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All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

DISCOVERY OF TWO VERY WIDE BINARIES WITH ULTRACOOL COMPANIONS AND A NEW BROWN DWARF AT THE L/T TRANSITION

We present the discovery and spectroscopic follow-up of a nearby late-type L dwarf (2M0614+3950), and two extremely wide very low mass binary systems (2M0525-7425AB and 2M1348-1344AB), resulting from our search for common proper motion pairs containing ultracool components in the Two Micron All Sky Survey and the Wide-field Infrared Survey Explorer catalogs. The near-infrared spectrum of 2M0614+3950 indicates a spectral type L9 {+-} 1 object residing at a distance of 26.0 {+-} 1.8 pc. The optical spectrum of 2M0525-7425A reveals an M3.0 {+-} 0.5 dwarf primary, accompanied by a secondary previously classified as L2. The system has an angular separation of {approx}44'', equivalent to {approx}2000 AU at a distance of 46.0 {+-} 3.0 pc. Using optical and infrared spectra, respectively, we classify the components of 2M1348-1344AB as M4.5 {+-} 0.5 and T5.5 {+-} 1. The angular separation of {approx}68'' is equivalent to {approx}1400 AU at a distance of 20.7 {+-} 1.4 pc. 2M1348-1344AB is one of only six very wide (separation >1000 AU) systems containing late T dwarfs known to date.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Radio emission and orbital motion from the close-encounter star–brown dwarf binary WISE J072003.20–084651.2

We report the detection of radio emission and orbital motion from the nearby star–brown dwarf binary WISE J072003.20–084651.2AB. Radio observations across the 4.5–6.5 GHz band with the Very Large Array identify at the position of the system quiescent emission with a flux density of 15 ± 3 μJy, and a highly polarized radio source that underwent a 2–3 minute burst with peak flux density 300 ± 90 μJy. The latter emission is likely a low-level magnetic flare similar to optical flares previously observed for this source. No outbursts were detected in separate narrow-band Hα monitoring observations. We report new high-resolution imaging and spectroscopic observations that confirm the presence of a co-moving T5.5 secondary and provide the first indications of three-dimensional orbital motion. We used these data to revise our estimates for the orbital period (4.1{sub −1.3}{sup +2.7} year) and tightly constrain the orbital inclination to be nearly edge-on (93.°6{sup +1.°6}{sub −1.°4}), although robust measures of the component and system masses will require further monitoring. The inferred orbital motion does not change the high likelihood that this radio-emitting very low-mass binary made a close pass to the Sun in the past 100 kyr.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

OBSERVATIONS OF HIERARCHICAL SOLAR-TYPE MULTIPLE STAR SYSTEMS

Twenty multiple stellar systems with solar-type primaries were observed at high angular resolution using the PALM-3000 adaptive optics system at the 5 m Hale telescope. The goal was to complement the knowledge of hierarchical multiplicity in the solar neighborhood by confirming recent discoveries by the visible Robo-AO system with new near-infrared observations with PALM-3000. The physical status of most, but not all, of the new pairs is confirmed by photometry in the Ks band and new positional measurements. In addition, we resolved for the first time five close sub-systems: the known astrometric binary in HIP 17129AB, companions to the primaries of HIP 33555, and HIP 118213, and the companions to the secondaries in HIP 25300 and HIP 101430. We place the components on a color–magnitude diagram and discuss each multiple system individually.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

Finely tunable dynamical coloration using bicontinuous micrometer-domains

Nanostructures similar to those found in the vividly blue wings of Morpho butterflies and colorful photonic crystals enable structural color through constructive interference of light waves. Different from commonly studied structure-colored materials using periodic structures to manipulate optical properties, we report a previously unrecognized approach to precisely control the structural color and light transmission via a novel photonic colloidal gel without long-range order. Nanoparticles in this gel form micrometer-sized bicontinuous domains driven by the microphase separation of binary solvents. This approach enables dynamic coloration with a precise wavelength selectivity over a broad range of wavelengths extended well beyond the visible light that is not achievable with traditional methods. The dynamic wavelength selectivity is thermally tunable, reversible, and the material fabrication is easily scalable.

42 ENGINEERING↗
DOE OSTI2010

TESTING THE DISTANCE-DUALITY RELATION WITH GALAXY CLUSTERS AND TYPE Ia SUPERNOVAE

In this Letter, we propose a new and model-independent cosmological test for the distance-duality (DD) relation, {eta} = D{sub L} (z)(1 + z){sup -2}/D{sub A} (z) = 1, where D{sub L} and D{sub A} are, respectively, the luminosity and angular diameter distances. For D{sub L} we consider two sub-samples of Type Ia supernovae (SNe Ia) taken from Constitution data whereas D{sub A} distances are provided by two samples of galaxy clusters compiled by De Filippis et al. and Bonamente et al. by combining Sunyaev-Zeldovich effect and X-ray surface brightness. The SNe Ia redshifts of each sub-sample were carefully chosen to coincide with the ones of the associated galaxy cluster sample ({Delta}z < 0.005), thereby allowing a direct test of the DD relation. Since for very low redshifts, D{sub A} (z) ape D{sub L} (z), we have tested the DD relation by assuming that {eta} is a function of the redshift parameterized by two different expressions: {eta}(z) = 1 + {eta}{sub 0} z and {eta}(z) = 1 + {eta}{sub 0} z/(1 + z), where {eta}{sub 0} is a constant parameter quantifying a possible departure from the strict validity of the reciprocity relation ({eta}{sub 0} = 0). In the best scenario (linear parameterization), we obtain {eta}{sub 0} = -0.28{sup +0.44} {sub -0.44} (2{sigma}, statistical + systematic errors) for the De Filippis et al. sample (elliptical geometry), a result only marginally compatible with the DD relation. However, for the Bonamente et al. sample (spherical geometry) the constraint is {eta}{sub 0} = -0.42{sup +0.34} {sub -0.34} (3{sigma}, statistical + systematic errors), which is clearly incompatible with the duality-distance relation.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Periodic Gamma-Ray Modulation of the Blazar PG 1553+113 Confirmed by Fermi-LAT and Multiwavelength Observations

A 2.1 yr periodic oscillation of the gamma-ray flux from the blazar PG 1553+113 has previously been tentatively identified in ∼7 yr of data from the Fermi Large Area Telescope. After 15 yr of Fermi sky-survey observations, doubling the total time range, we report >7 cycle gamma-ray modulation with an estimated significance of 4σ against stochastic red noise. Independent determinations of oscillation period and phase in the earlier and the new data are in close agreement (chance probability <0.01). Pulse timing over the full light curve is also consistent with a coherent periodicity. Multiwavelength new data from Swift X-Ray Telescope, Burst Alert Telescope, and UVOT, and from KAIT, Catalina Sky Survey, All-Sky Automated Survey for Supernovae, and Owens Valley Radio Observatory ground-based observatories as well as archival Rossi X-Ray Timing Explorer satellite-All Sky Monitor data, published optical data of Tuorla, and optical historical Harvard plates data are included in our work. Optical and radio light curves show clear correlations with the gamma-ray modulation, possibly with a nonconstant time lag for the radio flux. We interpret the gamma-ray periodicity as possibly arising from a pulsational accretion flow in a sub-parsec binary supermassive black hole system of elevated mass ratio, with orbital modulation of the supplied material and energy in the jet. Other astrophysical scenarios introduced include instabilities, disk and jet precession, rotation or nutation, and perturbations by massive stars or intermediate-mass black holes in polar orbit.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2010

ULTRA-BRIGHT OPTICAL TRANSIENTS ARE LINKED WITH TYPE Ic SUPERNOVAE

Recent searches by unbiased, wide-field surveys have uncovered a group of extremely luminous optical transients. The initial discoveries of SN 2005ap by the Texas Supernova Search and SCP-06F6 in a deep Hubble pencil beam survey were followed by the Palomar Transient Factory confirmation of host redshifts for other similar transients. The transients share the common properties of high optical luminosities (peak magnitudes {approx}-21 to -23), blue colors, and a lack of H or He spectral features. The physical mechanism that produces the luminosity is uncertain, with suggestions ranging from jet-driven explosion to pulsational pair instability. Here, we report the most detailed photometric and spectral coverage of an ultra-bright transient (SN 2010gx) detected in the Pan-STARRS 1 sky survey. In common with other transients in this family, early-time spectra show a blue continuum and prominent broad absorption lines of O II. However, about 25 days after discovery, the spectra developed type Ic supernova features, showing the characteristic broad Fe II and Si II absorption lines. Detailed, post-maximum follow-up may show that all SN 2005ap and SCP-06F6 type transients are linked to supernovae Ic. This poses problems in understanding the physics of the explosions: there is no indication from late-time photometry that the luminosity is powered by {sup 56}Ni, the broad light curves suggest very large ejected masses, and the slow spectral evolution is quite different from typical Ic timescales. The nature of the progenitor stars and the origin of the luminosity are intriguing and open questions.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

Dynamics of coupled simplest chaotic two-component electronic circuits and its potential application to random bit generation

We numerically investigate the possibility of using a coupling to increase the complexity in simplest chaotic two-component electronic circuits operating at high frequency. We subsequently show that complex behaviors generated in such coupled systems, together with the post-processing are suitable for generating bit-streams which pass all the NIST tests for randomness. The electronic circuit is built up by unidirectionally coupling three two-component (one active and one passive) oscillators in a ring configuration through resistances. It turns out that, with such a coupling, high chaotic signals can be obtained. By extracting points at fixed interval of 10 ns (corresponding to a bit rate of 100 Mb/s) on such chaotic signals, each point being simultaneously converted in 16-bits (or 8-bits), we find that the binary sequence constructed by including the 10(or 2) least significant bits pass statistical tests of randomness, meaning that bit-streams with random properties can be achieved with an overall bit rate up to 10×100 Mb/s =1Gbit/s (or 2×100 Mb/s =200 Megabit/s). Moreover, by varying the bias voltages, we also investigate the parameter range for which more complex signals can be obtained. Besides being simple to implement, the two-component electronic circuit setup is very cheap as compared to optical and electro-optical systems.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

MULTI-FILTER LIGHT CURVES OF 29 VERY SHORT PERIOD CANDIDATE CONTACT BINARIES

Light curves of 26 probable contact binary stars are made available, from a list of candidates with the shortest periods known. This is supplemented by sets of light curves of three previously studied systems. Photometry was obtained in the Johnson UBV, Cousins RI system. All stars but one were observed in four wavebands, either UBV R{sub C} or BV(RI){sub C}, depending on brightness. Tentative spectral classifications are given for 23 of the stars. Effective temperatures are derived from infrared and optical photometric indices, and from spectral types. These are generally in good agreement. The multicolor photometry, spectral typing, and estimated effective temperatures can be used to model these systems in detail. A preliminary study, based on Fourier coefficients of the light curves, suggests that all the systems are indeed eclipsing stars, with all but a handful probably in contact configurations.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

A milliparsec supermassive black hole binary candidate in the galaxy SDSS J120136.02+300305.5

Galaxy mergers play a key role in the evolution of galaxies and the growth of their central supermassive black holes (SMBHs). A search for (active) SMBH binaries (SMBHBs) at the centers of the merger remnants is currently ongoing. Perhaps the greatest challenge is to identify the inactive SMBHBs, which might be the most abundant, but are also the most difficult to identify. Liu et al. predicted characteristic drops in the light curves of tidal disruption events (TDEs), caused by the presence of a secondary SMBH. Here, we apply that model to the light curve of the optically inactive galaxy SDSS J120136.02+300305.5, which was identified as a candidate TDE with XMM-Newton. We show that the deep dips in its evolving X-ray light curve can be well explained by the presence of a SMBHB at its core. A SMBHB model with a mass of the primary of M {sub BH} = 10{sup 7} M {sub ☉}, a mass ratio q ≅ 0.08, and a semi-major axis a {sub b} ≅ 0.6 mpc is in good agreement with the observations. Given that primary mass, introducing an orbital eccentricity is needed, with e {sub b} ≅ 0.3. Alternatively, a lower mass primary of M {sub BH} = 10{sup 6} M {sub ☉} in a circular orbit fits the light curve well. Tight binaries like this one, which have already overcome the 'final parsec problem', are prime sources of gravitational wave radiation once the two SMBHs coalesce. Future transient surveys, which will detect TDEs in large numbers, will place tight constraints on the SMBHB fraction in otherwise non-active galaxies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

PERIOD CHANGES AND FOUR-COLOR LIGHT CURVES OF THE ACTIVE OVERCONTACT BINARY V396 MONOCEROTIS

This paper analyzes the first obtained four-color light curves of V396 Mon using the 2003 version of the W-D code. It is confirmed that V396 Mon is a shallow W-type contact binary system with a mass ratio q = 2.554({+-}0.004) and a degree of contact factor f = 18.9%({+-}1.2%). A period investigation based on all available data shows that the period of the system includes a long-term decrease (dP/dt = -8.57 x 10{sup -8} days yr{sup -1}) and an oscillation (A{sub 3} = 0.0160 day, T{sub 3} = 42.4 yr). They are caused by angular momentum loss and light-time effect, respectively. The suspect third body is possibly a small M-type star (about 0.31 solar mass). Though some observations indicate that this system has strong magnetic activity, by our analysis we found that the Applegate mechanism cannot explain the periodic changes. This binary is an especially important system according to Qian's statistics of contact binaries as its mass ratio lies near the proposed pivot point about which the physical structure of contact binaries supposedly oscillates.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

K-SHELL PHOTOABSORPTION OF MAGNESIUM IONS

X-ray photoabsorption cross sections have been computed for all magnesium ions with three or more electrons using the R-matrix method. A comparison with other available data for Mg II-Mg X shows good qualitative agreement in the resultant resonance shapes. However, for the lower ionization stages, and for singly ionized Mg II in particular, the previous R-matrix results overestimate the K-edge position due to the neglect of important orbital relaxation effects, and a global shift downward in photon energy of those cross sections is therefore warranted. We have found that the cross sections for Mg I and Mg II are further complicated by the M-shell (n = 3) occupancy. As a result, the treatment of spectator Auger decay of 1s → np resonances using a method based on multichannel quantum defect theory and an optical potential becomes problematic, making it necessary to implement an alternative, approximate treatment of Auger decay for neutral Mg I. The new cross sections are used to fit the Mg K edge in XMM-Newton spectra of the low-mass X-ray binary GS 1826-238, where most of the interstellar Mg is found to be in ionized form.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

SMALL-SCALE STRUCTURE OF THE INTERSTELLAR MEDIUM TOWARD {rho} Oph STARS: DIFFUSE BAND OBSERVATIONS

We present an investigation of small-scale structure in the distribution of large molecules/dust in the interstellar medium through observations of diffuse interstellar bands (DIBs). High signal-to-noise optical spectra were recorded toward the stars {rho} Oph A, B, C, and DE using the University College London Echelle Spectrograph on the Anglo-Australian Telescope. The strengths of some of the DIBs are found to differ by about 5%-9% between the close binary stars {rho} Oph A and B, which are separated by a projected distance on the sky of only c. 344 AU. This is the first star system in which such small-scale DIB strength variations have been reported. The observed variations are attributed to differences between a combination of carrier abundance and the physical conditions present along each sightline. The sightline toward {rho} Oph C contains relatively dense, molecule-rich material and has the strongest {lambda}{lambda}5850 and 4726 DIBs. The gas toward DE is more diffuse and is found to exhibit weak ''C{sub 2}'' (blue) DIBs and strong yellow/red DIBs. The differences in diffuse band strengths between lines of sight are, in some cases, significantly greater in magnitude than the corresponding variations among atomic and diatomic species, indicating that the DIBs can be sensitive tracers of interstellar cloud conditions.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

PTF 10bzf (SN 2010ah): A BROAD-LINE Ic SUPERNOVA DISCOVERED BY THE PALOMAR TRANSIENT FACTORY

We present the discovery and follow-up observations of a broad-line Type Ic supernova (SN), PTF 10bzf (SN 2010ah), detected by the Palomar Transient Factory (PTF) on 2010 February 23. The SN distance is {approx_equal}218 Mpc, greater than GRB 980425/SN 1998bw and GRB 060218/SN 2006aj, but smaller than the other SNe firmly associated with gamma-ray bursts (GRBs). We conducted a multi-wavelength follow-up campaign with Palomar 48 inch, Palomar 60 inch, Gemini-N, Keck, Wise, Swift, the Allen Telescope Array, Combined Array for Research in Millimeter-wave Astronomy, Westerbork Synthesis Radio Telescope, and Expanded Very Large Array. Here we compare the properties of PTF 10bzf with those of SN 1998bw and other broad-line SNe. The optical luminosity and spectral properties of PTF 10bzf suggest that this SN is intermediate, in kinetic energy and amount of {sup 56}Ni, between non-GRB-associated SNe like 2002ap or 1997ef, and GRB-associated SNe like 1998bw. No X-ray or radio counterpart to PTF 10bzf was detected. X-ray upper limits allow us to exclude the presence of an underlying X-ray afterglow as luminous as that of other SN-associated GRBs such as GRB 030329 or GRB 031203. Early-time radio upper limits do not show evidence for mildly relativistic ejecta. Late-time radio upper limits rule out the presence of an underlying off-axis GRB, with energy and wind density similar to the SN-associated GRB 030329 and GRB 031203. Finally, by performing a search for a GRB in the time window and at the position of PTF 10bzf, we find that no GRB in the interplanetary network catalog could be associated with this SN.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

The three-dimensional orbit and physical parameters of 47 OPH

Although 47 Oph has been shown to be a binary with a period of ∼27 days using both spectroscopic and interferometric techniques, only a preliminary orbit has been obtained in the previous work due to the shortage of high precision measurements. Since 1997, new spectroscopic and interferometric measurements have been obtained with much higher precision by the spectrograph of the 2.16 m telescope at Xinglong station and the Navy Precision Optical Interferometer, respectively. Combining all of the measurements, a three-dimensional orbit is obtained with high precision in this work. Thus, the component masses are calculated to be 1.50 ± 0.06 and 1.34 ± 0.06 M{sub ⊙}, respectively. The orbital parallax is 32.6 ± 0.6 mas, which is consistent with the Hipparcos parallax. With the known apparent magnitudes and color indices of the components, the derived luminosities are 7.80 ± 0.36 and 3.41 ± 0.25 L{sub ⊙}. The estimated radii of the components are 2.06 ± 0.07 and 1.36 ± 0.06 R{sub ⊙}. Finally, the evolutionary status of the components are investigated with the help of a stellar evolution model.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

THE GALACTIC BULGE SURVEY: OUTLINE AND X-RAY OBSERVATIONS

We introduce the Galactic Bulge Survey (GBS) and we provide the Chandra source list for the region that has been observed to date. Among the goals of the GBS are constraining the neutron star (NS) equation of state and the black hole (BH) mass distribution via the identification of eclipsing NS and BH low-mass X-ray binaries (LMXBs). The latter goal will, in addition, be obtained by significantly enlarging the number of BH systems for which a BH mass can be derived. Further goals include constraining X-ray binary formation scenarios, in particular the common envelope phase and the occurrence of kicks, via source-type number counts and an investigation of the spatial distribution of X-ray binaries, respectively. The GBS targets two strips of 6{sup 0} x 1{sup 0} (12 deg{sup 2} in total), one above (1{sup 0} < b < 2{sup 0}) and one below (-2{sup 0} < b < -1{sup 0}) the Galactic plane in the direction of the Galactic center at both X-ray and optical wavelengths. By avoiding the Galactic plane (-1{sup 0} < b < 1{sup 0}) we limit the influence of extinction on the X-ray and optical emission but still sample relatively large number densities of sources. The survey is designed such that a large fraction of the X-ray sources can be identified from their optical spectra. The X-ray survey, by design, covers a large area on the sky while the depth is shallow using 2 ks per Chandra pointing. In this way we maximize the predicted number ratio of (quiescent) LMXBs to cataclysmic variables. The survey is approximately homogeneous in depth to a 0.5-10 keV flux of 7.7 x 10{sup -14} erg cm{sup -2} s{sup -1}. So far, we have covered about two-thirds (8.3 deg{sup 2}) of the projected survey area with Chandra providing over 1200 unique X-ray sources. We discuss the characteristics and the variability of the brightest of these sources.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Bioactive Silver-Containing Compositions of Methyl Cellulose with a Natural Sorbent Zosterin: The Structure, Morphology, and Properties

The morphology, structure, and optical properties of polymeric compositions based on a natural sorbent Zosterin, methyl cellulose (MC), and a Poviargol (silver-containing preparation) are studied via atomic force microscopy (AFM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD). AFM studies show substantial changes in the morphology of the surface of obtained films from granular with different grain sizes (for Zosterin and an MC/Zosterin binary system) to spongy with nanopores and submicron pores on the surface (for an MC/Zosterin/Poviargol ternary system). Silver nanoparticles with different shapes and sizes are observed by TEM in the MC/Zosterin/Poviargol ternary system against the background of the MC/Zosterin polymer matrix which has fractal-type morphology. A reflection corresponding to zero-valent silver is found by XRD in the MC/Zosterin/Poviargol ternary composition.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2015

Bayesian investigation of isochrone consistency using the old open cluster NGC 188

This paper provides a detailed comparison of the differences in parameters derived for a star cluster from its color–magnitude diagrams (CMDs) depending on the filters and models used. We examine the consistency and reliability of fitting three widely used stellar evolution models to 15 combinations of optical and near-IR photometry for the old open cluster NGC 188. The optical filter response curves match those of theoretical systems and are thus not the source of fit inconsistencies. NGC 188 is ideally suited to this study thanks to a wide variety of high-quality photometry and available proper motions and radial velocities that enable us to remove non-cluster members and many binaries. Our Bayesian fitting technique yields inferred values of age, metallicity, distance modulus, and absorption as a function of the photometric band combinations and stellar models. We show that the historically favored three-band combinations of UBV and VRI can be meaningfully inconsistent with each other and with longer baseline data sets such as UBVRIJHK{sub S}. Differences among model sets can also be substantial. For instance, fitting Yi et al. (2001) and Dotter et al. (2008) models to UBVRIJHK{sub S} photometry for NGC 188 yields the following cluster parameters: age = (5.78 ± 0.03, 6.45 ± 0.04) Gyr, [Fe/H] = (+0.125 ± 0.003, −0.077 ± 0.003) dex, (m−M){sub V} = (11.441 ± 0.007, 11.525 ± 0.005) mag, and A{sub V} = (0.162 ± 0.003, 0.236 ± 0.003) mag, respectively. Within the formal fitting errors, these two fits are substantially and statistically different. Such differences among fits using different filters and models are a cautionary tale regarding our current ability to fit star cluster CMDs. Additional modeling of this kind, with more models and star clusters, and future Gaia parallaxes are critical for isolating and quantifying the most relevant uncertainties in stellar evolutionary models.

79 ASTRONOMY AND ASTROPHYSICS↗