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1

Studying the Physical Parameters of the Stellar Binary System Hip 42455 (HD 73900)

Abu-Dhaim A., Taani A., Tanineah D., Tamimi N., Mardini M., Al-Wardat M.

Acta Astronomica

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2022

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Vol. 72, No. 3

171--181

EN

We present the results of the combined spectrophotometric and dynamic analysis for the close visual binary star Hip 42455 (HD 73900, I 314). A model binary that consists of two main sequence stars with a clear magnitude difference, but completely different estimations of their spectral types, and different parallax measurements given by the four catalogs of the two main precise astrometric missions, Hipparcos and Gaia. The analysis follows Al-Wardat's method for analyzing binary and multiple stellar systems. It investigates the system's physical parameters using the parallax measurements given by the catalogs of Hip 1997, Hip 2007, Gaia DR2, and EDR3. The results were as follows: TeffA=6880±70 K, TeffB=5630±70 K, RA=1.554 R☉, RB=0.929 R☉, MA=1.44±0.15M ☉, MB=0.98±0.13M ☉, while the spectral type for the primary and secondary components are G7V and F2V, respectively. As a result, the new parallax for this system was given as πDyn=25.82±0.85, based on the best fit between the dynamical mass sum and the individual masses. This value lies between the old (1997) and new (2007) Hipparcos measurements, and is a bit far from those given by Gaia DR2 and Gaia EDR3.

2

Speckle Observations with PISCO in Calern (France): Orbit and Mass Determinations for 22 Visual Binaries

Ling J. F., Scardia M., Prieur J.-L., Argyle R. W., Aristidi E., Zanutta A., Abe L., Bendjoya P., Rivet J.-P., Vernet D.

Acta Astronomica

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2022

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Vol. 72, No. 2

113--140

EN

This paper presents orbits and masses for 22 visual double stars, partly derived using their last observations made with the speckle camera PISCO. For 13 of them we have determined their first-time orbits. Masses were calculated from Hipparcos and Gaia parallaxes when available, and from dynamical parallaxes otherwise. They are compared with masses deduced from spectral types. Other physical and orbital properties are also considered.

3

High Proper Motion Objects toward the Inner Milky Way: Characterization of Newly Identified Nearby Stars from the VISTA Variables in the Vía Láctea Survey

Gromadzki M., Kurtev R., Beamán J. C., Tekola A., Ramphul R., Ivanov V. D., Minniti D., Folkes S. L., Vaisanen P., Kniazev A. Y., Borissova J., Parsons S. G., Villanueva V.

Acta Astronomica

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2016

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Vol. 66, No. 3

293--306

EN

The census of the Solar neighborhood is still incomplete, as demonstrated by recent discoveries of many objects within 5-10 pc from the Sun. The area around the mid-plane and bulge of the Milky Way presents the most difficulties in searches for such nearby objects, and is therefore deficient in the known population. This is largely due to high stellar densities encountered. Spectroscopic, photometric and kinematic characterization of these objects allows better understanding of the local mass function, the binary fraction, and provides new interesting targets for more detailed studies. We report the spectroscopic follow-up and characterization of twelve bright high proper motion objects, identified from the VISTA Variables in Vía Láctea survey (VVV). We used the 1.9-m telescope of the South African Astronomical Observatory (SAAO) for low-resolution optical spectroscopy and spectral classification, and the MPG/ESP 2.2-m telescope Fiber-fed Extended Range Optical Spectrograph (FEROS) high-resolution optical spectroscopy to obtain the radial and space velocities for three of them. Six of our objects have co-moving companions. We derived optical spectral types and photometric distances, and classified all of them as K and M dwarfs within 27-264 pc from the Sun. Finally, we found that one of the sources, VVV J141421.23-602326.1 (a co-moving companion of VVV J141420.55-602337.1), appears to be a rare massive white dwarf located close to the ZZ Cet instability strip in the CMD and CC diagrams. Many of the objects in our list are interesting targets for exoplanet searches.

4

The Study of Triple Systems V949 Cen, V358 Pup and V1055 Sco

Zasche P., Hoňkovà K., Juryšek J., Mašek M.

Acta Astronomica

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2015

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Vol. 65, No. 2

151--168

EN

The systems V949 Cen, V358 Pup, and V1055 Sco are triples comprised of an eclipsing binary orbiting with a distant visual component on a much longer orbit. The first detailed photometric analysis of these interesting systems was performed using also the archival data from Hipparcos, ASAS, SuperWASP, OMC, and Pi of the Sky surveys. The system V358 Pup was also analyzed using the archival ESO spectra and the radial velocities were derived. The analyses of their light curves revealed the physical properties of the eclipsing components, while the interferometric data for these systems obtained during the last century show that the binaries are also weakly gravitationally bounded with the third components on much longer orbits. The photometry was carried out with the robotic telescope FRAM (part of the Pierre Auger Cosmic Ray Observatory), located in Argentina. The BVRI light curves were analyzed with the PHOEBE program, yielding the basic physical parameters of the systems and their orbits. V949 Cen and V358 Pup were found to be detached systems, while V1055 Sco is probably a semi-detached one. V358 Pup shows a slow apsidal motion, while for V1055 Sco we detected some period variation probably due to the third body in the system, which cannot easily be attributed to the close visual companion. Therefore, we speculate that V1055 Sco can be a quadruple system. For V949 Cen a new orbit was computed, having the orbital period of about 855 yr.

5

The Study of Triple Systems V819 Her, V2388 Oph, and V1031 Ori

Zasche P., Uhlàř R., Svoboda P.

Acta Astronomica

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2014

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Vol. 64, No. 2

125--150

EN

The systems V819 Her, V2388 Oph, and V1031 Ori are triples comprised of an eclipsing binary orbiting with a distant visual component on a longer orbit. A detailed analysis of these interesting systems, combining the two observational techniques: interferometry and apparent period variation, was performed. The interferometric data for these three systems obtained during the last century determine the visual orbits of the distant components in the systems. The combined analysis of the positional measurements together with the analysis of apparent period changes of the eclipsing binary (using the minima timings) can be used to study these systems in a combined approach, resulting in a set of parameters otherwise unobtainable without the radial velocities. The main advantage of the technique presented here is the fact that one needs no spectroscopic monitoring of the visual orbits, which have rather long periods: 5.5 yr for V819 Her, 9.0 yr for V2388 Oph, and 31.3 yr for V1031 Ori, respectively. The eccentricities of the outer orbits are 0.69, 0.33, and 0.92, respectively. Moreover, the use of minima timings of the eclipsing pairs helps us to derive the orientation of the orbit in space with no ambiguity around the celestial plane. And finally, the combined analysis yielded also an independent determination of the distance of V819 Her (68.7±1.8 pc), and V2388 Oph (70.6±8.9 pc). We also present a list of similar systems, which would be suitable for a combined analysis like this one.

6

The Optical Gravitational Lensing Experiment. The Catalog of Stellar Proper Motions toward the Magellanic Clouds

Poleski R., Soszyński I., Udalski A., Szymański M. K., Kubiak M., Pietrzyński G., Wyrzykowski Ł., Ulaczyk K.

Acta Astronomica

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2012

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Vol. 62, No. 1

1-22

EN

We present a catalog of over 6.2 million stars with measured proper motions. All these stars are observed in the direction of the Magellanic Clouds within the brightness range 12

7

The Optical Gravitational Lensing Experiment. High Proper Motion Stars in the OGLE-III Data for Magellanic Clouds Fields

Poleski R., Soszyński I., Udalski A., Szymański M. K., Kubiak M., Pietrzyński G., Wyrzykowski Ł., Ulaczyk K.

Acta Astronomica

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2011

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Vol. 61, No. 3

199--216

EN

We present the results of a search for High Proper Motion (HPM) stars, i.e., the ones with μ>100 mas/yr, in the direction to the Magellanic Clouds. This sky area was not examined in detail as the high stellar density hampers efforts in performing high-quality astrometry. Altogether 549 HPM stars were found with median uncertainties of proper motions per coordinate equal to 0.5 mas/yr. The fastest HPM star has the proper motion of 722.19±0.74 mas/yr. For the majority of objects (70%) parallaxes were also measured. The highest value found is π=91.3±1.6 mas. The parallaxes were used to estimate absolute magnitudes which enriched with color information show that 21 of HPM stars are white dwarfs. Other 23 candidate white dwarfs were selected of HPM stars with no measurable parallaxes using color-magnitude diagram. The search for common proper motion binaries revealed 27 such pairs in the catalog. The completeness of the catalog is estimated to be >80% and it is slightly higher than for previous catalogs in the direction to the Magellanic Clouds.

8

The Distance to Pleiades

Paczyński B.

Acta Astronomica

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2003

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Vol. 56, No. 2

209--211

EN

The distance to Pleiades remains controversial. There is a simple way to resolve the dispute definitely by measuring the distance to one of its brightest members, Atlas, which is an astrometric and spectroscopic binary.

9

The Distance to the Magellanic Clouds

Paczyński B.

Acta Astronomica

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2001

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Vol. 51, No. 2

81--89

EN

The distance to the LMC and SMC is a subject of controversy, with the difference between the extreme values in distance moduli exceeding 0.5 mag. While currently the best calibrated method is based on red clump giants, and the near future improvement is most likely to come from detached eclipsing binaries, the ultimate goal is to have a purely geometrical determination. The best prospect will be to use relatively wide binary stars, for which spectroscopic orbits will be obtained with large ground based telescopes, and astrometric orbits will be obtained either with SIM, or with future ground based interferometers. A preliminary list of 25 candidate systems is presented. It is based on OGLE catalogs of BVI photometry.

10

Catalog of Orbits and Ephemerides of Visual Double Stars

Docobo J. A., Ling J. G., Prieto C., Costa J. M., Costado M. T., Magdalena P.

Acta Astronomica

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2001

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Vol. 51, No. 4

353--356

EN

We describe a catalog of orbits and ephemerides of visual double star systems compiled at the Ramón Maria Aller Observatory. Starting with 1685 orbits for 1240 systems, the catalog will be updated twice yearly, and can be accessed via Internet at http://www.usc.es/astro/catalog.htm.

11

Orientation of the Orbital Planes of Visual Binary Systems

Głębocki R.

Acta Astronomica

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2000

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Vol. 50, No. 2

211--220

EN

The space distribution of orbital poles for 252 visual binaries is analyzed to check a possible tendency towards parallelism. It is confirmed that orbital planes do not show any trend to be parallel to the Galactic plane. No strong evidence is found for a preferential orientation of the orbital planes for subgroups of binaries with similar periods and eccentricities. Asymmetry in the distribution of orbital poles is seen only for a subgroup of 19 binaries lying closer than 10 pc. Small differences in the distribution of orbital poles are also detected for subgroups with different location on HR diagram.