97 research outputs found
The binding energy produced within the framework of the accretion of millisecond pulsars
The role and implication of binding energy through the accretion-induced
collapse (AIC) of accreting white dwarfs (WDs) for the production of
millisecond pulsars (MSPs) are investigated. I examine the binding energy model
due to the dynamical process in close binary systems and investigating the
possible mass of the companion sufficient to induce their orbital parameters.
The deterministic nature of this interaction has a strong sensitivity to the
equation of state of the binary systems (where the compactness of a neutron
star is proportional to the amount of binding energy) associated with their
initial conditions. This behavior will mimic the commonly assumed mass and
amount of accreted matter under the instantaneous mass loss (). As a result, this will indicate an increase in the MSP's
gravitational mass due to angular momentum losses. The outcome of such a system
will then be a circular binary MSP in which the companion is a low-mass WD,
thus distinguishing the binary formation scenarios. In addition, the results of
this work could provide constraints on the expected mass and binding energy of
a neutron star based on the accretion rat
Speckle-interferometric study of close visual binary system Hip 11253 (HD14874) using Gaia (DR2) and (EDR3)
We present a comprehensive set of physical and geometrical parameters for
each of the components of the close visual binary system Hip 11253 (HD14874).
We present an analysis for the binary and multiple stellar systems with the aim
to obtain a match between the overall observational spectral energy
distribution of the system and the spectral synthesis created from model
atmospheres. The epoch positions are used to determine the orbital parameters
and the total mass.Comment: Accepted for publication in Research in Astronomy and Astrophysics
(RAA
Quiescent photometric modulations of two low-inclination cataclysmic variables KZGem and TWVir
The quiescent periodic photometric modulations of two low-inclination
cataclysmic variables observed in Kepler K2 Campaigns 0 and 1, KZ Gem and TW
Vir, are investigated. A phase-correcting method was successfully used to
detect the orbital modulations of KZ Gem and TW Vir and improve their orbital
periods. The light curve morphologies of both CVs were further analyzed by
defining flux ratios and creating colormaps. KZ Gem shows ellipsoidal
modulations with an orbital period of 0.22242(1) day, twice the period listed
in the updated RK catalogue (Edition 7.24). With this newly determined period,
KZ Gem is no longer a CV in the period gap, but a long-period CV. A part of the
quiescent light curve of TW Vir that had the highest stability was used to
deduce its improved orbital period of 0.182682(3) day. The flat patterns shown
in the colormaps of the flux ratios for KZ Gem demonstrate the stability of
their orbital modulations, while TW Vir show variable orbital modulations
during the K2 datasets. In TW Vir, the single versus double-peaked nature of
the quiescent orbital variations before and after superoutburst may be related
to the effect of the superoutburst on the accretion disk.Comment: 10 pages, 12 figures, accepted by A&
Metal-poor stars observed with the automated planet finder telescope. I. Discovery of five carbon-enhanced metal-poor stars from LAMOST
We report on the discovery of five carbon-enhanced metal-poor (CEMP) stars in
the metallicity range of [Fe/H] . These stars were selected from
the LAMOST DR3 low-resolution (R 2,000) spectroscopic database as
metal-poor candidates and followed-up with high-resolution spectroscopy (R110,000) with the LICK/APF. Stellar parameters and individual abundances
for 25 chemical elements (from Li to Eu) are presented for the first time.
These stars exhibit chemical abundance patterns that are similar to those
reported in other literature studies of very and extremely metal-poor stars.
One of our targets, J21140616, shows high enhancement in carbon
([C/Fe]=1.37), nitrogen ([N/Fe]= 1.88), barium ([Ba/Fe]=1.00), and europium
([Eu/Fe]=0.84). Such chemical abundance pattern suggests that J21140616 can
be classified as CEMP-r/s star. In addition, the star J1054+0528 can be
classified as a CEMP-rI star, with [Eu/Fe]=0.44 and [Ba/Fe]=0.52. The other
stars in our sample show no enhancements in neutron-capture elements and can be
classified as CEMP-no stars. We also performed a kinematic and dynamical
analysis of the sample stars based on Gaia DR2 data. The kinematic parameters,
orbits, and binding energy of these stars, show that J21140616 is member of
the outer halo population, while the remaining stars belong to the inner halo
population but with an accreted origin. Collectively, these results add
important constraints on the origin and evolution of CEMP stars as well as on
their possible formation scenarios
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