scholarly journals Visual Light from the Eclipsing Supersoft X-Ray Source Cal 87

1996 ◽  
Vol 158 ◽  
pp. 425-426 ◽  
Author(s):  
S. Schandl ◽  
E. Meyer-Hofmeister ◽  
F. Meyer
Keyword(s):  
Light Curve ◽  
Accretion Disk ◽  
White Dwarf ◽  
Hot Spot ◽  
Roche Lobe ◽  
X Ray ◽  
Secondary Star ◽  
The Asymmetry ◽  
The Absolute ◽  
Visual Light

We calculate the visual light curve of CAL 87 based on the assumption that an accreting, steadily burning white dwarf irradiates the accretion disk and the secondary star, as suggested by van den Heuvel et al. (1992). The shape of the eclipse light curve and the absolute luminosities put strong constraints on the contributions of the various elements in the system. We find a reasonable fit is obtained with the following sources of visual light: a Roche lobe filling secondary star where the energy from irradiation is spread out over the surface, and an accretion disk with an optically thick, cold, clumpy spray which is caused by the massive accretion stream impinging on the disk (hot spot). This spray moving around the disk and illuminated by the white dwarf is found to be the brightest source of visual light in the binary and can account for the asymmetry in the light curve.

scholarly journals Optical Light Curve of Nova KT Eridani

2012 ◽  
Vol 8 (S290) ◽  
pp. 191-192
Author(s):  
W. P. Chen ◽  
L. W. Hung ◽  
Fred Walter
Keyword(s):  
Light Curve ◽  
White Dwarf ◽  
Hot Spot ◽  
X Ray ◽  
Optical Emissions ◽  
Optical Light Curve ◽  
Recurrent Nova ◽  
Orbital Modulation ◽  
Type Giant

AbstractWe present the optical light curve of the very fast nova, KT Eridani, from its outburst in November 2009 to quiescence in 2012. Comparison of our data with the 24-hour monitoring by Swift on 2010 March 31 indicates a possible anticorrelation between the X-ray and optical emissions. A period of 57 d is found in the long-term optical light curve, which we interpret as the orbital modulation of the hot spot on the white dwarf disk accreting material from an early K-type giant. Our study lends support to the notation that KT Eri may be a recurrent nova.

scholarly journals Superoutbursts and Superhumps of SU UMa Stars

1988 ◽  
Vol 108 ◽  
pp. 238-239
Author(s):  
Yoji Osaki ◽  
Masahito Hirose
Keyword(s):  
Accretion Disk ◽  
Orbital Period ◽  
White Dwarf ◽  
Binary Systems ◽  
Roche Lobe ◽  
Light Curves ◽  
Close Binary ◽  
Dwarf Novae ◽  
Dwarf Nova ◽  
Close Binary Systems

SU UMa stars are one of subclasses of dwarf novae. Dwarf novae are semi-detached close binary systems in which a Roche-lobe filling red dwarf secondary loses matter and the white dwarf primary accretes it through the accretion disk. The main characteristics of SU UMa subclass is that they show two kinds of outbursts: normal outbursts and superoutbursts. In addition to the more frequent narrow outbursts of normal dwarf nova, SU UMa stars exhibit “superoutbursts”, in which stars reach about 1 magnitude brighter and stay longer than in normal outburst. Careful photometric studies during superoutburst have almost always revealed the “superhumps”: periodic humps in light curves with a period very close to the orbital period of the system. However, the most curious of all is that this superhump period is not exactly equal to the orbital period, but it is always longer by a few percent than the orbital period.

An Extremely Massive White Dwarf of the Symbiotic Classical Nova V407 Cyg as Suggested by the RS Oph and U SCO Models

2012 ◽  
Vol 21 (1-2) ◽  
Author(s):  
I. Hachisu ◽  
M. Kato
Keyword(s):  
Light Curve ◽  
White Dwarf ◽  
Early Phase ◽  
Symbiotic Star ◽  
X Ray ◽  
Classical Nova ◽  
Optical Light Curve ◽  
Nova Outburst

AbstractWe have analyzed the optical light curve of the symbiotic star V407 Cyg that underwent a classical nova outburst in 2010 March. Being guided by a supersoft X-ray phase observed during days 20-40 after the nova outburst, we are able to reproduce the light curve during a very early phase of the nova outburst. Our model consists of an outbursting white dwarf and an extended equatorial disk. An extremely massive white dwarf of 1.35-1.37 M

scholarly journals Supersoft X-ray phases of recurrent novae as an indicator of their white dwarf masses

2020 ◽  
Vol 72 (5) ◽  
Author(s):  
Mariko Kato ◽  
Izumi Hachisu
Keyword(s):  
Light Curve ◽  
White Dwarf ◽  
Total Duration ◽  
Simple Relation ◽  
Light Curves ◽  
Curve Shape ◽  
Plateau Phase ◽  
Hydrogen Burning ◽  
X Ray ◽  
Recurrent Nova

Abstract We have examined the optical/X-ray light curves of seven well-observed recurrent novae, V745 Sco, M31N 2008-12a, LMC N 1968, U Sco, RS Oph, LMC N 2009a, T Pyx, and one recurrent nova candidate LMC N 2012a. Six novae out of the eight show a simple relation that the duration of supersoft X-ray source (SSS) phase is 0.70 times the total duration of the outburst (= X-ray turnoff time), i.e., tSSS = 0.70 toff, the total duration of which ranges from 10 to 260 d. These six recurrent novae show a broad rectangular X-ray light curve shape, the first half-period of which is highly variable in the X-ray count rate. The SSS phase also corresponds to an optical plateau phase that indicates a large accretion disk irradiated by a hydrogen-burning white dwarf (WD). The two other recurrent novae, T Pyx and V745 Sco, show a narrow triangular-shaped X-ray light curve without an optical plateau phase. Their relations between tSSS and toff are rather different from the above six recurrent novae. We also present theoretical SSS durations for recurrent novae with various WD masses and stellar metallicities (Z = 0.004, 0.01, 0.02, and 0.05) and compare them with the observed durations of these recurrent novae. We show that SSS duration is a good indicator of WD mass in recurrent novae with a broad rectangular X-ray light curve shape.

SN1993J: CHALLENGING NEW INSIGHTS FOR STELLAR STRUCTURE AND SUPERNOVA THEORIES

1995 ◽  
Vol 04 (04) ◽  
pp. 429-449
Author(s):  
RAMEN KUMAR PARUI
Keyword(s):  
Light Curve ◽  
Shell Structure ◽  
Stellar Structure ◽  
Present Review ◽  
Nearby Galaxy ◽  
X Ray ◽  
Gradual Development ◽  
Γ Ray ◽  
The Asymmetry

The appearance of supernova SN1993J in our nearby galaxy M81 is an important event in the modern study of supernovae. From the very beginning it created puzzles regarding its supernova type; then in its evolution further puzzles particularly in its spectra, light curve, nature of progenitor, X-ray and γ-ray emission, polarization, etc. Various puzzles have been solved with the help of both theoretical and observational investigations. Still many problems remain. In this present review we examine the gradual development of the various puzzles along with the evolution of SN1993J. We have also presented the unsolved problems as well as the important aspects which are to be measured. We particularly emphasize on the measurements of the shell structure of a radio supernova and of the asymmetry of the scattering envelope as a test to verify the prediction of shell structure in supernova theory i.e. supernova SN1993J will give us an opportunity to verify various aspects of supernova theory.

scholarly journals V2282 Sgr Revisited

2014 ◽  
Vol 1 (1) ◽  
pp. 118-122
Author(s):  
Roberto Nesci ◽  
Corinne Rossi ◽  
Antonio Frasca ◽  
Ettore Marilli ◽  
Paolo Persi ◽  
...  
Keyword(s):  
Light Curve ◽  
Accretion Disk ◽  
Main Sequence ◽  
Optical Spectra ◽  
Emission Lines ◽  
Main Sequence Star ◽  
Strong Emission ◽  
X Ray ◽  
Type Spectrum

The nature of V2282 Sgr is examined on the basis of several multiband observations: a 20 years long I-band light curve of V2282 Sgr obtained from archive photographic plates of the Asiago and Catania Observatories; a CCD R-band light curve obtained at Cornero Observatory; JHK photometry from 2MASS and UKDISS; <em>Spitzer</em> IRAC and MIPS images; optical spectra from Loiano Observatory; X-ray flux from <em>CHANDRA</em>. The star has a K-type spectrum with strong emission lines and is irregularly variable at all wavebands. The overall evidences suggest that V2282 Sgr is a Pre Main Sequence star with an accretion disk.

scholarly journals Modeling He-Rich Disks in AM CVn Binaries

2004 ◽  
Vol 194 ◽  
pp. 228-228
Author(s):  
T. Nagel ◽  
S. Dreizler ◽  
T. Rauch ◽  
K. Werner
Keyword(s):  
Accretion Disk ◽  
Time Scales ◽  
Accretion Disks ◽  
White Dwarf ◽  
Cataclysmic Variables ◽  
X Ray ◽  
Synthetic Spectra ◽  
Pure Helium ◽  
Low Mass ◽  
X Ray Binaries

We have developed a new code for the calculation of synthetic spectra and vertical structures of accretion disks in cataclysmic variables and compact X-ray binaries. Here we present results for the CV system AM CVn.AM CVn stars are a special type of cataclysmic variables, also called helium cataclysmics. They are systems of interacting binary white dwarfs, consisting of a degenerate C-O white dwarf primary and a low mass semi-degenerate secondary. The secondary loses mass, almost, pure helium, to the primary, forming an accretion disk. They have all in common a helium-rich composition, analoguous to the hydrogen-rich cataclysmic variables. They show photometric variabilities on time scales of ~ 1000s, the prototype of the class, AM CVn, e.g. exhibits a variability of ~ 18 min (Nelemans et al. 2001).

The Ultraviolet Light Curve of LMC X‐4: X‐Ray Heating of the O Star and Accretion Disk

2002 ◽  
Vol 114 (793) ◽  
pp. 340-349 ◽  
Author(s):  
Michael E. Preciado ◽  
Bram Boroson ◽  
Saeqa Dil Vrtilek
Keyword(s):  
Light Curve ◽  
Ultraviolet Light ◽  
Accretion Disk ◽  
X Ray

scholarly journals New Exosat Observations of TV Columbae: Preliminary Results

1987 ◽  
Vol 93 ◽  
pp. 261-267
Author(s):  
J. Schrijver ◽  
A.C. Brinkman ◽  
H. Van Der Woerd
Keyword(s):  
Light Curve ◽  
Orbital Period ◽  
White Dwarf ◽  
Lower Energy ◽  
Cataclysmic Variable ◽  
X Ray ◽  
Preliminary Results ◽  
First Results ◽  
Absorption Features ◽  
Energy Channels

AbstractThe first results of the analysis of new EXOSAT observations of the DQ Her type cataclysmic variable TV Col are presented. The period of the 1–10 kev X-ray pulsation associated with the white-dwarf rotation is now established as 1911 s. The pulsations are most pronounced in the lower energy channels (1–3.5 keV). The X-ray light curve shows absorption features associated with the orbital period of the system.

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.

Sign in / Sign up

Export Citation Format

Share Document