scholarly journals SWSex Stars, Old Novae, and the Evolution of Cataclysmic Variables

2015 ◽  
Vol 2 (1) ◽  
pp. 188-191 ◽  
Author(s):  
L. Schmidtobreick ◽  
C. Tappert
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
High Mass ◽  
Period Range ◽  
Transfer Rates ◽  
Low Mass ◽  
Orbital Periods ◽  
Nova Outburst

The population of cataclysmic variables with orbital periods right above the period gap are dominated by systems with extremely high mass transfer rates, the so-called SW Sextantis stars. On the other hand, some old novae in this period range which are expected to show high mass transfer rate instead show photometric and/or spectroscopic resemblance to low mass transfer systems like dwarf novae. We discuss them as candidates for so-called hibernating systems, CVs that changed their mass transfer behaviour due to a previously experienced nova outburst. This paper is designed to provide input for further research and discussion as the results as such are still very preliminary.

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 Observational Constraints on Evolution of Dwarf Novae in and Below ThePeriod Gap

1998 ◽  
Vol 11 (1) ◽  
pp. 374-374
Author(s):  
D. Nogami ◽  
T. Kato ◽  
H. Baba ◽  
S. Masuda
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
Wave Radiation ◽  
Observational Constraints ◽  
Dwarf Novae ◽  
Transfer Rates ◽  
Secular Changes ◽  
Orbital Periods

There is a gap in the distribution of the orbital periods of cataclysmic variables (CVs) between 2 and 3 hours. The period gap is explained at present by cessation of the mass transfer making CVs fainter and preventing them from being discovered. After restarting the mass transfer, CVs have been believed to evolve with the orbital periods becoming shorter, as angular momentum is released by gravitational wave radiation. In this view, the mass transfer rate depends almost only on the orbital period. However, reconsideration of these views is urged by a series of recent discoveries of ER UMa stars (a subclass of SU UMa stars having enormous mass-transfer rates), dwarf novae bridging “classical” SU UMa stars and ER UMa stars, and the first in-the-gap dwarf nova, PG 1510+234. These objects suggest two possibilities; 1) (a part of) SU UMa stars undergo large secular changes of the mass-transfer rate, and 2) there exist parameters overlooked but strongly influential in the evolution of CVs.

scholarly journals Super-Eddington Accretion in the Formation of Low-Mass X-ray Binaries and Millisecond Pulsars

1997 ◽  
Vol 163 ◽  
pp. 828-829 ◽  
Author(s):  
R. F. Webbink ◽  
V. Kalogera
Keyword(s):  
Mass Transfer ◽  
Initial Phase ◽  
Transfer Rate ◽  
Birth Rate ◽  
Mass Transfer Rate ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Low Mass ◽  
Orbital Periods ◽  
X Ray Binaries

AbstractConsiderations of donor star stability, age, and mass transfer rate show that low-mass X-ray binaries and binary millisecond pulsars with orbital periods longer than a few days must have survived an initial phase of super-Eddington mass transfer. We review the physical arguments leading to this conclusion, and examine its implications for the apparent discrepancy between the death rate for low-mass X-ray binaries and the birth rate of binary millisecond pulsars.

scholarly journals Minimum Orbital Period of Cataclysmic Variables

1979 ◽  
Vol 53 ◽  
pp. 504-504
Author(s):  
B. Paczynski ◽  
W. Krzeminski
Keyword(s):  
Mass Transfer ◽  
Angular Momentum ◽  
Orbital Period ◽  
Time Scale ◽  
Transfer Rate ◽  
Main Sequence ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
Transfer Rates ◽  
Angular Momentum Loss

The shortest known orbital period of a cataclysmic binary with a hydrogen dwarf secondary filling its Roche lobe is about 80 minutes. Theoretically the shortest possible orbital period for such a system is less than 60 minutes. We tried to explain why the periods shorter than 80 minutes are not observed. We estimated the time scale of angular momentum loss of a cataclysmic binary and the resulting mass transfer rate. The minimum orbital period for a given Ṁ is obtained during the transition of the secondary from the Main Sequence onto the Degenerate Dwarf Sequence. Pmin ∝ Ṁ½ Therefore, only those systems can reach low P for which Ṁ is small. This explains why among the shortest period cataclysmic variables there are no novae: presumably their mass transfer rates are too large. It also indicates that “polars” (AM Her-type stars) and SU UMa-type stars should have low Ṁ.

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.

scholarly journals Non Circular Disks in am CVn Systems?

1996 ◽  
Vol 158 ◽  
pp. 131-132
Author(s):  
J.-E. Solheim
Keyword(s):  
Mass Transfer ◽  
Light Curve ◽  
White Dwarf ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Transfer Rates ◽  
Group A ◽  
Orbital Periods ◽  
Group B ◽  
Circular Disks

The AM CVn stars are mass transferring, interacting binary, white dwarf systems with orbital periods of 15…45 minutes. Hydrogen is completely lost from these systems, and we observe small helium disks which may show thermal and tidal instabilities if the mass transfer rate is large enough (Osaki 1995). A tidal instability brings the disk into a superoutburst state, and in the light curve we may observe superhumps. Based on the observed periods and mass transfer rates we can divide the AM CVn stars into three groups:A: In permanent superoutburst: AM CVn and EC 15330-1403B: Regular superoutbursts: CR Boo, V803 Cen and CP EriC: Not yet observed superoutburst: GP ComGroup A consists of systems with disks which are too hot to decline into a low state. These disks are in a constant superoutburst state, analogous to nova-like CVs which show no outbursts, but still exhibit permanent superhumps (Skillman & Patterson 1993). Group B shows normal outbursts which can trigger superoutbursts, analogous to the VY Scl dwarf novae. The group C object may also be a superhumper, but with very infrequent outbursts analogous to the SU UMa stars (Warner 1995). In the following we will discuss evidence for superoutbursts in these systems, and the likelihood for these systems to develop elliptical disks.

Large-scale energetic coherent structures and their effects on wall mass transfer rate behind orifice in round pipe

2021 ◽  
Vol 927 ◽  
Author(s):  
F. Shan ◽  
S.Y. Qin ◽  
Y. Xiao ◽  
A. Watanabe ◽  
M. Kano ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Flow Field ◽  
Coherent Structures ◽  
Transfer Rate ◽  
Large Scale ◽  
Mass Transfer Rate ◽  
Low Frequency ◽  
Stochastic Estimation ◽  
Transfer Rates ◽  
Wall Mass

This paper first uses a low-speed stereoscopic particle image velocimetry (SPIV) system to measure the convergent statistical quantities of the flow field and then simultaneously measure the time-resolved flow field and the wall mass transfer rate by a high-speed SPIV system and an electrochemical system, respectively. We measure the flow field and wall mass transfer rate under upstream pipe Reynolds numbers between 25 000 and 55 000 at three specific locations behind the orifice plate. Moreover, we apply proper orthogonal decomposition (POD), stochastic estimation and spectral analysis to study the properties of the flow field and the wall mass transfer rate. More importantly, we investigate the large-scale coherent structures’ effects on the wall mass transfer rate. The collapse of the wall mass transfer rates’ spectra by the corresponding time scales at the three specific positions of orifice flow suggest that the physics of low-frequency wall mass transfer rates are probably the same, although the flow fields away from the wall are quite different. Furthermore, the spectra of the velocity reconstructed by the most energetic eigenmodes agree well with the wall mass transfer rate in the low-frequency region, suggesting that the first several energetic eigenmodes capture the flow dynamics relevant to the low-frequency variation of the wall mass transfer. Stochastic estimation results of the velocity field associated with large wall mass transfer rate at all three specific locations further reveal that the most energetic coherent structures are correlated with the wall mass transfer rate.

scholarly journals MASS TRANSFER CORRELATION FOR THE REMOVAL OF COPPER IONS FROM WASTEWATER

2010 ◽  
Vol 9 (1-2) ◽  
pp. 63
Author(s):  
N. M. S. Kaminari ◽  
M. J. J. S. Ponte ◽  
H. A. Ponte
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Copper Ions ◽  
Mass Transfer Rate ◽  
Reynolds Numbers ◽  
Electrochemical Reactor ◽  
High Mass ◽  
Ore Processing ◽  
Lead Nickel ◽  
Copper Lead

One of the biggest problems with ore processing in extractive metallurgical industries is the high toxicity of the heavy metals waste content (e.g., copper, lead, nickel and chrome). This work investigates the copper (II) íons removal from aqueous solutions in concentrations up to 1000 ppm. Therefore, a fluidized bed electrolytic reactor was used with flow-by configuration considered as a hopeful method due to the large specific surface area and the high mass transfer rate. The performance of the electrochemical reactor was investigated by using different porosities. Dimensionless Sherwood and Reynolds numbers were correlated to characterize the mass transport properties of the reactor, and they were fitted to the equation Sh = a.Reb.Sc1/3.

Sign in / Sign up

Export Citation Format

Share Document