scholarly journals Linking long-term planetaryN-body simulations with periodic orbits: application to white dwarf pollution

2016 ◽  
Vol 463 (4) ◽  
pp. 4108-4120 ◽  
Author(s):  
Kyriaki I. Antoniadou ◽  
Dimitri Veras
Keyword(s):  
Periodic Orbits ◽  
White Dwarf

scholarly journals Photometry of AM Her Stars – Line and Continuum Emission

1979 ◽  
Vol 53 ◽  
pp. 324-328
Author(s):  
Paula Szkody
Keyword(s):  
Emission Line ◽  
White Dwarf ◽  
Main Sequence ◽  
Close Binary ◽  
Line Spectrum ◽  
Continuum Emission ◽  
Late Type ◽  
Emission Line Spectrum ◽  
Orbital Periods

The 4 known AM Her stars or polars (AM Her, ANUMa, W Pup, and 2A0311-227) are characterized by large circular polarizations of 10-35%, (Tapia 1977a, b, Krzeminski and Serkowski 1977), an emission line spectrum with strong H and He lines (Crampton and Cowley 1977, Greenstein et al. 1977), complex photometric variations (Szkody 1978, Priedhorsky and Krzeminski 1978, Warner & Nather 1972), long term high and low states and short orbital periods (80-180 min.). Models of these systems envision a close binary containing a magnetic white dwarf primary (B ~ 108G) and late type main sequence secondary transferring material into an accretion funnel over one or both poles of the white dwarf (Stockman et al. 1977, Lamb & Masters 1979, Liebert et al. 1978).

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.

scholarly journals Analysis of Long-Term Single-Site Observations of the Pulsating DB White Dwarf GD 358

2002 ◽  
Vol 185 ◽  
pp. 382-383
Author(s):  
P.A. Bradley
Keyword(s):  
Fourier Transform ◽  
White Dwarf ◽  
Time Scale ◽  
Single Site ◽  
Difference Frequency ◽  
Data Sets ◽  
Period Range ◽  
Whole Earth

The pulsating DB white dwarf GD 358 was observed by the Whole Earth Telescope (WET) in 1990, 1994, and 2000. While these observing runs revealed a wealth of pulsation modes, they constitute only three “snapshots” of the behavior of this star. These “snapshots” show that GD 358 has a series of l = 1 modes present in the period range of 420 to 810 seconds, with numerous Fourier Transform peaks at the sums and differences of the l = 1 mode frequencies. In addition, the amplitudes of the l = 1 modes and the sum and difference frequency peaks (which I also call “combination peaks” in this paper) are different in each WET run. These data are not sufficient to determine the time scale of the amplitude changes and whether additional l = 1 modes might be present. For this, we need more frequent data sets, although not necessarily WET data.

The long-term optical activity of the propellers AE Aquarii and AR Scorpii

2020 ◽  
Vol 72 (2) ◽  
Author(s):  
Vojtěch Šimon
Keyword(s):  
Magnetic Field ◽  
Real Time ◽  
Optical Activity ◽  
White Dwarf ◽  
Transient Decrease ◽  
Mass Outflow ◽  
Orbital Modulation ◽  
The Magnetic Field

Abstract This analysis of the long-term optical activity of the propellers AE Aqr and AR Sco uses data from the Catalina Real-time Transient Survey, DASCH, and AAVSO. The site and character of the emissions from the phenomena caused by the magnetic field of the white dwarf (WD) vary from system to system. The histogram of intensities of the ensemble of flares of AE Aqr suggests that the long-term activity consists of a large variety of the peak magnitudes of the flares, with the probability of their detection gradually decreasing with increasing intensity. Any increase of activity only leads to an increase of the number of blobs of the transferring matter. We also detected a season with a transient decrease or even a cessation of the mass outflow from the donor to the lobe of the WD. The very strong orbital modulation of AR Sco is most stable in the phases of the extrema of brightness for about a century; its minor changes suggest that the trailing side of the synchrotron-emitting region is more unstable than the leading side.

scholarly journals LONG-TERM EVOLUTION OF DOUBLE WHITE DWARF BINARIES ACCRETING THROUGH DIRECT IMPACT

2015 ◽  
Vol 806 (1) ◽  
pp. 76 ◽  
Author(s):  
Kyle Kremer ◽  
Jeremy Sepinsky ◽  
Vassiliki Kalogera
Keyword(s):  
White Dwarf ◽  
Long Term Evolution ◽  
Direct Impact ◽  
Term Evolution

scholarly journals Swift J011511.0-725611: discovery of a rare Be star/white dwarf binary system in the SMC

2021 ◽  
Vol 508 (1) ◽  
pp. 781-788
Author(s):  
J A Kennea ◽  
M J Coe ◽  
P A Evans ◽  
L J Townsend ◽  
Z A Campbell ◽  
...  
Keyword(s):  
Neutron Star ◽  
Binary System ◽  
South African ◽  
White Dwarf ◽  
Compact Object ◽  
Type Ii ◽  
Large Telescope ◽  
X Ray ◽  
Be Star

ABSTRACT We report on the discovery of Swift J011511.0-725611, a rare Be X-ray binary system (BeXRB) with a white dwarf (WD) compact object, in the Small Magellanic Cloud (SMC) by S-CUBED, a weekly X-ray/UV survey of the SMC by the Neil Gehrels Swift Observatory. Observations show an approximately 3 month outburst from Swift J011511.0-725611, the first detected by S-CUBED since it began in 2016 June. Swift J011511.0-725611 shows supersoft X-ray emission, indicative of a WD compact object, which is further strengthened by the presence of an 0.871 keV edge, commonly attributed to O viii K-edge in the WD atmosphere. Spectroscopy by South African Large Telescope confirms the Be nature of the companion star, and long term light curve by OGLE finds both the signature of a circumstellar disc in the system at outburst time, and the presence of a 17.4 day periodicity, likely the orbital period of the system. Swift J011511.0-725611 is suggested to be undergoing a Type-II outburst, similar to the previously reported SMC Be white dwarf binary (BeWD), Swift J004427.3-734801. It is likely that the rarity of known BeWD is in part due to the difficulty in detecting such outbursts due to both their rarity, and their relative faintness compared to outbursts in Neutron Star BeXRBs.

scholarly journals Long-Term Photometric and Spectroscopic Behaviour of Symbiotic System AG Dra

2004 ◽  
Vol 194 ◽  
pp. 242-242
Author(s):  
R. Gális ◽  
L. Hric ◽  
K. Petrík
Keyword(s):  
Orbital Period ◽  
White Dwarf ◽  
Velocity Analysis ◽  
Symbiotic System ◽  
General Behaviour ◽  
Cool Component ◽  
Spectroscopic Behaviour ◽  
Thermonuclear Burning ◽  
Second Period

The general behaviour of AG DRA was studied in the context of the long-term photometry and radial velocity analysis.AG DRA is a symbiotic binary with quiescent and active stages; the latter may be explainable by increased thermonuclear burning of a white dwarf accreting from the wind of the cool component.In our previous studies a second period in addition to the orbital period of 549.7 days has been found for AG DRA. Such a period of about 350 days was indicated in our study using photometry (Friedjung et al. 1998, Petrík et al. 1998)as well as radial velocities (Gális et al. 1999 Friedjung et al. 2003).

Sign in / Sign up

Export Citation Format

Share Document