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Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
Coordinated Uv And X-Ray Spectroscopic Observations Of The O-Type Giant Ξ Per: The Connection Between X-Rays And Large-Scale Wind Structure, Derek Massa, Lidi Oskinova, Raman Prinja, Richard Ignace
Coordinated Uv And X-Ray Spectroscopic Observations Of The O-Type Giant Ξ Per: The Connection Between X-Rays And Large-Scale Wind Structure, Derek Massa, Lidi Oskinova, Raman Prinja, Richard Ignace
ETSU Faculty Works
We present new, contemporaneous Hubble Space Telescope STIS and XMM-Newton observations of the O7 III(n)((f)) star ξ Per. We supplement the new data with archival IUE spectra, to analyze the variability of the wind lines and X-ray flux of ξ Per. The variable wind of this star is known to have a 2.086-day periodicity. We use a simple, heuristic spot model that fits the low-velocity (near-surface) IUE wind line variability very well, to demonstrate that the low-velocity absorption in the new STIS spectra of N iv λ1718 and Si iv λ1402 vary with the same 2.086-day period. It …
Asymmetric Shapes Of Radio Recombination Lines From Ionized Stellar Winds, Richard Ignace
Asymmetric Shapes Of Radio Recombination Lines From Ionized Stellar Winds, Richard Ignace
ETSU Faculty Works
Recombination line profile shapes are derived for ionized spherical stellar winds at radio wavelengths. It is assumed that the wind is optically thick owing to free-free opacity. Emission lines of arbitrary optical depth are obtained assuming that the free-free photosphere forms in the outer, constant expansion portion of the wind. Previous works have derived analytic results for isothermal winds when the line and continuum source functions are equal. Here, semi-analytic results are derived for unequal source functions to reveal that line shapes can be asymmetric about line center. A parameter study is presented and applications discussed.
A Study Of Hα Line Profile Variations In Β Lyr, Richard Ignace, Sharon K. Gray, Macno A. Magno, Gary D. Henson, Derek Massa
A Study Of Hα Line Profile Variations In Β Lyr, Richard Ignace, Sharon K. Gray, Macno A. Magno, Gary D. Henson, Derek Massa
ETSU Faculty Works
We examine over 160 archival Hα spectra from the Ritter Observatory for the interacting binary β Lyr obtained between 1996 and 2000. The emission is characteristically double-peaked, but asymmetric, and with an absorption feature that is persistently blueshifted. Using a set of simplifying assumptions, phase varying emission line profiles are calculated for Hα formed entirely in a Keplerian disk, and separately for the line formed entirely from an off-center bipolar flow. However, a dynamic spectrum of the data indicates that the blueshifted feature is not always present, and the data are even suggestive of a drift of the …
A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Orionis Aa. Iii. Analysis Of Optical Photometric (Most) And Spectroscopic (Ground Based) Variations., Herbert Pablo, Noel Richardson, Anthony Moffat, Michael Corcoran, Tomer Shenar, Omar Benvenuto, Jim Fuller, Yaël Nazé, Jennifer Hoffman, Anatoly Miroshnichenko, Jesús Apellániz, Nancy Evans, Thomas Eversberg, Ken Gayley, Ted Gull, Kenji Hamaguchi, Wolf-Rainer Hamann, Huib Henrichs, Tabetha Hole, Richard Ignace, Rosina Iping, Jennifer Lauer, Maurice Leutenegger, Jamie Lomax, Joy Nichols, Lida Oskinova, Stan Owocki, Andy Pollock, Christopher Russell, Wayne Waldron, Christian Buil, Thierry Garrel, Keith Graham, Bernard Heathcote, Thierry Lemoult, Dong Li, Benjamin Mauclaire, Mike Potter, Jose Ribeiro, Jaymie Matthews, Chris Cameron, David Guenther, Rainer Kuschnig, Jason Rowe, Slavek Rucinski, Dimitar Sasselov, Werner Weiss
A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Orionis Aa. Iii. Analysis Of Optical Photometric (Most) And Spectroscopic (Ground Based) Variations., Herbert Pablo, Noel Richardson, Anthony Moffat, Michael Corcoran, Tomer Shenar, Omar Benvenuto, Jim Fuller, Yaël Nazé, Jennifer Hoffman, Anatoly Miroshnichenko, Jesús Apellániz, Nancy Evans, Thomas Eversberg, Ken Gayley, Ted Gull, Kenji Hamaguchi, Wolf-Rainer Hamann, Huib Henrichs, Tabetha Hole, Richard Ignace, Rosina Iping, Jennifer Lauer, Maurice Leutenegger, Jamie Lomax, Joy Nichols, Lida Oskinova, Stan Owocki, Andy Pollock, Christopher Russell, Wayne Waldron, Christian Buil, Thierry Garrel, Keith Graham, Bernard Heathcote, Thierry Lemoult, Dong Li, Benjamin Mauclaire, Mike Potter, Jose Ribeiro, Jaymie Matthews, Chris Cameron, David Guenther, Rainer Kuschnig, Jason Rowe, Slavek Rucinski, Dimitar Sasselov, Werner Weiss
ETSU Faculty Works
We report on both high-precision photometry from the Microvariability and Oscillations of Stars (MOST) space telescope and ground-based spectroscopy of the triple system δ Ori A, consisting of a binary O9.5II+early-B(Aa1 and Aa2) with P=5.7 days, and a more distant tertiary(O9 IV P 400 years). This data was collected in concert with X-ray spectroscopy from the Chandra X-ray Observatory. Thanks to continuous coverage for three weeks, the MOST light curve reveals clear eclipses between Aa1 and Aa2 for the first time in non-phased data. From the spectroscopy, we have a well-constrained radial velocity (RV)curve of Aa1. While we are unable …
A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Ori Aa: I. Overview Of The X-Ray Spectrum., Michael Corcoran, Joy Nichols, H. Pablo, Tomer Shenar, Andy Pollock, W. Waldron, A. Moffat, N. Richardson, C. Russell, K. Hamaguchi, D. Huenemoerder, L. Oskinova, W.-R. Hamann, Y. Nazé, Richard Ignace, Nancy Evans, Jamie Lomax, J. Hoffman, K. Gayley, S. Owocki, M. Leutenegger, T. Gull, K. Hole, J. Lauer, R. Iping
A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Ori Aa: I. Overview Of The X-Ray Spectrum., Michael Corcoran, Joy Nichols, H. Pablo, Tomer Shenar, Andy Pollock, W. Waldron, A. Moffat, N. Richardson, C. Russell, K. Hamaguchi, D. Huenemoerder, L. Oskinova, W.-R. Hamann, Y. Nazé, Richard Ignace, Nancy Evans, Jamie Lomax, J. Hoffman, K. Gayley, S. Owocki, M. Leutenegger, T. Gull, K. Hole, J. Lauer, R. Iping
ETSU Faculty Works
We present an overview of four deep phase-constrained Chandra HETGS X-ray observations of δ Ori A. Delta Ori A is actually a triple system that includes the nearest massive eclipsing spectroscopic binary, δ Ori Aa, the only such object that can be observed with little phase-smearing with the Chandra gratings. Since the fainter star, δ Ori Aa2, has a much lower X-ray luminosity than the brighter primary (δ Ori Aa1), δ Ori Aa provides a unique system with which to test the spatial distribution of the X-ray emitting gas around δ Ori Aa1 via occultation by the photosphere of, and …
Polarimetric Modeling Of Corotating Interaction Regions (Cirs) Threading Massive-Star Winds., Richard Ignace, Nicole St-Louis, Felix Proulx-Giraldeau
Polarimetric Modeling Of Corotating Interaction Regions (Cirs) Threading Massive-Star Winds., Richard Ignace, Nicole St-Louis, Felix Proulx-Giraldeau
ETSU Faculty Works
Massive star winds are complex radiation-hydrodynamic (sometimes magnetohydrodynamic) outflows that are propelled by their enormously strong luminosities. The winds are often found to be structured and variable, but can also display periodic or quasi-periodic behavior in a variety of wind diagnostics. The regular variations observed in putatively single stars, especially in UV wind lines, have often been attributed to corotating interaction regions (CIRs) like those seen in the solar wind. We present light curves for variable polarization from winds with CIR structures. We develop a model for a time-independent CIR based on a kinematical description. Assuming optically thin electron scattering, …
New Multiwavelength Observations Of The Of?P Star Cpd -28◦ 2561., S. Hubrig, M. Schöller, A. Kholtygin, H. Tsumura, A. Hoshino, S. Kitamoto, L. Oskinova, Richard Ignace, H. Todt, I. Ilyin
New Multiwavelength Observations Of The Of?P Star Cpd -28◦ 2561., S. Hubrig, M. Schöller, A. Kholtygin, H. Tsumura, A. Hoshino, S. Kitamoto, L. Oskinova, Richard Ignace, H. Todt, I. Ilyin
ETSU Faculty Works
A rather strong mean longitudinal magnetic field of the order of a few hundred gauss was detected a few years ago in the Of?p star CPD −28° 2561 using FORS2 (FOcal Reducer low dispersion Spectrograph 2) low-resolution spectropolarimetric observations. In this work, we present additional low-resolution spectropolarimetric observations obtained during several weeks in 2013 December using FORS 2 mounted at the 8-m Antu telescope of the Very Large Telescope (VLT). These observations cover a little less than half of the stellar rotation period of 73.41 d mentioned in the literature. The behaviour of the mean longitudinal magnetic field is consistent …
A Report On The X-Ray Properties Of The Τ Sco Class Of Stars., Richard Ignace, L. Oskinova, D. Massa
A Report On The X-Ray Properties Of The Τ Sco Class Of Stars., Richard Ignace, L. Oskinova, D. Massa
ETSU Faculty Works
An increasing number of OB stars have been shown to possess magnetic fields. Although the sample remains small, it is surprising that the magnetic and X-ray properties of these stars appear to be far less correlated than expected. This contradicts model predictions, which generally indicate that the X-rays from magnetic stars are harder and more luminous than their non-magnetic counterparts. Instead, the X-ray properties of magnetic OB stars are quite diverse. τ Sco is one example where the expectations are better met. This bright main-sequence, early B star has been studied extensively in a variety of wavebands. It has a …