Polarimetry and Spectroscopy of the `Oxygen Flaring' DQ Herculis-like nova: V5668 Sagittarii (2015)

Classical novae are eruptions on the surface of a white dwarf in a binary system. The material ejected from the white dwarf surface generally forms an axisymmetric shell of gas and dust around the system. The three-dimensional structure of these shells is difficult to untangle when viewed on the plane of the sky. In this work a geometrical model is developed to explain new observations of the 2015 nova V5668 Sagittarii. To understand the ionisation structure in terms of the nova shell morphology and estimate the emission distribution directly following the light-curve's dust-dip. High-cadence optical polarimetry and spectroscopy observations of a nova are presented. The ejecta is modelled in terms of morpho-kinematics and photoionisation structure. Initially observational results are presented, including broadband polarimetry and spectroscopy of V5668 Sgr nova during eruption. Variability over these observations provides clues towards the evolving structure of the nova shell. The position angle of the shell is derived from polarimetry, which is attributed to scattering from small dust grains. Shocks in the nova outflow are suggested in the photometry and the effect of these on the nova shell are illustrated with various physical diagnostics. Changes in density and temperature as the super soft source phase of the nova began are discussed. Gas densities are found to be of the order of 10$^{9}$ cm$^{-3}$ for the nova in its auroral phase. The blackbody temperature of the central stellar system is estimated to be around $2.2\times10^{5}$ K at times coincident with the super soft source turn-on. It was found that the blend around 4640 $\rm{\AA}$ commonly called `nitrogen flaring' is more naturally explained as flaring of the O~{\sc ii} multiplet (V1) from 4638 - 4696 $\rm{\AA}$, i.e. `oxygen flaring'

The impact of parental contact upon cortical noxious-related activity in human neonates

BACKGROUND: Neonates display strong behavioural, physiological and cortical responses to tissue-damaging procedures. Parental contact can successfully regulate general behavioural and physiological reactivity of the infant, but it is not known whether it can influence noxious-related activity in the brain. Brain activity is highly dependent upon maternal presence in animal models, and therefore this could be an important contextual factor in human infant pain-related brain activity. METHODS: Global topographic analysis was used to identify the presence and inter-group differences in noxious-related activity in three separate parental contexts. EEG was recorded during a clinically required heel lance in three age and sex-matched groups of neonates (a) while held by a parent in skin-to-skin (n = 9), (b) while held by a parent with clothing (n = 9) or (c) not held at all, but in individualized care (n = 9). RESULTS: The lance elicited a sequence of 4-5 event-related potentials (ERPs), including the noxious ERP (nERP), which was smallest for infants held skin-to-skin and largest for infants held with clothing (p=0.016). The nERP was then followed by additional and divergent long-latency ERPs (> 750 ms post-lance), not previously described, in each of the groups, suggesting the engagement of different higher level cortical processes depending on parental contact. CONCLUSIONS: These results show the importance of considering contextual factors in determining infant brain activity and reveal the powerful influence of parental contact upon noxious-related activity across the developing human brain. SIGNIFICANCE: This observational study found that the way in which the neonatal brain processes a noxious stimulus is altered by the type of contact the infant has with their mother. Specifically, being held in skin-to-skin reduces the magnitude of noxious-related cortical activity. This work has also shown that different neural mechanisms are engaged depending on the mother/infant context, suggesting maternal contact can change how a baby's brain processes a noxious stimulus

5D gravity and the discrepant G measurements

It is shown that 5D Kaluza-Klein theory stabilized by an external bulk scalar field may solve the discrepant laboratory G measurements. This is achieved by an effective coupling between gravitation and the geomagnetic field. Experimental considerations are also addressed.Comment: 13 pages, to be published in: Proceedings of the 18th Course of the School on Cosmology and Gravitation: The gravitational Constant. Generalized gravitational theories and experiments (30 April-10 May 2003, Erice). Ed. by G. T. Gillies, V. N. Melnikov and V. de Sabbata, (Kluwer), 13pp. (in print) (2003

Two New Nova Shells associated with V4362 Sagittarii and DO Aquilae

A classical nova is an eruption on the surface of a white dwarf in an accreting binary system. The material ejected from the white dwarf surface generally forms an axisymmetric shell. The shaping mechanisms of nova shells are probes of the processes that take place at energy scales between planetary nebulae and supernova remnants. We report on the discovery of nova shells surrounding the post-nova systems V4362 Sagittarii (1994) and more limited observations of DO Aquilae (1925). Distance measurements of 0.5p/m1.4 kpc for V4362 Sgr and 6.7 p/m 3.5 kpc -0.2 for DO Aql are found based on the expansion parallax method. The growth rates are measured to be 0.07``/year for DO Aql and 0.32``/year for V4362 Sgr. A preliminary investigation into the ionisation structure of the nova shell associated with V4362 Sgr is presented. The observed ionisation structure of nova shells depends strongly on their morphology and the orientation of the central component towards the observer. X-ray, IR and UV observations as well as optical integral field unit spectroscopy are required to better understand these interesting objects

A Review of Seafood Safety after the Deepwater Horizon Blowout

Background: The Deepwater Horizon (DH) blowout resulted in fisheries closings across the Gulf of Mexico. Federal agencies, in collaboration with impacted Gulf states, developed a protocol to determine when it is safe to reopen fisheries based on sensory and chemical analyses of seafood. All federal waters have been reopened, yet concerns have been raised regarding the robustness of the protocol to identify all potential harmful exposures and protect the most sensitive populations

EEG, behavioural and physiological recordings following a painful procedure in human neonates

We present a dataset of cortical, behavioural, and physiological responses following a single, clinically required noxious stimulus in a neonatal sample. Cortical activity was recorded from 112 neonates (29-47 weeks gestational age at study) using a 20-channel electroencephalogram (EEG), which was time-locked to a heel lance. This data is linked to pain-related behaviour (facial expression), physiology (heart rate, oxygenation) and a composite clinical score (Premature Infant Pain Profile, PIPP). The dataset includes responses to non-noxious sham and auditory controls. The infants' relevant medical and pain history was collected up to the day of the study and recorded in an extensive database of variables including clinical condition at birth, diagnoses, medications, previous painful procedures, injuries, and selected maternal information. This dataset can be used to investigate the cortical, physiological, and behavioural pain-related processing in human infants and to evaluate the impact of medical conditions and experiences upon the infant response to noxious stimuli. Furthermore, it provides information on the formation of individual pain phenotypes

Detection of Exocometary CO within the 440 Myr Old Fomalhaut Belt: A Similar CO+CO 2 Ice Abundance in Exocomets and Solar System Comets

Recent Atacama Large Millimeter/submillimeter Array observations present mounting evidence for the presence of exocometary gas released within Kuiper Belt analogs around nearby main-sequence stars. This represents a unique opportunity to study their ice reservoir at the younger ages when volatile delivery to planets is most likely to occur. We here present the detection of CO J = 2-1 emission colocated with dust emission from the cometary belt in the 440 Myr old Fomalhaut system. Through spectrospatial filtering, we achieve a 5.4σ detection and determine that the ring's sky-projected rotation axis matches that of the star. The CO mass derived ((0.65\mbox{--}42)\times {10}^{-7}\,{M}_{\oplus }) is the lowest of any circumstellar disk detected to date and must be of exocometary origin. Using a steady-state model, we estimate the CO+CO2 mass fraction of exocomets around Fomalhaut to be between 4.6% and 76%, consistent with solar system comets and the two other belts known to host exocometary gas. This is the first indication of a similarity in cometary compositions across planetary systems that may be linked to their formation scenario and is consistent with direct interstellar medium inheritance. In addition, we find tentative evidence that $(49\pm 27)$% of the detected flux originates from a region near the eccentric belt's pericenter. If confirmed, the latter may be explained through a recent impact event or CO pericenter glow due to exocometary release within a steady-state collisional cascade. In the latter scenario, we show how the azimuthal dependence of the CO release rate leads to asymmetries in gas observations of eccentric exocometary belts

Interstellar Dust Close to the Sun

The low density interstellar medium (ISM) close to the Sun and inside of the heliosphere provides a unique laboratory for studying interstellar dust grains. Grain characteristics in the nearby ISM are obtained from observations of interstellar gas and dust inside of the heliosphere and the interstellar gas towards nearby stars. Comparison between the gas composition and solar abundances suggests that grains are dominated by olivines and possibly some form of iron oxide. Measurements of the interstellar Ne/O ratio by the Interstellar Boundary Explorer spacecraft indicate that a high fraction of interstellar oxygen in the ISM must be depleted onto dust grains. Local interstellar abundances are consistent with grain destruction in ~150 km/s interstellar shocks, provided that the carbonaceous component is hydrogenated amorphous carbon and carbon abundances are correct. Variations in relative abundances of refractories in gas suggest variations in the history of grain destruction in nearby ISM. The large observed grains, > 1 micron, may indicate a nearby reservoir of denser ISM. Theoretical three-dimensional models of the interaction between interstellar dust grains and the solar wind predict that plumes of about 0.18 micron dust grains form around the heliosphere.Comment: 2011 AGOS Taiwan meeting; accepted for publication in Earth, Planets and Spac

A Complete ALMA Map of the Fomalhaut Debris Disk

© 2017. The American Astronomical Society. All rights reserved. We present ALMA mosaic observations at 1.3 mm (223 GHz) of the Fomalhaut system with a sensitivity of 14 μJy/beam. These observations provide the first millimeter map of the continuum dust emission from the complete outer debris disk with uniform sensitivity, enabling the first conclusive detection of apocenter glow. We adopt an MCMC modeling approach that accounts for the eccentric orbital parameters of a collection of particles within the disk. The outer belt is radially confined with an inner edge of 136.3 ± 0.9 au and width of 13.5 ± 1.8 au. We determine a best-fit eccentricity of 0.12 ± 0.01. Assuming a size distribution power-law index of q = 3.46 ± 0.09, we constrain the dust absorptivity power-law index β to be 0.9 < β < 1.5. The geometry of the disk is robustly constrained with inclination 65.°6 ± 0.°3, position angle 337.°9 ± 0.°3, and argument of periastron 22.°5 ± 4.°3. Our observations do not confirm any of the azimuthal features found in previous imaging studies of the disk with Hubble Space Telescope, SCUBA, and ALMA. However, we cannot rule out structures ≤10 au in size or that only affect smaller grains. The central star is clearly detected with a flux density of 0.75 ± 0.02 mJy, significantly lower than predicted by current photospheric models. We discuss the implications of these observations for the directly imaged Fomalhaut b and the inner dust belt detected at infrared wavelengths