66 research outputs found
Kepler Binary Stars in NGC 6819 Open Cluster: KIC 5113146 and KIC 5111815
In this study, investigation of two double-lined binary stars KIC 5113146 and
KIC 5111815 in NGC 6819 is presented based on both photometric and
spectroscopic data. Simultaneous analysis of light and radial velocity curves
was made and the absolute parameters of the systems' components were determined
for the first time. We find that both systems have F-type main-sequence
components. The masses and radii were found to be ,
and ,
for the primary and secondary components of KIC
5113146; , and
, for components of
KIC 5111815, respectively. Evolutionary status of the components was evaluated
based on the MESA evolutionary tracks and isochrones. The ages of the KIC
5111815 and KIC 5113146 were derived to be about Gyr and
Gyr, respectively. Photometric distances were calculated to be
pc for KIC 5113146 and pc for KIC 5111815. The
results obtained in this study, astrometric data and researches in the
literature reveal that both KIC 5113146 and KIC 5111815 systems are the most
likely member of NGC 6819.Comment: 26 pages, including 7 figures and 4 tables, accepted for publication
in Astronomical Journa
The Spectroscopic Orbits of Three Double-lined Eclipsing Binaries: I. BG Ind, IM Mon, RS Sgr
We present the spectroscopic orbit solutions of three double-lines eclipsing
binaries, BG Ind, IM Mon and RS Sgr. The first precise radial velocities (RVs)
of the components were determined using high resolution echelle spectra
obtained at Mt. John University Observatory in New Zealand. The RVs of the
components of BG Ind and RS Sgr were measured using Gaussian fittings to the
selected spectral lines, whereas two-dimensional cross-correlation technique
was preferred to determine the RVs of IM Mon since it has relatively short
orbital period among the other targets and so blending of the lines is more
effective. For all systems, the Keplerian orbital solution was used during the
analysis and also circular orbit was adopted because the eccentricities for all
targets were found to be negligible. The first precise orbit analysis of these
systems gives the mass ratios of the systems as 0.894, 0.606 and 0.325,
respectively for BG Ind, IM Mon and RS Sgr. Comparison of the mass ratio
values, orbital sizes and minimum masses of the components of the systems
indicates that all systems should have different physical, dynamical and
probable evolutionary status.Comment: 17 pages, 6 figures and 4 tables, accepted for publication in New
Astronom
On the Zero Point Constant of the Bolometric Correction Scale
Arbitrariness attributed to the zero point constant of the band
bolometric corrections () and its relation to "bolometric magnitude of a
star ought to be brighter than its visual magnitude" and "bolometric
corrections must always be negative" was investigated. The falsehood of the
second assertion became noticeable to us after IAU 2015 General Assembly
Resolution B2, where the zero point constant of bolometric magnitude scale was
decided to have a definite value ~. Since the zero
point constant of the scale could be written as , where
is the zero point constant of the visual magnitudes in the basic
definition , and , the zero point
constant () of the scale cannot be arbitrary anymore; rather, it
must be a definite positive number obtained from the two definite positive
numbers. The two conditions and are also sufficient for
, a similar case to negative numbers, which means that
"bolometric corrections are not always negative". In sum it becomes apparent
that the first assertion is misleading causing one to understand bolometric
corrections must always be negative, which is not necessarily true.Comment: 12 pages, including 3 figures and 1 table, accepted for publication
in Monthly Notices of the Royal Astronomical Societ
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