22 research outputs found
KIC 4150611: a rare multi-eclipsing quintuple with a hybrid pulsator
We present the results of our analysis of KIC 4150611 (HD 181469) - an
interesting, bright quintuple system that includes a hybrid
Sct/ Dor pulsator. Four periods of eclipses - 94.2, 8.65, 1.52 and 1.43
d - have been observed by the Kepler satellite, and three point sources (A, B,
and C) are seen in high angular resolution images.
From spectroscopic observations made with the HIDES spectrograph attached to
the 1.88-m telescope of the Okayama Astrophysical Observatory (OAO), for the
first time we calculated radial velocities (RVs) of the component B - a pair of
G-type stars - and combined them with Kepler photometry in order to obtain
absolute physical parameters of this pair. We also managed to directly measure
RVs of the pulsator, also for the first time. Additionally, we modelled the
light curves of the 1.52 and 1.43-day pairs, and measured their eclipse timing
variations (ETVs). We also performed relative astrometry and photometry of
three sources seen on the images taken with the NIRC2 camera of the Keck II
telescope. Finally, we compared our results with theoretical isochrones.
The brightest component Aa is the hybrid pulsator, transited every 94.2 days
by a pair of K/M-type stars (Ab1+Ab2), which themselves form a 1.52-day
eclipsing binary. The components Ba and Bb are late G-type stars, forming
another eclipsing pair with a 8.65 day period. Their masses and radii are
M, R for the
primary, and M, R
for the secondary. The remaining period of 1.43 days is possibly related to a
faint third star C, which itself is most likely a background object. The
system's properties are well-represented by a 35 Myr isochrone. There are also
hints of additional bodies in the system.Comment: 14 pages, 15 figures, 7 tables, to appear in A&A, abstract modified
in order to fit the arXiv limi
PIERNIK mhd code - a multi-fluid, non-ideal extension of the relaxing-TVD scheme (I)
We present a new multi-fluid, grid MHD code PIERNIK, which is based on the
Relaxing TVD scheme. The original scheme has been extended by an addition of
dynamically independent, but interacting fluids: dust and a diffusive cosmic
ray gas, described within the fluid approximation, with an option to add other
fluids in an easy way. The code has been equipped with shearing-box boundary
conditions, and a selfgravity module, Ohmic resistivity module, as well as
other facilities which are useful in astrophysical fluid-dynamical simulations.
The code is parallelized by means of the MPI library. In this paper we shortly
introduce basic elements of the Relaxing TVD MHD algorithm, following Trac &
Pen (2003) and Pen et al. (2003), and then focus on the conservative
implementation of the shearing box model, constructed with the aid of the
Masset's (2000) method. We present results of a test example of a formation of
a gravitationally bounded object (planet) in a self-gravitating and
differentially rotating fluid.Comment: 6 pages, 3 figures, conference proceedings of the Torun Exoplanets
200
Orbital and physical parameters of eclipsing binaries from the All-Sky Automated Survey catalogue - X. Three high-contrast systems with secondaries detected with IR spectroscopy
We present results of the combined photometric and spectroscopic analysis of
three detached eclipsing binaries, which secondary components are not visible
or very hard to identify in the optical spectra - ASAS J052743-0359.7, ASAS
J065134-2211.5, and ASAS J073507-0905.7. The first one is a known visual binary
ADS 4022, and we found that it is a quadruple system, composed of two
spectroscopic binaries, one of which shows eclipses. None of the systems was
previously recognized as a spectroscopic binary.
We collected a number of high-resolution optical and IR spectra to calculate
the radial velocities (RVs) and later combined them with MITSuME and ASAS
photometry. The IR spectra were crucial for secure identification of the cooler
components' lines. RV measurements were done with the TODCOR technique, and RV
curves modelled with our own procedure V2FIT. Light curve modelling was
performed with JKTEBOP and PHOEBE codes. Temperatures and metallicities of two
systems were estimated from spectra. For the ADS 4022 system we also used the
archival WDS data and new SOAR observations in order to derive the orbit of the
visual pair for the first time. Ages were estimated by comparing our results
with PARSEC isochrones.
The eclipsing pair A052743 A ( d) is composed of a 1.03(6) M,
1.03(2) R primary and a 0.60(2) M, 0.59(2) R secondary.
The components of the d non-eclipsing pair B likely have masses in
between the two eclipsing components, and both pairs are on a 188 yr
orbit around their common centre of mass. The system A065134 ( d)
consists of a 0.956(12) M, 0.997(4) R primary and a 0.674(5)
M, 0.690(7) R secondary. Finally, A073507 ( d), which
consists of a 1.452(34) M, 1.635(12) R primary and a 0.808(13)
M, 0.819(11) R secondary, is likely a PMS system.Comment: 22 pages, 13 figures, 8 tables, accepted for publication in A&A,
abstract modified for arXi
Cosmic-ray driven dynamo in galactic disks
We present new developments on the Cosmic--Ray driven, galactic dynamo,
modeled by means of direct, resistive CR--MHD simulations, performed with ZEUS
and PIERNIK codes. The dynamo action, leading to the amplification of
large--scale galactic magnetic fields on galactic rotation timescales, appears
as a result of galactic differential rotation, buoyancy of the cosmic ray
component and resistive dissipation of small--scale turbulent magnetic fields.
Our new results include demonstration of the global--galactic dynamo action
driven by Cosmic Rays supplied in supernova remnants. An essential outcome of
the new series of global galactic dynamo models is the equipartition of the gas
turbulent energy with magnetic field energy and cosmic ray energy, in saturated
states of the dynamo on large galactic scales.Comment: 6 pages, 3 figures, To be published in "Cosmic Magnetic Fields: From
Planets, to Stars and Galaxies", K.G. Strassmeier, A.G. Kosovichev & J.E.
Beckman, eds., Proc. IAU Symp. 259, CU
Near-Resonance In A System Of Sub-Neptunes From TESS
We report the Transiting Exoplanet Survey Satellite detection of a multi-planet system orbiting the V = 10.9 K0 dwarf TOI-125. We find evidence for up to five planets, with varying confidence. Three transit signals with high signal-to-noise ratio correspond to sub-Neptune-sized planets (2.76, 2.79, and 2.94 R⊕), and we statistically validate the planetary nature of the two inner planets (Pb = 4.65 days, Pc = 9.15 days). With only two transits observed, we report the outer object (P.03 = 19.98 days) as a planet candidate with high signal-to-noise ratio. We also detect a candidate transiting super-Earth (1.4 R⊕) with an orbital period of only 12.7 hr and a candidate Neptune-sized planet (4.2 R⊕) with a period of 13.28 days, both at low signal-to-noise ratio. This system is amenable to mass determination via radial velocities and transit-timing variations, and provides an opportunity to study planets of similar size while controlling for age and environment. The ratio of orbital periods between TOI-125 b and c (Pc/Pb = 1.97) is slightly lower than an exact 2:1 commensurability and is atypical of multiple planet systems from Kepler, which show a preference for period ratios just wide of first-order period ratios. A dynamical analysis refines the allowed parameter space through stability arguments and suggests that despite the nearly commensurate periods, the system is unlikely to be in resonance
Incorporating cosmic rays in local and global models of disk-halo interaction
We present new developments on the cosmic-ray driven, galactic dynamo, modeled by means of direct, resistive CR–MHD simulations, performed with ZEUS and PIERNIK codes. The dynamo action, leading to the amplification of large–scale galactic magnetic-fields on galactic rotation timescales, appears as a result of galactic differential rotation, buoyancy of the cosmic-ray component and resistive dissipation of small–scale turbulent magnetic-fields. Our new results include demonstration of the global–galactic dynamo action driven by cosmic-rays supplied in supernova remnants. An essential outcome of the new series of global galactic dynamo models is the equipartition of the gas turbulent energy with magnetic-field energy and cosmic-ray energy, in saturated states of the dynamo on large galactic scales