Physical Sciences and Mathematics Commons^™

The Cataclysmic Variable Cw 1045+525: A Secondary-Dominated Dwarf Nova?, C. Tappert, J. R. Thorstensen, W. H. Fenton, N. Bennert

Dartmouth Scholarship

We present spectroscopic and photometric observations of the cataclysmic variable CW 1045+525. Both the optical spectrum and the photometric lightcurve show a strong contribution of a K5V–M0V secondary. We derive an orbital period Porb = 0.271278(1) d by measuring the radial velocities of the absorption lines of the secondary. The period and spectral type of the secondary suggest a distance of 350–700 pc. There is evidence for additional sources of line- and continuum emission, but no direct evidence of an accretion disc. We discuss several scenarios for the nature of CW 1045+525 on the basis of our results, finding a …

A Newly-Discovered Cataclysmic Binary Near The Rosat Galactic Plane Source Rx J1910.8+2856, J R. Thorstensen, F Haberl

Dartmouth Scholarship

We report the discovery of a new cataclysmic binary star from the ROSAT Galactic Plane Survey. The star has V >∼ 18.5atminimumlightandwehavemeasureditasbrightasV = 15.7. Spectroscopy shows broad hydrogen and helium emission lines; HeII λ4686 is not detected. Hα radial velocities yield an orbital period of 0.1429 ± 0.0004 d (3.430 ± 0.010 h). Time- series photometry covering one orbital cycle near maximum light shows irregular variability, but no evidence of an eclipse. ThesystemappearstobeanewdwarfnovaoftheUGemorZ Cam type, and is unlikely to be a magnetic system. Its period is unusually short for a U Gem star.

Curiously, the new cataclysmic binary is 83′′ …

A Photometric And Spectroscopic Study Of The Cataclysmic Variable Sx Leonis Minoris In Quiescence And Superoutburst, R. Mark Wagner, John R. Thorstensen, R. K. Honeycutt, S. B. Howell

Dartmouth Scholarship

We present CCD imaging, CCD photometry on long and short timescales, and time-resolved spectroscopy of SX LMi, a new SU Ursae Majoris type dwarf nova. The quiescent optical spectrum shows broad double-peaked Balmer, He I, and He II emission lines, similar to other quiescent dwarf novae. Absorption lines from a late-type secondary are not detected. Time-resolved spectra obtained in quiescence reveal radial velocity variations of the Balmer emission lines on a period of 0.06717 ± 0.00011 days, or 96.72 ± 0.16 minutes, with only a slight possibility of a daily cycle-count error. Optical photometry obtained between 1987 and 1991 shows …

The Orbital Period Of Bk Lyncis (Pg 0917 + 342), F. A. Ringwald, J. R. Thorstensen, R. K. Honeycutt, J. W. Robertson

Dartmouth Scholarship

Long-term light curves of the cataclysmic variable BK Lyn = PG 0917 + 342 from the Indiana Automated CCD photometric telescope (‘RoboScope’) and the Harvard College Observatory plate archive reveal no dwarf nova outbursts. Two radial velocity studies show its orbital period to be 107.97 ;1 0.07 min, confirming that it does have an orbital period shorter than the period gap for cataclysmic variables. Whether this is the first nova-like variable below the period gap or a dwarf nova with rare outbursts resembling WZ Sge is still unclear, however.

The Orbital Period Of The Pre-Cataclysmic Binary Re 2013+400 And A Study Of The Atmosphere Of The Dao White Dwarf Primary, M. A. Barstow, M. R. Burleigh, T. A. Fleming, J. B. Holberg, D. Koester, M. C. Marsh, S. R. Rosen, R. G.M. Rutten, S. Sakai, R. W. Tweedy, G. Wegner

Dartmouth Scholarship

Several pre-cataclysmic binaries, comprising a hot white dwarf with a red dwarf companion, have been discovered as a result of the optical identification of EUV sources from the ROSAT all-sky survey. The optical spectra have the steep blue continuum and Balmer absorption typical of a hot white dwarf, but there are bright, narrow emission lines of H I (and sometimes He I and Ca II) superimposed. An intense campaign of follow-up observations has been devoted to these binary systems. So far, only RE 2013+400 has exhibited any measurable changes in the radial velocities of the emission components, from which it …

Orbital Studies Of The Cataclysmic Variables Cz Orionis, V1193 Orionis And Bz Ursae Majoris, F. A. Ringwald, J. R. Thorstensen, R. M. Hamwey

Dartmouth Scholarship

Time-resolved spectroscopy reveals the orbital periods of three cataclysmic variables. CZ Ori has an orbital period of 0.2189 d. This is within 3 per cent of a prediction relating orbital period and dwarf nova outburst decline time. We find the M2.5 ± 1.0 secondary, and infer an absolute magnitude for CZ Ori in RKc of 8.5 ± 1.0 and a distance of 260 ± 110 pc. V1193 Ori, also called Hamuy's Blue Variable, has an orbital period of 0.165 d. In 1988, Ha emission line profile variations suggested red star illumination. In 1989, this line's red wing flared at orbital …

A Far-Ultraviolet Atlas Of Symbiotic Stars Observed With Iue. I. The Swp Range, S. R. Meier, Menas Kafatos, R. P. Fahey, A. G. Michalitsianos

Mathematics, Physics, and Computer Science Faculty Articles and Research

This atlas contains sample spectra from the far-ultraviolet observations of32 symbiotic stars obtained with the lnternational Ultraviolet Explorer (IUE) satellite. In all, 394 low-resolution spectra from the short-wavelength pnmary (SWP) camera covering the range 1200-2000 A have been extracted from the IUE archive, calibrated, and measured. Absolute line fluxes and wavelengths for the prominent emission lines have been tabulated. Tables of both the general properties of these symbiotics and of features specific to the spectrum of each are included. The spectra shown are representative of the different classes of symbiotic stars that are currently in the IUE archive. These include …

The 14.8-H Orbital Period Of Gx339-4, P. J. Callanan, P. A. Charles, W. B. Honey, J. R. Thorstensen

Dartmouth Scholarship

We present the results of photometric observations of the black hole candidate GX339-4, obtained while the system was in an 'off' state. We show that a 14.8-h modulation was present, and provide evidence for a similar periodicity in the 'high' state from a reanalysis of previously published photometry and spectroscopy. The presence of the same period in both states implies that it is likely to be the orbital period of the system. The spectroscopy analysis provides evidence for an apparent change in the systemic velocity of the system. The amplitude of the observed radial velocity variations, however, permits only crude …

Gamma-Ray Emission From Cygnus-X-1 - Emission Mechanisms And Implications For The Standard Model, A Owens, Mark L. Mcconnell

Physics & Astronomy

No abstract provided.

Gamma-Ray Observations Of Cygnus X-1 And Cygnus X-3 Using A Coded-Aperture Telescope, Mark L. Mcconnell, D J. Forrest, A Owens, P. P. Dunphy, W T. Vestrand, E. L. Chupp

Physics & Astronomy

A balloon-borne coded-aperture telescope, measuring gamma-ray photons in the 160 keV to 9.3 MeV range, was used to observe the Cygnus region of the sky on October 1 and 2, 1984. In the 2-9.3-MeV band, evidence is found for a hard spectral component with a mean flux level at the top of the atmosphere of 7.4 + or - 2.5 x 10 to the -7th photons/sq cm per s per keV, inconsistent with the predictions of the inverse Compton models normally used to describe the X-ray emission. Both Cyg X-1 and Cyg X-3 could be observed simultaneously with the telescope. …