scholarly journals First detection of two superoutbursts during the rebrightening phase of a WZ Sge-type dwarf nova: TCP J21040470+4631129

2020 ◽  
Vol 72 (3) ◽  
Author(s):  
Yusuke Tampo ◽  
Kojiguchi Naoto ◽  
Keisuke Isogai ◽  
Taichi Kato ◽  
Mariko Kimura ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Accretion Disk ◽  
Late Stage ◽  
Large Radius ◽  
Mass Ratio ◽  
Dwarf Novae ◽  
Dwarf Nova ◽  
Spectroscopic Observations ◽  
The Third ◽  
Photometric And Spectroscopic Observations

Abstract We report on photometric and spectroscopic observations and analysis of the 2019 superoutburst of TCP J21040470+4631129. This object showed a 9 mag superoutburst with early superhumps and ordinary superhumps, which are the features of WZ Sge-type dwarf novae. Five rebrightenings were observed after the main superoutburst. The spectra during the post-superoutburst stage showed Balmer, He i, and possible sodium doublet features. The mass ratio is derived as 0.0880(9) from the period of the superhump. During the third and fifth rebrightenings, growing superhumps and superoutbursts were observed, which have never been detected during a rebrightening phase among WZ Sge-type dwarf novae with multiple rebrightenings. To induce a superoutburst during the brightening phase, the accretion disk needs to have expanded beyond the 3 : 1 resonance radius of the system again after the main superoutburst. These peculiar phenomena can be explained by the enhanced viscosity and large radius of the accretion disk suggested by the higher luminosity and the presence of late-stage superhumps during the post-superoutburst stage, plus by more mass supply from the cool mass reservoir and/or from the secondary because of the enhanced mass transfer than those of other WZ Sge-type dwarf novae.

Models of Cataclysmic Variables from Photometric and Spectroscopic Data

1979 ◽  
Vol 46 ◽  
pp. 65-74 ◽  
Author(s):  
A.C. Fabian ◽  
J.E. Pringle ◽  
J.A.J. Whelan ◽  
J.A. Bailey
Keyword(s):  
Spectroscopic Data ◽  
Cataclysmic Variables ◽  
System Parameters ◽  
Dwarf Nova ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations

Abstract.Recent photometric and spectroscopic observations of the dwarf nova system Z Cha are discussed. Methods for constraining the system parameters are applied and the disc emissivity is deduced as a function of radius. Indications are found that the disc shrinks in size with increasing time after outburst.

scholarly journals Theory of Dwarf Novae

1976 ◽  
Vol 73 ◽  
pp. 173-192
Author(s):  
G. T. Bath
Keyword(s):  
Mass Transfer ◽  
Steady State ◽  
Recent Work ◽  
Accretion Disc ◽  
Optical Behaviour ◽  
Dwarf Novae ◽  
Physical Processes ◽  
Dwarf Nova ◽  
Theoretical Results

Recent work on the physical processes resulting from mass transfer between the red and blue components of dwarf nova binaries is reviewed. The optical behaviour of the blue component's accretion disc suggests that it may be the infall, accretion energy which is being liberated during outbursts. Theoretical results which suggest that the red component may suffer quasi-periodic mass transfer instabilities are discussed. The resulting accretion disc properties are considered and compared with the observed optical outburst behaviour for the simplest steady state disc models. The complexity of the interaction between the two stellar components in these systems is emphasized.

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.

scholarly journals Photometric and Spectroscopic Investigation of the Dwarf Nova HS 0218+3229: A Short Review

2015 ◽  
Vol 2 (1) ◽  
pp. 123-127 ◽  
Author(s):  
N. Katysheva ◽  
S. Shugarov ◽  
N. Borisov ◽  
M. Gabdeev ◽  
P. Golysheva
Keyword(s):  
Spectroscopic Investigation ◽  
Short Review ◽  
Cataclysmic Variable ◽  
Dwarf Nova ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations

This paper is devoted to the study of the cataclysmic variable HS 0218+3229 using the photometric and spectroscopic observations.

scholarly journals Results of Optical Monitoring of the Dwarf Nova SS Cyg During the 1993 Campaign of co-ordinated Observations with the Asca Satellite

1996 ◽  
Vol 158 ◽  
pp. 73-74
Author(s):  
Irina Voloshina
Keyword(s):  
Cataclysmic Variable ◽  
Optical Monitoring ◽  
X Ray ◽  
Dwarf Nova ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations ◽  
Wide Range

SS Cyg is the brightest known and therefore best studied classical dwarf nova and it was the first one from which X-ray radiation was discovered. SS Cyg is unique because it has been detected at very wide range of energies, from a few eV up to ~ 10 keV (Jones & Watson 1992). It was chosen as the first cataclysmic variable for X-ray observations with the Japanese satellite ASCA. Simultaneous optical photometric and spectroscopic observations were also provided for completeness of the study.

scholarly journals Simultaneous Multiwavelength Observations of Dwarf Novae Systems at Quiescence and in Outburst

1996 ◽  
Vol 158 ◽  
pp. 79-80
Author(s):  
G. Tovmassian ◽  
J. Echevarria ◽  
E. Perez ◽  
D. H. P. Jones ◽  
M. Shara ◽  
...  
Keyword(s):  
Dwarf Novae ◽  
Preliminary Results ◽  
International Program ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations ◽  
Photometric Observations ◽  
Northern And Southern Hemispheres ◽  
Multiwavelength Observations

The results of photometric and spectroscopic observations of dwarf novae are presented. The data were obtained during an international program of multiwavelength observations, held in 1986 February at several observatories, of dwarf novae during the first and subsequent days of outburst. During the campaign numerous dwarf novae were monitored in order to catch them in outburst. Preliminary results and analysis of some objects are reported elsewhere. A total of 30 dwarf novae were observed in the northern and southern hemispheres. Among them 37% were caught in outburst, including 10% on the rise to outburst and 17% in decline. Photometric observations were carried out in the UBVRI system and colour indexes were calculated.

scholarly journals ASASSN-18aan: An eclipsing SU UMa-type cataclysmic variable with a 3.6-hr orbital period and a late G-type secondary star

2021 ◽  
Author(s):  
Yasuyuki Wakamatsu ◽  
John R Thorstensen ◽  
Naoto Kojiguchi ◽  
Keisuke Isogai ◽  
Mariko Kimura ◽  
...  
Keyword(s):  
Spectral Type ◽  
Orbital Period ◽  
Mass Ratio ◽  
Dwarf Novae ◽  
Tidal Dissipation ◽  
High Q ◽  
Secondary Star ◽  
Long Period ◽  
Photometric And Spectroscopic Observations ◽  
Sodium Abundance

Abstract We report photometric and spectroscopic observations of the eclipsing SU UMa-type dwarf nova ASASSN-18aan. We observed the 2018 superoutburst with 2.3 mag brightening and found the orbital period (Porb) to be 0.149454(3) d, or 3.59 hr. This is longward of the period gap, establishing ASASSN-18aan as one of a small number of long-Porb SU UMa-type dwarf novae. The estimated mass ratio, [q = M2/M1 = 0.278(1)], is almost identical to the upper limit of tidal instability by the 3 : 1 resonance. From eclipses, we found that the accretion disk at the onset of the superoutburst may reach the 3 : 1 resonance radius, suggesting that the superoutburst of ASASSN-18aan results from the tidal instability. Considering the case of long-Porb WZ Sge-type dwarf novae, we suggest that the tidal dissipation at the tidal truncation radius is enough to induce SU UMa-like behavior in relatively high-q systems such as SU UMa-type dwarf novae, but that this is no longer effective in low-q systems such as WZ Sge-type dwarf novae. The unusual nature of the system extends to the secondary star, for which we find a spectral type of G9, much earlier than typical for the orbital period, and a secondary mass M2 of around 0.18 M⊙, smaller than expected for the orbital period and the secondary’s spectral type. We also see indications of enhanced sodium abundance in the secondary’s spectrum. Anomalously hot secondaries are seen in a modest number of other CVs and related objects. These systems evidently underwent significant nuclear evolution before the onset of mass transfer. In the case of ASASSN-18aan, this apparently resulted in a mass ratio lower than typically found at the system’s Porb, which may account for the occurrence of a superoutburst at this relatively long period.

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 Do We See Magnetic Effects in Dwarf Nova Outbursts?

1995 ◽  
Vol 151 ◽  
pp. 285-285
Author(s):  
N. Vogt ◽  
E. Meyer-Hofmeister ◽  
F. Meyer
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Accretion Disk ◽  
White Dwarf ◽  
Magnetic Activity ◽  
Light Curves ◽  
Dwarf Novae ◽  
Dwarf Nova ◽  
Cyclic Behaviour ◽  
Nova Outbursts

Many observations indicate that fast rotating late type stars show magnetic activity. We therefore argue that some of the secondary stars in cataclysmic binaries might also have magnetic fields. Such magnetic fields would reach over the accretion disk around the white dwarf primary. We investigate their effect on dwarf nova outbursts. The magnetic field lines will penetrate the disk and remove angular momentum. This shifts the accumulation of mass towards the inner disk, closer to the white dwarf, and therefore leads to a different outburst behaviour, which can be recognized in observed light curves of dwarf novae. If a magnetic field of the order 50 - 100 gauss is acting on the accretion disk, we expect narrower and more frequent outbursts as compared to the non-magnetic case. Outburst records of three dwarf novae above the period gap (P > 3h), whose long-term light curves are well covered, were used to search for traces of magnetic activity. All three cases display a pronounced bimodality in the distribution of their outburst width, i.e. either narrow or wide outbursts occur. We found evidence for a cyclic behaviour in one case, SS Aur: possible “magnetic episodes” repeating every 18 years reveal epochs with abnormally frequent narrow outbursts and nearly or totally missing wide ones. There are also indications for a similar behaviour of SS Cyg with a 7-years cycle, but with less pronounced periodicity. The third case, U Gem, does not show clear evidence of magnetic activity although we found some indications for a transitory oscillation of the width of wide outbursts after 1926, with a period of 13.6 years. The behaviour of SS Aur and SS Cyg resembles the theoretical predictions, there is, however, an important difference: Throughout the entire cycle, marked by the “magnetic episodes”, neither wide nor narrow outbursts alter their mean light curves: magnetic fields seem to affect only the observed proportion in the frequency of both outburst types without altering the light curves of individual outbursts. Remarkably, most of the “anomalous outbursts” (which are characterized by an abnormally slow rising branch to an outburst) occur also at or near the “magnetic episodes”.

scholarly journals ASASSN-14ho: Longest-period dwarf nova with multiple rebrightenings

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Taichi Kato
Keyword(s):  
Mass Transfer ◽  
Radial Velocity ◽  
Accretion Disks ◽  
Orbital Period ◽  
Formal Solution ◽  
Dwarf Novae ◽  
X Ray ◽  
Dwarf Nova ◽  
Orbital Periods ◽  
The Stability

Abstract The post-outburst rebrightening phenomenon in dwarf novae and X-ray novae is still one of the most challenging subjects for theories of accretion disks. It has been widely recognized that post-outburst rebrightenings are a key feature of WZ Sge-type dwarf novae, which predominantly have short (≲0.06 d) orbital periods. The author found four post-outburst rebrightenings in ASASSN-14ho during its 2014 outburst, whose orbital period was recently measured to be exceptionally long [0.24315(10) d]. Using the formal solution of the radial velocity study in the literature, this paper discusses the possibility that this object could be an SU UMa-type dwarf nova near the stability border of the 3 : 1 resonance, despite its exceptionally long orbital period. Such objects are considered to be produced if mass transfer occurs after the secondary has undergone significant nuclear evolution, and they may be hidden in a significant number of dwarf novae showing multiple post-outburst rebrightenings.

Sign in / Sign up

Export Citation Format

Share Document