Showing papers in "Astrophysical Journal Supplement Series in 2017"

Mind Your Ps and Qs: The Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars

Abstract: We compile observations of early-type binaries identified via spectroscopy, eclipses, long-baseline interferometry, adaptive optics, common proper motion, etc. Each observational technique is sensitive to companions across a narrow parameter space of orbital periods P and mass ratios q = M_comp/M_1. After combining the samples from the various surveys and correcting for their respective selection effects, we find the properties of companions to O-type and B-type main-sequence (MS) stars differ among three regimes. First, at short orbital periods P = 0.5, and exhibit a small excess of twins q > 0.95. Second, the companion frequency peaks at intermediate periods log P (days) = 3.5 (a = 10 AU), where the binaries have mass ratios weighted toward small values q = 0.2-0.3 and follow a Maxwellian "thermal" eccentricity distribution. Finally, companions with long orbital periods log P (days) = 5.5-7.5 (a = 200-5,000 AU) are outer tertiary components in hierarchical triples, and have a mass ratio distribution across q = 0.1-1.0 that is nearly consistent with random pairings drawn from the initial mass function. We discuss these companion distributions and properties in the context of binary star formation and evolution. We also reanalyze the binary statistics of solar-type MS primaries, taking into account that (30+/-10)% of single-lined spectroscopic binaries likely contain white dwarf companions instead of low-mass stellar secondaries. The mean frequency of stellar companions with q > 0.1 and log P (days) < 8.0 per primary increases from 0.50+/-0.04 for solar-type MS primaries to 2.1+/-0.3 for O-type MS primaries. We fit joint probability density functions f(M_1,q,P,e) to the corrected distributions, which can be incorporated into binary population synthesis studies.

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

Abstract: The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in 2014 July. It pursues three core programs: the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2), Mapping Nearby Galaxies at APO (MaNGA), and the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). As well as its core program, eBOSS contains two major subprograms: the Time Domain Spectroscopic Survey (TDSS) and the SPectroscopic IDentification of ERosita Sources (SPIDERS). This paper describes the first data release from SDSS-IV, Data Release 13 (DR13). DR13 makes publicly available the first 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA. It includes new observations from eBOSS, completing the Sloan Extended QUasar, Emission-line galaxy, Luminous red galaxy Survey (SEQUELS), which also targeted variability-selected objects and X-ray-selected objects. DR13 includes new reductions of the SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification, and new reductions of the SDSS-III APOGEE-1 data, improving stellar parameters for dwarf stars and cooler stars. DR13 provides more robust and precise photometric calibrations. Value-added target catalogs relevant for eBOSS, TDSS, and SPIDERS and an updated red-clump catalog for APOGEE are also available. This paper describes the location and format of the data and provides references to important technical papers. The SDSS web site, http://www.sdss.org, provides links to the data, tutorials, examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned ∼6 yr operations of SDSS-IV.

XCOLD GASS: The Complete IRAM 30 m Legacy Survey of Molecular Gas for Galaxy Evolution Studies

Abstract: We introduce xCOLD GASS, a legacy survey providing a census of molecular gas in the local universe. Building on the original COLD GASS survey, we present here the full sample of 532 galaxies with CO (1–0) measurements from the IRAM 30 m telescope. The sample is mass-selected in the redshift interval $0.01\lt z\lt 0.05$ from the Sloan Digital Sky Survey (SDSS) and therefore representative of the local galaxy population with ${M}_{* }\ \gt {10}^{9}\,{M}_{\odot }$. The CO (1–0) flux measurements are complemented by observations of the CO (2–1) line with both the IRAM 30 m and APEX telescopes, H i observations from Arecibo, and photometry from SDSS, WISE, and GALEX. Combining the IRAM and APEX data, we find that the ratio of CO (2–1) to CO (1–0) luminosity for integrated measurements is ${r}_{21}=0.79\pm 0.03$, with no systematic variations across the sample. The CO (1–0) luminosity function is constructed and best fit with a Schechter function with parameters ${L}_{\mathrm{CO}}^{* }=(7.77\pm 2.11)\times {10}^{9}\,{\rm{K}}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{pc}}^{2}$, ${\phi }^{* }=(9.84\pm 5.41)\times {10}^{-4}\,{\mathrm{Mpc}}^{-3}$, and $\alpha =-1.19\pm 0.05$. With the sample now complete down to stellar masses of 109 ${M}_{\odot }$, we are able to extend our study of gas scaling relations and confirm that both molecular gas fractions (${f}_{{{\rm{H}}}_{2}}$) and depletion timescale (${t}_{\mathrm{dep}}({{\rm{H}}}_{2})$) vary with specific star formation rate (or offset from the star formation main sequence) much more strongly than they depend on stellar mass. Comparing the xCOLD GASS results with outputs from hydrodynamic and semianalytic models, we highlight the constraining power of cold gas scaling relations on models of galaxy formation.

Revised Stellar Properties of Kepler Targets for the Q1-17 (DR25) Transit Detection Run

Abstract: The determination of exoplanet properties and occurrence rates using Kepler data critically depends on our knowledge of the fundamental properties (such as temperature, radius, and mass) of the observed stars. We present revised stellar properties for 197,096 Kepler targets observed between Quarters 1–17 (Q1-17), which were used for the final transiting planet search run by the Kepler Mission (Data Release 25, DR25). Similar to the Q1–16 catalog by Huber et al., the classifications are based on conditioning published atmospheric parameters on a grid of Dartmouth isochrones, with significant improvements in the adopted method and over 29,000 new sources for temperatures, surface gravities, or metallicities. In addition to fundamental stellar properties, the new catalog also includes distances and extinctions, and we provide posterior samples for each stellar parameter of each star. Typical uncertainties are ~27% in radius, ~17% in mass, and ~51% in density, which is somewhat smaller than previous catalogs because of the larger number of improved $\mathrm{log}g$ constraints and the inclusion of isochrone weighting when deriving stellar posterior distributions. On average, the catalog includes a significantly larger number of evolved solar-type stars, with an increase of 43.5% in the number of subgiants. We discuss the overall changes of radii and masses of Kepler targets as a function of spectral type, with a particular focus on exoplanet host stars.

3FHL: The Third Catalog of Hard Fermi-LAT Sources

Abstract: We present a catalog of sources detected above 10 GeV by the Fermi Large Area Telescope (LAT) in the first 7 years of data using the Pass 8 event-level analysis. This is the Third Catalog of Hard Fermi-LAT Sources (3FHL), containing 1556 objects characterized in the 10 GeV–2 TeV energy range. The sensitivity and angular resolution are improved by factors of 3 and 2 relative to the previous LAT catalog at the same energies (1FHL). The vast majority of detected sources (79%) are associated with extragalactic counterparts at other wavelengths, including 16 sources located at very high redshift (z > 2). Eight percent of the sources have Galactic counterparts and 13% are unassociated (or associated with a source of unknown nature). The high-latitude sky and the Galactic plane are observed with a flux sensitivity of 4.4 to 9.5 ×10 −11 ph cm −2 s −1 , respectively (this is approximately 0.5 % and 1 % of the Crab Nebula flux above 10 GeV). The catalog includes 214 new γ-ray sources. The substantial increase in the number of photons (more than 4 times relative to 1FHL and 10 times to 2FHL) also allows us to measure significant spectral curvature for 32 sources and find flux variability for 163 of them. Furthermore, we estimate that for the same flux limit of 10 −12 erg cm −2 s −1 , the energy range above 10 GeV has twice as many sources as above 50 GeV, highlighting the importance, for future Cherenkov telescopes, of lowering the energy threshold as much as possible.

An Accurate Flux Density Scale from 50 MHz to 50 GHz

Abstract: The flux density scale of Perley and Butler (2013) is extended downwards to ~50 MHz by utilizing recent observations with the Karl G. Jansky Very Large Array (VLA) of 20 sources between 220 MHz and 48.1 GHz, and legacy VLA observations at 73.8 MHz. The derived spectral flux densities are placed on an absolute scale by utilizing the Baars et al. (1977) values of Cygnus A (3C405) for frequencies below 2 GHz, and the Mars-based polynomials for 3C286, 3C295, and 3C196 from Perley and Butler (2013) above 2 GHz. Polynomial expressions are presented for all 20 sources, with accuracy limited by the primary standards to 3 -- 5% over the entire frequency range. Corrections to the scales proposed by Perley and Butler (2013) and by Scaife and Heald (2012) are given.

BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift/BAT 70-month AGN Catalog

Abstract: Hard X-ray (≥10 keV) observations of active galactic nuclei (AGNs) can shed light on some of the most obscured episodes of accretion onto supermassive black holes. The 70-month Swift/BAT all-sky survey, which probes the 14–195 keV energy range, has currently detected 838 AGNs. We report here on the broadband X-ray (0.3–150 keV) characteristics of these AGNs, obtained by combining XMM-Newton, Swift/XRT, ASCA, Chandra, and Suzaku observations in the soft X-ray band ( keV) with 70-month averaged Swift/BAT data. The nonblazar AGNs of our sample are almost equally divided into unobscured () and obscured () AGNs, and their Swift/BAT continuum is systematically steeper than the 0.3–10 keV emission, which suggests that the presence of a high-energy cutoff is almost ubiquitous. We discuss the main X-ray spectral parameters obtained, such as the photon index, the reflection parameter, the energy of the cutoff, neutral and ionized absorbers, and the soft excess for both obscured and unobscured AGNs.

Revised Catalog of GALEX Ultraviolet Sources. I. The All-Sky Survey: GUVcat_AIS

Abstract: The Galaxy Evolution Explorer (GALEX) imaged the sky in two ultraviolet (UV) bands, far-UV (FUV, λ eff ~ 1528 A), and near-UV (NUV, λ eff ~ 2310 A), delivering the first comprehensive sky surveys at these wavelengths. The GALEX database contains FUV and NUV images, ~500 million source measurements and over 100,000 low-resolution UV spectra. The UV surveys are a unique resource for statistical studies of hot stellar objects, z 2 QSOs, star-forming galaxies, nebulae and the interstellar medium, and provide a roadmap for planning future UV instrumentation and follow-up observing programs. We present science-enhanced, "clean" catalogs of GALEX UV sources, with useful tags to facilitate scientific investigations. The catalogs are an improved and expanded version of our previous catalogs of UV sources (BCScat). With respect to BCScat, we have patched 640 fields for which the pipeline had improperly coadded non-overlapping observations, and we provide a version with a larger sky coverage (about 10%) by relaxing the restriction to the central area of the GALEX field to 11 diameter (GUVcat_AIS_fov055), as well as the cleaner, more restrictive version using only the 1° central portion of each field as in BCScat (GUVcat_AIS_fov050). We added new tags to facilitate selection and cleaning of statistical samples for science applications: we flag sources within the footprint of extended objects (nearby galaxies, stellar clusters) so that these regions can be excluded for estimating source density. As in our previous catalogs, in GUVcat duplicate measurements of the same source are removed, so that each astrophysical object has only one entry. Such a unique-source catalog is needed to study the density and distributions of sources, and to match UV sources with catalogs at other wavelengths. The catalog includes all observations from the All-Sky Imaging Survey (AIS), the survey with the largest area coverage, with both FUV and NUV detectors exposed: over 28,700 fields, made up of a total of 57,000 observations ("visits"). The total area covered, when overlaps are removed and gaps are accounted for, is 24,790 square degrees for GUVcat_AIS_fov055 (GUVcat_AIS_fov055) and 22,125 square degrees for (GUVcat_AIS_fov050). The total numbers of "unique" AIS sources (eliminating duplicate measurements) are 82,992,086 () and 69,772,677 (). The typical depth of the GUVcat_AIS catalog is FUV = 19.9, NUV = 20.8 AB mag.

Individual Dynamical Masses of Ultracool Dwarfs

Abstract: We present the full results of our decade-long astrometric monitoring programs targeting 31 ultracool binaries with component spectral types M7-T5. Joint analysis of resolved imaging from Keck Observatory and Hubble Space Telescope and unresolved astrometry from CFHT/WIRCam yields parallactic distances for all systems, robust orbit determinations for 23 systems, and photocenter orbits for 19 systems. As a result, we measure 38 precise individual masses spanning 30-115 $M_{\rm Jup}$. We determine a model-independent substellar boundary that is $\approx$70 $M_{\rm Jup}$ in mass ($\approx$L4 in spectral type), and we validate Baraffe et al. (2015) evolutionary model predictions for the lithium-depletion boundary (60 $M_{\rm Jup}$ at field ages). Assuming each binary is coeval, we test models of the substellar mass-luminosity relation and find that in the L/T transition, only the Saumon & Marley (2008) "hybrid" models accounting for cloud clearing match our data. We derive a precise, mass-calibrated spectral type-effective temperature relation covering 1100-2800 K. Our masses enable a novel direct determination of the age distribution of field brown dwarfs spanning L4-T5 and 30-70 $M_{\rm Jup}$. We determine a median age of 1.3 Gyr, and our population synthesis modeling indicates our sample is consistent with a constant star formation history modulated by dynamical heating in the Galactic disk. We discover two triple-brown-dwarf systems, the first with directly measured masses and eccentricities. We examine the eccentricity distribution, carefully considering biases and completeness, and find that low-eccentricity orbits are significantly more common among ultracool binaries than solar-type binaries, possibly indicating the early influence of long-lived dissipative gas disks. Overall, this work represents a major advance in the empirical view of very low-mass stars and brown dwarfs.

White Dwarf Rotation as a Function of Mass and a Dichotomy of Mode Line Widths: Kepler Observations of 27 Pulsating DA White Dwarfs through K2 Campaign 8

Abstract: We present photometry and spectroscopy for 27 pulsating hydrogen-atmosphere white dwarfs (DAVs; a.k.a. ZZ Ceti stars) observed by the Kepler space telescope up to K2 Campaign 8, an extensive compilation of observations with unprecedented duration (>75 days) and duty cycle (>90%). The space-based photometry reveals pulsation properties previously inaccessible to ground-based observations. We observe a sharp dichotomy in oscillation mode line widths at roughly 800 s, such that white dwarf pulsations with periods exceeding 800 s have substantially broader mode line widths, more reminiscent of a damped harmonic oscillator than a heat-driven pulsator. Extended Kepler coverage also permits extensive mode identification: we identify the spherical degree of 87 out of 201 unique radial orders, providing direct constraints of the rotation period for 20 of these 27 DAVs, more than doubling the number of white dwarfs with rotation periods determined via asteroseismology. We also obtain spectroscopy from 4 m-class telescopes for all DAVs with Kepler photometry. Using these homogeneously analyzed spectra, we estimate the overall mass of all 27 DAVs, which allows us to measure white dwarf rotation as a function of mass, constraining the endpoints of angular momentum in low- and intermediate-mass stars. We find that 0.51–0.73 M ⊙ white dwarfs, which evolved from 1.7–3.0 M ⊙ ZAMS progenitors, have a mean rotation period of 35 hr with a standard deviation of 28 hr, with notable exceptions for higher-mass white dwarfs. Finally, we announce an online repository for our Kepler data and follow-up spectroscopy, which we collect at http://k2wd.org.

The First APOKASC Catalog of Kepler Dwarf and Subgiant Stars

Abstract: (Abridged) We present the first APOKASC catalog of spectroscopic and asteroseismic data for 415 dwarfs and subgiants. Asteroseismic data have been obtained by Kepler in short cadence. The spectroscopic parameters are based on spectra taken as part of APOGEE and correspond to DR13 of SDSS. We analyze our data using two Teff scales, the spectroscopic values from DR13 and those derived from SDSS griz photometry. We use the differences in our results arising from these choices as a test of systematic Teff, and find that they can lead to significant differences in the derived stellar properties. Determinations of surface gravity ($\log{g}$), mean density ($\rho$), radius ($R$), mass ($M$), and age ($\tau$) for the whole sample have been carried out with stellar grid-based modeling. We have assessed random and systematic error sources in the spectroscopic and seismic data, as well as in the grid-based modeling determination of the stellar quantities in the catalog. We provide stellar properties for both Teff scales. The median combined (random and systematic) uncertainties are 2% (0.01 dex; $\log{g}$), 3.4% ($\rho$), 2.6% ($R$), 5.1% ($M$), and 19% ($\tau$) for the photometric Teff scale and 2% ($\log{g}$), 3.5% ($\rho$), 2.7% ($R$), 6.3% ($M$), and 23% ($\tau$) for the spectroscopic scale. Comparisons with stellar quantities in the catalog by Chaplin et al.(2014) highlight the importance of metallicity measurements for determining stellar parameters accurately. We compare our results with those from other sources, including stellar radii determined from TGAS parallaxes and asteroseismic analyses based on individual frequencies. We find a very good agreement in all cases. Comparisons give strong support to the determination of stellar quantities based on global seismology, a relevant result for future missions such as TESS and PLATO. Table 5 corrected (wrongly listed SDSS Teff before).

VULCAN: An Open-source, Validated Chemical Kinetics Python Code for Exoplanetary Atmospheres

Abstract: We present an open-source and validated chemical kinetics code for studying hot exoplanetary atmospheres, which we name VULCAN. It is constructed for gaseous chemistry from 500 to 2500 K using a reduced C-H-O chemical network with about 300 reactions. It uses eddy diffusion to mimic atmospheric dynamics and excludes photochemistry. We have provided a full description of the rate coefficients and thermodynamic data used. We validate VULCAN by reproducing chemical equilibrium and by comparing its output versus the disequilibrium-chemistry calculations of Moses et al. and Rimmer & Helling. It reproduces the models of HD 189733b and HD 209458b by Moses et al., which employ a network with nearly 1600 reactions. We also use VULCAN to examine the theoretical trends produced when the temperature-pressure profile and carbon-to-oxygen ratio are varied. Assisted by a sensitivity test designed to identify the key reactions responsible for producing a specific molecule, we revisit the quenching approximation and find that it is accurate for methane but breaks down for acetylene, because the disequilibrium abundance of acetylene is not directly determined by transport-induced quenching, but is rather indirectly controlled by the disequilibrium abundance of methane. Therefore, we suggest that the quenching approximation should be used with caution and must always be checked against a chemical kinetics calculation. A one-dimensional model atmosphere with 100 layers, computed using VULCAN, typically takes several minutes to complete. VULCAN is part of the Exoclimes Simulation Platform (ESP; this http URL) and publicly available at this http URL .

The second flight of the sunrise balloon-borne solar observatory: Overview of instrument updates, the flight, the data, and first results

Abstract: The SUNRISE balloon-borne solar observatory, consisting of a 1~m aperture telescope that provided a stabilized image to a UV filter imager and an imaging vector polarimeter, carried out its second science flight in June 2013. It provided observations of parts of active regions at high spatial resolution, including the first high-resolution images in the Mg~{\sc ii}~k line. The obtained data are of very high quality, with the best UV images reaching the diffraction limit of the telescope at 3000~\AA\ after Multi-Frame Blind Deconvolution reconstruction accounting for phase-diversity information. Here a brief update is given of the instruments and the data reduction techniques, which includes an inversion of the polarimetric data. Mainly those aspects that evolved compared with the first flight are described. A tabular overview of the observations is given. In addition, an example time series of a part of the emerging active region NOAA AR~11768 observed relatively close to disk centre is described and discussed in some detail. The observations cover the pores in the trailing polarity of the active region, as well as the polarity inversion line where flux emergence was ongoing and a small flare-like brightening occurred in the course of the time series. The pores are found to contain magnetic field strengths ranging up to 2500~G and, while large pores are clearly darker and cooler than the quiet Sun in all layers of the photosphere, the temperature and brightness of small pores approach or even exceed those of the quiet Sun in the upper photosphere.

Calibration of the Large Area X-Ray Proportional Counter (LAXPC) Instrument on board AstroSat

Abstract: We present the calibration and background model for the Large Area X-ray Proportional Counter (LAXPC) detectors on-board AstroSat. LAXPC instrument has three nominally identical detectors to achieve large collecting area. These detectors are independent of each other and in the event analysis mode, they record the arrival time and energy of each photon that is detected. The detectors have a time-resolution of 10 $\mu$s and a dead-time of about 42 $\mu$s. This makes LAXPC ideal for timing studies. The energy resolution and peak channel to energy mapping were obtained from calibration on ground using radioactive sources coupled with GEANT4 simulations of the detectors. The response matrix was further refined from observations of the Crab X-ray source after launch. At around 20 keV the energy resolution of detector is about 10--15\%, while the combined effective area of the 3 detectors is about 6000 cm$^2$.

Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) 1.0: A General Circulation Model for Simulating the Climates of Rocky Planets

Abstract: Resolving Orbital and Climate Keys of Earth and Extraterrestrial Environments with Dynamics (ROCKE-3D) is a three-dimensional General Circulation Model (GCM) developed at the NASA Goddard Institute for Space Studies for the modeling of atmospheres of solar system and exoplanetary terrestrial planets. Its parent model, known as ModelE2, is used to simulate modern Earth and near-term paleo-Earth climates. ROCKE-3D is an ongoing effort to expand the capabilities of ModelE2 to handle a broader range of atmospheric conditions, including higher and lower atmospheric pressures, more diverse chemistries and compositions, larger and smaller planet radii and gravity, different rotation rates (from slower to more rapid than modern Earth's, including synchronous rotation), diverse ocean and land distributions and topographies, and potential basic biosphere functions. The first aim of ROCKE-3D is to model planetary atmospheres on terrestrial worlds within the solar system such as paleo-Earth, modern and paleo-Mars, paleo-Venus, and Saturn's moon Titan. By validating the model for a broad range of temperatures, pressures, and atmospheric constituents, we can then further expand its capabilities to those exoplanetary rocky worlds that have been discovered in the past, as well as those to be discovered in the future. We also discuss the current and near-future capabilities of ROCKE-3D as a community model for studying planetary and exoplanetary atmospheres.

CANDELS multi-wavelength catalogs: source identification and photometry in the CANDELS extended groth strip

Abstract: We present a 0.4–8 μm multi-wavelength photometric catalog in the Extended Groth Strip (EGS) field. This catalog is built on the Hubble Space Telescope (HST) WFC3 and ACS data from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), and it incorporates the existing HST data from the All-wavelength Extended Groth strip International Survey (AEGIS) and the 3D-HST program. The catalog is based on detections in the F160W band reaching a depth of F160W = 26.62 AB (90% completeness, point sources). It includes the photometry for 41,457 objects over an area of ≈206 arcmin^2 in the following bands: HST/ACS F606W and F814W; HST WFC3 F125W, F140W, and F160W; Canada–France–Hawaii Telescope (CFHT)/Megacam u*, g’, r’, i’ and z’ CFHT/WIRCAM J, H, and K_S; Mayall/NEWFIRM J1, J2, J3, H1, H2, and K; Spitzer IRAC 3.6, 4.5, 5.8, and 8.0 μm. We are also releasing value-added catalogs that provide robust photometric redshifts and stellar mass measurements. The catalogs are publicly available through the CANDELS repository.

Candels multi-wavelength catalogs: source identification and photometry in the candels cosmos survey field

Abstract: We present a multi-wavelength photometric catalog in the COSMOS field as part of the observations by the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. The catalog is based on Hubble Space Telescope Wide Field Camera 3 (HST/WFC3) and Advanced Camera for Surveys observations of the COSMOS field (centered at R.A.: 10^h00^m28^s, Decl.:+02^o12^'21^"). The final catalog has 38671 sources with photometric data in 42 bands from UV to the infrared (~ 0.3-8 µm). This includes broadband photometry from HST, CFHT, Subaru, the Visible and Infrared Survey Telescope for Astronomy, and Spitzer Space Telescope in the visible, near-infrared, and infrared bands along with intermediate- and narrowband photometry from Subaru and medium-band data from Mayall NEWFIRM. Source detection was conducted in the WFC3 F160W band (at 1.6 μm) and photometry is generated using the Template FITting algorithm. We further present a catalog of the physical properties of sources as identified in the HST F160W band and measured from the multi-band photometry by fitting the observed spectral energy distributions of sources against templates.

Photometry and Proper Motions of M, L, and T Dwarfs from the Pan-STARRS1 3π Survey

Abstract: We present a catalog of 9888 M, L and T dwarfs detected in the Pan-STARRS1 3π Survey (PS1), covering three-quarters of the sky. Our catalog contains nearly all known objects of spectral types L0–T2 in the PS1 field, with objects as early as M0 and as late as T9, and includes PS1, 2MASS, AllWISE, and Gaia DR1 photometry. We analyze the different types of photometry reported by PS1 and use two types in our catalog in order to maximize both depth and accuracy. Using parallaxes from the literature, we construct empirical SEDs for field ultracool dwarfs spanning 0.5–12 μm. We determine typical colors of M0–T9 dwarfs and highlight the distinctive colors of subdwarfs and young objects. We combine astrometry from PS1, 2MASS, and Gaia DR1 to calculate new proper motions for our catalog. We achieve a median precision of 2.9 mas yr−1, a factor of ≈3−10 improvement over previous large catalogs. Our catalog contains proper motions for 2405 M6–T9 dwarfs and includes the largest set of homogeneous proper motions for L and T dwarfs published to date, 406 objects for which there were no previous measurements, and 1176 objects for which we improve upon previous literature values. We analyze the kinematics of ultracool dwarfs in our catalog and find evidence that bluer but otherwise generic late-M and L field dwarfs (i.e., not subdwarfs) tend to have tangential velocities higher than those of typical field objects. With the public release of the PS1 data, this survey will continue to be an essential tool for characterizing the ultracool dwarf population.

A Herschel Space Observatory Spectral Line Survey of Local Luminous Infrared Galaxies from 194 to 671 Microns

Abstract: We describe a Herschel Space Observatory 194–671 μm spectroscopic survey of a sample of 121 local luminous infrared galaxies and report the fluxes of the CO J to J–1 rotational transitions for 4 ⩽ J ⩽ 13, the [N ii] 205 μm line, the [C i] lines at 609 and 370 μm, as well as additional and usually fainter lines. The CO spectral line energy distributions (SLEDs) presented here are consistent with our earlier work, which was based on a smaller sample, that calls for two distinct molecular gas components in general: (i) a cold component, which emits CO lines primarily at J ≾ 4 and likely represents the same gas phase traced by CO (1−0), and (ii) a warm component, which dominates over the mid-J regime (4 10. The flux ratios of the two [C i] lines imply modest excitation temperatures of 15–30 K; the [C i] 370 μm line scales more linearly in flux with CO (4−3) than with CO (7−6). These findings suggest that the [C i] emission is predominantly associated with the gas component defined in (i) above. Our analysis of the stacked spectra in different far-infrared (FIR) color bins reveals an evolution of the SLED of the rotational transitions of H_2 O vapor as a function of the FIR color in a direction consistent with infrared photon pumping.

A Catalog of Narrow Line Seyfert 1 Galaxies from the Sloan Digital Sky Survey Data Release 12

Abstract: We present a new catalog of narrow-line Seyfert 1 (NLSy1) galaxies from the Sloan Digital Sky Survey Data Release 12 (SDSS DR12). This was obtained by a systematic analysis through modeling of the continuum and emission lines of the spectra of all the 68,859 SDSS DR12 objects that are classified as "QSO" by the SDSS spectroscopic pipeline with z 2 per pixel. This catalog contains a total of 11,101 objects, which is about 5 times larger than the previously known NLSy1 galaxies. Their monochromatic continuum luminosity at 5100 A is found to be strongly correlated with H-beta, H-alpha, and [O III] emission line luminosities. The optical Fe II strength in NLSy1 galaxies is about two times larger than the broad- line Seyfert 1 (BLSy1) galaxies. About 5% of the catalog sources are detected in the FIRST survey. The Eddington ratio (XEdd) of NLSy1 galaxies has an average of log XEdd of -0.34, much higher than -1.03 found for BLSy1 galaxies. Their black hole masses (MBH) have an average of log MBH of 6.9 Msun, which is less than BLSy1 galaxies, which have an average of log MBH of 8.0 Msun. The MBH of NLSy1 galaxies is found to be correlated with their host galaxy velocity dispersion. Our analysis suggests that geometrical effects playing an important role in defining NLSy1 galaxies and their MBH deficit is perhaps due to their lower inclination compared to BLSy1 galaxies.

Solar Coronal Loops Associated with Small-scale Mixed Polarity Surface Magnetic Fields

Abstract: How and where are coronal loops rooted in the solar lower atmosphere? The details of the magnetic environment and its evolution at the footpoints of coronal loops are crucial to understanding the processes of mass and energy supply to the solar corona. To address the above question, we use high-resolution line-of-sight magnetic field data from the Imaging Magnetograph eXperiment instrument on the Sunrise balloon-borne observatory and coronal observations from the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory of an emerging active region. We find that the coronal loops are often rooted at the locations with minor small-scale but persistent opposite-polarity magnetic elements very close to the larger dominant polarity. These opposite-polarity small-scale elements continually interact with the dominant polarity underlying the coronal loop through flux cancellation. At these locations we detect small inverse Y-shaped jets in chromospheric Ca ii H images obtained from the Sunrise Filter Imager during the flux cancellation. Our results indicate that magnetic flux cancellation and reconnection at the base of coronal loops due to mixed polarity fields might be a crucial feature for the supply of mass and energy into the corona.

BANYAN. IX. The Initial Mass Function and Planetary-mass Object Space Density of the TW HYA Association

Abstract: A determination of the initial mass function (IMF) of the current, incomplete census of the 10 Myr-old TW Hya association (TWA) is presented. This census is built from a literature compilation supplemented with new spectra and 17 new radial velocities, as well as a re-analysis of Hipparcos data that confirmed HR 4334 (A2Vn) as a member. Though the dominant uncertainty in the IMF remains census incompleteness, a detailed statistical treatment is carried out to make the IMF determination independent of binning, while accounting for small number statistics. The currently known high-likelihood members are fitted by a log-normal distribution with a central mass of $0.21^{+0.11}_{-0.06}$ $M_{\odot}$ and a characteristic width of $0.8^{+0.2}_{-0.1}$ dex in the 12 $M_{\rm Jup}$-2 $M_{\odot}$ range, whereas a Salpeter power law with $\alpha = 2.2^{+1.1}_{-0.5}$ best describes the IMF slope in the $0.1-2$ $M_{\odot}$ range. This characteristic width is higher than other young associations, which may be due to incompleteness in the current census of low-mass TWA stars. A tentative overpopulation of isolated planetary-mass members similar to 2MASS J11472421-2040204 and 2MASS J11193254-1137466 is identified: this indicates that there might be as many as $10^{+13}_{-5}$ similar members of TWA with hot-start model-dependent masses estimated at $\sim$ 5-7 $M_{\rm Jup}$, most of which would be too faint to be detected in 2MASS. Our new radial velocity measurements corroborate the membership of 2MASS J11472421-2040204, and secure TWA 28 (M8.5$\gamma$), TWA 29 (M9.5$\gamma$) and TWA 33 (M4.5e) as members. The discovery of 2MASS J09553336-0208403, a young L7-type interloper unrelated to TWA, is also presented.

The splashback radius of halos from particle dynamics. I. The SPARTA algorithm

Abstract: Motivated by the recent proposal of the splashback radius as a physical boundary of dark-matter halos, we present a parallel computer code for Subhalo and PARticle Trajectory Analysis (Sparta). The code analyzes the orbits of all simulation particles in all host halos, billions of orbits in the case of typical cosmological N-body simulations. Within this general framework, we develop an algorithm that accurately extracts the location of the first apocenter of particles after infall into a halo, or splashback. We define the splashback radius of a halo as the smoothed average of the apocenter radii of individual particles. This definition allows us to reliably measure the splashback radii of 95% of host halos above a resolution limit of 1000 particles. We show that, on average, the splashback radius and mass are converged to better than 5% accuracy with respect to mass resolution, snapshot spacing, and all free parameters of the method.

Stellar Flares Observed in Long-cadence Data from the Kepler Mission

Abstract: We aim to perform a statistical study of stellar flares observed by Kepler. We want to study the flare amplitude, duration, energy, and occurrence rates, and how they are related to the spectral type and rotation period. To that end, we have developed an automated flare detection and characterization algorithm. We have harvested the stellar parameters from the Kepler input catalog and the rotation periods from McQuillan et al. We find several new candidate A stars showing flaring activity. Moreover, we find 653 giants with flares. From the statistical distribution of flare properties, we find that the flare amplitude distribution has a similar behavior between F+G types and K+M types. The flare duration and flare energy seem to be grouped between G+K+M types versus F types and giants. We also detect a tail of stars with high flare occurrence rates across all spectral types (but most prominent in the late spectral types), and this is compatible with the existence of "flare stars." Finally, we have found a strong correlation of the flare occurrence rate and the flare amplitude with the stellar rotation period: a quickly rotating star is more likely to flare often and has a higher chance of generating large flares.

Statistical analysis of supernova remnants in the Large Magellanic Cloud

Abstract: We construct the most complete sample of supernova remnants (SNRs) in any galaxy - the Large Magellanic Cloud (LMC) SNR sample. We study their various properties such as spectral index ($\alpha$), size and surface-brightness. We suggest an association between the spatial distribution, environment density of LMC SNRs and their tendency to be located around supergiant shells. We find evidence that the 16 known type Ia LMC SNRs are expanding in a lower density environment compared to the Core-Collapse (CC) type. The mean diameter of our entire population (74) is 41 pc, which is comparable to nearby galaxies. We didn't find any correlation between the type of SN explosion, ovality or age. The $N(

A STEREO Survey of Magnetic Cloud Coronal Mass Ejections Observed at Earth in 2008–2012

Abstract: We identify coronal mass ejections (CMEs) associated with magnetic clouds (MCs) observed near Earth by the Wind spacecraft from 2008 to mid-2012, a time period when the two STEREO spacecraft were well positioned to study Earth-directed CMEs. We find 31 out of 48 Wind MCs during this period can be clearly connected with a CME that is trackable in STEREO imagery all the way from the Sun to near 1 AU. For these events, we perform full 3-D reconstructions of the CME structure and kinematics, assuming a flux rope morphology for the CME shape, considering the full complement of STEREO and SOHO imaging constraints. We find that the flux rope orientations and sizes inferred from imaging are not well correlated with MC orientations and sizes inferred from the Wind data. However, velocities within the MC region are reproduced reasonably well by the image-based reconstruction. Our kinematic measurements are used to provide simple prescriptions for predicting CME arrival times at Earth, provided for a range of distances from the Sun where CME velocity measurements might be made. Finally, we discuss the differences in the morphology and kinematics of CME flux ropes associated with different surface phenomena (flares, filament eruptions, or no surface activity).

The Ages and Masses of a Million Galactic-disk Main-sequence Turnoff and Subgiant Stars from the LAMOST Galactic Spectroscopic Surveys

Abstract: We present estimates of stellar age and mass for 0.93 million Galactic-disk main-sequence turnoff and subgiant stars from the LAMOST Galactic Spectroscopic Surveys. The ages and masses are determined by matching with stellar isochrones using a Bayesian algorithm, utilizing effective temperature , absolute magnitude , metallicity [Fe/H], and α-element to iron abundance ratio [α/Fe] deduced from the LAMOST spectra. Extensive examinations suggest the age and mass estimates are robust. Overall, the sample stars have a median error of 34% for the age estimates, and half of the stars older than 2 Gyr have age uncertainties of only 20%–30%. The median error for the mass estimates of the whole sample of stars is ~8%. The huge data set demonstrates good correlations among stellar age, [Fe/H] ([α/H]), and [α/Fe]. Particularly, double-sequence features are revealed in both the age–[α/Fe] and age–[Fe/H]([α/H]) spaces. In the [Fe/H]–[α/Fe] space, stars of 8–10 Gyr exhibit both the thin and thick disk sequences, while younger (older) stars show only the thin (thick) disk sequence, indicating that the thin disk became prominent 8–10 Gyr ago, while the thick disk formed earlier and was almost quenched 8 Gyr ago. Stellar ages exhibit positive vertical and negative radial gradients across the disk, and the outer disk of R 9 kpc exhibits a strong flare in stellar age distribution.