scholarly journals Catching VY Sculptoris in a low state

2018 ◽  
Vol 617 ◽  
pp. A16 ◽  
Author(s):  
L. Schmidtobreick ◽  
E. Mason ◽  
S. B. Howell ◽  
K. S. Long ◽  
A. F. Pala ◽  
...  
Keyword(s):  
White Dwarf ◽  
Cataclysmic Variables ◽  
Emission Lines ◽  
High Mass ◽  
Absorption Bands ◽  
Radial Velocity Curve ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Secondary Star ◽  
Narrow Emission

Context. In the context of a large campaign to determine the system parameters of high mass transfer cataclysmic variables, we found VY Scl in a low state in 2008. Aims. Making use of this low state, we study the stellar components of the binary with little influence of the normally dominating accretion disc. Methods. Time-resolved spectroscopy and photometry of VY Scl taken during the low state are presented. We analysed the lightcurve and radial velocity curve and use time-resolved spectroscopy to calculate Doppler maps of the dominant emission lines. Results. The spectra show narrow emission lines of Hα, Hβ, He I, Na I D, and Fe II, as well as faint TiO absorption bands that trace the motion of the irradiated secondary star, and Hα and He I emission line wings that trace the motion of the white dwarf. From these radial velocities, we find an orbital period of 3.84 h, and put constraints on binary parameters such as the mass ratio M2/M1 of 0.43 and the inclination of 15°. With a secondary’s mass between 0.3 and 0.35 M⊙, we derive the mass for the white dwarf as M1 = 0.6–1.1 M⊙.

scholarly journals Masses and Magnetic Fields of White Dwarfs in Cataclysmic Variables

1989 ◽  
Vol 114 ◽  
pp. 337-340
Author(s):  
J.P. Lasota ◽  
J.M. Hameury ◽  
A.R. King
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Magnetic Fields ◽  
White Dwarf ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Strong Support ◽  
Drastic Reduction ◽  
Secondary Star ◽  
Maximum Magnetic Field

We show that the existence of the AM Her period spike implies (i) a unique white dwarf mass ≃ 0.6 − 0.7M⊙ for most magnetic CV’s (ii) nova explosions remove exactly the accreted mass from magnetic white dwarfs, and (iii) the maximum magnetic field for most CV’s is ≤ 4 × 107 G. The existence of the spike is very strong support for the idea that the period gap results from a drastic reduction of angular momentum losses when the secondary star becomes fully convective.

scholarly journals Physical Parameters of Inhomogeneities in Wolf-Rayet Winds

1991 ◽  
Vol 143 ◽  
pp. 147-154
Author(s):  
C. Robert ◽  
A. F. J. Moffat ◽  
W. Seggewiss
Keyword(s):  
Unknown Origin ◽  
Emission Lines ◽  
Physical Parameters ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Broad Emission

Time-resolved spectroscopy has revealed small, systematically varying features superimposed on the broad emission lines of WR stars. We believe that these structures are due to inhomogeneities of emitting wind material propagating with the general wind. Here we suggest a common, but still unknown, origin for the intrinsic variations observed in WR stars.

Elimination of the Intraion Spectral Interference between the 5D0 and 5D1 Emission Bands of Eu3+ in EuP5O14 by Using the Time-Resolved Spectroscopy Technique

1985 ◽  
Vol 39 (3) ◽  
pp. 546-549
Author(s):  
I. Laulicht ◽  
I. Peer
Keyword(s):  
Rare Earth ◽  
Spectral Interference ◽  
Rare Earth Ions ◽  
Emission Lines ◽  
Spectroscopy Technique ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Fluorescence Studies

The advantage of the time-resolved spectroscopy technique for reducing the spectral interference between the 5D0 and 5D1 emission lines of Eu3+ ions in EuP5O14 crystals is explained in detail. It is shown that this technique may be very helpful for rare earth ions fluorescence studies in general whenever a group of two or more neighboring levels emit photons to the same lower levels but their lifetimes are different. The wavelengths of many new lines of the 5D0 → 7Fj (j = 3–6) emission bands of Eu3+ in EuP5O14 are measured by this technique.

scholarly journals Mass Measurement of Accreting Magnetic White Dwarfs with Hard X-Ray Spectroscopy

1998 ◽  
Vol 188 ◽  
pp. 97-100
Author(s):  
M. Ishida ◽  
R. Fujimoto
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Mass Measurement ◽  
Cataclysmic Variables ◽  
Magnetic Pole ◽  
X Ray ◽  
Secondary Star ◽  
Magnetic Cataclysmic Variables ◽  
Image Position ◽  
The Magnetic Field

Accreting magnetic white dwarfs are usually found as component stars in Magnetic Cataclysmic Variables (MCVs), in which a white dwarf with B = 105-8 G accepts mass from a late type (secondary) star via Roche Lobe overflow. Matter from the secondary is funneled by the magnetic field and concentrates on the magnetic pole(s) of the white dwarf. Since the accretion flow becomes highly supersonic, a standing shock wave is formed close to the white dwarf. The temperature of the plasma at the shock front reflects the gravitational potential and can be denoted as a function of the mass (M) and the radius (R) of the white dwarf as: Note here that the height of the shock is expected to be within 10% of the white dwarf radius, and hence neglected here.

scholarly journals HST Eclipse Studies of Magnetic CVs: Resolving the UV Hot Spot and Accretion Stream

1997 ◽  
Vol 163 ◽  
pp. 396-402
Author(s):  
H.S. Stockman
Keyword(s):  
White Dwarf ◽  
Hot Spot ◽  
Cataclysmic Variables ◽  
Average Density ◽  
Two Phase ◽  
Time Resolved ◽  
Physical Size ◽  
Uv Emission ◽  
Accretion Shock ◽  
Absorption Features

AbstractTime-resolved photometry and spectroscopy of cataclysmic variables (CV) are powerful tools for clarifying the physical size, placement, and conditions of emission regions in these compact systems. We present HST time resolved UV spectroscopic data for one self-eclipsing mCV system, ST LMi, and two secondary eclipsing systems, DP Leo and UZ For. These observations clearly show the relative contributions of three emission components: the white dwarf, a hotter region surrounding the accretion shock, and the photoionized accretion stream. UZ For was observed in an unusually active state by both HST and EUVE. These data provide strong evidence that the accretion stream is “clumpy”, with overdensities 100–1000 times the average density. Using photoionization codes such as XSTAR and CLOUDY, we find that steady, supersonic, and homogenous flow in the UZ For accretion stream is unstable to compression heating. As a consequence, we propose a two-phase model for the stream and obtain density enhancements comparable to those deduced from the strengths of the UV emission lines and EUVE absorption features. Similar behavior may be expected from active, asynchronous magnetic CVs with coupling radii greater than several white dwarf radii.

scholarly journals Time-Resolved Spectroscopy and Doppler Tomography of UX UMa

2004 ◽  
Vol 194 ◽  
pp. 270-270 ◽  
Author(s):  
V. F. Suleimanov ◽  
V. V. Neustroev ◽  
N. V. Borisov ◽  
I. S. Fioktistova
Keyword(s):  
Radial Velocity ◽  
Emission Line ◽  
Orbital Period ◽  
Velocity Curve ◽  
Cataclysmic Variable ◽  
Radial Velocity Curve ◽  
Doppler Tomography ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Medium Resolution

Medium resolution spectroscopy of nova-like cataclysmic variable UX UMA was performed using the 6-m telescope SAO RAS in April 1999. Obtained spectra cover the total orbital period including eclipse phases and allow us to reproduce the radial velocity curve. The radial-velocity variations of the Hβ emission line are found to have semi-amplitude of about 100 km/s.

scholarly journals 1RXS J232953.9+062814: A Possible Progenitor of AM CVn Stars

2004 ◽  
Vol 194 ◽  
pp. 109-110
Author(s):  
M. Uemura
Keyword(s):  
Mass Transfer ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
High Mass ◽  
Recurrence Time ◽  
Apparent Magnitude ◽  
Evolutionary Status ◽  
Transfer Rates ◽  
Secondary Star ◽  
Orbital Periods

AbstractWe revealed that the hydrogen-rich cataclysmic variable lRXS J232953.9+062814 is an SU UMa-type dwarf nova with a superbump period of 66.774±0.010 min. A photometric orbital period is determined to be 64.184± 0.003 min, which is below the period minimum. Although the standard evolutionary scenario of cataclysmic variables predicts lower mass-transfer rates in systems with shorter orbital periods, its short recurrence time of outbursts and bright apparent magnitude indicate that this object has a relatively high mass-transfer rate. With the analogous system V485 Cen, these objects establish the first subpopulation in hydrogen-rich cataclysmic variables below the period minimum. Concerning the evolutionary status of them, we propose that they are progenitors of AM CVn stars on evolutionary courses in which systems have an evolved secondary star with a hydrogen-exhausted core.

scholarly journals BC Cassiopeiae: First detection of IW Andromedae-type phenomenon among post-eruption novae

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Taichi Kato ◽  
Naoto Kojiguchi
Keyword(s):  
Mass Transfer ◽  
White Dwarf ◽  
Transfer Rate ◽  
White Dwarfs ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
High Mass ◽  
Average Mass ◽  
Classical Nova ◽  
Decline Rate

Abstract IW And-type dwarf novae are a recently recognized group of cataclysmic variables which are characterized by a sequence of brightening from a standstill-like phase with damping oscillations often followed by a deep dip. We found that the supposed classical nova BC Cas which erupted in 1929 experienced a state of an IW And-type dwarf nova in 2018, 89 yr after the eruption. This finding suggests that a high mass-transfer rate following the nova eruption is associated with the IW And-type phenomenon. The mass of the white dwarf inferred from the decline rate of the nova is considerably higher than the average mass of the white dwarfs in cataclysmic variables, and these massive white dwarfs may be responsible for the manifestation of the IW And-type phenomenon.

Sign in / Sign up

Export Citation Format

Share Document