Waiting Time Distribution of Emissions in Complex Coronal Mass Ejections

The waiting time distribution of emissions in Coronal Mass Ejections (CMEs) with several emissions is examined. We define the waiting time as the time interval between the commencement of an emission and the commencement of the next emission considered as parts of a unique CME. The distribution seems to follow a power-law. Two classes of CMEs several emissions are considered: “close” and “separate” depending on angular distance between emissions.     

Thermal desorption of CH4 retained in CO2 ice

CO₂ ices are known to exist in different astrophysical environments. In spite of this, its physical properties (structure, density, refractive index) have not been as widely studied as those of water ice. It would be of great value to study the adsorption properties of this ice in conditions related to astrophysical environments. In this paper, we explore the possibility that CO₂ traps relevant molecules in astrophysical environments at temperatures higher than expected from their characteristic sublimation point. To fulfil this aim we have carried out desorption experiments under High Vacuum conditions based on a Quartz Crystal Microbalance and additionally monitored with a Quadrupole Mass Spectrometer. From our results, the presence of CH₄ in the solid phase above the sublimation temperature in some astrophysical scenarios could be explained by the presence of several retaining mechanisms related to the structure of CO₂ ice.     

Ionospheric Disturbances and Their Impact on IPS Using MEXART Observations

We study the impact of ionospheric disturbances on the Earth’s environment caused by the solar events that occurred from 20 April to 31 May 2010, using observations from the Mexican Array Radio Telescope (MEXART). During this period of time, several astronomical sources presented fluctuations in their radio signals. Wavelet analysis, together with complementary information such as the vertical total electron content (vTEC) and the Dst index, were used to identify and understand when the interplanetary scintillation (IPS) could be contaminated by ionospheric disturbances (IOND). We find that radio signal perturbations were sometimes associated with IOND and/or IPS fluctuations; however, in some cases, it was not possible to clearly identify their origin. Our Fourier and wavelet analyses showed that these fluctuations had frequencies in the range ≈?0.01 Hz?–?≈?1.0 Hz (periodicities of 100 s to 1 s).     

Spectroscopic Observations of the 2011 Draconids Meteor Shower

Some past October Draconid shower meteoroids fell apart in a spray of fragments at the end of their trajectory before slowing down, from which it was concluded that these were among the most fragile meteoroids known. In those instances, the dust could not be reliably traced to a particular return of the parent comet 21P/Giaconini-Zinner. On October 8th, 2011, Earth was predicted to transverse the 1900 A.D. dust ejecta of the comet. In 1900, the comet’s perihelion distance first moved significantly inwards to the Sun and ejection conditions could have been unusual. An airborne observing campaign was organized, with several teams contributing imaging and spectrographic cameras to study the manner in which these meteoroids released the volatile element sodium during the ablation process in the Earth’s atmosphere. IMCCE, ESA, and the SETI Institute contributed spectrographic cameras based on low-light WATEC 902H2 Ultimate, low-light LCC1, and GenII XX1332 image intensified cameras. An outburst was observed, much as predicted. Despite a lack of bright meteors, a total of 15 Draconid spectra were recorded. All show evidence of an early release of sodium. The loss of sodium was observed to coincide with the formation of a distinct wake of fragments. The observations show that 21P/Giacobini-Zinner ejected fragile meteoroids during the return in 1900. Those grains may have lost some sodium even before impacting Earth.     

WSO-UV—ultraviolet mission for the next decade

The World Space Observatory UltraViolet (WSO–UV) is an international space mission devoted to UV spectroscopy and imaging. The observatory includes a 170 cm aperture telescope capable of high-resolution and long slit low-resolution spectroscopy, and deep UV and optical imaging. The observatory is designed for observations in the ultraviolet domain where most of astrophysical processes can be efficiently studied with unprecedented capability.     

Very peculiar wind from BD+53°2790, the optical counterpart to 4U 2206+54

BD+53°2790, an O9.5V star, is the optical counterpart to the HMXRB 4U 2206+54. This system was classified initially as a BeX, but observational evidence soon stressed the need to revise this classification. The permanent asymmetry in the Hα line profiles (in contrast with the cyclic variations shown by Be stars), the variations in the profile of this line in time scales of hours (while time scales from weeks to months are expected in Be stars), and the lack of correlation between IR observables and Hα line parameters, strongly suggest that, while BD+53°2790 contains a circumstellar disc, it is not like the one present in Be stars (Blay et al. 2006). Furthermore, there is evidence of overabundance of He in BD+53°2790. Together with the presence of an anomalous wind, found through UV spectroscopy, the possibility to link this star with the group of He rich stars is open. We will discuss the work done with IUE data from BD+53°2790 and the unexpected finding of a slow and dense wind, very rare for an O9.5V star.     

The formation of planetary disks and winds: an ultraviolet view

Planetary systems are angular momentum reservoirs generated during star formation. This accretion process produces very powerful engines able to drive the optical jets and the molecular outflows. A fraction of the engine energy is released into heating thus the temperature of the engine ranges from the 3000 K of the inner disk material to the 10 MK in the areas where magnetic reconnection occurs. There are important unsolved problems concerning the nature of the engine, its evolution and the impact of the engine in the chemical evolution of the inner disk. Of special relevance is the understanding of the shear layer between the stellar photosphere and the disk; this layer controls a significant fraction of the magnetic field building up and the subsequent dissipative processes ougth to be studied in the UV. This contribution focus on describing the connections between 1 Myr old suns and the Sun and the requirements for new UV instrumentation to address their evolution during this period. Two types of observations are shown to be needed: monitoring programmes and high resolution imaging down to, at least, milliarsecond scales.     

A Hubble Space Telescope/NICMOS view of the prototypical giant Hii region NGC604 in M33

We present the first high-spatial-resolution near-infrared (NIR) imaging of NGC604, obtained with the NICMOS camera onboard the Hubble Space Telescope (HST). These NICMOS broad-band images reveal new NIR point sources, clusters, and diffuse structures. We find an excellent spatial correlation between the 8.4 GHz radio continuum and the 2.2 μm nebular emission. Moreover, massive young stellar object candidates appear aligned with these radio peaks, reinforcing the idea that those areas are star-forming regions. Three different scaled OB associations are recognized in the NICMOS images. The brightest NIR sources in our images have properties that suggest that they are red supergiant stars, of which one was previously known. This preliminary analysis of the NICMOS images shows the complexity of the stellar content of the NGC604 nebula.     

STEREO Observations of Energetic Ions in Corotating Interaction Regions During the May 2007 Solar Events

Solar Physics - Elemental composition and energy spectra of ～?0.1?–?1.0 MeV/n heavy ions were analyzed in two corotating interaction region (CIR) events...     

MONS OT J004240.69+405142.0: An orphan GRB optical afterglow candidate in Andromeda?

Here we report the serendipitous identification of a bright optical transient in the vicinity of the dwarf elliptical galaxy M 32 (NGC 221). This transient (MONS OT J004240.69+405142.0) was detected using filtered CCD imaging, about 20 arcsec southwest from the core of M 32, at equatorial coordinates α = 00:42:40.69 ± 0.05, δ = +40:51:42.0 ± 0.5, between 04:20:16 and 04:21:46 UT on June 22, 2007. A detailed analysis of the intensity profile of the feature suggests that it is of stellar nature with apparent visual magnitude 9.69 ± 0.15 which gives an absolute magnitude of ?14.7 ± 0.3 if the feature is located in M 31/M 32. Under the assumption of the event reported here being of cosmic origin and although no correlation with GRBs in time or space has been found, the behaviour of the optical transient appears to resemble that of the recently observed GRB 080319B: very fast ascent and decay of several magnitudes within a few minutes. If this interpretation is correct, the afterglow decay was extremely rapid, decreasing by more than 5 mag. in about 2 min, α = 2.4. Given its properties, the event is a possible orphan GRB optical afterglow candidate originated beyond the Local Group. Alternative explanations are also discussed.