CO(1-0) ratio. Since the ratio is thought to be an indicator of the fraction of warm and dense molecular gas, our results imply that the fraction of warm and dense gas increases with GMC mass. Especially, since the ratio in the GMCs with low star forming activity is in the range where the ratio depends mainly on the density, we speculate that dense gas fraction increases with GMC mass.
Cosmic magnetic field observations with next generation instrumentation
Authors: Beck Rainer
Published: October 2010

The origin of magnetic fields in the Universe is an open problem in astrophysics and fundamental physics. Forthcoming radio telescopes will open a new era in studying cosmic magnetic fields. Low-frequency radio waves will reveal the structure of weak magnetic fields in the outer regions and halos of galaxies and in intracluster media. At higher frequencies, the EVLA and the SKA will map the structure of magnetic fields in galaxies in unprecedented detail. All-sky surveys of Faraday rotation measures (RM) towards a huge number of polarized background sources with the SKA and its pathfinders will allow us to model the structure and strength of the regular magnetic fields in the Milky Way, the interstellar medium of galaxies, in galaxy clusters and the intergalactic medium.
Numerical simulations of Hall MHD small-scale dynamos
Authors: Gómez Daniel O. , Mininni Pablo D. , Dmitruk Pablo
Published: October 2010

Much of the progress in our understanding of dynamo mechanisms, has been made within the theoretical framework of magnetohydrodynamics (MHD). However, for sufficiently diffuse media, the Hall effect eventually becomes non-negligible. We present results from three dimensional simulations of the Hall-MHD equations subjected to random non-helical forcing. We study the role of the Hall effect in the dynamo efficiency for different values of the Hall parameter, using a pseudospectral code to achieve exponentially fast convergence.
Multi-Phase Dynamics of Magnetized Interstellar Medium
Authors: Inutsuka Shu-ichiro
Published: October 2010

The recent progress in our understanding of the dynamics of muliti-phase interstellar medium (ISM) is reviewed. Non-linear perturbations (e.g., shock waves or time-dependent radiation field) lead to the interchange between warm phase and cold phase via thermal instability. Dynamical modelling of this phase transition dynamics is essential in describing ubiquitous turbulence in ISM and the formation of molecular clouds. A concept of magnetically multi-phase medium is introduced. Recent finding of the magnetic field amplification in the blast wave propagating in magnetized multi-phase ISM is providing a strong motivation for rapid acceleration of cosmic rays.
Atomic alignment: New Diagnostics of Magnetic Field in Diffuse Medium
Authors: Yan Huirong , Lazarian A.
Published: October 2010

We discuss a new technique of studying magnetic fields in diffuse astrophysical media, e.g. interstellar and intergalactic gas/plasma. This technique is based on the angular momentum alignment of atoms and ions in their ground or metastable states. The alignment reveals itself in terms of the polarization of the absorbed and emitted light. The corresponding studies of magnetic fields can be performed with multiband spectropolarimetry, from UV, optical, to IR/radio. A unique feature of these studies is that they can reveal the 3D orientation of magnetic field. We mention several cases of interplanetary, circumstellar and interstellar magnetic fields for which the studies of magnetic fields using ground state atomic alignment effect are promising.
Magnetic fields in the Galactic halo
Authors: Haverkorn M.
Published: October 2010

Interstellar magnetic fields play a major role in the ionized gas away from the Galactic disk, but their strength and direction is still unclear. Radio spectro-polarimetry and rotation measure synthesis, for example used in the Parkes Galactic Meridian Survey and a number of all (southern and northern) sky surveys, enable determination of the properties of magnetic fields in the Galactic halo and their role in the disk-halo interaction.
Large scale magnetic fields of our Galaxy
Authors: Han JinLin
Published: October 2010

Large-scale magnetic fields in the Galactic disk have been revealed by distributions of pulsar rotation measures (RMs) and Zeeman splitting data of masers in star formation regions, which have several reversals in arm and interarm regions. Magnetic fields in the Galactic halo are reflected by the antisymmetric sky distribution of RMs of extragalactic radio sources, which have azimuthal structure with reversed directions below and above the Galactic plane. Large-scale magnetic fields in the Galactic center probably have a poloidal and toroidal structure.
Properties of MHD turbulence and its consequences for the ISM and ICM
Authors: Falceta-Gonçalves D. , Kowal G. , Lazarian A.
Published: October 2010

It is well known that the interstellar (ISM) and intergalactic (ICM) media are threaded by large scale magnetic fields. The understanding of its role on the dynamics of the media is, however, still in progress. For the ISM, magnetic fields may control or, at least, play a major role on the turbulence cascade leading to the star formation process. The ICM, on the other hand, is assumed to be thermally dominated but still the magnetic field may play an important role on the processes of acceleration and propagation of cosmic rays. In this work we provide a review of the latest theoretical results on the evolution of MHD turbulence under collisional and collisionless plasma approaches.
Whole Heliosphere Interval: Overview of JD16
Authors: Webb David F. , Gibson Sarah E. , Thompson Barbara J.
Published: October 2010

The Whole Heliosphere Interval is an international observing and modeling effort to characterize the three-dimensional interconnected solar-heliospheric-planetary system, i.e., the “heliophysical” system. WHI was part of the International Heliophysical Year, on the 50th anniversary of the International Geophysical Year, and benefited from hundreds of observatories and instruments participating in IHY activities. WHI describes the 3-D heliosphere originating from solar Carrington Rotation 2068, March 20–April 16, 2008. The focus of IAU JD16 was on analyses of observations obtained during WHI, and simulations and modeling involving those data and that period. Consideration of the WHI interval in the context of surrounding solar rotations and/or compared to last solar minimum was also encouraged. Our goal was to identify connections and commonalities between the various regions of the heliosphere.
Peculiar Current Solar-Minimum Structure of the Heliosphere
Authors: Manoharan P. K.
Published: October 2010

In this paper, I review the results of 3-D evolution of the inner heliosphere over the solar cycle 23, based on observations of interplanetary scintillation (IPS) made at 327 MHz using the Ooty Radio Telescope. The large-scale features of solar wind speed and density turbulence of the current minimum are remarkably different from that of the previous cycle. The results on the solar wind density turbulence show that (1) the current solar minimum is experiencing a low level of coronal density turbulence, to a present value of ~50% lower than the previous similar phase, and (2) the scattering diameter of the corona has decreased steadily after the year 2003. The results on solar wind speed are consistent with the magnetic field strength at the poles and the warping of heliospheric current sheet.
Global MHD Modeling of the Solar Corona and Inner Heliosphere for the Whole Heliosphere Interval
Authors: Riley Pete , Linker Jon A. , Mikic Zoran
Published: October 2010

With the goal of understanding the three-dimensional structure of the solar corona and inner heliosphere during the “Whole Heliosphere Interval” (WHI), we have developed a global MHD solution for Carrington rotation (CR) 2068. Our model, which includes energy transport processes, such as coronal heating, conduction of heat parallel to the magnetic field, radiative losses, and the effects of Alfvén waves, is capable of producing significantly better estimates of the plasma temperature and density in the corona than have been possible in the past. With such a model, we can compute emission in extreme ultraviolet (EUV) and X-ray wavelengths, as well as scattering in polarized white light. Additionally, from our heliospheric solutions, we can deduce magnetic field and plasma parameters along specific spacecraft trajectories. We have made detailed comparisons of both remote solar and in situ observations with the model results, allowing us to: (1) Connect these disparate sets of observations; (2) Infer the global structure of the inner heliosphere; and (3) Provide support for (or against) assumptions in the MHD model, such as the empirically-based coronal heating profiles.
Eruptive Signatures in the Solar Atmosphere During the WHI Campaign (20 March–16 April 2008)
Authors: Sterling Alphonse C.
Published: October 2010

We examined EUV movies of the Sun during the period of the Whole Heliospheric Interval (WHI) campaign of 20 March–16 April 2008, searching for indications of eruptive events. Our data set was obtained from EIT on SOHO, using its 195 Å filter, and from EUVI on the two STEREO satellites, using their 171 Å, 195 Å, 284 Å, and 304 Å filters. Here we present a table showing results from our preliminary search.
Special Session 1 - IR and Sub-mm Spectroscopy - a new tool for studying Stellar Evolution
Authors: Wahlgren Glenn , Käufl Hans , Kerber Florian
Published: October 2010

Infrared astronomy has come into its own over the last decade. Based on mature detector technology and sophisticated instrumentation it is contributing exciting science in many fields of astrophysics. Stellar evolution is a field that has long been dominated by ultraviolet and optical work, but one that has benefited from a strongly increasing contribution from the infrared (IR) and sub-millimeter (sub-mm) domains. In particular, spectroscopy in these domains holds the promise to enable important advances through quantitative analysis of individual stars and stellar systems.
SpS1-From molecular clouds to massive stars
Authors: Cunningham Maria R.
Published: October 2010

The life cycles of massive stars have a major impact on the evolution of galaxies, while in turn, position in galaxy has a major impact on the efficiency and type of star formation which occurs in a molecular cloud (see e.g. Luna et al. 2006). However, exactly how massive stars form, on what timescales, and how they shape their environments during this active and energetic phase is poorly understood.
SpS1-Circumstellar disks & their evolution: Dust
Authors: Grady Carol A.
Published: October 2010

Circumstellar disks are an intrinsic part of star formation and are also where planets form, migrate, and where the materials capable of producing life-bearing worlds are produced. The most flamboyant signatures of the presence of disks are at infrared through millimeter wavelengths, where thermal emission from dust dominates the system light. The discovery and characterization of the emission from such disks has been a major activity for ground-based observatories and space missions (IRAS, ISO, MSX, AKARI, andSpitzer), and continues with the newest generation of infrared (IR) capabilities.
SpS1-Measuring magnetic fields on young stars
Authors: Johns-Krull Christopher M. , Valenti Jeff A.
Published: October 2010

T Tauri stars (TTSs) are young (~few Myr) late type stars that have only recently emerged from their natal molecular cloud material to become visible at optical wavelengths. It is now generally accepted that accretion of circumstellar disk material onto the surface of a TTS is controlled by a strong stellar magnetic field (e.g. see review by Bouvier et al. 2007). The stellar field appears critical for explaining the rotational properties of TTSs (Bouvier et al. 2007, Herbst et al. 2007) and may also play a critical role in driving the outflows seen from many of these sources (e.g. Shang et al. 2007, Mohanty & Shu 2008). As a result, there is a great deal of interest in measuring the magnetic field properties of TTSs (e.g. Johns–Krull 2007, Donati et al. 2008). In particular, disk locking theories predict that an equilibrium is established where the disk is trunctated at or close to corotation and the stellar rotation rate depends only on the (assumed) dipolar magnetic field strength, the stellar mass, radius, and the mass accretion rate in the disk (see Bouvier et al. 2007).
SpS1-SOFIA studies of stellar evolution
Authors: Gehrz R. D. , Becklin E. E. , Roellig T. L.
Published: October 2010

The U.S./German Stratospheric Observatory for Infrared Astronomy (SOFIA, Figure 1) is a 2.5-meter infrared airborne telescope in a Boeing 747-SP flying in the stratosphere at altitudes as high as 45,000 feet where the atmospheric transmission averages ≥ 80% throughout the 0.3 - 1600 μm spectral region. SOFIA's first-generation instruments include broadband imagers, moderate resolution spectrographs capable of resolving broad features due to dust and large molecules, and high resolution spectrometers suitable for kinematic studies of molecular and atomic gas lines at km s−1resolution. These and future instruments will enable SOFIA to make unique contributions to studies of the physics and chemistry of stellar evolution for many decades. Science flights will begin in 2010. A full operations schedule of at least 100 flights per year will begin in 2014 and will continue for 20 years. The SOFIA Guest Investigator (GI) program, open to investigators worldwide, will constitute the major portion of the SOFIA observing program.
Extreme adaptive optics in the mid-IR: The METIS AO system
Authors: Stuik Remko , Jolissaint Laurent , Kendrew Sarah , Hippler Stefan , Brandl Bernhard
Published: October 2010

METIS, the Mid-infrared ELT Imager and Spectrograph, is currently in its phase A study as one of the candidate first-light instruments for the European Extremely Large Telescope. METIS will feature several observational modes, ranging from diffraction limited imaging in L, M and N-bands to high-resolution Integral Field spectroscopy for the L and M-bands. METIS in its current design gives sensitivities similar to Spitzer in imaging and low-resolution spectroscopy and with its high-resolution spectrograph will provide unprecedented line sensitivity. The design of METIS is optimized for both galactic science cases (e.g. conditions in the early solar system, formation and evolution of proto-planetary disks and properties of exoplanets) and extragalactic science cases (e.g. the growth of Supermassive Black Holes). METIS will require a high-order adaptive optics (AO) system to meet its scientific goals, both to provide correction for atmospheric turbulence as well as reduce the impact of wind shake, leading to a residual image motion of 3 - 5 mas rms. METIS is expected to feature both an internal Single Conjugate AO system as well as an external Laser Tomography AO system. The challenges for the METIS AO system are mainly in the broad correction range, an excellent image stability required for coronagraphy and in providing a high sky coverage to be available for as many science targets as possible. An additional challenge for METIS is the need to compensate for composition turbulence, mainly in the form of fast fluctuations in water vapor concentration. Water vapor fluctuations impact the performance of METIS in several ways: Atmospheric dispersion causes a broadening of the point-spread function, both in the science channel and the wavefront channel, but can be corrected using a Atmospheric Dispersion Corrector. Variations in the water vapor composition cannot be corrected this way and are currently estimated to give a residual image motion of ≤10 mas rms. This effect can, especially for coronagraphy, not be neglected. Chromatic optical path difference errors, caused by changes in the index of refraction along the path through the atmosphere were found to be negligible in the case of METIS due to attenuation by the outer scale (at typical values of 25 m). Chromatic anisoplanatism is the effect that the light at different wavelengths travels through a slightly different light path through the atmosphere and can be–at least partly–corrected. The last effect is composition turbulence, mainly caused by fast (> 1 Hz) fluctuations in the water vapor content. Based on data for ALMA and radiometer probes, this leads to a maximum loss in Strehl ratio between 5 and 10%. This mainly has an impact on coronagraphy and the METIS AO team is actively investigating ways to compensate also water vapor turbulence. The main challenge is currently obtaining reliable data on the distribution and magnitude of precipitable water vapor fluctuations.
A tool for modelling telluric spectra
Authors: Smette Alain , Sana Hugues , Horst Hannes
Published: October 2010

Accurate synthetic telluric spectra are required for efficient use of telescope time, in particular, with large telescopes and high-resolution NIR spectroscopy: (i) In the preparation of observations, are the telluric features at the same wavelength as spectroscopic features of scientific interest? Since water vapor is the molecule whose abundance varies most in the atmosphere, what values of precipitable water vapor are suitable to carry out successful observations? Are the observations of a telluric star required? Or better, can telluric features in the science spectrum be accurately represented by an appropriate synthetic spectrum? This point is also very important in the planning of telescope time, as observations of a telluric star may sometimes take longer than the one of the science target. (ii) In the analysis of the observations, how do telluric lines affect the scientifically interesting features in the observed spectrum? Is it possible to recover the useful information when telluric star observations could not be obtained, do not have sufficient SNR, or suffer from a significant change in instrumental or observing conditions?
SpS1-High-resolution infrared spectroscopy at high and low altitudes
Authors: Kendrew Sarah
Published: October 2010

The advantages of a high altitude, dry site for ground-based astronomy at infrared (IR) wavelengths are well-known: the lower temperature and pressure associated with increased altitude reduce the emissivities of both atmosphere and telescope, and a lower atmospheric absorption improves the transmission of IR radiation. The next generation of IR instruments under development (for ELTs) will open up a new discovery space, particularly in high-resolution (HR) spectroscopy, which will not have a space-based counterpart and has proven to be a powerful tool for studying all stages of stellar evolution (e.g. (e.g. Jaffle et al., 2003). I present here a summary of quantitative work into transmission-dependent aspects of HR IR spectroscopy at high and low altitudes.
Astrophotonics and IR astronomy
Authors: OByrne J. W. , Bland-Hawthorn J. , Haynes R. , Horton A. , Bryant J. , Robertson J. G.
Published: October 2010

Working in collaboration with industry, the University of Sydney, the Anglo-Australian Observatory and Macquarie University are developing new ‘astrophotonic’ solutions to problems in astronomical instrumentation. A key first step involves overcoming the limitations imposed by multimode (MM) optical fibres that have been used by astronomers for many years to transport or reformat light from the telescope focus to an optical spectrograph. These large-core MM fibres maximise light into an astronomical instrument but at the expense of propagating many unpolarized modes. Until recently, this has deterred the use of more complex in-fibre processing of the light since this is typically limited to single-mode (SM) propagation. A MM to SM converter, known as a ‘photonic lantern’, was first demonstrated by Leon-Saval et al. (2005). If the number of transverse modes equals the number of SM fibres, and if a gradual and adiabatic transition between the MM fiber and the ensemble of SM fibres can be achieved, lossless coupling can take place in either propagation direction. Noordegraaf et al. (2009) demonstrated an efficient 1 x 7 photonic lantern (1 MM input and 7 SM outputs) for the first time.
SpS1-Digging in the solar COmosphere with NAC
Authors: Ayres Thomas R.
Published: October 2010

The solar “COmosphere” is an enigmatic region of cold gas (temperatures as low as ~3500 K) coexisting in the low chromosphere with plasma much hotter (~7000 K). This zone probably consists of patchy clouds of cool gas, seen readily in off-limb emissions of CO 4667 nm lines, threaded by hot gas entrained in long-lived magnetic filaments as well as transient shock fronts. The COmosphere was not anticipated in classical 1D models of the solar outer atmosphere, but is quite at home in the contemporary 3D highly dynamic view, which one might call the Magnetic Complexity Zone.
SpS1-Infrared spectroscopy of post-AGB objects
Authors: Hinkle Kenneth H. , Brittain Sean D. , Joyce Richard R.
Published: October 2010

Post-AGB (pAGB) objects are low to intermediate initial mass (≤8 M⊙) objects that have terminated normal nuclear burning and as a result are undergoing rapid evolution toward the white dwarf sequence. In classical pAGB objects evolution is to hotter effective temperatures at roughly constant luminosity. However, there are also several classes of pAGB objects that have revived nuclear burning after approaching or being on the white dwarf sequence. These include objects with delayed final helium shell flashes (e.g. Sakurai's star) and white dwarf mergers (e.g. R CrB stars). Binary evolution plays a critical role in many of these systems. A group of pAGB supergiants with large infrared excesses are suspected to be binaries that have undergone common envelope evolution. Further details on many of these objects can be found in reviews, see for instance Van Winckel (2003) and Herwig (2005).
Globular clusters in the near–infrared
Authors: Valenti E. , Origlia L. , Rich R. M.
Published: October 2010

The study of Globular Cluster (GC) stellar populations (SPs) addresses fundamental astrophysical questions ranging from stellar structure, evolution and dynamics, to Galaxy formation. Indeed, they represent:i)fossilsfrom the remote and violent epoch of Galaxy formation,ii) test particles for studying Galaxy dynamics and stellar dynamical model, andiii) fiducial templates for studying integrated light from distant stellar systems. In particular,high resolution spectroscopyof GC SPs provides abundance patterns which are crucial for understanding the formation and chemical enrichment time–scale of the host galaxy. Here the major results on Galactic GCs based on high-resolution near-infrared (near–IR) spectroscopy are briefly reviewed. Optical and IR spectroscopy are complementary tools to investigate SPs in different environments, the latter being more suitable in the case of moderately–high extinction regions (AV≥2) and high metallicity.
IceCube neutrino observatory at the South Pole: recent results
Authors: Filimonov Kirill
Published: October 2010

The IceCube neutrino observatory, the largest particle detector in the world (1 km3), is currently being built at the South Pole. IceCube looks down through the Earth to filter out lower-energy particles and uses optical sensors embedded deep in the ultra-clean Antarctic ice to detect high energy neutrinos via Cherenkov radiation from charged particles produced in neutrino interactions. A summary of selected recent results is presented.
The ARENA roadmap
Authors: Epchtein N. , Zinnecker H.
Published: October 2010

We present the main achievements of the ARENA network and a set of recommendations for the development of astronomy and astrophysics at CONCORDIA (Dome C)
Supernovae and solar cycles embedded in a Dome F ice core
Authors: Motizuki Yuko , Naka Yoichi , Takahashi Kazuya
Published: October 2010

We have recently found signals of candidates for two historical supernovae and past solar cycles in a depth profile of nitrate ion concentrations in an ice core portion corresponding to the 10th and the 11th centuries. This ice core was drilled in 2001 at Dome Fuji (Dome F) station in Antarctica. We briefly review our findings and discuss why Dome F is appropriate for this study.
Future plans for astronomy at Dome Fuji
Authors: Ichikawa Takashi
Published: October 2010

In Antarctica the cold and dry air is expected to provide the best observing conditions on the Earth for astronomical observations from the infra-red to the sub-millimetre. To utilise these advantages of Antarctica, we have devised a plan to construct an astronomical observatory at Dome Fuji, which is located in inland Antarctica. For pilot research and site testing at Dome Fuji, we have developed 40 cm infrared and 30 cm THz telescopes, which are durable for the harsh environment of inland Antarctica. As our project for astronomical research at Dome Fuji is approved for the 3-year program of NIPR, we will start the site testing and pilot research for astronomy at Dome Fuji from 2010.
Astronomy from the Antarctic Plateau: a global personal vision
Authors: Zinnecker Hans
Published: October 2010

The Antarctic Plateau (Dome C, also Dome A) is emerging as an especially good sitefor astronomical observations (high, dry, cold, no wind, good free seeing above a certainboundary layer). Over the last few years, several meetings and conferences tookplace to discuss potential astrophysical science cases for such exceptional atmosphericconditions. I summarise my personal conclusions from these discussions and presenta global vision (roadmap) for Antarctic Astronomy for future optical, near-IR, thermal-IR, andfar-IR/sub-mm observations. The need for international collaboration between Europe, Australia and China is stressed.
Challenges in Astronomy Education
Authors: De Greve Jean-Pierre
Published: October 2010

Astronomy is an attractive subject for education. It deals with fascination of the unknown and the unreachable, yet is uses tools, concepts and insights from various fundamental sciences such as mathematics, physics, chemistry, biology. Because of this it can be well used for introducing sciences to young people and to raise their interest in further studies in that direction. It is also an interesting subject for teaching as its different aspects (observation techniques, theory, data sampling and analysis, modelling,?) offer various didactical approaches towards different levels of pupils, students and different backgrounds. And it gives great opportunities to teach and demonstrate the essence of scientific research, through tutorials and projects. In this paper we discuss some of the challenges education in general, and astronomy in particular, faces in the coming decades, given the major geophysical and technological changes that can be deducted from our present knowledge. This defines a general, but very important background in terms of educational needs at various levels, and in geographical distribution of future efforts of the astronomical community. Special emphasis will be given to creative approaches to teaching, to strategies that are successful (such as the use of tutorials with element from computer games), and to initiatives complementary to the regular educational system. The programs developed by the IAU will be briefly highlighted.
Europa, Enceladus, and Titan as possible sites for life
Authors: Courtin Régis
Published: October 2010

Despite quite distinct bulk properties, Europa, the third largest Jovian satellite (d=3138 km), and the Saturnian satellites Enceladus (d~500 km) and Titan (d=5151 km) share a remarkable common feature which is a strong indication of the presence of liquid water at some level below the surface. The possibilities for the development of life organisms on these bodies are reviewed.
Gas-phase prebiotic chemistry in extraterrestrial environments
Authors: Balucani Nadia
Published: October 2010

A variety of molecular species up to complex polyatomic molecules/radicals have been identified in many extraterrestrial gaseous environments, including interstellar clouds, cometary comae and planetary atmospheres. Amongst the identified molecules/radicals, a large percentage are organic in nature and encompass also prebiotic molecules. Different types of microscopic processes are believed to be involved in their formation, including surface processes, ion- and radical- molecule reactions. A thorough characterization of such a complex chemistry relies on a multi-disciplinary approach, where the observations are complemented by accurate chemical modeling. Unfortunately, a literature survey reveals that only a small percentage of the elementary reactions considered in the available models have been characterized in laboratory experiments. In this contribution, a brief overview will be given of recent experimental techniques that have allowed us to reach a better description of neutral-neutral gas-phase reactions, which might be responsible for the formation of simple prebiotic molecules.
Surviving on Mars: test with LISA simulator
Authors: Galletta Giuseppe , D'Alessandro Maurizio , Bertoloni G. , Castellani F.
Published: October 2010

We present the results of experiments performed in the Padua simulators of planetary environments, named LISA, used to study the limits of bacterial life on the planet Mars. The survival of Bacillus strains for some hours in Martian environment is briefly discussed.
High cadence near-infrared transit timing observations of extrasolar planets
Authors: Cáceres Claudio , Ivanov Valentin D. , ~Minniti Dante , Naef Dominique , Melo Claudio , Mason Elena , Selman Fernando , Pietrzynsky Grzegorz
Published: October 2010

Currently the only technique sensitive to Earth mass planets around nearby stars (that are too close for microlensing) is the monitoring of the transit time variations of the transiting extrasolar planets. We search for additional planets in the systems of the hot-Neptune GJ-436 b, and the hot-Jupiter XO-1 b, using high cadence observations in the J and KS bands, with the SofI and ISAAC instruments from La Silla Paranal Observatory. New high-precision transit timing measurements were used to derive new ephemeris. No statistically significant timing deviations were detected. We demonstrate that the high cadence ground based near-infrared observations are successful in constraining the mean transit time to 30 sec, and are a viable alternative to space missions.