Early Results of the 3mm Spectral Line Survey toward the L1157 B1 Shocked Region

We have conducted a sensitive 3mm observation toward the shocked region, Lynds 1157 B1, which is an interaction spot between a molecular outflow and its ambient gas. We have successfully detected the CH3CHO, HCOOCH3, and HCOOH lines, as well as the CH2DOH line. The abundances of these molecules relative to CH3OH are found to be lower than those in the low-mass star-forming core, IRAS 16293-2422. Since these molecules are thought to evaporate from grain mantles, the observational results mean that complex molecules are less abundant in grain mantles residing in the ambient cloud surrounding a prestellar/protostellar core. Instead, efficient formation of the complex organic species and deuterated species should take place in a prestellar/protostellar core. The present result verifies the importance of an unbiased line survey of this source.

WASP-39b: a highly inflated Saturn-mass planet orbiting a late G-type star

We present the discovery of WASP-39b, a highly inflated transiting Saturn-mass planet orbiting a late G-type dwarf star with a period of 4.055259 +/- 0.000008 d, Transit Epoch T-0 = 2 455 342.9688 +/- 0.0002 (HJD), of duration 0.1168 +/- 0.0008 d. A combined analysis of the WASP photometry, high-precision follow-up transit photometry, and radial velocities yield a planetary mass of M-pl = 0.28 +/- 0.03 M-J and a radius of R-pl = 1.27 +/- 0.04 R-J, resulting in a mean density of 0.14 +/- 0.02 rho(J). The stellar parameters are mass M-star = 0.93 +/- 0.03 M-circle dot, radius R-star = 0.895 +/- 0.23 R-circle dot, and age 9(-4)(+3) Gyr. Only WASP-17b and WASP-31b have lower densities than WASP-39b, although they are slightly more massive and highly irradiated planets. From our spectral analysis, the metallicity of WASP-39 is measured to be [Fe/H] = -0.12 +/- 0.1 dex, and we find the planet to have an equilibrium temperature of 1116(-32)(+33) K. Both values strengthen the observed empirical correlation between these parameters and the planetary radius for the known transiting Saturn-mass planets.

The Type IIb SN 2008ax: spectral and light curve evolution

We present spectroscopy and photometry of the He-rich supernova (SN) 2008ax. The early-time spectra show prominent P-Cygni H lines, which decrease with time and disappear completely about 2 months after the explosion. In the same period He I lines become the most prominent spectral features. SN 2008ax displays the ordinary spectral evolution of a Type IIb supernova. A stringent pre-discovery limit constrains the time of the shock breakout of SN 2008ax to within only a few hours. Its light curve, which peaks in the B band about 20 d after the explosion, strongly resembles that of other He-rich core-collapse supernovae. The observed evolution of SN 2008ax is consistent with the explosion of a young Wolf-Rayet (of WNL type) star, which had retained a thin, low-mass shell of its original H envelope. The overall characteristics of SN 2008ax are reminiscent of those of SN 1993J, except for a likely smaller H mass. This may account for the findings that the progenitor of SN 2008ax was a WNL star and not a K supergiant as in the case of SN 1993J, that a prominent early-time peak is missing in the light curve of SN 2008ax, and that H alpha is observed at higher velocities in SN 2008ax than in SN 1993J.

The empirical metallicity dependence of the mass-loss rate of O- and early B-type stars

We present a comprehensive study of the observational dependence of the mass-loss rate in stationary stellar winds of hot massive stars on the metal content of their atmospheres. The metal content of stars in the Magellanic Clouds is discussed, and a critical assessment is given of state-of-the-art mass-loss determinations of OB stars in these two satellite systems and the Milky-Way. Assuming a power-law dependence of mass loss on metal content,. M. Z(m), and adopting a theoretical relation between the terminal flow velocity and metal content, v(infinity). Z(0.13) (Leitherer et al. 1992, ApJ, 401, 596), we find m = 0.83 +/- 0.16 for non-clumped outflows from an analysis of the wind momentum luminosity relation (WLR) for stars more luminous than 105.2 L circle dot. Within the errors, this result is in agreement with the prediction m = 0.69 +/- 0.10 by Vink et al. (2001, A& A, 369, 574). Absolute empirical values for the mass loss, based on Ha and ultraviolet (UV) wind lines, are found to be a factor of two higher than predictions in this high luminosity regime. If this difference is attributed to inhomogeneities in the wind, and this clumping does not impact the predictions, this would imply that luminous O and early-B stars have clumping factors in their Ha and UV line forming regions of about a factor of four. For lower luminosity stars, the winds are so weak that their strengths can generally no longer be derived from optical spectral lines (essentially Ha) and one must currently rely on the analysis of UV lines. We confirm that in this low-luminosity domain the observed Galactic WLR is found to be much steeper than expected from theory (although the specific sample is rather small), leading to a discrepancy between UV mass-loss rates and the predictions by a factor 100 at luminosities of L similar to 10(4.75) L circle dot, the origin of which is unknown. We emphasize that even if the current mass-loss rates of hot luminous stars would turn out to be overestimated as a result of wind clumping, but the degree of clumping would be rather independent of metallicity, the scalings derived in this study are expected to remain correct.

Double-detonation sub-Chandrasekhar supernovae: Synthetic observables for minimum helium shell mass models

In the double-detonation scenario for Type Ia supernovae, it is suggested that a detonation initiates in a shell of helium-rich material accreted from a companion star by a sub-Chandrasekhar-mass white dwarf. This shell detonation drives a shock front into the carbon-oxygen white dwarf that triggers a secondary detonation in the core. The core detonation results in a complete disruption of the white dwarf. Earlier studies concluded that this scenario has difficulties in accounting for the observed properties of Type Ia supernovae since the explosion ejecta are surrounded by the products of explosive helium burning in the shell. Recently, however, it was proposed that detonations might be possible for much less massive helium shells than previously assumed (Bildsten et al.). Moreover, it was shown that even detonations of these minimum helium shell masses robustly trigger detonations of the carbon-oxygen core (Fink et al.). Therefore, it is possible that the impact of the helium layer on observables is less than previously thought. Here, we present time-dependent multi-wavelength radiative transfer calculations for models with minimum helium shell mass and derive synthetic observables for both the optical and ? -ray spectral regions. These differ strongly from those found in earlier simulations of sub-Chandrasekhar-mass explosions in which more massive helium shells were considered. Our models predict light curves that cover both the range of brightnesses and the rise and decline times of observed Type Ia supernovae. However, their colors and spectra do not match the observations. In particular, their B - V colors are generally too red. We show that this discrepancy is mainly due to the composition of the burning products of the helium shell of the Fink et al. models which contain significant amounts of titanium and chromium. Using a toy model, we also show that the burning products of the helium shell depend crucially on its initial composition. This leads us to conclude that good agreement between sub-Chandrasekhar-mass explosions and observed Type Ia supernovae may still be feasible but further study of the shell properties is required.

A J-band detection of the sub-stellar mass donor in SDSS J1433+1011

We present time-resolved J-band spectroscopy of the short-period cataclysmic variable SDSS J143317.78+101123.3. We detect absorption lines from the sub-stellar donor star in this system, which contributes 38 +/- 5 per cent to the J-band light. From the relative strengths of the absorption lines in the J band, we estimate the spectral type of the donor star to be L2 +/- 1. These data are the first spectroscopic detection of a donor with a confirmed sub-stellar mass in a cataclysmic variable, and the spectral type is consistent with that expected from semi-empirical evolutionary models.

Using skew mapping, we have been able to derive an estimate for the radial velocity of the donor of K-d = 520 +/- 60 km/s. This value is consistent with, though much less precise than, predictions from mass determinations found via photometric fitting of the eclipse light curves.

WASP-54b, WASP-56b and WASP-57b: Three new sub-Jupiter mass planets from SuperWASP

We present three newly discovered sub-Jupiter mass planets from the SuperWASP survey: WASP-54b is a heavily bloated planet of mass 0.636$^{+0.025}_{-0.024}$ \mj and radius 1.653$^{+0.090}_{-0.083}$ \rj. It orbits a F9 star, evolving off the main sequence, every 3.69 days. Our MCMC fit of the system yields a slightly eccentric orbit ($e=0.067^{+0.033}_{-0.025}$) for WASP-54b. We investigated further the veracity of our detection of the eccentric orbit for WASP-54b, and we find that it could be real. However, given the brightness of WASP-54 V=10.42 magnitudes, we encourage observations of a secondary eclipse to draw robust conclusions on both the orbital eccentricity and the thermal structure of the planet. WASP-56b and WASP-57b have masses of 0.571$^{+0.034}_{-0.035}$ \mj and $0.672^{+0.049}_{-0.046}$ \mj, respectively; and radii of $1.092^{+0.035}_{-0.033}$ \rj for WASP-56b and $0.916^{+0.017}_{-0.014}$ \rj for WASP-57b. They orbit main sequence stars of spectral type G6 every 4.67 and 2.84 days, respectively. WASP-56b and WASP-57b show no radius anomaly and a high density possibly implying a large core of heavy elements; possibly as high as $\sim$50 M$_{\oplus}$ in the case of WASP-57b. However, the composition of the deep interior of exoplanets remain still undetermined. Thus, more exoplanet discoveries such as the ones presented in this paper, are needed to understand and constrain giant planets' physical properties.

Comparison of progenitor mass estimates for the type IIP SN 2012A

We present the one-year long observing campaign of SN 2012A which exploded in the nearby (9.8 Mpc) irregular galaxy NGC 3239. The photometric evolution is that of a normal type IIP supernova. The absolute maximum magnitude, with MB = -16.23 +- 0.16 mag. SN2012A reached a peak luminosity of about 2X10**42 erg/s, which is brighter than those of other SNe with a similar 56Ni mass. The latter was estimated from the luminosity in the exponential tail of the light curve and found to be M(56Ni) = 0.011 +-0.004 Msun. The spectral evolution of SN 2012A is also typical of SN IIP, from the early spectra dominated by a blue continuum and very broad (~10**4 km/s) Balmer lines, to the late-photospheric spectra characterized by prominent P-Cygni features of metal lines (Fe II, Sc II, Ba II, Ti II, Ca II, Na ID). The photospheric velocity is moderately low, ~3X10**3 km/s at 50 days, for the low optical depth metal lines. The nebular spectrum obtained 394 days after the shock breakout shows the typical features of SNe IIP and the strength of the [O I] doublet suggests a progenitor of intermediate mass, similar to SN 2004et (~15 Msun). A candidate progenitor for SN 2012A has been identified in deep, pre-explosion K'-band Gemini North (NIRI) images, and found to be consistent with a star with a bolometric magnitude -7.08+-0.36 (log L/Lsun = 4.73 +- 0.14$ dex). The magnitude of the recovered progenitor in archival images points toward a moderate-mass 10.5 (-2/+4.5) Msun star as the precursor of SN 2012A. The explosion parameters and progenitor mass were also estimated by means of a hydrodynamical model, fitting the bolometric light curve, the velocity and the temperature evolution. We found a best fit for a kinetic energy of 0.48 foe, an initial radius of 1.8X10**13 cm and ejecta mass of 12.5 Msun.

A Stubbornly Large Mass of Cold Dust in the Ejecta of Supernova 1987A

We present new Herschel photometric and spectroscopic observations of Supernova 1987A, carried out in 2012. Our dedicated photometric measurements provide new 70 mu m data and improved imaging quality at 100 and 160 mu m compared to previous observations in 2010. Our Herschel spectra show only weak CO line emission, and provide an upper limit for the 63 mu m [O-I] line flux, eliminating the possibility that line contaminations distort the previously estimated dustmass. The far-infrared spectral energy distribution (SED) is well fitted by thermal emission from cold dust. The newly measured 70 mu m flux constrains the dust temperature, limiting it to nearly a single temperature. The far-infrared emission can be fitted by 0.5 +/- 0.1M(circle dot) of amorphous carbon, about a factor of two larger than the current nucleosynthetic mass prediction for carbon. The observation of SiO molecules at early and late phases suggests that silicates may also have formed and we could fit the SED with a combination of 0.3M(circle dot) of amorphous carbon and 0.5M(circle dot) of silicates, totalling 0.8M(circle dot) of dust. Our analysis thus supports the presence of a large dust reservoir in the ejecta of SN 1987A. The inferred dust mass suggests that supernovae can be an important source of dust in the interstellar medium, from local to high-redshift galaxies.

Polarization spectral synthesis for Type Ia supernova explosion models

We present a Monte Carlo radiative transfer technique for calculating synthetic spectropolarimetry for multidimensional supernova explosion models. The approach utilizes 'virtual-packets' that are generated during the propagation of the Monte Carlo quanta and used to compute synthetic observables for specific observer orientations. Compared to extracting synthetic observables by direct binning of emergent Monte Carlo quanta, this virtual-packet approach leads to a substantial reduction in the Monte Carlo noise. This is not only vital for calculating synthetic spectropolarimetry (since the degree of polarization is typically very small) but also useful for calculations of light curves and spectra. We first validate our approach via application of an idealized test code to simple geometries. We then describe its implementation in the Monte Carlo radiative transfer code ARTIS and present test calculations for simple models for Type Ia supernovae. Specifically, we use the well-known one-dimensional W7 model to verify that our scheme can accurately recover zero polarization from a spherical model, and to demonstrate the reduction in Monte Carlo noise compared to a simple packet-binning approach. To investigate the impact of aspherical ejecta on the polarization spectra, we then use ARTIS to calculate synthetic observables for prolate and oblate ellipsoidal models with Type Ia supernova compositions.

Late-time spectral line formation in Type IIb supernovae, with application to SN 1993J, SN 2008ax, and SN 2011dh

We investigate line formation processes in Type IIb supernovae (SNe) from 100 to 500 days post-explosion using spectral synthesis calculations. The modelling identifies the nuclear burning layers and physical mechanisms that produce the major emission lines, and the diagnostic potential of these. We compare the model calculations with data on the three best observed Type IIb SNe to-date - SN 1993J, SN 2008ax, and SN 2011dh. Oxygen nucleosynthesis depends sensitively on the main-sequence mass of the star and modelling of the [O I] lambda lambda 6300, 6364 lines constrains the progenitors of these three SNe to the M-ZAMS = 12-16 M-circle dot range (ejected oxygen masses 0.3-0.9 M-circle dot), with SN 2011dh towards the lower end and SN 1993J towards the upper end of the range. The high ejecta masses from M-ZAMS greater than or similar to 17 M-circle dot progenitors give rise to brighter nebular phase emission lines than observed. Nucleosynthesis analysis thus supports a scenario of low-to-moderate mass progenitors for Type IIb SNe, and by implication an origin in binary systems. We demonstrate how oxygen and magnesium recombination lines may be combined to diagnose the magnesium mass in the SN ejecta. For SN 2011dh, a magnesium mass of 0.02-0.14 M-circle dot is derived, which gives a Mg/O production ratio consistent with the solar value. Nitrogen left in the He envelope from CNO burning gives strong [N II] lambda lambda 6548, 6583 emission lines that dominate over Ha emission in our models. The hydrogen envelopes of Type IIb SNe are too small and dilute to produce any noticeable H alpha emission or absorption after similar to 150 days, and nebular phase emission seen around 6550 angstrom is in many cases likely caused by [N II] lambda lambda 6548, 6583. Finally, the influence of radiative transport on the emergent line profiles is investigated. Significant line blocking in the metal core remains for several hundred days, which affects the emergent spectrum. These radiative transfer effects lead to early-time blueshifts of the emission line peaks, which gradually disappear as the optical depths decrease with time. The modelled evolution of this effect matches the observed evolution in SN 2011dh.

PTF11iqb: cool supergiant mass-loss that bridges the gap between Type IIn and normal supernovae

PTF11iqb was initially classified as a TypeIIn event caught very early after explosion. It showed narrow Wolf-Rayet (WR) spectral features on day 2, but the narrow emission weakened quickly and the spectrum morphed to resemble those of Types II-L and II-P. At late times, Halpha emission exhibited a complex, multipeaked profile reminiscent of SN1998S. In terms of spectroscopic evolution, we find that PTF11iqb was a near twin of SN~1998S, although with weaker interaction with circumstellar material (CSM) at early times, and stronger CSM interaction at late times. We interpret the spectral changes as caused by early interaction with asymmetric CSM that is quickly (by day 20) enveloped by the expanding SN ejecta photosphere, but then revealed again after the end of the plateau when the photosphere recedes. The light curve can be matched with a simple model for weak CSM interaction added to the light curve of a normal SN~II-P. This plateau requires that the progenitor had an extended H envelope like a red supergiant, consistent with the slow progenitor wind speed indicated by narrow emission. The cool supergiant progenitor is significant because PTF11iqb showed WR features in its early spectrum --- meaning that the presence of such WR features in an early SN spectrum does not necessarily indicate a WR-like progenitor. [abridged] Overall, PTF11iqb bridges SNe~IIn with weaker pre-SN mass loss seen in SNe II-L and II-P, implying a continuum between these types.

A Correlation Between Host Star Activity and Planet Mass for Close-in Extrasolar Planets?

The activity levels of stars are influenced by several stellar properties, such as stellar rotation, spectral type, and the presence of stellar companions. Analogous to binaries, planetary companions are also thought to be able to cause higher activity levels in their host stars, although at lower levels. Especially in X-rays, such influences are hard to detect because coronae of cool stars exhibit a considerable amount of intrinsic variability. Recently, a correlation between the mass of close-in exoplanets and their host star's X-ray luminosity has been detected, based on archival X-ray data from the ROSAT All-Sky Survey. This finding has been interpreted as evidence for star-planet interactions. We show in our analysis that this correlation is caused by selection effects due to the flux limit of the X-ray data used and due to the intrinsic planet detectability of the radial velocity method, and thus does not trace possible planet-induced effects. We also show that the correlation is not present in a corresponding complete sample derived from combined XMM-Newton and ROSAT data.

Novel Metabolite Biomarkers of Huntington's Disease As Detected by High-Resolution Mass Spectrometry

Huntington's disease (HD) is a fatal autosomal-dominant neurodegenerative disorder that affects approximately 3-10 people per 100 000 in the Western world. The median age of onset is 40 years, with death typically following 15-20 years later. In this study, we biochemically profiled post-mortem frontal lobe and striatum from HD sufferers (n = 14) and compared their profiles with controls (n = 14). LC-LTQ-Orbitrap-MS detected a total of 5579 and 5880 features for frontal lobe and striatum, respectively. An ROC curve combining two spectral features from frontal lobe had an AUC value of 0.916 (0.794 to 1.000) and following statistical cross-validation had an 83% predictive accuracy for HD. Similarly, two striatum biomarkers gave an ROC AUC of 0.935 (0.806 to 1.000) and after statistical cross-validation predicted HD with 91.8% accuracy. A range of metabolite disturbances were evident including but-2-enoic acid and uric acid, which were altered in both frontal lobe and striatum. A total of seven biochemical pathways (three in frontal lobe and four in striatum) were significantly altered as a result of HD. This study highlights the utility of high-resolution metabolomics for the study of HD. Further characterization of the brain metabolome could lead to the identification of new biomarkers and novel treatment strategies for HD.

Application of thermal ion-molecule reactions in tackling spectroscopic inferences in inductively coupled plasma mass spectrometry

Part I: Ultra-trace determination of vanadium in lake sediments: a performance comparison using O2, N20, and NH3 as reaction gases in ICP-DRC-MS Thermal ion-molecule reactions, targeting removal of specific spectroscopic interference problems, have become a powerful tool for method development in quadrupole based inductively coupled plasma mass spectrometry (ICP-MS) applications. A study was conducted to develop an accurate method for the determination of vanadium in lake sediment samples by ICP-MS, coupled with a dynamic reaction cell (DRC), using two differenvchemical resolution strategies: a) direct removal of interfering C10+ and b) vanadium oxidation to VO+. The performance of three reaction gases that are suitable for handling vanadium interference in the dynamic reaction cell was systematically studied and evaluated: ammonia for C10+ removal and oxygen and nitrous oxide for oxidation. Although it was able to produce comparable results for vanadium to those using oxygen and nitrous oxide, NH3 did not completely eliminate a matrix effect, caused by the presence of chloride, and required large scale dilutions (and a concomitant increase in variance) when the sample and/or the digestion medium contained large amounts of chloride. Among the three candidate reaction gases at their optimized Eonditions, creation of VO+ with oxygen gas delivered the best analyte sensitivity and the lowest detection limit (2.7 ng L-1). Vanadium results obtained from fourteen lake sediment samples and a certified reference material (CRM031-040-1), using two different analytelinterference separation strategies, suggested that the vanadium mono-oxidation offers advantageous performance over the conventional method using NH3 for ultra-trace vanadium determination by ICP-DRC-MS and can be readily employed in relevant environmental chemistry applications that deal with ultra-trace contaminants.Part II: Validation of a modified oxidation approach for the quantification of total arsenic and selenium in complex environmental matrices Spectroscopic interference problems of arsenic and selenium in ICP-MS practices were investigated in detail. Preliminary literature review suggested that oxygen could serve as an effective candidate reaction gas for analysis of the two elements in dynamic reaction cell coupled ICP-MS. An accurate method was developed for the determination of As and Se in complex environmental samples, based on a series of modifications on an oxidation approach for As and Se previously reported. Rhodium was used as internal standard in this study to help minimize non-spectral interferences such as instrumental drift. Using an oxygen gas flow slightly higher than 0.5 mL min-I, arsenic is converted to 75 AS160+ ion in an efficient manner whereas a potentially interfering ion, 91Zr+, is completely removed. Instead of using the most abundant Se isotope, 80Se, selenium was determined by a second most abundant isotope, 78Se, in the form of 78Se160. Upon careful selection of oxygen gas flow rate and optimization ofRPq value, previous isobaric threats caused by Zr and Mo were reduced to background levels whereas another potential atomic isobar, 96Ru+, became completely harmless to the new selenium analyte. The new method underwent a strict validation procedure where the recovery of a suitable certified reference material was examined and the obtained sample data were compared with those produced by a credible external laboratory who analyzed the same set of samples using a standardized HG-ICP-AES method. The validation results were satisfactory. The resultant limits of detection for arsenic and selenium were 5 ng L-1 and 60 ng L-1, respectively.