scholarly journals Determination of the parameters of polar V379 Vir components, magnetic field and accretion

2021 ◽  
Author(s):  
M. V. Suslikov ◽  
◽  
A. I. Kolbin ◽  
◽  
Keyword(s):  
Magnetic Field ◽  
Simple Model ◽  
White Dwarf ◽  
Spectral Study ◽  
Zeeman Splitting ◽  
Light Curves ◽  
Magnetic Curve ◽  
The Masses ◽  
Ir Light

In this work we performed a photometric and spectral study of the polar V379 Vir. We used the modeling of the IR light curves based on a simple model of cyclotrone radiation source, the method of synthetic photometry to fit the observed spectral distribution of the energy, as well as the modeling of the magnetic curve obtained from Zeeman splitting of the Hβ line to determine the parameters of the system. We managed to estimate the temperature of the white dwarf Teff = 11 450 K, the masses and radii of the primary and secondary components: M1 = 0.696 M , R1 = 0.011 R , M2 = 0.105 M , R2 = 0.14 R . The separation of the components was about 0.6 AU, and the inclination i lies in the range 47—60◦.

scholarly journals The determination of the supernovae parameters from their light curves using the machine learning

2021 ◽  
pp. 1-11
Author(s):  
Egor Mikhailovich Urvachev
Keyword(s):  
Machine Learning ◽  
Light Curve ◽  
Learning Algorithm ◽  
Radioactive Decay ◽  
Light Curves ◽  
Radioactive Isotopes ◽  
Curve Model ◽  
Total Light ◽  
The Masses

The paper discusses the application of the machine learning library, CatBoost, to determine the masses of radioactive isotopes from the supernova light curve at a later epochs. The synthetic light curve model used for the demonstration is based on the contribution of the five major radioactive decay chains starting with <sup>56</sup>Ni, <sup>57</sup>Ni, <sup>44</sup>Ti, <sup>22</sup>Na, <sup>60</sup>Co. Separately, we considered sets of random light curves calculated for different isotope masses of both the three dominant chains (<sup>56</sup>Ni, <sup>57</sup>Ni, <sup>44</sup>Ti) and all five. It is shown that the masses of dominant isotopes are determined with acceptable accuracy in both cases, even with the standard settings of the machine learning algorithm. In the second case, the accuracy of determining the masses of the other two isotopes (<sup>22</sup>Na, <sup>60</sup>Co) turns out to be unsatisfactory, probably due to their weak contribution to the total light curve.

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 The Magnetic Field of the Intermediate Polar RE 0751+14

1996 ◽  
Vol 158 ◽  
pp. 183-183
Author(s):  
H. Väth
Keyword(s):  
Magnetic Field ◽  
White Dwarf ◽  
Accretion Rate ◽  
Shock Structure ◽  
Light Curves ◽  
X Rays ◽  
Strong Magnetic Fields ◽  
X Ray ◽  
Spin Period ◽  
The Magnetic Field

Piirola, Hakala & Coyne (1993) modeled the optical/IR light curve of RE 0751+14 assuming a uniform shock structure and neglecting the hard X-ray emission. In this paper, we model the light curves at optical/IR and hard X-ray wavelengths and include the effects of the shock structure.We base our model on accretion onto a white dwarf with a displaced magnetic dipole for a range of likely white dwarf masses. We find that the observed intensity variations of X-rays and in the I band over one spin period largely determine the position of the emission regions. Furthermore, the observed maximum X-ray flux constrains the specific accretion rate. We deduce that the magnetic field at the pole is likely to be in the range 9 .. .21 MG, which is consistent with the estimates of Piirola et al. (1993). It had been proposed previously that there must exist asynchronous rotators with sufficiently strong magnetic fields such that the binaries will evolve into AM Her binaries (Chanmugam & Ray 1984; King, Frank & Ritter 1985). With this deduced high magnetic field RE 0751+14 is the most likely example of such a system known to date.

scholarly journals Modeling of the IR Light Curves of the Symbiotic Recurrent Nova T CrB

2011 ◽  
Vol 7 (S281) ◽  
pp. 203-204
Author(s):  
A. A. Tatarnikova ◽  
A. M. Tatarnikov ◽  
V. I. Shenavrin
Keyword(s):  
White Dwarf ◽  
Roche Lobe ◽  
Light Curves ◽  
Mass Ratio ◽  
Cool Component ◽  
Recurrent Nova ◽  
Photometric Monitoring ◽  
Chandrasekhar Limit ◽  
Ir Light

AbstractWe analyze the results of our IR photometric monitoring of T CrB during 1987-2003 and describe the ellipsoidal variability of the Roche lobe filling cool component. We obtain limits to the binary inclination of i ∈ [50,60] deg and binary mass ratio q ∈ [0.4,2] (90 per cent confidence). The mass of the hot component is therefore 1.3-3 M⊙. If the hot component of T CrB is a white dwarf, its mass will be near the Chandrasekhar limit.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

scholarly journals Temperature-Induced Plasmon Excitations for the α–T3 Lattice in Perpendicular Magnetic Field

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1720
Author(s):  
Antonios Balassis ◽  
Godfrey Gumbs ◽  
Oleksiy Roslyak
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Zeeman Splitting ◽  
Mass Term ◽  
Energy Dispersive Spectrum ◽  
Wave Functions ◽  
Transition Energies ◽  
Gap Opening ◽  
Quantizing Magnetic Field

We have investigated the α–T3 model in the presence of a mass term which opens a gap in the energy dispersive spectrum, as well as under a uniform perpendicular quantizing magnetic field. The gap opening mass term plays the role of Zeeman splitting at low magnetic fields for this pseudospin-1 system, and, as a consequence, we are able to compare physical properties of the the α–T3 model at low and high magnetic fields. Specifically, we explore the magnetoplasmon dispersion relation in these two extreme limits. Central to the calculation of these collective modes is the dielectric function which is determined by the polarizability of the system. This latter function is generated by transition energies between subband states, as well as the overlap of their wave functions.

scholarly journals New Data on the Eclipsing Binary V1848 Ori and Improved Orbital and Light Curve Solutions

2020 ◽  
Vol 29 (1) ◽  
pp. 72-80 ◽  
Author(s):  
Fatemeh Davoudi ◽  
Atila Poro ◽  
Fahri Alicavus ◽  
Afshin Halavati ◽  
Saeed Doostmohammadi ◽  
...  
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Mass Function ◽  
Light Curves ◽  
Complete Analysis ◽  
Physical Parameters ◽  
Mass Ratio ◽  
Third Body ◽  
Eclipsing Binary

AbstractNew observations of the eclipsing binary system V1848 Ori were carried out using the V filter resulting in a determination of new times of minima and new ephemeris were obtained. We presented the first complete analysis of the system’s orbital period behavior and analysis of O-C diagram done by the GA and MCMC approaches in OCFit code. The O-C diagram demonstrates a sinusoidal trend in the data; this trend suggests a cyclic change caused by the LITE effect with a period of 10.57 years and an amplitude of 7.182 minutes. It appears that there is a third body with mass function of f (m3) = 0.0058 M⊙ in this binary system. The light curves were analyzed using the Wilson-Devinney code to determine some geometrical and physical parameters of the system. These results show that V1848 Ori is a contact W UMa binary system with the mass ratio of q = 0.76 and a weak fillout factor of 5.8%. The O’Connell effect was not seen in the light curve and there is no need to add spot.

Sign in / Sign up

Export Citation Format

Share Document