scholarly journals A Photometric and Spectroscopic Comparison of the Cataclysmic Variables on the 2 Sides of the Period Gap and at a Specific Orbital Period

1987 ◽  
Vol 93 ◽  
pp. 69-73
Author(s):  
P. Szkody
Keyword(s):  
Orbital Period ◽  
Cataclysmic Variables ◽  
Detailed Comparison ◽  
High Excitation ◽  
Accretion Rates ◽  
The Mean ◽  
Line Strengths

AbstractNew and previously existing photometric colors and spectroscopic H and He line strengths are used to compare CV disk systems below the period gap (P=80–130 min) with those directly above (P=190–240 min). Significant differences are found in the mean U-B,V-J colors and in the Hβ equivalent widths on the 2 sides of the gap. A detailed comparison from UV-IR of 3 high inclination novalike systems with periods near 3.3 hr (PG1012−029, PG1030+590 and V1315 Aql) shows similar continuum distributions (and implied mass accretion rates) but large differences in high excitation lines (HeII1640,4686;CIV1550).

scholarly journals Superoutburst of a New Sub-Period-Minimum Dwarf Nova CSS130418 in Hercules

2015 ◽  
Vol 2 (1) ◽  
pp. 165-169 ◽  
Author(s):  
D. Chochol ◽  
S. Shugarov ◽  
N. Katysheva ◽  
I. Volkov ◽  
A. Zharova ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Stellar Evolution ◽  
Orbital Period ◽  
Late Stage ◽  
Cataclysmic Variables ◽  
Light Curves ◽  
Dwarf Nova ◽  
The Mean ◽  
Normal Hydrogen

Multicolour photometry of a new dwarf nova CSS130418 in Hercules, which underwent superoutburst on April 18, 2013, allow to classified it as a WZ Sge-type dwarf nova. The phase light curves for different stages of superoutburst are presented. The early superhumps were used to determine the orbital period P<sub>orb</sub> = 64.84(1) minutes, which is shorter than the period minimum ~78 minutes for normal hydrogen-rich cataclysmic variables. We found the mean period of ordinary superhumps P<sub>sh</sub> = 65.559(1) minutes. The quiescent spectrum is rich in helium, showing double peaked emission<br />lines of H I and He I from accretion disk, so the dwarf nova is in a late stage of stellar evolution.

scholarly journals White Dwarf Masses and Accretion Rates of Recurrent Novae: an X-ray Perspective

2011 ◽  
Vol 7 (S281) ◽  
pp. 186-189
Author(s):  
Koji Mukai ◽  
Jennifer L. Sokoloski ◽  
Thomas Nelson ◽  
Gerardo J. M. Luna
Keyword(s):  
White Dwarf ◽  
Cataclysmic Variables ◽  
The Other ◽  
X Ray ◽  
Other Hand ◽  
Accretion Rates

AbstractWe present recent results of quiescent X-ray observations of recurrent novae (RNe) and related objects. Several RNe are luminous hard X-ray sources in quiescence, consistent with accretion onto a near Chandrasekhar mass white dwarf. Detection of similar hard X-ray emissions in old novae and other cataclysmic variables may lead to identification of additional RNe candidates. On the other hand, other RNe are found to be comparatively hard X-ray faint. We present several scenarios that may explain this dichotomy, which should be explored further.

Extraction Techniques and Analysis of Turbulence Quantities From In-Cylinder Velocity Data

1989 ◽  
Vol 111 (3) ◽  
pp. 466-478 ◽  
Author(s):  
A. E. Catania ◽  
A. Mittica
Keyword(s):  
Direct Injection ◽  
Detailed Comparison ◽  
Ensemble Average ◽  
Small Scale ◽  
Velocity Data ◽  
Mean Flow ◽  
Reciprocating Engine ◽  
Reduction Methods ◽  
The Mean ◽  
Correlation And Spectral Analysis

In addition to the frequently used statistical ensemble-average, non-Reynolds filtering operators have long been proposed for nonstationary turbulent quantities. Several techniques for the reduction of velocity data acquired in the cylinder of internal combustion reciprocating engines have been developed by various researchers in order to separate the “mean flow” from the “fluctuating motion,” cycle by cycle, and to analyze small-scale engine turbulence by statistical methods. Therefore a thorough examination of these techniques and a detailed comparison between them would seem to be a preliminary step in attempting a general study of unconventional averaging procedures for reciprocating engine flow application. To that end, in the present work, five different cycle-resolved data reduction methods and the conventional ensemble-average were applied to the same in-cylinder velocity data, so as to review and compare them. One of the methods was developed by the authors. The data were acquired in the cylinder of a direct-injection automotive diesel engine, during induction and compression strokes, using an advanced hot-wire anemometry technique. Correlation and spectral analysis of the engine turbulence, as determined from the data with the different procedures, were also performed.

scholarly journals Ultraviolet Observations of Cataclysmic Variables

1987 ◽  
Vol 93 ◽  
pp. 205-205 ◽  
Author(s):  
F. Verbunt
Keyword(s):  
Orbital Period ◽  
Cataclysmic Variables ◽  
Type Systems ◽  
Terminal Velocity ◽  
Dwarf Novae ◽  
Preliminary Results ◽  
System Type ◽  
International Ultraviolet Explorer ◽  
Flux Level ◽  
Ultraviolet Observations

AbstractThe preliminary results of the analysis of more than 1000 spectra of cataclysmic variables in the archive of the International Ultraviolet Explorer were presented at the meeting. To characterize the slope of the spectra I use F = log(f1460Å/f2880Å). For most spectra F lies between 0.2 and 0.7. No correlation of F with orbital period, inclination, system type or (for dwarf novae) length of the interoutburst interval are found, apart from somewhat lower values of F for DQ Her type systems. Out of 16 dwarf novae for which spectra both at outburst maximum and minimum are available 11 show no large difference in F between maximum and minimum, and in 5 F declines with the flux level. Out of 6 dwarf novae 5 show very red spectra during the rise to maximum, and 1 shows slopes during rise similar to those during decline.In the ultraviolet resonance lines, due to a wind from the disc, no correlation is found between inclination and terminal velocity.

scholarly journals CVs Around the Minimum Orbital Period

2015 ◽  
Vol 2 (1) ◽  
pp. 41-45
Author(s):  
S. Zharikov ◽  
G. Tovmassian
Keyword(s):  
Accretion Disk ◽  
Accretion Disks ◽  
Orbital Period ◽  
Cataclysmic Variables ◽  
Outer Edge ◽  
Light Curves ◽  
Mass Ratio ◽  
Period Limit ◽  
Bounce Back ◽  
The Continuum

We discussed features of Cataclysmic Variables at the period minimum. In general, most of them must be WZ Sge-type objects. Main characteristics of the prototype star (WZ Sge) are discussed. A part of WZ Sge-type objects has evolved past the period limit and formed the bounce back systems. We also explore conditions and structure of accretion disks in such systems. We show that the accretion disk in a system with extreme mass ratio grows in size reaching a 2:1 resonance radius and are relatively cool. They also become largely optically thin in the continuum, contributing to the total flux less than the stellar components of the system. In contrast, the viscosity and the temperature in spiral arms formed at the outer edge of the disk are higher and their contribution in continuum plays an increasingly important role. We model such disks and generate light curves which successfully simulate the observed double-humped light curves in the quiescence.

Angular Momentum Losses and the Orbital Period Distribution of Cataclysmic Variables below the Period Gap: Effects of Circumbinary Disks

2005 ◽  
Vol 635 (2) ◽  
pp. 1263-1280 ◽  
Author(s):  
Bart Willems ◽  
Ulrich Kolb ◽  
Eric L. Sandquist ◽  
Ronald E. Taam ◽  
Guillaume Dubus
Keyword(s):  
Angular Momentum ◽  
Orbital Period ◽  
Cataclysmic Variables ◽  
Period Distribution ◽  
Gap Effects

scholarly journals The Characteristics of Magnetic CVs in the Period Gap

2004 ◽  
Vol 190 ◽  
pp. 15-21 ◽  
Author(s):  
Gaghik Tovmassian ◽  
Sergey Zharikov ◽  
Ronald Mennickent ◽  
Jochen Greiner
Keyword(s):  
Mass Transfer ◽  
Orbital Period ◽  
Accretion Rate ◽  
Cataclysmic Variables ◽  
Magnetic Systems ◽  
Transfer Rates ◽  
Significant Difference ◽  
Magnetic Cataclysmic Variables

AbstractWe have observed several magnetic cataclysmic variables located in the range between 2 and 3 hours, known as the period gap. This work was prompted by the recent discovery of RXJ1554.2+2721. It has 2.54 hours orbital period and shows almost pure cyclotron continuum in a low luminosity state, similar to HS1023+3900, HS0922+1333 and RBS206. These are low accretion rate polars (LARPs) known to have mass transfer rates of order of a few 10-13M⊙/year. The aim of the study was to find out, if magnetic systems filling the period gap are in any way different from their counterparts outside that range of periods. The only significant difference we encounter is a much higher number of asynchronous magnetic systems towards longer periods than below the gap.

scholarly journals X-ray binaries with neutron stars at different accretion stages

2018 ◽  
Vol 14 (S346) ◽  
pp. 219-227
Author(s):  
Konstantin A. Postnov ◽  
Alexander G. Kuranov ◽  
Lev R. Yungelson
Keyword(s):  
Magnetic Fields ◽  
Neutron Stars ◽  
Orbital Period ◽  
Population Synthesis ◽  
Circular Orbits ◽  
X Ray ◽  
Accretion Rates ◽  
Supercritical Accretion ◽  
Binary Evolution ◽  
X Ray Binaries

Abstract. Different accretion regimes onto magnetized NSs in HMXBs are considered: wind-fed supersonic (Bondi) regime at high accretion rates <math/> g s-1, subsonic settling regime at lower <math/> and supercritical disc accretion during Roche lobe overflow. In wind-fed stage, NSs in HMXBs reach equilibrium spin periods P* proportional to binary orbital period Pb. At supercritical accretion stage, the system may appear as a pulsating ULX. Population synthesis of Galactic HMXBs using standard assumptions on the binary evolution and NS formation is presented. Comparison of the model P* – Pb (the Corbet diagram), P* – Lx and Pb – Lx distributions with those for the observed HMXBs (including Be X-ray binaries) and pulsating ULXs suggests the importance of the reduction of P* in non-circular orbits, explaining the location of Be X-ray binaries in the model Corbet diagram, and the universal parameters of pulsating ULXs depending only on the NS magnetic fields.

scholarly journals PTF1 J085713+331843, a new post-common-envelope binary in the orbital period gap of cataclysmic variables

2017 ◽  
Vol 468 (3) ◽  
pp. 3109-3122 ◽  
Author(s):  
J. van Roestel ◽  
P. J. Groot ◽  
D. Levitan ◽  
T. A. Prince ◽  
S. Bloemen ◽  
...  
Keyword(s):  
Orbital Period ◽  
Cataclysmic Variables ◽  
Common Envelope

scholarly journals The Effective Temperature Distribution Function of Cataclysmic Variable White Dwarfs

1987 ◽  
Vol 93 ◽  
pp. 47-51
Author(s):  
E.M. Sion
Keyword(s):  
Distribution Function ◽  
Temperature Distribution ◽  
Orbital Period ◽  
White Dwarf ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Cataclysmic Variable ◽  
Term Evolution ◽  
Effective Temperatures

AbstractWith the recent detection of direct white dwarf photospheric radiation from certain cataclysmic variables in quiescent (low accretion) states, important implications and clues about the nature and long-term evolution of cataclysmic variables can emerge from an analysis of their physical properties. Detection of the underlying white dwarfs has led to a preliminary empirical CV white dwarf temperature distribution function and, in a few cases, the first detailed look at a freshly accreted while dwarf photosphere. The effective temperatures of CV white dwarfs plotted versus orbital period for each type of CV appears to reveal a tendency for the cooler white dwarf primaries to reside in the shorter period systems. Possible implications are briefly discussed.

Sign in / Sign up

Export Citation Format

Share Document