We report observations of a filament eruption, two-ribbon flare, and coronal mass ejection (CME) that occurred in Active Region NOAA 10898 on 6 July 2006. The filament was located South of a strong sunspot that dominated the region. In the evolution leading up to the eruption, and for some time after it, a counter-clockwise rotation of the sunspot of about 30 degrees was observed. We suggest that the rotation triggered the eruption by progressively expanding the magnetic field above the filament. To test this scenario, we study the effect of twisting the initially potential field overlying a pre-existing flux rope, using three-dimensional zero–β MHD simulations. We consider a magnetic configuration whose photospheric flux distribution and coronal structure is guided by the observations and a potential field extrapolation. We find that the twisting leads to the expansion of the overlying field. As a consequence of the progressively reduced magnetic tension, the flux rope quasi-statically adapts to the changed environmental field, rising slowly. Once the tension is sufficiently reduced, a distinct second phase of evolution occurs where the flux rope enters an unstable regime characterized by a strong acceleration. Our simulation thus suggests a new mechanism for the triggering of eruptions in the vicinity of rotating sunspots.

We present some preliminary results from our investigation of giant planetary core formation using numerical simulations with the Lagrangian Integrator for Planetary Accretion and Dynamics (LIPAD) by Levison et al. (2012). LIPAD couples dynamics with collisional evolution, including fragmentation. We start with a cold planetesimal disk using particles of a few kilometres in size. Our simulations show growth from kilometre-sized planetesimals to several Earth-mass sized embryos (tens of thousands of kilometers) can occur. However, these embryos may not be large enough to start runaway gas accretion necessary to build the envelopes of gas giant planets.

The Sun somehow accelerates the solar wind, an incessant stream of plasma originating in coronal holes and some, as yet unidentified, regions. Occasionally, coronal, and possibly sub-photospheric structures, conspire to energize a spectacular eruption from the Sun which we call a coronal mass ejection (CME). These can leave the Sun at very high speeds and travel through the interplanetary medium, resulting in a large-scale disturbance of the ambient background plasma. These interplanetary CMEs (ICMEs) can drive shocks which in turn accelerate particles, but also have a distinct intrinsic magnetic structure which is capable of disturbing the Earth's magnetic field and causing significant geomagnetic effects. They also affect other planets, so they can and do contribute to space weather throughout the heliosphere. This paper presents a historical review of early space weather studies, a modern-day example, and discusses space weather throughout the heliosphere.

High contrast imaging observations with the Hubble Space Telescope show that the nearby star Fomalhaut is surrounded by a dusty debris belt and a candidate planet, Fomalhaut b, located just inside the edge of the belt. Fomalhaut b has unexpected characteristics, such as a relatively blue spectrum, leading to the hypothesis that the detected object is a low-mass planet hosting a giant planetary dust ring or cloud seen in reflected light. Here we present new HST/STIS observations made in 2010 and 2012 that authenticate the existence of Fomalhaut b. Our MCMC analysis of four epochs of astrometry spread over eight years indicate that the orbit has a~170 AU and e~0.85. Fomalhaut b's orbit is apsidally aligned with the main belt, and periapse is located approximately ~30 AU south of the star. We also show the existence of a ~50 AU wide azimuthal dust depletion in the dust belt. These new findings provide a revised picture of Fomalhaut as a dynamically complex system, where the orbit of Fomalhaut b and the belt structure signify the presence of additional massive planets orbiting the star.

On the long road from dust to planets there are planetesimals. We review and criticize proposed mechanisms for planetesimal formation, and point out topics for future work.

We report the detection of multi-armed spirals in the environment of HD 100546 using NICI at Gemini South in the Ks band. These data feature a better angular resolution and higher contrast than previous HST images, which allows to resolve the former known spiral into a multiple pattern. An analytic model with a gravitational perturber is used to fit the spiral pattern. We derived limit of detections which set constraints on the discovered forming planet.

DX Cha (HD 104237) is a southern, optically bright Herbig Ae star with an infrared excess, that is part of a small stellar group younger than 5 Myr. We used the APEX and ASTE submillimeter telescopes in Chile to search for continuum and gas emission around this system. Using LABOCA on APEX we detect strong continuum emission around HD104237-A and system component HD104237-E. Our ASTE spectrum detects a double-peaked 12CO(3-2) line profile towards the system, typical of a rotating disk. The new data are used as constraints with MCFOST to produce a disk model that fits the entire SED as well as the observed CO line profile.

In our own solar system, the necessity of understanding space weather is readily evident. Fortunately for Earth, our nearest stellar neighbor is relatively quiet, exhibiting activity levels several orders of magnitude lower than young, solar-type stars. In protoplanetary systems, stellar magnetic phenomena observed are analogous to the solar case, but dramatically enhanced on all physical scales: bigger, more energetic, more frequent. While coronal mass ejections (CMEs) could play a significant role in the evolution of protoplanets, they could also affect the evolution of the central star itself. To assess the consequences of prominence eruption/CMEs, we have invoked the solar-stellar connection to estimate, for young, solar-type stars, how frequently stellar CMEs may occur and their attendant mass and angular momentum loss rates. We will demonstrate the necessary conditions under which CMEs could slow stellar rotation.

The primary objective of the 2-m National Large Solar Telescope (NLST) is to study the solar atmosphere with high spatial and spectral resolution. With an innovative optical design, NLST is an on-axis Gregorian telescope with a low number of optical elements and a high throughput. In addition, it is equipped with a high order adaptive optics system to produce close to diffraction limited performance.

NLST will address a large number of scientific questions with a focus on high resolution observations. With NLST, high spatial resolution observations of prominences will be possible in multiple spectral lines. Studies of magnetic fields, filament eruptions as a whole, and the dynamics of filaments on fine scales using high resolution observations will be some of the major areas of focus.

The geo-effectiveness of coronal mass ejections (CME) is determined by a complex chain of processes. This paper highlights this fact by first discussing the importance of CMEs intrinsic properties set at the Sun (e.g., trajectory, eruption process, orientation, etc.). We then review other key processes that may occur during propagation (e.g., shocks, compressions, magnetic flux erosion) and in the specific interaction with Earth's magnetosphere (e.g., magnetic properties, preconditioning mechanisms). These processes sequentially have a significant influence on the final geo-effectiveness of CMEs. Their relative importance is discussed. While the CME's trajectory, magnetic field orientation, velocity and their duration as set at the Sun certainly are key ingredients to geo-effectiveness, other processes and properties, that at first appear secondary, often may be as important.

We present preliminary results of a detailed chemical abundance analysis for a sample of solar-type stars known to exhibit excess infrared emission associated with dusty debris disks. Our sample of 28 stars was selected based on results from the Formation and Evolution of Planetary Systems (FEPS) Spitzer Legacy Program, for the purpose of investigating whether the stellar atmospheres have been polluted with planetary material, which could indicate that the metallicity enhancement in stars with planets is due to metal-rich infall in the later stages of star and planet formation. The preliminary results presented here consist of precise abundances for 15 elements (C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Fe, Co, and Ni) for half of the stars in our sample. We find that none of the stars investigated so far exhibit the expected trend of increasing elemental abundance with increasing condensation temperature, which would result from the stars having accreted planetary debris. Rather, the slopes of linear least-squares fits to the abundance data are either negative or consistent with zero. In both cases, our results may indicate that, like the Sun, the debris disk host stars are deficient in refractory elements, a possible signature of terrestrial and/or gas giant planet formation.

The launch of STEREO spacecraft in October 2006 provided an opportunity to view filament eruptions from two viewpoints giving new insights into their three-dimensional (3D) geometry and true trajectory. The kinematical parameters (velocity and acceleration vectors), the rotation motion, non-radial motion and the helical twist around the filament axis in 3D space have been obtained for the first time. All these properties of erupting filaments are very important to our understanding of the physical phenomena triggering the eruption and their early evolution. In the present paper we review different reconstruction techniques of erupting filaments and the main results obtained using the STEREO observations.

The transit of coronal mass ejections (CMEs) from the Sun to 1 AU lasts on average one to five days. As they propagate, CMEs interact with the solar wind and preceding eruptions, which modify their properties. In the past ten years, the evolution of CMEs in the inner heliosphere has been investigated with the help of numerical simulations, through the analysis of remote-sensing heliospheric observations, especially with the SECCHI suite onboard STEREO, and through the analysis of multi-spacecraft in situ measurements. Most studies have focused on understanding the characteristics of the magnetic flux rope thought to form the core of the CME. Here, we first review recent work related to CME propagation in the heliosphere, which point towards the need to develop more complex models to analyze CME observations. In the second part of this article, we review some recent studies of CME-CME interaction, which also illustrate the complexity of phenomena occurring in the inner heliosphere.

The proper characterisation of stellar winds is crucial to constrain interactions between exoplanets and their surrounding environments and also essential for the study of space weather events on exoplanets. Although the great majority of exoplanets discovered so far are orbiting cool, low-mass stars with properties (mass, radius and effective temperatures) similar to solar, the stellar magnetism can be significantly different from the solar one, both in topology and intensity. Due to the current technology used in exoplanetary searches, most of the currently known exoplanets are found orbiting at extremely close distances to their host stars (< 0.1 au). The dramatic differences in stellar magnetism and orbital radius can make the interplanetary medium of exoplanetary systems remarkably distinct from the one present in the solar system. In addition, the interaction of the stellar winds with exoplanets can lead, among others, to observable signatures that are absent in our own solar system.

Prominence oscillations have been mostly detected using Doppler velocity, although there are also claimed detections by means of the periodic variations of half-width or line intensity. Our main aim here is to explore the relationship between spectral indicators such as Doppler shift, line intensity and line half-width and the linear perturbations excited in a simple prominence model.

We review the nearby debris disk structures revealed by multi-wavelength images from Spitzer and Herschel, and complemented with detailed spectral energy distribution modeling. Similar to the definition of habitable zones around stars, debris disk structures should be identified and characterized in terms of dust temperatures rather than physical distances so that the heating power of different spectral type of stars is taken into account and common features in disks can be discussed and compared directly. Common features, such as warm (~150 K) dust belts near the water-ice line and cold (~50 K) Kuiper-belt analogs, give rise to our emerging understanding of the levels of order in debris disk structures and illuminate various processes about the formation and evolution of exoplanetary systems. In light of the disk structures in the debris disk twins (Vega and Fomalhaut), and the current limits on the masses of planetary objects, we suggest that the large gap between the warm and cold dust belts is the best signpost for multiple (low-mass) planets beyond the water-ice line.

High-resolution spectra of a giant solar quiescent filament were taken with the Echelle spectrograph at the Vacuum Tower Telescope (VTT; Tenerife, Spain). A mosaic of various spectroheliograms (Hα, Hα±0.5 Å and Na D2) were chosen to examine the filament at different heights in the solar atmosphere. In addition, full-disk images (He i 10830 Å and Ca ii K) of the Chromspheric Telescope and full-disk magnetograms of the Helioseismic and Magnetic Imager were used to complement the spectra. Preliminary results are shown of this filament, which had extremely large linear dimensions (~740″) and was observed in November 2011 while it traversed the northern solar hemisphere.

We present some highlights of two ongoing investigations that deal with the dynamics of planetary systems. Firstly, until recently, observed eccentric patterns in debris disks were found in young systems. However recent observations of Gyr-old eccentric debris disks leads to question the survival timescale of this type of asymmetry. One such disk was recently observed in the far-IR by the Herschel Space Observatory around ζ2 Reticuli. Secondly, as a binary companion orbits a circumprimary disk, it creates regions where planet formation is strongly handicapped. However, some planets were detected in this zone in tight binary systems (γ Cep, HD 196885). We aim to determine whether a binary companion can affect migration such that planets are brought in these regions and focus in particular on the planetesimal-driven migration mechanism.

I find the location of the ice line in circumbinary disks heated by steady mass accretion and stellar irradiation, comparing the position with the minimum stable semimajor axis, interior to which planetary orbits are unstable. I show that there is a critical binary separation for which binaries with separations larger than this critical value have ice lines that lie interior to the boundary of stability. The critical separation for an equal-mass binary of 1 M⊙ stars is ≈ 1.04 AU, scaling weakly with mass accretion rate and Rosseland mean opacity of the disk. For a steady mass accretion rate of Ṁ ~ 10−8 M⊙ yr−1 and a Rosseland mean opacity of κR ~ 1 cm2 g−1, I show that ≳ 80% of all binary systems with component masses M☆ ≲ 2.0 M⊙ have ice lines interior to the boundary of stability. This suggests that rocky planets should not be common in these systems. Searching for planets around binaries with separations larger than the critical separation with Kepler or microlensing will provide a test of this prediction.

We present column density measurements of a polar crown prominence observed on March 9th, 2012 by the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory. The structure was viewed on the east limb by AIA and erupted about 30 hours after the observations shown here. We estimate column density by approximating the obscured background emission to obtain an optical depth. This can then be combined with the absorption cross sections of neutral hydrogen and helium, along with the He:H abundance ratio, to calculate column density. We perform this calculation for the 171, 193, 211, and 335 Å AIA passbands.