High-precision photometry with Ariel Szabó, Gyula M.; Kálmán, Szilárd; Pribulla, Theodor ...
Experimental astronomy,
04/2022, Letnik:
53, Številka:
2
Journal Article
Recenzirano
Odprti dostop
In this paper we describe the photometry instruments of Ariel, consisting of the VISPhot, FGS1 and FGS2 photometers in the visual and mid-IR wavelength. These photometers have their own cadence, ...which can be independent from each other and the cadence of the spectral instruments. Ariel will be capable to do high cadence and high precision photometry in independent bands. There is also a possibility for synthetic
J
synth
,
H
synth
, and wide-band thermal infrared photometry from spectroscopic data. Although the cadence of the synthetic bands will be identical to that of the spectrographs, the precision of synthetic photometry in the suggested synthetic bands will be at least as precise as the optical data. We present the accuracy of these instruments. We also review selected fields of new science which will be opened up by the possibility of high cadence multiband space photometry, including stellar rotation, spin-orbit misalignment, orbital precession, planetary rotation and oblateness, tidal distortions, rings, and moons.
Code ROCHE is devoted to modeling multi-dataset observations of close eclipsing binaries such as radial velocities, multi-wavelength light curves, and broadening functions. The code includes circular ...surface spots, eccentric orbits, asynchronous or/and differential rotation, and third light. The program makes use of synthetic spectra to compute observed UBVRIJHK magnitudes from the surface model and the parallax. The surface grid is derived from a regular icosahedron to secure more-or-less equal (triangular) surface elements with observed intensities computed from synthetic spectra for supplied passband transmission curves. The limb-darkening is automatically interpolated from the tables after each computing step. All proximity effects (tidal deformation, reflection effect, gravity darkening) are taken into account. Integration of synthetic curves is improved by adaptive phase step (important for wide eclipsing systems). The code is still under development. It is planned to extend its capabilities towards low mass ratios and widely different radii of components to facilitate modeling of extrasolar planet transits. Another planned extension of the code will be modeling of spatially-resolved eclipsing binaries using relative visual orbits and/or interferometric visibilities.
High-resolution spectra of visual multiple stars were taken in 2008-2009 to detect or confirm spectroscopic subsystems and to determine their orbits. Radial velocities of 93 late-type stars belonging ...to visual multiple systems were measured by numerical cross-correlation. We provide the individual velocities, the width, and the amplitude of the Gaussians that approximate the correlations. The new information on the multiple systems resulting from these data is discussed. We discovered double-lined binaries in HD 41742B, HD 56593C, and HD 122613AB, confirmed several other known subsystems, and constrained the existence of subsystems in some visual binaries where both components turned out to have similar velocities. The orbits of double-lined subsystems with periods of 148 and 13 days are computed for HD 104471 Aa,Ab and HD 210349 Aa,Ab, respectively. We estimate individual magnitudes and masses of the components in these triple systems and update the outer orbit of HD 104471 AB.
This study is the first attempt to determine the metallicities of W UMa-type binary stars using spectroscopy. We analyzed about 4500 spectra collected at the David Dunlap Observatory. To circumvent ...problems caused by the extreme spectral line broadening and blending and by the relatively low quality of the data, all spectra were subject to the same broadening function (BF) processing to determine the combined line strength in the spectral window centered on the Mg I triplet between 5080 A and 5285 A. All individual integrated BFs were subsequently orbital-phase averaged to derive a single line-strength indicator for each star. The best defined results were obtained for an F-type sub-sample (0.32 < (B - V) sub(0) < 0.62) of 52 binaries for which integrated BF strengths could be interpolated in the model atmosphere predictions.
ABSTRACT High-resolution spectra of visual multiple stars were taken in 2008-2009 to detect or confirm spectroscopic subsystems and to determine their orbits. Radial velocities of 93 late-type stars ...belonging to visual multiple systems were measured by numerical cross-correlation. We provide the individual velocities, the width, and the amplitude of the Gaussians that approximate the correlations. The new information on the multiple systems resulting from these data is discussed. We discovered double-lined binaries in HD 41742B, HD 56593C, and HD 122613AB, confirmed several other known subsystems, and constrained the existence of subsystems in some visual binaries where both components turned out to have similar velocities. The orbits of double-lined subsystems with periods of 148 and 13 days are computed for HD 104471 Aa,Ab and HD 210349 Aa,Ab, respectively. We estimate individual magnitudes and masses of the components in these triple systems and update the outer orbit of HD 104471 AB.
We present results of the Canada-France-Hawaii Telescope adaptive optics (AO) search for companions of a homogeneous group of contact binary stars, as a contribution to our attempts to prove the ...hypothesis that these binaries require a third star to become as close as observed. In addition to directly discovering companions at separations of >=1'', we introduced a new method of AO image analysis utilizing distortions of the AO diffraction ring pattern at separations of 0.07''-1''. Very close companions, with separations in the latter range, were discovered in the systems HV Aqr, OO Aql, CK Boo, XY Leo, BE Scl, and RZ Tau. More distant companions were detected in V402 Aur, AO Cam, and V2082 Cyg. Our results provide a contribution to the mounting evidence that the presence of close companions is a very common phenomenon for very close binaries with orbital periods <1 day.
Abstract
Only a few exoplanets are known to orbit around fast rotating stars. One of them is XO-6b, which orbits an F5V-type star. Shortly after the discovery, we started multicolor photometric and ...radial-velocity follow-up observations of XO-6b, using the telescopes of Astronomical Institute of the Slovak Academy of Sciences. Our main scientific goals were to better characterize the planetary system and to search for transit timing variations. We refined several planetary and orbital parameters. Based on our measurements, the planet XO-6b seems to be about 10% larger, which is, however, only about 2σ difference, but its orbit inclination angle, with respect to the plane of the sky, seems to be significantly smaller, than it was determined originally by the discoverers. In this case we found about 9.5σ difference. Moreover, we observed periodic transit timing variations of XO-6b with a semi-amplitude of about 14 min and with a period of about 450 days. There are two plausible explanations of such transit timing variations: (1) a third object in the system XO-6 causing light-time effect, or (2) resonant perturbations between the transiting planet XO-6b and another unknown low-mass planet in this system. From the O-C diagram we derived that the assumed third object in the system should have a stellar mass, therefore significant variations are expected in the radial-velocity measurements of XO-6. Since this is not the case, and since all attempts to fit radial velocities and O-C data simultaneously failed to provide a consistent solution, more realistic is the second explanation.
Abstract
There is a small group of peculiar early-type stars on the main sequence that show different rotation velocities from different spectral lines. This inconsistency might be due to the binary ...nature of these objects. We aim to verify this hypothesis by a more detailed spectroscopic and photometric investigation of one such object: HD 183986. We obtained 151 high- and medium-resolution spectra that covered an anticipated long orbital period. There is clear evidence of the orbital motion of the primary component. We uncovered a very faint and broad spectrum of the secondary component. The corresponding SB2 orbital parameters, and the component spectra, were obtained by Fourier disentangling using the
KOREL
code. The component spectra were further modeled by
iSpec
code to arrive at the atmospheric quantities and the projected rotational velocities. We have proven that this object is a binary star with a period
P
= 1268.2(11) days, eccentricity
e
= 0.5728(20), and mass ratio
q
= 0.655. The primary component is a slowly rotating star (
v
sin
i
=
27
km s
−1
) while the cooler and less massive secondary rotates much faster (
v
sin
i
∼
120 km s
−1
). Photometric observations obtained by the Transiting Exoplanet Survey Satellite (TESS) satellite were also investigated to shed more light on this object. A multiperiod photometric variability was detected in the TESS data ranging from hours (the
δ
Sct-type variability) to a few days (spots/rotational variability). The physical parameters of the components and the origin of the photometric variability are discussed in more detail.
The shortest period field contact binary Rucinski, Slavek M.; Pribulla, Theodor
Monthly Notices of the Royal Astronomical Society,
08/2008, Letnik:
388, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Photometric and spectroscopic results for the contact binary GSC 01387–00475 (ASAS 083128+1953.1) are presented. The existence of this binary with the orbital period of P= 0.2178 d strengthens the ...argument that the cut-off of the period distribution for contact binaries – until now defined by CC Comae – is very sharp. The only case of a still shorter period is known in a globular cluster where more compact contact configurations are in fact expected. While the spectroscopic orbit of GSC 01387–00475 is well defined, the low orbital inclination of the binary and the presence of a spectroscopic companion contributing about 1/3 of the total light conspire to reduce the photometric variability to ≃0.09 mag. The photometric data are currently inadequate to identify the source of the small amplitude (0.02–0.03 mag) intrinsic variability of the system.
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