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EXQUISITE NOVA LIGHT CURVES FROM THE SOLAR MASS EJECTION IMAGER (SMEI)

We present light curves of three classical novae (CNe; KT Eridani, V598 Puppis, V1280 Scorpii) and one recurrent nova (RS Ophiuchi) derived from data obtained by the Solar Mass Ejection Imager (SMEI) on board the Coriolis satellite. SMEI provides near complete skymap coverage with precision visible-light photometry at 102 minute cadence. The light curves derived from these skymaps offer unprecedented temporal resolution around, and especially before, maximum light, a phase of the eruption normally not covered by ground-based observations. They allow us to explore fundamental parameters of individual objects including the epoch of the initial explosion, the reality and duration of any pre-maximum halt (found in all three fast novae in our sample), the presence of secondary maxima, speed of decline of the initial light curve, plus precise timing of the onset of dust formation (in V1280 Sco) leading to estimation of the bolometric luminosity, white dwarf mass, and object distance. For KT Eri, Liverpool Telescope SkyCamT data confirm important features of the SMEI light curve and overall our results add weight to the proposed similarities of this object to recurrent rather than to CNe. In RS Oph, comparison with hard X-ray data from the 2006 outburst implies that the onset of the outburst coincides with extensive high-velocity mass loss. It is also noted that two of the four novae we have detected (V598 Pup and KT Eri) were only discovered by ground-based observers weeks or months after maximum light, yet these novae reached peak magnitudes of 3.46 and 5.42, respectively. This emphasizes the fact that many bright novae per year are still overlooked, particularly those of the very fast speed class. Coupled with its ability to observe novae in detail even when relatively close to the Sun in the sky, we estimate that as many as five novae per year may be detectable by SMEI.

79 ASTRONOMY AND ASTROPHYSICS↗

WHAT IS THE MOST PROMISING ELECTROMAGNETIC COUNTERPART OF A NEUTRON STAR BINARY MERGER?

The final inspiral of double neutron star and neutron-star-black-hole binaries are likely to be detected by advanced networks of ground-based gravitational wave (GW) interferometers. Maximizing the science returns from such a discovery will require the identification of an electromagnetic counterpart. Here we critically evaluate and compare several possible counterparts, including short-duration gamma-ray bursts (SGRBs), 'orphan' optical and radio afterglows, and day-long optical transients powered by the radioactive decay of heavy nuclei synthesized in the merger ejecta ('kilonovae'). We assess the promise of each counterpart in terms of four 'Cardinal Virtues': detectability, high fraction, identifiability, and positional accuracy. Taking into account the search strategy for typical error regions of tens of square degrees, we conclude that SGRBs are the most useful to confirm the cosmic origin of a few GW events, and to test the association with neutron star mergers. However, for the more ambitious goal of localizing and obtaining redshifts for a large sample of GW events, kilonovae are instead preferred. Off-axis optical afterglows are detectable for at most tens of percent of events, while radio afterglows are promising only for energetic relativistic ejecta in a high-density medium. Our main recommendations are: (1) an all-sky gamma-ray satellite is essential for temporal coincidence detections, and for GW searches of gamma-ray-triggered events; (2) the Large Synoptic Survey Telescope should adopt a one-day cadence follow-up strategy, ideally with 0.5 hr per pointing to cover GW error regions; and (3) radio searches should focus on the relativistic case, which requires observations for a few months.

79 ASTRONOMY AND ASTROPHYSICS↗

A ∼ 3.8 hr PERIODICITY FROM AN ULTRASOFT ACTIVE GALACTIC NUCLEUS CANDIDATE

Very few galactic nuclei are found to show significant X-ray quasi-periodic oscillations (QPOs). After carefully modeling the noise continuum, we find that the ∼3.8 hr QPO in the ultrasoft active galactic nucleus candidate 2XMM J123103.2+110648 was significantly detected (∼5σ) in two XMM-Newton observations in 2005, but not in the one in 2003. The QPO root mean square (rms) is very high and increases from ∼25% in 0.2-0.5 keV to ∼50% in 1-2 keV. The QPO probably corresponds to the low-frequency type in Galactic black hole X-ray binaries, considering its large rms and the probably low mass (∼10{sup 5} M {sub ☉}) of the black hole in the nucleus. We also fit the soft X-ray spectra from the three XMM-Newton observations and find that they can be described with either pure thermal disk emission or optically thick low-temperature Comptonization. We see no clear X-ray emission from the two Swift observations in 2013, indicating lower source fluxes than those in XMM-Newton observations.

79 ASTRONOMY AND ASTROPHYSICS↗

Nuclear 'pasta phase' and its consequences on neutrino opacities

In this paper, we calculate the diffusion coefficients that are related to the neutrino opacities considering the formation of nuclear pasta and homogeneous matter at low densities. Our results show that the mean-free paths are significantly altered by the presence of nuclear pasta in stellar matter when compared with the results obtained with homogeneous matter. These differences in neutrino opacities certainly influence the Kelvin-Helmholtz phase of protoneutron stars and consequently the results of supernova explosion simulations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

ULTRALUMINOUS X-RAY SOURCES IN ARP 147

The Chandra X-Ray Observatory was used to image the collisional ring galaxy Arp 147 for 42 ks. We detect nine X-ray sources with luminosities in the range of (1.4-7) x 10{sup 39} erg s{sup -1} (assuming that the sources emit isotropically) in or near the blue knots of star formation associated with the ring. A source with an X-ray luminosity of 1.4 x 10{sup 40} erg s{sup -1} is detected in the nuclear region of the intruder galaxy. X-ray sources associated with a foreground star and a background quasar are used to improve the registration of the X-ray image with respect to Hubble Space Telescope (HST) high-resolution optical images. The intruder galaxy, which apparently contained little gas before the collision, shows no X-ray sources other than the one in the nuclear bulge which may be a poorly fed supermassive black hole. These observations confirm the conventional wisdom that collisions of gas-rich galaxies trigger large rates of star formation which, in turn, generate substantial numbers of X-ray sources, some of which have luminosities above the Eddington limit for accreting stellar-mass black holes (i.e., ultraluminous X-ray sources, 'ULXs'). We also utilize archival Spitzer and Galex data to help constrain the current star formation rate in Arp 147 to {approx}7 M{sub sun} yr{sup -1}. All of these results, coupled with binary evolution models for ULXs, allow us to tentatively conclude that the most intense star formation may have ended some 15 Myr in the past.

79 ASTRONOMY AND ASTROPHYSICS↗

THE SPECTRUM OF THE RECYCLED PSR J0437-4715 AND ITS WHITE DWARF COMPANION

We present extensive spectral and photometric observations of the recycled pulsar/white dwarf binary containing PSR J0437-4715, which we analyzed together with archival X-ray and gamma-ray data, to obtain the complete mid-infrared to gamma-ray spectrum. We first fit each part of the spectrum separately, and then the whole multi-wavelength spectrum. We find that the optical-infrared part of the spectrum is well fit by a cool white dwarf atmosphere model with pure hydrogen composition. The model atmosphere (T{sub eff} = 3950 {+-} 150 K, log g = 6.98 {+-} 0.15, R{sub WD} = (1.9 {+-} 0.2) Multiplication-Sign 10{sup 9} cm) fits our spectral data remarkably well for the known mass and distance (M = 0.25 {+-} 0.02 M{sub Sun }, d = 156.3 {+-} 1.3 pc), yielding the white dwarf age ({tau}{sub WD} = 6.0 {+-} 0.5 Gyr). In the UV, we find a spectral shape consistent with thermal emission from the bulk of the neutron star surface, with surface temperature between 1.25 Multiplication-Sign 10{sup 5} and 3.5 Multiplication-Sign 10{sup 5} K. The temperature of the thermal spectrum suggests that some heating mechanism operates throughout the life of the neutron star. The temperature distribution on the neutron star surface is non-uniform. In the X-rays, we confirm the presence of a high-energy tail which is consistent with a continuation of the cutoff power-law component ({Gamma} = 1.56 {+-} 0.01, E{sub cut} = 1.1 {+-} 0.2 GeV) that is seen in gamma rays and perhaps even extends to the near-UV.

79 ASTRONOMY AND ASTROPHYSICS↗

Toward understanding the B[e] phenomenon. V. Nature and spectral variations of the MWC 728 binary system

We report the results of a long-term spectroscopic monitoring of the FS CMa type object MWC 728. We found that it is a binary system with a B5 ve (T{sub eff} = 14,000 ± 1000 K) primary and a G8 iii type (T{sub eff} ∼ 5000 K) secondary. Absorption line positions of the secondary vary, with a semi-amplitude of ∼20 km s{sup −1} and a period of 27.5 days. The system’s mass function is 2.3 × 10{sup −2} M{sub ⊙}, and its orbital plane is ∼13°–15° tilted from the plane of the sky. The primary’s vsin i∼110 km s{sup −1}, combined with this tilt, implies that it rotates at a nearly breakup velocity. We detected strong variations of the Balmer and He i emission-line profiles on timescales from days to years. This points to a variable stellar wind of the primary in addition to the presence of a circum-primary gaseous disk. The strength of the absorption-line spectrum, along with the optical and near infrared (IR) continuum, suggest that the primary contributes ∼60% of the V-band flux, the disk contributes ∼30%, and the secondary contributes ∼10%. The system parameters, along with the interstellar extinction, suggest a distance of ∼1 kpc, that the secondary does not fill its Roche lobe, and that the companions’ mass ratio is q ∼ 0.5. Overall, the observed spectral variability and the presence of a strong IR-excess are in agreement with a model of a close binary system that has undergone a non-conservative mass-transfer.

79 ASTRONOMY AND ASTROPHYSICS↗

Gamma-Ray Emission Concurrent with the Nova in the Symbiotic Binary V407 Cygni

Novae are thermonuclear explosions on a white dwarf surface fueled by mass accreted from a companion star. Current physical models posit that shocked expanding gas from the nova shell can produce x-ray emission, but emission at higher energies has not been widely expected. Here in this paper, we report the Fermi Large Area Telescope detection of variable γ-ray emission (0.1 to 10 billion electron volts) from the recently detected optical nova of the symbiotic star V407 Cygni. We propose that the material of the nova shell interacts with the dense ambient medium of the red giant primary and that particles can be accelerated effectively to produce π 0 decay γ-rays from proton-proton interactions. Lastly, emission involving inverse Compton scattering of the red giant radiation is also considered and is not ruled out.

79 ASTRONOMY AND ASTROPHYSICS↗

XMM-NEWTON OBSERVATIONS OF THE DWARF NOVA RU Peg IN QUIESCENCE: PROBE OF THE BOUNDARY LAYER

We present an analysis of X-ray and UV data obtained with the XMM-Newton Observatory of the long-period dwarf nova RU Peg. RU Peg contains a massive white dwarf (WD), possibly the hottest WD in a dwarf nova (DN), it has a low inclination, thus optimally exposing its X-ray emitting boundary layer (BL), and has an excellent trigonometric parallax distance. We modeled the X-ray data using XSPEC assuming a multi-temperature plasma emission model built from the MEKAL code (i.e., CEVMKL). We obtained a maximum temperature of 31.7 keV, based on the European Photon Imaging Camera MOS1, 2 and pn data, indicating that RU Peg has an X-ray spectrum harder than most DNe, except U Gem. This result is consistent with and indirectly confirms the large mass of the WD in RU Peg. The X-ray luminosity we computed corresponds to a BL luminosity for a mass accretion rate of 2 Multiplication-Sign 10{sup -11} M{sub sun} yr{sup -1} (assuming M{sub wd} = 1.3 M{sub sun}), in agreement with the expected quiescent accretion rate. The modeling of the O VIII emission line at 19 A as observed by the Reflection Grating Spectrometer implies a projected stellar rotational velocity v{sub rot}sin i = 695 km s{sup -1}, i.e., the line is emitted from material rotating at {approx}936-1245 km s{sup -1} (i {approx} 34 Degree-Sign -48 Degree-Sign) or about 1/6 of the Keplerian speed; this velocity is much larger than the rotation speed of the WD inferred from the Far Ultraviolet Spectroscopic Explorer spectrum. Cross-correletion analysis yielded an undelayed (time lag {approx} 0) component and a delayed component of 116 {+-} 17 s where the X-ray variations/fluctuations lagged the UV variations. This indicates that the UV fluctuations in the inner disk are propagated into the X-ray emitting region in about 116 s. The undelayed component may be related to irradiation effects.

79 ASTRONOMY AND ASTROPHYSICS↗

Confirmation of a high magnetic field in GRO J1008–57

GRO J1008–57 is a high-mass X-ray binary for which several claims of a cyclotron resonance scattering feature near 80 keV have been reported. We use NuSTAR, Suzaku, and Swift data from its giant outburst of 2012 November to confirm the existence of the 80 keV feature and perform the most sensitive search to date for cyclotron scattering features at lower energies. We find evidence for a 78{sub −2}{sup +3} keV line in the NuSTAR and Suzaku data at >4σ significance, confirming the detection using Suzaku alone by Yamamoto et al. A search of both the phase-averaged and phase-resolved data rules out a fundamental at lower energies with optical depth larger than 5% of the 78 keV line. These results indicate that GRO J1008–57 has a magnetic field of 6.7 × 10{sup 12}(1 + z) G, the highest among known accreting pulsars.

79 ASTRONOMY AND ASTROPHYSICS↗

Si K EDGE STRUCTURE AND VARIABILITY IN GALACTIC X-RAY BINARIES

We survey the Si K edge structure in various absorbed Galactic low-mass X-ray binaries (LMXBs) to study states of silicon in the inter- and circum-stellar medium. The bulk of these LMXBs lie toward the Galactic bulge region and all have column densities above 10{sup 22} cm{sup −2}. The observations were performed using the Chandra High Energy Transmission Grating Spectrometer. The Si K edge in all sources appears at an energy value of 1844 ± 0.001 eV. The edge exhibits significant substructure that can be described by a near edge absorption feature at 1849 ± 0.002 eV and a far edge absorption feature at 1865 ± 0.002 eV. Both of these absorption features appear variable with equivalent widths up to several mÅ. We can describe the edge structure using several components: multiple edge functions, near edge absorption excesses from silicates in dust form, signatures from X-ray scattering optical depths, and a variable warm absorber from ionized atomic silicon. The measured optical depths of the edges indicate much higher values than expected from atomic silicon cross sections and interstellar medium abundances, and they appear consistent with predictions from silicate X-ray absorption and scattering. A comparison with models also indicates a preference for larger dust grain sizes. In many cases, we identify Si xiii resonance absorption and determine ionization parameters between log ξ = 1.8 and 2.8 and turbulent velocities between 300 and 1000 km s{sup −1}. This places the warm absorber in close vicinity of the X-ray binaries. In some data, we observe a weak edge at 1.840 keV, potentially from a lesser contribution of neutral atomic silicon.

79 ASTRONOMY AND ASTROPHYSICS↗

Understanding the Impacts of Stellar Companions on Planet Formation and Evolution: A Survey of Stellar and Planetary Companions within 25 pc

We explore the impact of outer stellar companions on the occurrence rate of giant planets detected with radial velocities. We searched for stellar and planetary companions to a volume-limited sample of solar-type stars within 25 pc. Using adaptive optics imaging observations from the Lick 3 m and Palomar 200″ Telescopes, we characterized the multiplicity of our sample stars, down to the bottom of the main sequence. With these data, we confirm field star multiplicity statistics from previous surveys. We additionally combined three decades of radial velocity (RV) data from the California Planet Search with newly collected RV data from Keck/HIRES and the Automated Planet Finder/Levy Spectrometer to search for planetary companions in these same systems. Using an updated catalog of both stellar and planetary companions, as well as detailed injection/recovery tests to determine our sensitivity and completeness, we measured the occurrence rate of planets among the single- and multiple-star systems. We found that planets with masses in the range of 0.1–10 M {sub J} and with semimajor axes of 0.1–10 au have an occurrence rate of 0.18{sub −0.03}{sup +0.04} planets per star when they orbit single stars and an occurrence rate of 0.12 ± 0.04 planets per star when they orbit a star in a binary system. Breaking the sample down by the binary separation, we found that only one planet-hosting binary system had a binary separation <100 au, and none had a separation <50 au. These numbers yielded planet occurrence rates of 0.20{sub −0.06}{sup +0.07} planets per star for binaries with separation a {sub B} > 100 au and 0.04{sub −0.02}{sup +0.04} planets per star for binaries with separation a {sub B} < 100 au. The similarity in the planet occurrence rate around single stars and wide primaries implies that wide binary systems should actually host more planets than single-star systems, since they have more potential host stars. We estimated a system-wide planet occurrence rate of 0.3 planets per wide binary system for binaries with separations a {sub B} > 100 au. Finally, we found evidence that giant planets in binary systems have a different semimajor-axis distribution than their counterparts in single-star systems. The planets in the single-star sample had a significantly higher occurrence rate outside of 1 au than inside 1 au by nearly 4σ, in line with expectations that giant planets are most common near the snow line. However, the planets in the wide binary systems did not follow this distribution, but rather had equivalent occurrence rates interior and exterior to 1 au. This may point to binary-mediated planet migration acting on our sample, even in binaries wider than 100 au.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Empirical links between XRB and AGN accretion using the complete z < 0.4 spectroscopic CSC/SDSS catalog

Striking similarities have been seen between accretion signatures of Galactic X-ray binary (XRB) systems and active galactic nuclei (AGNs). XRB spectral states show a V-shaped correlation between X-ray spectral hardness and Eddington ratio as they vary, and some AGN samples reveal a similar trend, implying analogous processes at vastly larger masses and timescales. To further investigate the analogies, we have matched 617 sources from the Chandra Source Catalog to Sloan Digital Sky Survey spectroscopy, and uniformly measured both X-ray and optical spectral characteristics across a broad range of AGN and galaxy types. We provide useful tabulations of X-ray spectral slope for broad- and narrow-line AGNs, star-forming and passive galaxies, and composite systems, also updating relationships between optical (Hα and [O III]) line emission and X-ray luminosity. We further fit broadband spectral energy distributions with a variety of templates to estimate bolometric luminosity. Our results confirm a significant trend in AGNs between X-ray spectral hardness and Eddington ratio expressed in X-ray luminosity, albeit with significant dispersion. The trend is not significant when expressed in the full bolometric or template-estimated AGN luminosity. We also confirm a relationship between the X-ray/optical spectral slope α{sub ox} and Eddington ratio, but it may not follow the trend predicted by analogy with XRB accretion states.

79 ASTRONOMY AND ASTROPHYSICS↗

Fabrication of anti-adhesion surfaces on aluminium substrates of rubber plastic moulds using electrolysis plasma treatment

An anti-adhesion surface with a water contact angle of 167° was fabricated on aluminium samples of rubber plastic moulds by electrolysis plasma treatment using mixed electrolytes of C{sub 6}H{sub 5}O{sub 7}(NH{sub 4}){sub 3} and Na{sub 2}SO{sub 4}, followed by fluorination. To optimise the fabrication conditions, several important processing parameters such as the discharge voltage, discharge time, concentrations of supporting electrolyte and stearic acid ethanol solution were examined systematically. Using scanning electron microscopy (SEM) to analyse surfaces morphology, micrometer scale pits, and protrusions were found on the surface, with numerous nanometer mastoids contained in the protrusions. These binary micro/nano-scale structures, which are similar to the micro-structures of soil-burrowing animals, play a critical role in achieving low adhesion properties. Otherwise, the anti-adhesion behaviours of the resulting samples were analysed by the atomic force microscope (AFM), Fourier-transform infrared spectrophotometer (FTIR), electrons probe micro-analyzer (EPMA), optical contact angle meter, digital Vickers microhardness (Hv) tester, and electronic universal testing. The results show that the electrolysis plasma treatment does not require complex processing parameters, using a simple device, and is an environment-friendly and effective method. Under the optimised conditions, the contact angle (CA) for the modified anti-adhesion surface is up to 167°, the sliding angle (SA) is less than 2°, roughness of the sample surface is only 0.409μm. Moreover, the adhesion force and H{sub v} are 0. 9KN and 385, respectively.

36 MATERIALS SCIENCE↗

The trends high-contrast imaging survey. IV. The occurrence rate of giant planets around M dwarfs

Doppler-based planet surveys have discovered numerous giant planets but are incomplete beyond several AU. At larger star-planet separations, direct planet detection through high-contrast imaging has proven successful, but this technique is sensitive only to young planets and characterization relies upon theoretical evolution models. Here we demonstrate that radial velocity measurements and high-contrast imaging can be combined to overcome these issues. The presence of widely separated companions can be deduced by identifying an acceleration (long-term trend) in the radial velocity of a star. By obtaining high spatial resolution follow-up imaging observations, we rule out scenarios in which such accelerations are caused by stellar binary companions with high statistical confidence. We report results from an analysis of Doppler measurements of a sample of 111 M-dwarf stars with a median of 29 radial velocity observations over a median time baseline of 11.8 yr. By targeting stars that exhibit a radial velocity acceleration ({sup t}rend{sup )} with adaptive optics imaging, we determine that 6.5% ± 3.0% of M-dwarf stars host one or more massive companions with 1 < m/M{sub J} < 13 and 0 < a < 20 AU. These results are lower than analyses of the planet occurrence rate around higher-mass stars. We find the giant planet occurrence rate is described by a double power law in stellar mass M and metallicity F ≡ [Fe/H] such that f(M,F)=0.039{sub −0.028}{sup +0.056}M{sup 0.8{sub −}{sub 0}{sub .}{sub 9}{sup +{sup 1{sup .{sup 1}}}}}10{sup (3.8±1.2)F}. Our results are consistent with gravitational microlensing measurements of the planet occurrence rate; this study represents the first model-independent comparison with microlensing observations.

79 ASTRONOMY AND ASTROPHYSICS↗

PoroTomo - Distributed Temperature Sensing (DTS) Measurements made in Brady Observation Well 56-1

This submission is a follow-up to Distributed Temperature Sensing (DTS) measurements made in Brady observation well 56-1 during the PoroTomo field experiment conducted in March, 2016. The measurements in this data set were made on August 24, 2018 over an approximately 20 hour period. The fiber-optic cable extends to the bottom of the well at 367 m below the wellhead. Measurements were made with a Silixa XT DTS interrogator configured to continuously record in each file a sixty-second average of stokes and anti-stokes readings on a single channel with a bottom hole U-bend. The 2016 data were collected using a Silixia Ultima with 12.5 cm spatial sampling, whereas the XT spatial sampling interval is 25 cm with a temperature resolution of 0.03 degrees C. Raw, uncalibrated data were converted to a single .MAT file using code provided by Oregon State University's CTEMPs https://ctemps.org/data-processing. The binary Matlab file containing processed Silixa XT data is read using the Matlab statement "load('Brady_25Aug2018_ch1.mat')", which contains the arrays below. Arrays with 2361 rows represent the channels and arrays with 1210 columns represent the one-minute samples.

15 GEOTHERMAL ENERGY↗

High-resolution multi-band imaging for validation and characterization of small Kepler planets

High-resolution ground-based optical speckle and near-infrared adaptive optics images are taken to search for stars in close angular proximity to host stars of candidate planets identified by the NASA Kepler Mission. Neighboring stars are a potential source of false positive signals. These stars also blend into Kepler light curves, affecting estimated planet properties, and are important for an understanding of planets in multiple star systems. Deep images with high angular resolution help to validate candidate planets by excluding potential background eclipsing binaries as the source of the transit signals. A study of 18 Kepler Object of Interest stars hosting a total of 28 candidate and validated planets is presented. Validation levels are determined for 18 planets against the likelihood of a false positive from a background eclipsing binary. Most of these are validated at the 99% level or higher, including five newly validated planets in two systems: Kepler-430 and Kepler-431. The stellar properties of the candidate host stars are determined by supplementing existing literature values with new spectroscopic characterizations. Close neighbors of seven of these stars are examined using multi-wavelength photometry to determine their nature and influence on the candidate planet properties. Most of the close neighbors appear to be gravitationally bound secondaries, while a few are best explained as closely co-aligned field stars. Revised planet properties are derived for each candidate and validated planet, including cases where the close neighbors are the potential host stars.

79 ASTRONOMY AND ASTROPHYSICS↗