1,915 research outputs found
Improvements to the Indiana Geological Survey’s Petroleum Database Management System
This poster was presented at the 2011 Annual Meeting of the American Association of Petroleum Geologists, Eastern Section, in Arlington, Virginia, in September 2011.The Indiana Geological Survey’s Petroleum Database Management System (PDMS) is a web application that provides online access to petroleum-related geological information. Since its debut in 2004, the application has been widely used by the petroleum industry, academia, government agencies, and the general public. On June 6, 2011, a significantly enhanced version of the PDMS went online. New features include a robust search menu that permits elaborate queries of more than 74,000 petroleum wells, rapid and convenient online viewing and downloading of PDF-file well reports and both PDF- and TIFF-file geophysical and other well logs, and streamlined menus for easily accessing extensive well data. An interactive, context-driven web help explains every concept or term used.
The PDMS is organized in three main sections. The Well Tables Section includes such information as well location descriptions, completion zones, logs, operators, lease names, tests, reports, hydrocarbon shows, samples, cores, geologic formations and tops, and directional survey data. The Map Viewer Section contains many user-selectable layer options for showing well locations, petroleum fields, producing formations, aerial photographs, and topographic maps. Wells shown in the Map Viewer are hyperlinked to the Well Tables for easy access to the well data. The Fields and Production Section summarizes oil, natural gas, and gas storage field data, including historical oil production volumes in both tables and charts
Spectroscopic Sensitivity
We describe the overall performance of the STIS CCD after HST Servicing Mission #4 and the associated updates to calibration reference files. Most aspects of CCD performance are found to be fairly consistent with extrapolations of the trends seen prior to the failure of STIS in August 2004. The CCD gain value for the CCDGAIN = 4 setting has been redetermined using net count ratios of standard star spectra taken in the CCDGAIN = 1 and CCDGAIN = 4 settings, resulting in a gain value of 4.016 ± 0.003 e − /DN, which is 0.5% lower than the value used for the calibration of archival STIS CCD data taken before August 2004. Finally, we identify two independent indications of a temperature dependence of the Charge Transfer Efficiency (CTE). However, more calibration data are needed to verify the significance of this effect and, if verified, to calibrate it as a function of CCD housing temperature (as a proxy for CCD chip temperature). This option will be reassessed later during the Cycle 17 calibration program.
Limits on the Optical Brightness of the Epsilon Eridani Dust Ring
The STIS/CCD camera on the {\em Hubble Space Telescope (HST)} was used to
take deep optical images near the K2V main-sequence star Eridani in
an attempt to find an optical counterpart of the dust ring previously imaged by
sub-mm observations. Upper limits for the optical brightness of the dust ring
are determined and discussed in the context of the scattered starlight expected
from plausible dust models. We find that, even if the dust is smoothly
distributed in symmetrical rings, the optical surface brightness of the dust,
as measured with the {\em HST}/STIS CCD clear aperture at 55 AU from the star,
cannot be brighter than about 25 STMAG/". This upper limit excludes some
solid grain models for the dust ring that can fit the IR and sub-mm data.
Magnitudes and positions for 59 discrete objects between 12.5" to 58"
from Eri are reported. Most if not all of these objects are likely
to be background stars and galaxies.Comment: Revision corrects author lis
Transport Out of the Antarctic Polar Vortex from a Three-dimensional Transport Model
[1] A three-dimensional chemical transport model is utilized to study the transport out of the Antarctic polar vortex during the southern hemisphere spring. On average, over five consecutive years between 1993 and 1997, horizontal transport out of the vortex into the midlatitude stratosphere is smaller than vertical transport into the troposphere. However, there is significant interannual variability in the magnitude of mass exchange, which is related to year-to-year fluctuations in planetary wave activity. In 1994 the net loss of the vortex tracer mass in September is similar to that in October. However, the relative mass flux entering the midlatitude stratosphere and the troposphere differ between the two months. The ratio of horizontal transport out of the vortex to vertical transport into the troposphere is about 3:7 in September and 5:5 in October, indicating the higher permeability of the vortex in October compared to September. The September mass flux into the troposphere is larger than in October, consistent with the fact that stronger diabatic cooling occurs in September than October over Antarctica. The estimated ozone change at southern midlatitudes due to the intrusion of ozone-depleted air from high latitudes during September–October 1994 is about −0.44% per decade, which could contribute up to 10% of observed ozone decline at southern midlatitudes in spring. This amount is an underestimate of the dilution effect from high latitudes during the spring season, as it does not include the vortex breakup in late spring
Stratification and Isotope Separation in CP Stars
We investigate the elemental and isotopic stratification in the atmospheres
of selected chemically peculiar (CP) stars of the upper main sequence.
Reconfiguration of the UVES spectrograph in 2004 has made it possible to
examine all three lines of the Ca II infrared triplet. Much of the material
analyzed was obtained in 2008.
We support the claim of Ryabchikova, Kochukhov & Bagnulo (RKB) that the
calcium isotopes have distinct stratification profiles for the stars 10 Aql, HR
1217, and HD 122970, with the heavy isotope concentrated toward the higher
layers. Better observations are needed to learn the extent to which Ca-40
dominates in the deepest layers of all or most CP stars that show the presence
of Ca-48. There is little evidence for Ca-40 in the spectra of some HgMn stars,
and the infrared triplet in the magnetic star HD 101065 is well fit by pure
Ca-48. In HR 5623 (HD 133792) and HD 217522 it is likely that the heavy isotope
dominates, though models are possible where this is not the case.
While elemental stratification is surely needed in many cases, we point out
the importance of including adjustments in the assumed Teff and log(g) values,
in attempts to model stratification. We recommend emphasis on profiles of the
strongest lines, where the influence of stratification is most evident.
Isotopic mixtures, involving the 4 stable calcium nuclides with masses
between 40 and 48 are plausible, but are not emphasized.Comment: 16 Pages, 20 Figures, 10 Tables. Accepted for publication in Monthly
Notices of the RA
Detailed Analysis of Nearby Bulgelike Dwarf Stars II. Lithium Abundances
Li abundances are derived for a sample of bulgelike stars with isochronal
ages of 10-11 Gyr. These stars have orbits with pericentric distances, Rp, as
small as 2-3 kpc and Zmax < 1 kpc. The sample comprises G and K dwarf stars in
the metallicity range -0.80<[Fe/H]< +0.40. Few data of Li abundances in old
turn-off stars (> 4.5 Gyr) within the present metallicity range are available.
M67 (4.7 Gyr) and NGC 188 (6 Gyr) are the oldest studied metal-rich open
clusters with late-type stars. Li abundances have also been studied for few
samples of old metal-rich field stars. In the present work a high dispersion in
Li abundances is found for bulgelike stars for all the metallicity range,
comparable with values in M67. The role of metallicity and age on a Li
depletion pattern is discussed. The possible connection between Li depletion
and oxygen abundance due to atmospheric opacity effects is investigated.Comment: 9 pages, 7 figure
Testing Rotational Mixing Predictions with New Boron Abundances in Main Sequence B-type Stars
(Abridged) New boron abundances for seven main-sequence B-type stars are
determined from HST STIS spectroscopy around the BIII 2066A line. Boron
abundances provide a unique and critical test of stellar evolution models that
include rotational mixing since boron is destroyed in the surface layers of
stars through shallow mixing long before other elements are mixed from the
stellar interior through deep mixing. Boron abundances range from 12+log(B/H) =
1.0 to 2.2. The boron abundances are compared to the published values of their
stellar nitrogen abundances (all have 12+log(N/H) < 7.8, i.e., they do not show
significant CNO-mixing) and to their host cluster ages (4 to 16 Myr) to
investigate the predictions from models of massive star evolution with
rotational mixing effects (Heger & Langer 2000). Only three stars (out of 34)
deviate from the model predictions, including HD36591, HD205021, and HD30836.
These three stars suggest that rotational mixing could be more efficient than
currently modelled at the highest rotation rates.Comment: 10 figures, 7 tables; accepted for publication in the Astrophysical
Journa
Spitzer/IRAC Limits to Planetary Companions of Fomalhaut and epsilon Eridani
Fomalhaut and epsilon Eridani are two young, nearby stars that possess
extended debris disks whose structures suggest the presence of perturbing
planetary objects. With its high sensitivity and stable point spread function,
Spitzer/IRAC is uniquely capable of detecting cool, Jupiter-like planetary
companions whose peak emission is predicted to occur near 4.5 um. We report on
deep IRAC imaging of these two stars, taken at 3.6 and 4.5 um using subarray
mode and in all four channels in wider-field full array mode. Observations
acquired at two different telescope roll angles allowed faint surrounding
objects to be separated from the stellar diffraction pattern. No companion
candidates were detected at the reported position of Fomalhaut b with 3 sigma
model-dependent mass upper limits of 3 MJ (for an age of 200 Myr). Around
epsilon Eridani we instead set a limit of 4 and <1 MJ (1 Gyr model age) at the
inner and outer edge of the sub-millimeter debris ring, respectively. These
results are consistent with non-detections in recent near-infrared imaging
searches, and set the strongest limits to date on the presence of planets
outside epsilon Eridani sub-millimeter ring.Comment: Accepted by The Astrophysical Journal. Request electronic-only plates
to M. Marengo ([email protected]
Using the seismology of non-magnetic chemically peculiar stars as a probe of dynamical processes in stellar interiors
Chemical composition is a good tracer of hydrodynamical processes that occur
in stars as they often lead to mixing and particle transport. By comparing
abundances predicted by models and those observed in stars we can infer some
constraints on those mixing processes. As pulsations in stars are often very
sensitive to chemical composition, we can use asteroseismology to probe the
internal chemical composition of stars where no direct observations are
possible. In this paper I focus on main sequence stars Am, lambda bootis, and
HgMn stars and discuss what we can learn of mixing processes in those stars
from seismology.Comment: 10 pages,6 figures. accepted in Journal of astrophysics and
astronomy. proceedings of aries conferemce on asteroseismology. december 200
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