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At least 1,801 records · Page 100
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DOE OSTI2012

QUASI-PERIODIC FAST-MODE WAVE TRAINS WITHIN A GLOBAL EUV WAVE AND SEQUENTIAL TRANSVERSE OSCILLATIONS DETECTED BY SDO/AIA

We present the first unambiguous detection of quasi-periodic wave trains within the broad pulse of a global EUV wave (so-called EIT wave) occurring on the limb. These wave trains, running ahead of the lateral coronal mass ejection (CME) front of 2-4 times slower, coherently travel to distances {approx}> R{sub Sun }/2 along the solar surface, with initial velocities up to 1400 km s{sup -1} decelerating to {approx}650 km s{sup -1}. The rapid expansion of the CME initiated at an elevated height of 110 Mm produces a strong downward and lateral compression, which may play an important role in driving the primary EUV wave and shaping its front forwardly inclined toward the solar surface. The wave trains have a dominant 2 minute periodicity that matches the X-ray flare pulsations, suggesting a causal connection. The arrival of the leading EUV wave front at increasing distances produces an uninterrupted chain sequence of deflections and/or transverse (likely fast kink mode) oscillations of local structures, including a flux-rope coronal cavity and its embedded filament with delayed onsets consistent with the wave travel time at an elevated (by {approx}50%) velocity within it. This suggests that the EUV wave penetrates through a topological separatrix surface into the cavity, unexpected from CME-caused magnetic reconfiguration. These observations, when taken together, provide compelling evidence of the fast-mode MHD wave nature of the primary (outer) fast component of a global EUV wave, running ahead of the secondary (inner) slow component of CME-caused restructuring.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

CONSTRAINTS ON THE MAGELLANIC CLOUDS' INTERACTION FROM THE DISTRIBUTION OF OB STARS AND THE KINEMATICS OF GIANTS

Young, OB-type candidates are identified in a {approx}7900 deg{sup 2} region encompassing the Large and Small Magellanic Clouds (LMC/SMC) periphery, the Bridge, part of the Magellanic Stream (MS), and Leading Arm (LA). Selection is based on UV, optical, and IR photometry from existing large-area surveys and proper motions from the Southern Proper Motion 4 (SPM4) catalog. The spatial distribution of these young star candidates shows (1) a well-populated SMC wing which continues westward with two branches partially surrounding the SMC, (2) a rather narrow path from the SMC wing eastward toward the LMC which is offset by 1 Degree-Sign -2 Degree-Sign from the high-density H I ridge in the Bridge, (3) a well-populated periphery of the LMC dominated by clumps of stars at the ends of the LMC bar, and (4) a few scattered candidates in the MS and two overdensities in the LA regions above and below the Galactic plane. Additionally, a proper-motion analysis is made of a radial-velocity-selected sample of red giants and supergiants in the LMC, previously shown to be a kinematically and chemically distinct subgroup, most likely captured from the SMC. SPM4 proper motions of these stars also indicate they are distinct from the LMC population. The observational results presented here, combined with the known orbits of the Clouds and other aspects of the LMC morphology, suggest an off-center, moderate to highly inclined collision between the SMC and the LMC's disk that took place between 100 and 200 Myr ago.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

THE PTF ORION PROJECT: A POSSIBLE PLANET TRANSITING A T-TAURI STAR

We report observations of a possible young transiting planet orbiting a previously known weak-lined T-Tauri star in the 7-10 Myr old Orion-OB1a/25-Ori region. The candidate was found as part of the Palomar Transient Factory (PTF) Orion project. It has a photometric transit period of 0.448413 {+-} 0.000040 days, and appears in both 2009 and 2010 PTF data. Follow-up low-precision radial velocity (RV) observations and adaptive optics imaging suggest that the star is not an eclipsing binary, and that it is unlikely that a background source is blended with the target and mimicking the observed transit. RV observations with the Hobby-Eberly and Keck telescopes yield an RV that has the same period as the photometric event, but is offset in phase from the transit center by Almost-Equal-To - 0.22 periods. The amplitude (half range) of the RV variations is 2.4 km s{sup -1} and is comparable with the expected RV amplitude that stellar spots could induce. The RV curve is likely dominated by stellar spot modulation and provides an upper limit to the projected companion mass of M{sub p}sin i{sub orb} {approx}< 4.8 {+-} 1.2 M{sub Jup}; when combined with the orbital inclination, i{sub orb}, of the candidate planet from modeling of the transit light curve, we find an upper limit on the mass of the planetary candidate of M{sub p} {approx}< 5.5 {+-} 1.4 M{sub Jup}. This limit implies that the planet is orbiting close to, if not inside, its Roche limiting orbital radius, so that it may be undergoing active mass loss and evaporation.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

SAGITTARIUS A* ACCRETION FLOW AND BLACK HOLE PARAMETERS FROM GENERAL RELATIVISTIC DYNAMICAL AND POLARIZED RADIATIVE MODELING

We obtain estimates of Sgr A* accretion flow and black hole parameters by fitting polarized submillimeter observations with spectra computed using three-dimensional general relativistic (GR) magnetohydrodynamical (MHD) (GRMHD) simulations. Observations are compiled from averages over many epochs from reports in 29 papers for estimating the mean fluxes F{sub {nu}}, linear polarization (LP) fractions, circular polarization (CP) fractions, and electric vector position angles. GRMHD simulations are computed with dimensionless spins a{sub *} = 0, 0.5, 0.7, 0.9, 0.98 over a 20, 000M time interval. We perform fully self-consistent GR polarized radiative transfer using our new code to explore the effects of spin a{sub *}, inclination angle {theta}, position angle (P.A.), accretion rate M-dot , and electron temperature T{sub e} (T{sub e} is reported for radius 6M). By fitting the mean submillimeter fluxes and LP/CP fractions, we obtain estimates for these model parameters and determine the physical effects that could produce polarization signatures. Our best-bet model has a{sub *} = 0.5, {theta} = 75 Degree-Sign , P.A. = 115 Degree-Sign , M-dot = 4.6 x 10{sup -8} M{sub Sun} yr{sup -1}, and T{sub e} = 3.1 Multiplication-Sign 10{sup 10} K at 6M. The submillimeter CP is mainly produced by Faraday conversion as modified by Faraday rotation, and the emission region size at 230 GHz is consistent with the very long baseline interferometry size of 37 {mu}as. Across all spins, model parameters are in the ranges {theta} = 42 Degree-Sign -75 Degree-Sign , M-dot = (1.4-7.0) x 10{sup -8} M{sub Sun} yr{sup -1}, and T{sub e} = (3-4) Multiplication-Sign 10{sup 10} K. Polarization is found both to help differentiate models and to introduce new observational constraints on the effects of the magnetic field that might not be fit by accretion models so far considered.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

FURTHER EVIDENCE THAT QUASAR X-RAY EMITTING REGIONS ARE COMPACT: X-RAY AND OPTICAL MICROLENSING IN THE LENSED QUASAR Q J0158-4325

We present four new seasons of optical monitoring data and six epochs of X-ray photometry for the doubly imaged lensed quasar Q J0158-4325. The high-amplitude, short-period microlensing variability for which this system is known has historically precluded a time delay measurement by conventional methods. We attempt to circumvent this limitation by the application of a Monte Carlo microlensing analysis technique, but we are only able to prove that the delay must have the expected sign (image A leads image B). Despite our failure to robustly measure the time delay, we successfully model the microlensing at optical and X-ray wavelengths to find a half-light radius for soft X-ray emission log (r{sub 1/2,X,soft}/cm) = 14.3{sup +0.4}{sub -0.5}, an upper limit on the half-light radius for hard X-ray emission log (r{sub 1/2,X,hard}/cm) {<=} 14.6, and a refined estimate of the inclination-corrected scale radius of the optical R-band (rest frame 3100 A) continuum emission region of log (r{sub s} /cm) = 15.6 {+-} 0.3.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

THE SPINDLE: AN IRRADIATED DISK AND BENT PROTOSTELLAR JET IN ORION

We present Hubble Space Telescope observations of a bent, pulsed Herbig-Haro jet, HH 1064, emerging from the young star Parenago 2042 embedded in the H II region NGC 1977 located about 30' north of the Orion Nebula. This outflow contains eight bow shocks in the redshifted western lobe and five bow shocks in the blueshifted eastern lobe. Shocks within a few thousand AU of the source star exhibit proper motions of {approx}160 km s{sup -1} but motions decrease with increasing distance. Parenago 2042 is embedded in a proplyd-a photoevaporating protoplanetary disk. A remarkable set of H{alpha} arcs resembling a spindle surround the redshifted (western) jet. The largest arc with a radius of 500 AU may trace the ionized edge of a circumstellar disk inclined by {approx}30 Degree-Sign . The spindle may be the photoionized edge of either a {approx}3 km s{sup -1} FUV-driven wind from the outer disk or a faster MHD-powered flow from an inner disk. The HH 1064 jet appears to be deflected north by photoablation of the south-facing side of a mostly neutral jet beam. V2412 Ori, located 1' west of Parenago 2042 drives a second bent flow, HH 1065. Both HH 1064 and 1065 are surrounded by LL Ori-type bows marking the boundary between the outflow cavity and the surrounding nebula.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

TEMPORAL EVOLUTION OF VELOCITY AND MAGNETIC FIELD IN AND AROUND UMBRAL DOTS

We study the temporal evolution of umbral dots (UDs) using measurements from the CRISP imaging spectropolarimeter at the Swedish 1 m Solar Telescope. Scans of the magnetically sensitive 630 nm iron lines were performed under stable atmospheric conditions for 71 minutes with a cadence of 63 s. These observations allow us to investigate the magnetic field and velocity in and around UDs at a resolution approaching 0.''13. From the analysis of 339 UDs, we draw the following conclusions: (1) UDs show clear hints of upflows, as predicted by magnetohydrodynamic simulations. By contrast, we could not find systematic downflow signals. Only in very deep layers, we detect localized downflows around UDs, but they do not persist in time. (2) We confirm that UDs exhibit weaker and more inclined fields than their surroundings, as reported previously. However, UDs that have strong fields above 2000 G or are in the decay phase show enhanced and more vertical fields. (3) There are enhanced fields at the migration front of UDs detached from penumbral grains, as if their motion were impeded by the ambient field. (4) Long-lived UDs travel longer distances with slower proper motions. Our results appear to confirm some aspects of recent numerical simulations of magnetoconvection in the umbra (e.g., the existence of upflows in UDs), but not others (e.g., the systematic weakening of the magnetic field at the position of UDs).

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

KINEMATICS OF THE CO GAS IN THE INNER REGIONS OF THE TW Hya DISK

We present a detailed analysis of the spatially and spectrally resolved {sup 12}CO J = 2-1 and J = 3-2 emission lines from the TW Hya circumstellar disk, based on science verification data from the Atacama Large Millimeter/submillimeter Array (ALMA). These lines exhibit substantial emission in their high-velocity wings (with projected velocities out to 2.1 km s{sup -1}, corresponding to intrinsic orbital velocities >20 km s{sup -1}) that trace molecular gas as close as 2 AU from the central star. However, we are not able to reproduce the intensity of these wings and the general spatio-kinematic pattern of the lines with simple models for the disk structure and kinematics. Using three-dimensional non-local thermodynamic equilibrium molecular excitation and radiative transfer calculations, we construct some alternative models that successfully account for these features by modifying either (1) the temperature structure of the inner disk (inside the dust-depleted disk cavity; r < 4 AU), (2) the intrinsic (Keplerian) disk velocity field, or (3) the distribution of disk inclination angles (a warp). The latter approach is particularly compelling because a representative warped disk model qualitatively reproduces the observed azimuthal modulation of optical light scattered off the disk surface. In any model scenario, the ALMA data clearly require a substantial molecular gas reservoir located inside the region where dust optical depths are known to be substantially diminished in the TW Hya disk, in agreement with previous studies based on infrared spectroscopy. The results from these updated model prescriptions are discussed in terms of their potential physical origins, which might include dynamical perturbations from a low-mass companion with an orbital separation of a few AU.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

A NON-RADIAL ERUPTION IN A QUADRUPOLAR MAGNETIC CONFIGURATION WITH A CORONAL NULL

We report one of the several homologous non-radial eruptions from NOAA active region (AR) 11158 that are strongly modulated by the local magnetic field as observed with the Solar Dynamic Observatory. A small bipole emerged in the sunspot complex and subsequently created a quadrupolar flux system. Nonlinear force-free field extrapolation from vector magnetograms reveals its energetic nature: the fast-shearing bipole accumulated {approx}2 Multiplication-Sign 10{sup 31} erg free energy (10% of AR total) over just one day despite its relatively small magnetic flux (5% of AR total). During the eruption, the ejected plasma followed a highly inclined trajectory, over 60 Degree-Sign with respect to the radial direction, forming a jet-like, inverted-Y-shaped structure in its wake. Field extrapolation suggests complicated magnetic connectivity with a coronal null point, which is favorable of reconnection between different flux components in the quadrupolar system. Indeed, multiple pairs of flare ribbons brightened simultaneously, and coronal reconnection signatures appeared near the inferred null. Part of the magnetic setting resembles that of a blowout-type jet; the observed inverted-Y structure likely outlines the open field lines along the separatrix surface. Owing to the asymmetrical photospheric flux distribution, the confining magnetic pressure decreases much faster horizontally than upward. This special field geometry likely guided the non-radial eruption during its initial stage.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

THE SOURCE OF 3 MINUTE MAGNETOACOUSTIC OSCILLATIONS IN CORONAL FANS

We use images of high spatial, spectral, and temporal resolution, obtained using both ground- and space-based instrumentation, to investigate the coupling between wave phenomena observed at numerous heights in the solar atmosphere. Analysis of 4170 A continuum images reveals small-scale umbral intensity enhancements, with diameters {approx}0.''6, lasting in excess of 30 minutes. Intensity oscillations of Almost-Equal-To 3 minutes are observed to encompass these photospheric structures, with power at least three orders of magnitude higher than the surrounding umbra. Simultaneous chromospheric velocity and intensity time series reveal an 87 Degree-Sign {+-} 8 Degree-Sign out-of-phase behavior, implying the presence of standing modes created as a result of partial wave reflection at the transition region boundary. We find a maximum waveguide inclination angle of Almost-Equal-To 40 Degree-Sign between photospheric and chromospheric heights, combined with a radial expansion factor of <76%. An average blueshifted Doppler velocity of Almost-Equal-To 1.5 km s{sup -1}, in addition to a time lag between photospheric and chromospheric oscillatory phenomena, confirms the presence of upwardly propagating slow-mode waves in the lower solar atmosphere. Propagating oscillations in EUV intensity are detected in simultaneous coronal fan structures, with a periodicity of 172 {+-} 17 s and a propagation velocity of 45 {+-} 7 km s{sup -1}. Numerical simulations reveal that the damping of the magnetoacoustic wave trains is dominated by thermal conduction. The coronal fans are seen to anchor into the photosphere in locations where large-amplitude umbral dot (UD) oscillations manifest. Derived kinetic temperature and emission measure time series display prominent out-of-phase characteristics, and when combined with the previously established sub-sonic wave speeds, we conclude that the observed EUV waves are the coronal counterparts of the upwardly propagating magnetoacoustic slow modes detected in the lower solar atmosphere. Thus, for the first time, we reveal how the propagation of 3 minute magnetoacoustic waves in solar coronal structures is a direct result of amplitude enhancements occurring in photospheric UDs.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

THE ROSSITER-McLAUGHLIN EFFECT FOR EXOMOONS OR BINARY PLANETS

In this paper, we study possible signatures of binary planets or exomoons on the Rossiter-McLaughlin (R-M) effect. Our analyses show that the R-M effect for a binary planet or an exomoon during its complete transit phase can be divided into two parts. The first is the conventional one similar to the R-M effect from the transit of a single planet, of which the mass and the projected area are the combinations of the binary components; the second is caused by the orbital rotation of the binary components, which may add a sine- or linear-mode deviation to the stellar radial velocity curve. We find that the latter effect can be up to several ten m s{sup -1}. Our numerical simulations as well as analyses illustrate that the distribution and dispersion of the latter effects obtained from multiple transit events can be used to constrain the dynamical configuration of the binary planet, such as how the inner orbit of the binary planet is inclined to its orbit rotating around the central star. We find that the signatures caused by the orbital rotation of the binary components are more likely to be revealed if the two components of a binary planet have different masses and mass densities, especially if the heavy one has a high mass density and the light one has a low density. Similar signatures on the R-M effect may also be revealed in a hierarchical triple star system containing a dark compact binary and a tertiary star.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

A HST/WFC3-IR MORPHOLOGICAL SURVEY OF GALAXIES AT z = 1.5-3.6. II. THE RELATION BETWEEN MORPHOLOGY AND GAS-PHASE KINEMATICS

We analyze rest-frame optical morphologies and gas-phase kinematics as traced by rest-frame far-UV and optical spectra for a sample of 204 star-forming galaxies in the redshift range z {approx} 2-3 drawn from the Keck Baryonic Structure Survey. We find that spectroscopic properties and gas-phase kinematics are closely linked to morphology: compact galaxies with semimajor axis radii r {approx}< 2 kpc are substantially more likely than their larger counterparts to exhibit Ly{alpha} in emission. Although Ly{alpha} emission strength varies widely within galaxies of a given morphological type, all but one of 19 galaxies with Ly{alpha} equivalent width W {sub Ly{alpha}} > 20 A have compact and/or multiple-component morphologies with r {<=} 2.5 kpc. The velocity structure of absorption lines in the galactic continuum spectra also varies as a function of morphology. Galaxies of all morphological types drive similarly strong outflows (as traced by the blue wing of interstellar absorption line features), but the outflows of larger galaxies are less highly ionized and exhibit larger optical depth at the systemic redshift that may correspond to a decreasing efficiency of feedback in evacuating gas from the galaxy. This v {approx} 0 km s{sup -1} gas is responsible both for shifting the mean absorption line redshift and attenuating W {sub Ly{alpha}} (via a longer resonant scattering path) in galaxies with larger rest-optical half-light radii. In contrast to galaxies at lower redshifts, there is no evidence for a correlation between outflow velocity and inclination, suggesting that outflows from these puffy and irregular systems may be poorly collimated. Our observations are broadly consistent with theoretical models of inside-out growth of galaxies in the young universe, in which typical z {approx} 2-3 star-forming galaxies are predominantly unstable, dispersion-dominated, systems fueled by rapid gas accretion that later form extended rotationally supported disks when stabilized by a sufficiently massive stellar component.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

ON THE MECHANISM OF HARD X-RAY EMISSION FROM MAGNETARS

Persistent activity of magnetars is associated with electric discharge that continually injects relativistic particles into the magnetosphere. Large active magnetic loops around magnetars must be filled with outflowing particles that interact with radiation via resonant scattering and spawn electron-positron pairs. The outflow energy is processed into copious e {sup {+-}} until the plasma enters outer parts of the loop where the magnetic field is reduced below 10{sup 13} G. In the outer zone, photons scattered by the outflow do not convert to e {sup {+-}} pairs and the outflow radiates its energy away. The escaping radiation forms a distinct hard X-ray peak in the magnetar spectrum. It has the following features: (1) its luminosity L = 10{sup 35}-10{sup 36} erg s{sup -1} can easily exceed the thermal luminosity from the magnetar surface, (2) its spectrum extends from 10 keV to the MeV band with a hard spectral slope, which depends on the object inclination to the line of sight, (3) the anisotropic hard X-ray emission exhibits strong pulsations as the magnetar spins, (4) the emission spectrum typically peaks around 1 MeV, but the peak position significantly oscillates with the spin period, (5) the emission is dominated by the extraordinary polarization mode at photon energies below {approx}1 MeV, and (6) the decelerated pairs accumulate and annihilate at the top of the magnetic loop, and emit the 511 keV line with luminosity L {sub ann} {approx} 0.1 L. Features (1)-(3) agree with available data; (4)-(6) can be tested by future observations.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

ON THE SURVIVABILITY AND METAMORPHISM OF TIDALLY DISRUPTED GIANT PLANETS: THE ROLE OF DENSE CORES

A large population of planetary candidates in short-period orbits have been found recently through transit searches, mostly with the Kepler mission. Radial velocity surveys have also revealed several Jupiter-mass planets with highly eccentric orbits. Measurements of the Rossiter-McLaughlin effect indicate that the orbital angular momentum vector of some planets is inclined relative to the spin axis of their host stars. This diversity could be induced by post-formation dynamical processes such as planet-planet scattering, the Kozai effect, or secular chaos which brings planets to the vicinity of their host stars. In this work, we propose a novel mechanism to form close-in super-Earths and Neptune-like planets through the tidal disruption of gas giant planets as a consequence of these dynamical processes. We model the core-envelope structure of gas giant planets with composite polytropes which characterize the distinct chemical composition of the core and envelope. Using three-dimensional hydrodynamical simulations of close encounters between Jupiter-like planets and their host stars, we find that the presence of a core with a mass more than 10 times that of the Earth can significantly increase the fraction of envelope which remains bound to it. After the encounter, planets with cores are more likely to be retained by their host stars in contrast with previous studies which suggested that coreless planets are often ejected. As a substantial fraction of their gaseous envelopes is preferentially lost while the dense incompressible cores retain most of their original mass, the resulting metallicity of the surviving planets is increased. Our results suggest that some gas giant planets can be effectively transformed into either super-Earths or Neptune-like planets after multiple close stellar passages. Finally, we analyze the orbits and structure of known planets and Kepler candidates and find that our model is capable of producing some of the shortest-period objects.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

THE BALDWIN EFFECT IN THE NARROW EMISSION LINES OF ACTIVE GALACTIC NUCLEI

The anti-correlations between the equivalent widths of emission lines and the continuum luminosity in active galactic nuclei (AGNs), known as the Baldwin effect, are well established for broad lines, but are less well studied for narrow lines. In this paper we explore the Baldwin effect of narrow emission lines over a wide range of ionization levels and critical densities using a large sample of broad-line, radio-quiet AGNs taken from Sloan Digital Sky Survey Data Release 4. These type 1 AGNs span three orders of magnitude in continuum luminosity. We show that most narrow lines show a similar Baldwin effect slope of about -0.2, while the significant deviations of the slopes for [N II] {lambda}6583, [O II] {lambda}3727, [Ne V] {lambda}3425, and the narrow component of H{alpha} can be explained by the influence of metallicity, star formation contamination, and possibly by the difference in the shape of the UV-optical continuum. The slopes do not show any correlation with either the ionization potential or the critical density. We show that a combination of 50% variations in continuum near 5100 A and a lognormal distribution of observed luminosity can naturally reproduce a constant Baldwin effect slope of -0.2 for all narrow lines. The variations of the continuum could be due to variability, intrinsic anisotropic emission, or an inclination effect.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

AN ACCRETION MODEL FOR THE ANOMALOUS X-RAY PULSAR 4U 0142+61

We propose that the quiescent emission of anomalous X-ray pulsars/soft gamma-ray repeaters (AXPs/SGRs) is powered by accretion from a fallback disk, requiring magnetic dipole fields in the range 10{sup 12}-10{sup 13} G, and that the luminous hard tails of their X-ray spectra are produced by bulk-motion Comptonization in the radiative shock near the bottom of the accretion column. This radiation escapes as a fan beam, which is partly absorbed by the polar cap photosphere, heating it up to relatively high temperatures. The scattered component and the thermal emission from the polar cap form a polar beam. We test our model on the well-studied AXP 4U 0142+61, whose energy-dependent pulse profiles show double peaks, which we ascribe to the fan and polar beams. The temperature of the photosphere (kT {approx} 0.4 keV) is explained by the heating effect. The scattered part forms a hard component in the polar beam. We suggest that the observed high temperatures of the polar caps of AXPs/SGRs, compared with other young neutron stars, are due to the heating by the fan beam. Using beaming functions for the fan beam and the polar beam and taking gravitational bending into account, we fit the energy-dependent pulse profiles and obtain the inclination angle and the angle between the spin axis and the magnetic dipole axis, as well as the height of the radiative shock above the stellar surface. We do not explain the high-luminosity bursts, which may be produced by the classical magnetar mechanism operating in super-strong multipole fields.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

APOSTLE: 11 TRANSIT OBSERVATIONS OF TrES-3b

The Apache Point Survey of Transit Lightcurves of Exoplanets (APOSTLE) observed 11 transits of TrES-3b over two years in order to constrain system parameters and look for transit timing and depth variations. We describe an updated analysis protocol for APOSTLE data, including the reduction pipeline, transit model, and Markov Chain Monte Carlo analyzer. Our estimates of the system parameters for TrES-3b are consistent with previous estimates to within the 2{sigma} confidence level. We improved the errors (by 10%-30%) on system parameters such as the orbital inclination (i {sub orb}), impact parameter (b), and stellar density ({rho}{sub *}) compared to previous measurements. The near-grazing nature of the system, and incomplete sampling of some transits, limited our ability to place reliable uncertainties on individual transit depths and hence we do not report strong evidence for variability. Our analysis of the transit timing data shows no evidence for transit timing variations and our timing measurements are able to rule out super-Earth and gas giant companions in low-order mean motion resonance with TrES-3b.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

Mg II ABSORPTION AT 2 < z < 6 WITH MAGELLAN/FIRE. II. A LONGITUDINAL STUDY OF H I, METALS, AND IONIZATION IN GALACTIC HALOS

We present a detailed study of H I and metals for 110 Mg II absorption systems discovered at 1.98 {<=} z {<=} 5.33 in the infrared spectra of high-redshift QSOs. Using new measurements of rest-frame UV lines from optical spectra of the same targets, we compare the high-redshift sample with carefully constructed low-redshift control samples from the literature to study evolutionary trends from z = 0 {yields} 5.33 (>12 Gyr). We observe a significant strengthening in the characteristic N(H I) for fixed Mg II equivalent width as one moves toward higher redshift. Indeed, at our sample's mean z-bar = 3.402, all Mg II systems are either damped Ly{alpha} absorbers (DLAs) or sub-DLAs, with 40.7% of systems exceeding the DLA threshold (compared to 16.7% at z-bar = 0.927). We set lower limits on the metallicity of the Mg II systems where we can measure H I; these results are consistent with the full DLA population. The classical Mg II systems (W {sup {lambda}2796} {sub 0} = 0.3-1.0 A), which preferentially associate with sub-DLAs, are quite metal rich at {approx}0.1 solar. We applied quantitative classification metrics to our absorbers to compare with low-redshift populations, finding that weak systems are similar to classic Mg II absorbers at low redshift. The strong systems either have very large Mg II and Fe II velocity spreads implying non-virialized dynamics or are more quiescent DLAs. There is tentative evidence that the kinetically complex systems evolve in similar fashion to the global star formation rate. We speculate that if weaker Mg II systems represent accreting gas as suggested by recent studies of galaxy-absorber inclinations, then their high metal abundance suggests re-accretion of recently ejected material rather than first-time infall from the metal-poor intergalactic medium, even at early times.

79 ASTRONOMY AND ASTROPHYSICS↗

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