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Physics and Astronomy Faculty Publications

2003

Articles 1 - 10 of 10

Full-Text Articles in Physical Sciences and Mathematics

The Flaring H2o Megamaser And Compact Radio Source In Markarian 348, A. B. Peck, C. Henkel, J. S. Ulvestad, A. Brunthaler, H. Falcke, Moshe Elitzur, K. M. Menten, J. F. Gallimore Jun 2003

The Flaring H2o Megamaser And Compact Radio Source In Markarian 348, A. B. Peck, C. Henkel, J. S. Ulvestad, A. Brunthaler, H. Falcke, Moshe Elitzur, K. M. Menten, J. F. Gallimore

Physics and Astronomy Faculty Publications

We report on single-dish monitoring and extremely high angular resolution observations of the flaring H2O megamaser in the Seyfert 2 galaxy Mrk 348. The H2O line is redshifted by ~130 km s-1 with respect to the systemic velocity, is very broad, with an FWHM of 130 km s-1, and has no detectable high-velocity components within 1500 km s-1 on either side of the strong line. Monitoring observations made with the Effelsberg 100 m telescope show that the maser varies significantly on timescales as short as 1 day and that the integrated line …

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Optical Photometry And X-Ray Monitoring Of The "Cool Algol" Bd+05˚706: Determination Of The Physical Properties, Guillermo Torres, Jeff A. Mader, Laurence A. Marschall, Ralph Neuhauser, Alaine S. Duffy Jun 2003

Optical Photometry And X-Ray Monitoring Of The "Cool Algol" Bd+05˚706: Determination Of The Physical Properties, Guillermo Torres, Jeff A. Mader, Laurence A. Marschall, Ralph Neuhauser, Alaine S. Duffy

Physics and Astronomy Faculty Publications

We present new photometric observations in the BVRI bands of the double-lined eclipsing binary BD +05706 conducted over three observing seasons, as well as new X-ray observations obtained with ROSAT covering a full orbital cycle (P = 18.9 days). A detailed light-curve analysis of the optical data shows the system to be semidetached, confirming indications from an earlier analysis by Torres et al. (published in 1998), with the less massive and cooler star filling its Roche lobe. The system is a member of the rare class of cool Algol systems, which are different from the ‘‘ classical ’’ Algol systems …

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Fluorescence In Ultraviolet Active Binaries: The Case Of Ff Aquarii, Todd R. Vaccaro, R. E. Wilson Jun 2003

Fluorescence In Ultraviolet Active Binaries: The Case Of Ff Aquarii, Todd R. Vaccaro, R. E. Wilson

Physics and Astronomy Faculty Publications

The eclipsing binary FF Aquarii (FF Aqr) consists of a small hot star of uncertain type and a red giant. An Hα feature varies from absorption during eclipse to maximum emission during hot star transit. We have obtained simultaneous differential photometry in BVRI bands and Hα spectroscopy in 1998 that covered an entire orbit with some overlap. A binary star model was used with our light-curve, radial velocity and Hα data to refine stellar and orbital parameters. A new ephemeris indicates that the period has increased or is longer than previously thought. A physically simple algorithm is developed that generates …

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Potential Impact Of Subsonic And Supersonic Aircraft Exhaust On Water Vapor In The Lower Stratosphere Assessed Via A Trajectory Model, Gary A. Morris, Joan A. Rosenfield, Mark R. Schoeberl, Charles A. Jackman Feb 2003

Potential Impact Of Subsonic And Supersonic Aircraft Exhaust On Water Vapor In The Lower Stratosphere Assessed Via A Trajectory Model, Gary A. Morris, Joan A. Rosenfield, Mark R. Schoeberl, Charles A. Jackman

Physics and Astronomy Faculty Publications

We employ a trajectory model to assess the impact on the stratosphere of water vapor present in the exhaust of subsonic and a proposed fleet of supersonic aircraft. Air parcels into which water vapor from aircraft exhaust has been injected are run through a 6-year simulation in the trajectory model using meteorological data from the UKMO analyses with emissions dictated by the standard 2015 emissions scenario. For the subsonic aircraft, our results suggest maximum enhancements of ~150 ppbv just above the Northern Hemisphere tropopause and of much less than 50 ppbv in most other regions. Inserting the perturbed water vapor …

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Chemical Abundances In Broad Emission Line Regions: The "Nitrogen-Loud'' Quasi-Stellar Object Q0353-383, J. A. Baldwin, F. Hamann, K. T. Korista, Gary J. Ferland, M. Dietrich, C. Warner Feb 2003

Chemical Abundances In Broad Emission Line Regions: The "Nitrogen-Loud'' Quasi-Stellar Object Q0353-383, J. A. Baldwin, F. Hamann, K. T. Korista, Gary J. Ferland, M. Dietrich, C. Warner

Physics and Astronomy Faculty Publications

The intensity of the strong N V λ1240 line relative to C IV λ1549 or to He II λ1640 has been proposed as an indicator of the metallicity of quasi-stellar object (QSO) broad emission line regions, allowing abundance measurements in a large number of QSOs out to the highest redshifts. Previously, it had been shown that the (normally) much weaker lines N III] λ1750 and N IV] λ1486 could be used in the same way. The redshift 1.96 QSO 0353-383 has long been known to have N III] and N IV] lines that are far stronger relative to Lyα or …

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Radial Velocity Survey Of Members And Candidate Members Of The Tw Hydrae Association, Guillermo Torres, Eike W. Guenther, Laurence A. Marschall, Ralph Neuhauser, David W. Latham, Robert P. Stefanik Feb 2003

Radial Velocity Survey Of Members And Candidate Members Of The Tw Hydrae Association, Guillermo Torres, Eike W. Guenther, Laurence A. Marschall, Ralph Neuhauser, David W. Latham, Robert P. Stefanik

Physics and Astronomy Faculty Publications

We report spectroscopic observations of stars belonging to the young nearby group known as the TW Hydrae association, as well as of a number of potential members of the association identified in kinematic and X-ray surveys. Multiple radial velocity measurements were obtained for each object, several of which turn out to be multiple systems. Orbital solutions are presented for three double-lined binaries, one singlelined binary, and a double-lined triple system, all with short periods. Effective temperatures and projected rotational velocities are presented for each visible object. None of the candidate members of the association in our sample are confirmed as …

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The Mass Of Quasar Broad Emission Line Regions, J. A. Baldwin, Gary J. Ferland, K. T. Korista, F. Hamann, M. Dietrich Jan 2003

The Mass Of Quasar Broad Emission Line Regions, J. A. Baldwin, Gary J. Ferland, K. T. Korista, F. Hamann, M. Dietrich

Physics and Astronomy Faculty Publications

We show that the mass of ionized gas in the broad-line regions (BLRs) of luminous quasars is at least several hundred M☉, and probably of the order of 103-104 Msolar. BLR mass estimates in several existing textbooks suggest lower values but pertain to much less luminous Seyfert galaxies or include only a small fraction of the ionized/emitting volume of the BLR. The previous estimates also fail to include the large amounts of BLR gas that emit at low efficiency (in a given line) but that must be present based on reverberation and other …

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Temperature Variations From Hubble Space Telescope Spectroscopy Of The Orion Nebula, R. H. Rubin, P. G. Martin, R. J. Dufour, Gary J. Ferland, K. P. M. Blagrave, X.-W. Liu, J. F. Nguyen, J. A. Baldwin Jan 2003

Temperature Variations From Hubble Space Telescope Spectroscopy Of The Orion Nebula, R. H. Rubin, P. G. Martin, R. J. Dufour, Gary J. Ferland, K. P. M. Blagrave, X.-W. Liu, J. F. Nguyen, J. A. Baldwin

Physics and Astronomy Faculty Publications

We present Hubble Space Telescope (HST)/STIS long-slit spectroscopy of NGC 1976. Our goal is to measure the intrinsic line ratio [O III] 4364/5008 and thereby evaluate the electron temperature (Te) and the fractional mean-square Te variation (t2A)across the nebula. We also measure the intrinsic line ratio [N II] 5756/6585 in order to estimate Te and t2A in the N+region. The interpretation of the [N II] data is not as clear cut as the [O III] data because of a higher sensitivity to knowledge …

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Properties Of High-Latitude Cme-Driven Disturbances During Ulysses Second Northern Polar Passage, Daniel B. Reisenfeld, J. T. Gosling, R. J. Forsyth, P. Riley, O. C. St. Cyr Jan 2003

Properties Of High-Latitude Cme-Driven Disturbances During Ulysses Second Northern Polar Passage, Daniel B. Reisenfeld, J. T. Gosling, R. J. Forsyth, P. Riley, O. C. St. Cyr

Physics and Astronomy Faculty Publications

Ulysses observed five coronal mass ejections (CMEs) and their associated disturbances while the spacecraft was immersed in the polar coronal hole (CH) flow above 70° N in late 2001. Of these CMEs, two were very fast (>850 km s−1) driving strong shocks in the wind ahead, and two others were over-expanding. The two fast CMEs were observed leaving the Sun by LASCO/SOHO, and were observed in the ecliptic by Genesis and ACE. These were large events, spanning at least from the northern heliospheric pole to the ecliptic. One-dimensional hydrodynamic simulations indicate that these could be described as …

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Inner-Shell Photoexcitation Of Fe Xv And Fe Xvi, R. Kisielius, A. Hibbert, Gary J. Ferland, M. E. Foord, S. J. Rose, P. A. M. Vanhoof, F. P. Keenan Jan 2003

Inner-Shell Photoexcitation Of Fe Xv And Fe Xvi, R. Kisielius, A. Hibbert, Gary J. Ferland, M. E. Foord, S. J. Rose, P. A. M. Vanhoof, F. P. Keenan

Physics and Astronomy Faculty Publications

The configuration-interaction method as implemented in the computer code CIV3 is used to determine energy levels, electric dipole radiative transition wavelengths, oscillator strengths and transition probabilities for inner-shell excitation of transitions in Fe XV and Fe XVI. Specifically, transitions are considered of the type 1s22s22p63s2–1s22s22p53l3l′3l′′ (l, l′ and l′′= s, p or d) in Fe XV and 1s22s22p63s–1s22s22p53l3l′ (l …

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