DSpace Collection:
http://dspace.onu.edu.ua:8080/handle/123456789/13174
2024-03-29T02:03:03ZMASTER OT J172758.09+380021.5: a peculiar ER UMa-type dwarf nova, probably a missed nova in the recent past
http://dspace.onu.edu.ua:8080/handle/123456789/33375
Title: MASTER OT J172758.09+380021.5: a peculiar ER UMa-type dwarf nova, probably a missed nova in the recent past
Authors: Pavlenko, E.; Kato, T.; Antonyuk, K.; Pit, N.; Keir, L.; Udovichenko, Serhii M.; Dubovsky, P.; Sosnovskij, A.; Antonyuk, O.; Shimansky, V.; Gabdeev, M.; Rakhmatullaeva, F.; Kokhirova, G.; Belan, S.; Simon, A.; Baklanov, A.; Kojiguchi, N.; Godunova, V.; Удовіченко, Сергій Миколайович; Удовиченко, Сергей Николаевич
Abstract: A CCD photometry of the dwarf nova MASTER OT J172758.09
+380021.5 was carried out in 2019 during 134 nights. Observations covered
three superoutbursts, ve normal outbursts and quiescence between them. The
available ASASSN and ZTF data for 2014 { 2020 were also examined. Spectral
observations were done in 2020 when the object was in quiescence. Spectra
and photometry revealed that the star is an H-rich active ER UMa-type dwarf
nova with a highly variable supercycle (time interval between two successive
superoutbursts) of 50 { 100 d that implies a high and variable mass-transfer
rate. MASTER OT J172758.09+380021.5 demonstrated peculiar behaviour:
short-lasted superoutbursts (a week); a slow superoutburst decline and cases of rebrightenings; low frequency (from none to a few) of the normal outbursts
during the supercycle. In 2019 a mean period of positive superhumps was found
to be 0.05829 d during the superoutbursts. Late superhumps with a mean
period of 0.057915 d which lasted about 20 d after the end of superoutburst
and were replaced by an orbital period of 0.057026 d or its orbital-negative
superhump beat period were detected. An absence of eclipse in the orbital light
curve and its moderate amplitude are consistent with the orbital inclination
of about 40 found from spectroscopy. The blue peaks of the V-Ic and B-Rc
colour indices of superhumps during the superoutburst coincided with minima
of the light curves, while B-Rc of the late superhumps coincided with a rising
branch of the light curves. We found that a low mass ratio q = 0:08 could
explain most of the peculiarities of MASTER OT J172758.09+380021.5. The
mass-transfer rate should be accordingly higher than what is expected from
gravitational radiation only, this assumes the object is in a post-nova state and
underwent a nova eruption relatively recently { hundreds of years ago. This
object would provide probably the rst observational evidence that a nova
eruption can occur even in CVs near the period minimum.2021-01-01T00:00:00ZGroups of meteorites and meteorite-dropping fireballs in asteroidal orbits
http://dspace.onu.edu.ua:8080/handle/123456789/33270
Title: Groups of meteorites and meteorite-dropping fireballs in asteroidal orbits
Authors: Gorbanev, Yuriy M.; Konovalova, N. A.; Davruqov, N. Kh.; Горбаньов, Юрій Михайлович; Горбанёв, Юрий Михайлович
Abstract: This paper presents the results of a study of the existence of nine near-Earth meteorite-producing
groups in asteroidal orbits, containing sporadic reballs from the IAU MDC-2007 database, sporadic
meteors from the SonotaCo database, meteorites namely, L5, L6 and H4−H6 ordinary chondrites
and an ureilite, for which atmospheric and orbital parameters are known from instrumental observations.
Orbits of the selected members of meteorite-producing groups were classi ed as asteroid orbits
according to the Tisserand parameter Tj > 3.1.
Dynamic links between the members of the identi ed meteorite-producing groups and
instrumentally observed known meteorites which were taken as a reference for the search of potential
group members were tested using orbital similarity criteria, in particular the Drummond criterion
DD and the Southworth and Hawkins criterion DSH. As a result, several meteorite-dropping
sporadic reballs and small meteors, whose orbits are similar to the asteroid orbits of nine known
meteorites, were detected and reckoned as possible members of meteorite-producing groups.2021-01-01T00:00:00ZGravitational Interaction in the Chimney Lattice Universe †
http://dspace.onu.edu.ua:8080/handle/123456789/33269
Title: Gravitational Interaction in the Chimney Lattice Universe †
Authors: Eingorn, Maxim; McLaughlin II, Andrew; Canay, Ezgi; Brilenkov, Maksym; Zhuk, Oleksandr I.; Жук, Олександр Іванович; Жук, Александр Иванович
Abstract: We investigate the influence of the chimney topology T T R of the Universe on the
gravitational potential and force that are generated by point-like massive bodies. We obtain three
distinct expressions for the solutions. One follows from Fourier expansion of delta functions into
series using periodicity in two toroidal dimensions. The second one is the summation of solutions of
the Helmholtz equation, for a source mass and its infinitely many images, which are in the form of
Yukawa potentials. The third alternative solution for the potential is formulated via the Ewald sums
method applied to Yukawa-type potentials. We show that, for the present Universe, the formulas
involving plain summation of Yukawa potentials are preferable for computational purposes, as they
require a smaller number of terms in the series to reach adequate precision.2021-01-01T00:00:00ZEffect of the Cubic Torus Topology on Cosmological Perturbations
http://dspace.onu.edu.ua:8080/handle/123456789/33268
Title: Effect of the Cubic Torus Topology on Cosmological Perturbations
Authors: Eingorn, Maxim; Canay, Ezgi; Metcalf, Jacob M.; Brilenkov, Maksym; Zhuk, Oleksandr I.; Жук, Олександр Іванович; Жук, Александр Иванович
Abstract: We study the effect of the cubic torus topology of the Universe on scalar cosmological
perturbations which define the gravitational potential. We obtain three alternative forms of the
solution for both the gravitational potential produced by point-like masses, and the corresponding
force. The first solution includes the expansion of delta-functions into Fourier series, exploiting
periodic boundary conditions. The second one is composed of summed solutions of the Helmholtz
equation for the original mass and its images. Each of these summed solutions is the Yukawa
potential. In the third formula, we express the Yukawa potentials via Ewald sums. We show that
for the present Universe, both the bare summation of Yukawa potentials and the Yukawa-Ewald
sums require smaller numbers of terms to yield the numerical values of the potential and the force
up to desired accuracy. Nevertheless, the Yukawa formula is yet preferable owing to its much
simpler structure.2021-01-01T00:00:00Z