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 J-, H-, and K-band Spectra of Three SU UMa-Type Dwarf Novae

2006 ◽  
Vol 2 (S240) ◽  
pp. 547-549
Author(s):  
Ryoko Ishioka ◽  
Kazuhiro Sekiguchi ◽  
Hiroyuki Maehara
Keyword(s):  
Orbital Period ◽  
Spectral Features ◽  
Late Type ◽  
Power Law Distribution ◽  
Dwarf Novae ◽  
Evolutionary Path ◽  
Secondary Star ◽  
Orbital Periods ◽  
Band Spectra ◽  
Absorption Features

AbstractWe present the results of J-, H-, and K-band spectroscopy on three SU UMa-type dwarf novae with orbital periods of 1.33 – 1.37 hr. We performed the SED fitting for the obtained spectra by assuming a power-law distribution for the accretion disk and using template spectra of late-type dwarfs for secondary star. ASAS 002511+1217.2 and EQ J183926+260409 are WZ Sge-type or WX Cet-type dwarf novae. We found strong water absorption features in their spectra, which are characteristic in late M- or L-type dwarfs. The SED fitting suggests that their secondary contributions to the overall SED are less than one third. We identified the secondary stars as M9 and L1 type dwarfs, which are rather less massive but still normal stars. The spectrum of SDSS J013701−091235 is dominated by the secondary component. Spectral features of this object are similar to those of an early M-type dwarf in spite of its short orbital period. The spectrum of SDSS 0137 strongly suggests that the evolutionary path of this object is different from that of ordinary CVs, and this object is a candidate of EI Psc-like systems.

scholarly journals Spectroscopic properties of the dwarf nova-type cataclysmic variables observed by LAMOST

2020 ◽  
Vol 72 (5) ◽  
Author(s):  
Zhongtao Han ◽  
Soonthornthum Boonrucksar ◽  
Shengbang Qian ◽  
Fang Xiaohui ◽  
Qishan Wang ◽  
...  
Keyword(s):  
Emission Line ◽  
Spectral Type ◽  
Orbital Period ◽  
White Dwarf ◽  
Accretion Rate ◽  
Cataclysmic Variables ◽  
Spectroscopic Properties ◽  
Accretion Disc ◽  
Spectral Features ◽  
Dwarf Novae

Abstract Spectra of 76 known dwarf novae from the LAMOST survey were presented. Most of the objects were observed in quiescence, and about 16 systems have typical outburst spectra. 36 of these systems were observed by SDSS, and most of their spectra are similar to the SDSS spectra. Two objects, V367 Peg and V537 Peg, are the first spectra of the object. The spectrum of V367 Peg shows a contribution from an M-type donor and its spectral type could be estimated as M3-5 by combining its orbital period. The signature of a white dwarf spectrum can be seen clearly in four low-accretion-rate WZ Sge stars. Other special spectral features worthy of further observations are also noted and discussed. We present a LAMOST spectral atlas of outbursting dwarf novae. Six objects have their first outburst spectra given here, and the others were also compared with the published outburst spectra. We argue that these data will be useful for further investigation of the accretion disc properties. The He ii λ4686 emission line can be found in the outburst spectra of seven dwarf novae. These objects are excellent candidates for probing the spiral asymmetries of accretion disc.

Recent Photometric and Spectroscopic Observations of Southern Dwarf Novae

1979 ◽  
Vol 46 ◽  
pp. 24-28
Author(s):  
N. Vogt
Keyword(s):  
Orbital Period ◽  
Special Interest ◽  
Dwarf Novae ◽  
Spectroscopic Observations ◽  
Photometric And Spectroscopic Observations ◽  
Cataclysmic Binaries

This contribution concerns three dwarf novae of special interest: one of them has the longest known orbital period of all dwarf novae (BV Cen); the remaining two variables (Z Cha and EX Hya) belong to the group of the ultra-short periodic cataclysmic binaries. Here only short summaries are given. The detailed results will be published elsewhere, in the case of BV Cen together with J. Breysacher, and in the case of EX Hya together with D. Comte, C. Sterken and W. Krzeminski.

scholarly journals Mass transfer and stellar wind effects in the eclipsing binary RT Andromedae

1981 ◽  
Vol 59 ◽  
pp. 491-494
Author(s):  
G.A. Bakos ◽  
J. Tremko
Keyword(s):  
Mass Transfer ◽  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Stellar Wind ◽  
Mass Ratio ◽  
Eclipsing Binary ◽  
Short Period ◽  
Photometric Elements ◽  
Number Of Authors

In recent years the short period eclipsing binary RT And has been studied extensively by a number of authors. From photo electric observations the light curve and the photometric elements were derived by Dean (1974) and Mancuso et al. (1979). The geometric dimensions of the binary confirm that the system is detached consisting of two stars of spectral type F8 V and KO V. The mass ratio is 0.66. In spite of this classification, effects appearing among semidetached systems have been observed, namely, variations of the amplitude and the shape of the light curve and changes of the length of the orbital period.

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.

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

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 1RXS J232953.9+062814: A Dwarf Nova with a 64 Minute Orbital Period and a Conspicuous Secondary Star

2002 ◽  
Vol 567 (1) ◽  
pp. L49-L52 ◽  
Author(s):  
John R. Thorstensen ◽  
William H. Fenton ◽  
Joseph O. Patterson ◽  
Jonathan Kemp ◽  
Thomas Krajci ◽  
...  
Keyword(s):  
Orbital Period ◽  
Dwarf Nova ◽  
Secondary Star

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.

Longevity of moons around habitable planets

2014 ◽  
Vol 13 (4) ◽  
pp. 324-336 ◽  
Author(s):  
Takashi Sasaki ◽  
Jason W. Barnes
Keyword(s):  
Orbital Period ◽  
Extrasolar Planets ◽  
The Sun ◽  
Habitable Zone ◽  
Evolution Theory ◽  
Earth System ◽  
The Moon ◽  
Tidal Dissipation ◽  
Habitable Planets ◽  
Rocky Planets

AbstractWe consider tidal decay lifetimes for moons orbiting habitable extrasolar planets using the constant Q approach for tidal evolution theory. Large moons stabilize planetary obliquity in some cases, and it has been suggested that large moons are necessary for the evolution of complex life. We find that the Moon in the Sun–Earth system must have had an initial orbital period of not slower than 20 h rev−1 for the moon's lifetime to exceed a 5 Gyr lifetime. We assume that 5 Gyr is long enough for life on planets to evolve complex life. We show that moons of habitable planets cannot survive for more than 5 Gyr if the stellar mass is less than 0.55 and 0.42 M⊙ for Qp=10 and 100, respectively, where Qp is the planetary tidal dissipation quality factor. Kepler-62e and f are of particular interest because they are two actually known rocky planets in the habitable zone. Kepler-62e would need to be made of iron and have Qp=100 for its hypothetical moon to live for longer than 5 Gyr. A hypothetical moon of Kepler-62f, by contrast, may have a lifetime greater than 5 Gyr under several scenarios, and particularly for Qp=100.

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