38 research outputs found

    New High Proper Motion Stars from the Digitized Sky Survey. II. Northern Stars with 0.5<mu<2.0 arcsec/yr at High Galactic Latitudes

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    In a continuation of our systematic search for high proper motion stars in the Digitized Sky Survey, we have completed the analysis of northern sky fields at galactic latitudes above 25 degrees. With the help of our SUPERBLINK software, a powerful automated blink comparator developed by us, we have identified 1146 stars in the magnitude range 8<r<20 with proper motions 0.500<mu<2.000 arcsec/yr. These include 1080 stars previously listed in Luyten's proper motion catalogs (LHS, NLTT), 9 stars not previously listed in the Luyten catalogs but reported elsewhere in the literature (including 1 previously reported by our team), and 57 new objects reported here for the first time. This paper includes a list of positions, proper motions, magnitudes, and finder charts for all the new high proper motion stars. Combined with our previous study of low galactic latitude fields (see Paper I), our survey now covers over 98% of the northern sky. We conclude that the Luyten catalogs were 90% complete in the northern sky for stars with 0.5<mu<2.0 arcsec/yr down to magnitude r=19. We discuss the incompleteness of the old Luyten proper motion survey, and estimate completeness limits for our new survey.Comment: To appear in The Astronomical Journa

    TASS Mark IV Photometric Survey of the Northern Sky

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    The Amateur Sky Survey (TASS) is a loose confederation of amateur and professional astronomers. We describe the design and construction of our Mark IV systems, a set of wide-field telescopes with CCD cameras which take simultaneous images in the VV and ICI_C passbands. We explain our observational procedures and the pipeline which processes and reduces the images into lists of stellar positions and magnitudes. We have compiled a large database of measurements for stars in the northern celestial hemisphere with VV-band magnitudes in the range 7 < V < 13. This paper describes data taken over the four-year period starting November, 2001. One of our results is a catalog of repeated measurements on the Johnson-Cousins system for over 4.3 million stars.Comment: Accepted for publication in December, 2006, issue of PASP. 44 pages including 20 figures. Patches catalog available at http://spiff.rit.edu/tass/patches

    A Ring of Warm Dust in the HD 32297 Debris Disk

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    We report the detection of a ring of warm dust in the edge-on disk surrounding HD 32297 with the Gemini-N/MICHELLE mid-infrared imager. Our N'-band image shows elongated structure consistent with the orientation of the scattered-light disk. The Fnu(11.2 um) = 49.9+/-2.1 mJy flux is significantly above the 28.2+/-0.6 mJy photosphere. Subtraction of the stellar point spread function reveals a bilobed structure with peaks 0.5"-0.6" from the star. An analysis of the stellar component of the SED suggests a spectral type later than A0, in contrast to commonly cited literature values. We fit three-dimensional, single-size grain models of an optically thin dust ring to our image and the SED using a Markov chain Monte Carlo algorithm in a Bayesian framework. The best-fit effective grain sizes are submicron, suggesting the same dust population is responsible for the bulk of the scattered light. The inner boundary of the warm dust is located 0.5"-0.7" (~65 AU) from the star, which is approximately cospatial with the outer boundary of the scattered-light asymmetry inward of 0.5". The addition of a separate component of larger, cooler grains that provide a portion of the 60 um flux improves both the fidelity of the model fit and consistency with the slopes of the scattered-light brightness profiles. Previous indirect estimates of the stellar age (~30 Myr) indicate the dust is composed of debris. The peak vertical optical depths in our models (~0.3-1 x 1e-2) imply that grain-grain collisions likely play a significant role in dust dynamics and evolution. Submicron grains can survive radiation pressure blow-out if they are icy and porous. Similarly, the inferred warm temperatures (130-200 K) suggest that ice sublimation may play a role in truncating the inner disk.Comment: ApJ accepted, 8 pages, 4 figure

    The DDO IVC Distance Project: Survey Description and the Distance to G139.6+47.6

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    We present a detailed analysis of the distance determination for one intermediate Velocity Cloud (IVC G139.6+47.6) from the ongoing DDO IVC Distance Project. Stars along the line of sight to G139.6+47.6 are examined for the presence of sodium absorption attributable to the cloud, and the distance bracket is established by astrometric and spectroscopic parallax measurements of demonstrated foreground and background stars. We detail our strategy regarding target selection, observational setup, and analysis of the data, including a discussion of wavelength calibration and sky subtraction uncertainties. We find a distance estimate of 129 (+/- 10) pc for the lower limit and 257 (+211-33) pc for the upper limit. Given the high number of stars showing absorption due to this IVC, we also discuss the small-scale covering factor of the cloud and the likely significance of non-detections for subsequent observations of this and other similar IVC's. Distance measurements of the remaining targets in the DDO IVC project will be detailed in a companion paper.Comment: 10 pages, 6 figures, LaTe

    NYU-VAGC: a galaxy catalog based on new public surveys

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    Here we present the New York University Value-Added Galaxy Catalog (NYU-VAGC), a catalog of local galaxies (mostly below a redshift of about 0.3) based on a set of publicly-released surveys (including the 2dFGRS, 2MASS, PSCz, FIRST, and RC3) matched to the Sloan Digital Sky Survey (SDSS) Data Release 2. Excluding areas masked by bright stars, the photometric sample covers 3514 square degrees and the spectroscopic sample covers 2627 square degrees (with about 85% completeness). Earlier, proprietary versions of this catalog have formed the basis of many SDSS investigations of the power spectrum, correlation function, and luminosity function of galaxies. We calculate and compile derived quantities (for example, K-corrections and structural parameters for galaxies). The SDSS catalog presented here is photometrically recalibrated, reducing systematic calibration errors across the sky from about 2% to about 1%. We include an explicit description of the geometry of the catalog, including all imaging and targeting information as a function of sky position. Finally, we have performed eyeball quality checks on a large number of objects in the catalog in order to flag deblending and other errors. This catalog is complementary to the SDSS Archive Servers, in that NYU-VAGC's calibration, geometrical description, and conveniently small size are specifically designed for studying galaxy properties and large-scale structure statistics using the SDSS spectroscopic catalog.Comment: accepted by AJ; full resolution version available at http://sdss.physics.nyu.edu/vagc/va_paper.ps; data files available at http://sdss.physics.nyu.edu/vagc

    XO-5b: A Transiting Jupiter-sized Planet With A Four Day Period

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    The star XO-5 (GSC 02959-00729, V=12.1, G8V) hosts a Jupiter-sized, Rp=1.15+/-0.12 Rjup, transiting extrasolar planet, XO-5b, with an orbital period of P=4.187732+/-0.00002 days. The planet mass (Mp=1.15+/-0.08 Mjup) and surface gravity (gp=22+/-5 m/s^2) are significantly larger than expected by empirical Mp-P and Mp-P-[Fe/H] relationships. However, the deviation from the Mp-P relationship for XO-5b is not large enough to suggest a distinct type of planet as is suggested for GJ 436b, HAT-P-2b, and XO-3b. By coincidence XO-5 overlies the extreme H I plume that emanates from the interacting galaxy pair NGC 2444/NGC 2445 (Arp 143).Comment: 10 pages, 9 Figures, Submitted to Ap

    Comparison of computationally- and manually-assigned Gene Ontology annotations to improve functional characterization of gene products.

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    The Gene Ontology (GO) describes molecular functions, biological processes, and cellular components of gene products using controlled-vocabulary terms that are related to each other in a structure that facilitates computing on GO annotations within and across species. Experimentally-based GO annotations that are manually curated from the literature are often used to predict the functions of related uncharacterized proteins. The accuracy of such annotations is thus critically important, particularly for a well-studied model organism such as _Saccharomyces cerevisiae_ which is frequently used as the source of the experimental data. &#xd;&#xa;&#xd;&#xa;Comparison of experimentally-based annotations with those predicted by computational methods for the same gene products may reveal inaccuracies in curation of the experimental data, and could additionally be used to evaluate and improve the computational methods. We will present the results of an analysis at SGD that identified four major reasons for discrepancies between the two kinds of annotation. Some discrepancies revealed cases in which human error led to errors or omissions in the manual curation, prompting prioritization for review and correction. In another category, the computational annotations were not supported or were refuted by the literature, thereby suggesting ways in which the accuracy of the prediction methods could be improved. Yet another type of discrepancy resulted from issues with the GO structure, such as missing parentage for certain terms, leading to reexamination and improvement of the ontology. Finally, some discrepancies arose because the computational predictions were entirely novel, and no relevant experimental evidence was available. These cases highlight potential interesting new avenues for experimentation.&#xd;&#xa

    XO-2b: Transiting Hot Jupiter in a Metal-rich Common Proper Motion Binary

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    We report on a V=11.2 early K dwarf, XO-2 (GSC 03413-00005), that hosts a Rp=0.98+0.03/-0.01 Rjup, Mp=0.57+/-0.06 Mjup transiting extrasolar planet, XO-2b, with an orbital period of 2.615857+/-0.000005 days. XO-2 has high metallicity, [Fe/H]=0.45+/-0.02, high proper motion, mu_tot=157 mas/yr, and has a common proper motion stellar companion with 31" separation. The two stars are nearly identical twins, with very similar spectra and apparent magnitudes. Due to the high metallicity, these early K dwarf stars have a mass and radius close to solar, Ms=0.98+/-0.02 Msolar and Rs=0.97+0.02/-0.01 Rsolar. The high proper motion of XO-2 results from an eccentric orbit (Galactic pericenter, Rper<4 kpc) well confined to the Galactic disk (Zmax~100 pc). In addition, the phase space position of XO-2 is near the Hercules dynamical stream, which points to an origin of XO-2 in the metal-rich, inner Thin Disk and subsequent dynamical scattering into the solar neighborhood. We describe an efficient Markov Chain Monte Carlo algorithm for calculating the Bayesian posterior probability of the system parameters from a transit light curve.Comment: 14 pages, 10 Figures, Accepted in ApJ. Negligible changes to XO-2 system properties. Removed Chi^2 light curve analysis section, and simplified MCMC light curve analysis discussio

    Thermal Infrared MMTAO Observations of the HR 8799 Planetary System

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    We present direct imaging observations at wavelengths of 3.3, 3.8 (L',band), and 4.8 (M band) microns, for the planetary system surrounding HR 8799. All three planets are detected at L'. The c and d component are detected at 3.3 microns, and upper limits are derived from the M band observations. These observations provide useful constraints on warm giant planet atmospheres. We discuss the current age constraints on the HR 8799 system, and show that several potential co-eval objects can be excluded from being co-moving with the star. Comparison of the photometry is made to models for giant planet atmospheres. Models which include non-equilibrium chemistry provide a reasonable match to the colors of c and d. From the observed colors in the thermal infrared we estimate T_eff < 960 K for b, and T_eff=1300 and 1170 K for c and d, respectively. This provides an independent check on the effective temperatures and thus masses of the objects from the Marois 2008 results.Comment: 16 pages, 6 figures, accepted to Ap
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