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Аль-Вардат Машхур Ахмад. Интерферометрия и спектрофотометрия двойных звезд солнечного типа : Дис. ... канд. физ.-мат. наук : 01.03.02 : Нижний Архыз, 2003 171 c. РГБ ОД, 61:04-1/355

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Table of Contents 1

1 The Astrophysical Problems of Studying Binary Stars 15

1.1 Milestones in the history of binary stars 15

1.2 Classification of binary stars 17

1.3 Binary star formation mechanisms 18

1.4 Statistics of binary stars and their catalogues 21

1.5 Conclusion 25

2 Speckle Interferometry of Binary Stars 28

2.1 Introduction 28

2.2 Qualitative description 29

2.3 Theoretical description 30

2.4 Programme of the stars 34

2.5 Observations and data analysis 36

2.6 Results and discussion 38

2.6.1 HIP 689 38

2.6.2 HD 25811 (BAG 4) 41

2.6.3 COU 1289 44

2.6.4 COU 1291 47

2.6.5 41 Dra 50

2.7 Conclusions 54

3 Spectrophotometry of Binary Stars 55

3.1 Introduction 55

3.2 Programme of the stars 56

3.3 Observations and data analysis 56

3.4 Results and discussion 61

3.5 Conclusions 76

4 Physical Parameters of the Components of Binary Stars 77

4.1 Introduction 77

4.2 The quadruple system ADS 11061 80

4.2.1 Observational results 82

4.2.2 Atmospheric modeling and discussion 86

1 4.3 The two systems COU 1289 and COU 1291 95

4.3.1 Observational results 96

4.3.2 Atmospheric modeling and discussion 98

4.4 The system HD 25811 105

4.4.1 Observational results 105

4.4.2 Atmospheric modeling and discussion 108

4.5 The system HIP 689 113

4.5.1 Observational results 113

4.5.2 Atmospheric modeling and discussion 116

4.6 Conclusion 121

Conclusion 123

Bibliography 129

A Tables of The Entire Spectral Energy Distributions of Binary Stars  

Введение к работе:

The correlation between spatial locations, dynamical characteristics, ages and metallicities of the main sequence stars is the key for the understanding of the chemical and dynamical evolution of our Galaxy. But even in the vicinity of the sun (d 50 pc), this correlation still remains hardly vague because of the big uncertainties in the determination of the main stellar parameters (Andersen J. 1991,1998).

Nearby stellar populations are occupied mainly by dwarfs of F, G, К and M spectral types, with metallicities in the range -1.0 [Me/H] +0.3. More than 50% of these stars are members of binary and multiple systems(Abt $z Levy 1976; Duquennoy &: Mayor 1991). For such unrecognized systems, natural uncertainties in the determination of photometrical parallaxes, masses, ages and metallicities might be the main reasons of scattering of the points in the known statistical dependencies (Nordstrom et al. 1999).

Most of the unrecognized binary and multiple systems are of the young rapidly rotating main sequence F-stars. For which, the radial velocities as well as the existence of a companion is difficult to define by spectroscopy. Also young F-dwarfs, which have not had enough time to leave their forming regions, are quite important for metallicity distribution studies. Generally, such problem can be solve only by means of interferometric and spectrophotometric observations.

Unresolved binaries, for which separate determination of spectral and photometrical properties is impossible, are usually excluded from observational programs and statistical analysis of normal stars. But big part of the unrecognized multiple systems can significantly change dependencies such as mass-luminosity, mass-radius, age-luminosity and scale of effective temperatures. Moreover, statistical properties are directly connected with the stars formation, but accuracy in such relationships is not enough for the investigation of the modern theories of stellar formation and evolution.

So, the complex study of binary and multiple systems by different observational methods have in principal significant importance in the determination of the main features of the different types of stellar populations in the Galaxy.

Binary systems give a unique possibility for the direct determination of the complete set of stellar parameters without depending on any statistical relations. Such possibility, however, can only be applied for objects having a possibility to be observe by means of different observational methods.

Progress in observational techniques and data processing have greatly increased the number of binary and multiple systems available to the complex studies. This provides a possibility of revision of the statistical dependencies on the basis of the direct determination of the complete set of fundamental parameters of the components of these systems. These parameters are defined by parallax measurements, interferometry, radial velocity measurements and spectrophotometry.

Hipparcos catalogue (ESA, 1997) is the most full and reliable source of the information about stellar parallaxes - it contains more than 20000 parallax measurements for nearby stars with distance estimation errors better than 10%. However, binary systems parallax determinations were distorted by their orbital motions, the reason why their real accuracy was much lower than those of single stars. So, Speckle-Interferometry remains the main method of determination of binary stars visual orbits.

In the Fourth Catalogue of Interferometric Measurements of Binary Stars (http://ad/-usno.navy.mil/wds/mt4.html), one can find more than 28600 observations, made at different telescopes. In comparison with the classical methods of studying visual binary stars, interferometry enables the measurements of less separated systems with higher accuracy.

The only mission which has more observations than speckle-interferometry is Hipparcos, but it had a lower accuracy, larger limited separation and insufficient mission lifeime for reconstructing of the orbits. Concerning long-base interferometry, its advantages of high precision and resolution were restricted by low sensitivity and small number of observations.

Speckle-interferometry also enables us to measure the magnitude differences. But due to methodical problems, high-precision Am speckle-measurements were not possible until recent time (Worley et ah 2001). So, such measurements have been obtained only episodically by means of different algorithms in random photometrical bands. The precision of these measurements was not better than 07 2, and it is even difficult to estimate their reliability.

Differential photometry of binary stars was made by HIPPARCOS, but for pairs as faint as 10"1 — 12m with separation less than (X 3, errors were comparable with the measured values. The method of Am definition carried at SAO RAS via speckle-interferometry provides magnitude differences measurements for systems brighter than 13m with Am 4m and precision about СГ 05. For pairs wider than 0/3, interferometric errors are comparable to those of HIPPARCOS, but for closer pairs they are much smaller (Balega et al. 2002).

Interferometric binary orbits combination with the components radial velocities provides direct masses and parallaxes estimations with precision much better than any other method.

Systematic monitoring of several thousands of nearby solar type stars is carrying out with the velocity measuring device CORAVEL in both north and south hemispheres (Duquennoy & Mayor 1991; Halbwachs et al. 2003). Significant part of these objects (pairs with orbital periods from several hundreds of days till decades) are the candidates for speckle-interferometric measurements on the largest telescopes.

The combination of interferometric Am results with the spectrophotometry data allows to build individual model atmospheres for each component of a binary system. The Result of such measurements is the determination of the statistical dependencies for stars of different types with accuracy enough for theoretical researches.

Thereby, the actuality of the dissertation s task raised from the necessity and opportunity to improve statistical dependencies for F, G and К stars, a knowledge will improve - in its turn - the understanding of the formation and evolution of single and multiple stars and clusters of stars in different parts of our galaxy.

The main goals

The main goals of the dissertation are:

1. To develop a method of direct determination of the complete set of the fundamental parameters of the components of a binary system on the basis of the combination of speckle-interferometric and spectrophotometric observations with the radial velocities and parallaxes measurements.

2. To make a catalogue of spectral energy distributions of the main-sequence F,G and К speckle-interferometric binaries, to estimate their colors and to reinvestigate their entire spectral types.

3. To observe several chosen objects by means of speckle-interferometric techniques in order to reconstruct their visual orbits, measure their Дт and obtain their absolute magnitudes.

4. To build individual spectral energy distributions for the components the selected systems by means of atmospheres modeling combination with their measured magnitude differences and known parallaxes. Hence, to determine their complete set of fundamental parameters: effective temperatures, luminosities, spectral types, masses, gravity accelerations and ages.

5. To investigate advantages and restrictions of the developed method in the revision of the existing statistical dependencies.

New scientific results

To developed method of direct determination of the fundamental stellar parameters was investigated on the basis of the combination of speckle-interferometric and spectrophotometric observations of binary systems.

Composite spectral energy distributions of 46 speckle binary stars were measured for the first time. The measurements were made at the Cassegrain focus of the Carl Zeiss Jena (Zeiss-1000) 1 m telescope of SAO. The measured SED s covered the range between 3700A and 8300A. The BVR magnitudes A good agreement has been found between the calculated colour magnitudes and colour indices and those of Hipparcos and Tycho catalogues. Also a comparison of the estimated spectral types with those given by SIMBAD (http://simbad.u-strasburg/Simbad) shows a good agreement for most of the stars within the error values of В — V. and the В — V colour indices for all of the 46 stars were calculated, and their composite spectral types were estimated.

New relative positions of five speckle interferometric binary systems were measured using the speckle interferometric techniques at the 6-meter telescope of the Special Astrophysical Observatory (SAO RAS), these are: 41 Dra, COU 1289, COU 1291, HD 25811 HIP 689. For the first time, modified orbital elements of these stars were obtained. Their magnitude differences were estimated and they were combined with Hipparcos parallax (ESA 1997) and the known entire V magnitude to calculate the absolute magnitudes of their components, and hence their spectral types.

For the first time, individual theoretical SEDs were build for each of the two components of the binary systems: 40 Dra, 41 Dra, COU 1289, COU 1291, HD 25811 and HIP 689. The method used Kurucz (1993) line-blanketed plane-parallel model atmospheres combination with the results of speckle interferometry and spectrophotometry.

Presentations

The main results of this work were presented in the following international conferences and seminars:

The Second Arab Astronomical Conference (Amman, Jordan; 8-10 September 1997);

The First All-Russian Astronomical Conference (Saint Petersburg; 6-12 August 2001);

IAU Symposium No. 210, Modelling of Stellar Atmospheres (Uppsala, Sweden; 17-21 June 2002);

The 5th Arab Astronomical Conference & The 3rd Conference for AUASS (Amman, Jordan; 19 - 22 August 2002);

The sstrophysical seminars at the Special Astrophysical Observatory (SAO) (Nizhnij Arkhyz), and at the Higher Institute of Astronomy and Space Sciences, АІ al-Bayt University, Mafraq, Jordan. 

Main items proposed for defense

1. The results of spectrophotometric study of 46 speckle interferometric binary systems, which include their entire spectral energy distributions in the range 3700-8400 A, BVR Johnson-Cousins magnitudes, В — V magnitude differences, and their entire spectral types.

2. The results of speckle interferometric measurements of 41 Dra, COU 1289, COU 1291, HD 25811 and HIP 689, which include measurements of their relative positions, determination of their orbital parameters, mass sums and magnitude differences.

3. Results of the combination of speckle interferometry and spectrophotometry with the atmospheres modeling to estimate the fundamental parameters of the components of 40 Dra, 41 Dra, COU 1289, COU 1291, HD 25811 and HIP 689. The parameters include their spectral types, luminosities, effective temperatures, radii, masses, gravity accelerations and ages.

Personal input of the author

Speckle interferometric observations and data reduction were made together with the group of The Laboratory of High Resolution in Astronomy (SAO RAS). The final estimations and results were made by the author.

All spectrophotometric observations, data reductions, atmospheres modeling and results extraction were made by the author.

Contents of the dissertation

This dissertation consists of introduction, four chapters, conclusion, bibliography of 121 items, and appendix. It consists of 145 pages including 54 figures and 54 tables.

In the Introduction the importance of the work was explained in addition to the actuality, the main goals, the new scientific results, the presentations, the main items proposed for defense, the personal input of the author, a brief contents of the dissertation and a list of the author s publications.

In the 1st chapter The Astrophysical Problems of Studying Binai-y Stars brief review of modern knowledge in the field is given, including relationships between fundamental stellar parameters and the formation and evolution theories. Conclusions were made about the low precision of the statistical dependencies of mass-luminosity, mass-radius, age-luminosity and the scale of the effective temperatures with the comparisons of theoretical models. The concepts of improvement of these statistical dependencies were discussed on the basis of the complex study of visual close binary stars which depends on the combination between speckle interferometry, spectrophotometry, radial velocities and parallaxes. At the end of the chapter, the stars selection criteria to apply the direct method of estimation of the fundamental parameters were discussed.

In the 2nd chapter Speckle Interferometry of Binary Stars, description of the speckle interferometric method of measuring relative positions and magnitude differences of binary and multiple systems is presented.

The method enabled us to achieve high accuracy measurements of the relative positions of binary stars using large ground based telescopes.

Although diffraction limit of the telescope a = 1.22Л/Д is only several milli-arc-seconds (0/02 in the case of BTA), resolution of ground telescopes is rarely more than 1".

The main reason which decreased the resolution is the turbulence of the earth atmosphere. However, at exposures comparable to the atmospheric turbulence time (which freeze the atmospheric degradation), monochromatic images of the stars powerfully save information with the diffraction limits of the telescope.

The statistical processing method proposed by Labeyrie A.( 1970) enables obtaining power spectra or auto-correlation functions of the set of instant images of the source. In the case of binary stars, the method made it possible to determine relative positions and relative intensities of the components using geometrical parameters and fringes contrast of the measured power spectrum.

The system used to obtain speckle interferometric data at the prime focus of BAT was discussed along with the procedures of processing the sets of speckle interferograms, determination of the relative positions and magnitude differences of the binary and multiple stars.

The method was applied to five binary systems: 41 Dra, Cou 1289, Cou 1291, HD 25811 and HIP 689. The results of observations performed in 2001 and 2002 include their relative position measurements with accuracy C. OQl- ОС ООЗ and magnitude differences with accuracy 0Г 04- 07 12 (Al-Wardat et al. 2003). Improved orbits for the five systems were archived using the new points along with those from the Fourth Catalog of Interferometric Measurements of Binary Stars, the new estimated orbital elements were compared with the other authors. Direct proof of 15 years period for the system COU 1289 was obtained, the system was resolved three times during the closest approach of its components when the angular separation was between 0V018 and 0 019.

The computed orbital parameters and magnitude differences were combined with the parallaxes, from Hipparcos, to derive the mass sums, the individual absolute magnitudes and the spectral types of the components. The accuracy of the estimated masses and absolute magnitudes depends, mainly, on the errors of the used parallax.

In the 3rd chapter Spectrophotometry of Binary Stars, a wide range ( 4500 A), low resolution (18 A, 6 A/px) spectrophotometry of 46 speckle interferometric binary stars were presented, where I got their entire spectral energy distributions, BVR magnitudes, В — V colour indices, and their entire spectral types. The objects of the study were taken from the speckle interferometric programme, which has been carried out at the 6-m BTA telescope of the Special Astrophysical Observatory since the early nineties. The programme mainly includes late type dwarfs in the vicinity of the Sun, which fundamental parameters are badly known.

Beside the direct results of these observations, a part of the presented data were used as a reference for building theoretical spectral energy distribution curves on the basis of Kurucz blanketed models. These along with the magnitude differences from speckle interferometric observations, were used to build spectral energy distributions for the components of the binary systems, from which we got their complete set of fundamental parameters (see chapter 4).

The stars were divided into three sets (Set A, Set В and Set C) according to the observational campaigns. The spectra were obtained using a low resolution grating (325/4° grooves/mm, 5.97 A/px reciprocal dispersion) within the UAGS spectrograph at the Cassegrain focus of the Carl Zeiss Jena (Zeiss-1000) 1 m telescope of SAO during the photometrical nights: January 28 and February 4, 2002 for set A; May 25, 26 and 27, 2002 for set B; and July 20 and 21, 2002 for set C. The seeing in all nights was around 1.5". The stars are listed in three tables, which include their different identifications, coordinates and times of observations in Julian Date.

The used spectrograph has an 1SD015A 530x580 px CCD detector, its parameters and sensitivity curves at the blue and red parts of the spectrum are shown in the chapter.

A well known standards were used for the calibration and investigation of the external agreement of the system. The standard deviation of В and V magnitudes, obtained for each star from the sample of the spectra, was typically better than 074)6, and for the R band it was better than СГ07.

The results of the measured flux, corrected for the atmospheric extinction, are listed in the Appendix and plotted in the chapter in units of erg/cm2 • s-A.

BVR synthetic magnitudes were computed using the zero points of the spectrophotometric calibration of Vega. For V band ZP was solved using the spectrophotometric calibration of Vega published by Hayes (1985) and the V magnitude of 07 03 measured by Johnson et al. (1966). While for В and R bands it was solved using the Vega magnitudes published by Hamuy et al. (2001) as В = 07Ю14, and R = (Г042.

A good agreement has been found between the calculated colour magnitudes and colour indices and those of Hipparcos and Tycho catalogues.

The entire spectral types of the binaries were estimated by comparing В — V with the intrinsic colours of FitzGerald (1970). The comparison of the estimated spectral types with those given by SIMBAD showed a good agreement for most of the stars within the error values of В — V.

In the 4th chapter Physical Parameters of the Components of Binary Stars, I presented the study of six binary systems (the quadruple system ADS 11061, the binary systems COU 1289, COU 1291, HD 25811 and HIP 689) as examples for the combination method of atmospheric modeling with the observational results of speckle interferometry and spectrophotometry to estimate the fundamental parameters of their components.

The description of each system started by introduction about the system includes its importance in such study, list of data concerning the system from different sources like SIMBAD, Hipparcos and other sources. Followed by individual description of spectrophotometrical results.

Using the magnitude differences from the results of speckle interferometry and the entire visual magnitudes from the spectrophotometric results, the individual magnitudes of the components were calculated. These along the parallax were used со calculate the absolute visual magnitudes, from which we estimate the preliminary effective temperatures, radii and gravity accelerations. This allows construction of model atmospheres for each component using the grid of the Kurucz {1994) blanketed models.

The entire SED s of these pairs from the spectrophotometric results were used as a reference for the best fitting with the theoretical ones, and for the feedback of the parameters of their components. Hence the complete set of parameters of each component were estimated including: effective temperature, luminosity, spectral type, mass and gravity acceleration.

The positions of systems components on the evolutionary tracks and isochrones of Girardi et al. (2000) were assigned, and their ages were estimated. Formation and evolution of the systems were discussed according to the formation theories, where filament fragmentation was proposed as the most likely process for the formation and evolution of the quadruple system ADS 11061, and Fragmentation was proposed as the most likely process for the formation and evolution of the systems COU 1289, COU 1291, HD 25811 and HIP 689. 

In the Conclusion, the main results of this work were listed.

Particulary, we developed a complex method of estimation of the fundamental stellar parameters of the components of binary and multiple systems of stars. The method depends on the combination between speckle interferometry, spectrophotometry and atmospheres modeling.

The method uses the magnitude differences between the components and the mass sums of the systems measured by means of speckle interferometry with the entire spectral energy distributions and apparent magnitudes of the systems measured by spectrophotometry to build individual theoretical SED for each of the subcomponents using Kurucz (1993) line-blanketed plane-parallel model atmospheres. From which we estimate the complete set of the fundamental parameters of each component of a binary system.

The method was applied to a sample of six speckle interferometric binary systems of the nearby Fype dwarfs, these were: 40 Dra, 41 Dra, COU 1289, COU 1291, HD 25811 and HIP 689.

The orbital elements of the studied systems, their magnitude differences, absolute magnitudes, mass sums and spectral Types were estimated in addition to the the complete set of the individual fundamental parameters of the components (effective temperatures, luminosities, spectral types, masses, gravity accelerations and ages).

The estimated parameters forms the most detailed and accurate ones ever estimated for the studied systems. Comparisons with the known relations for disk lateype dwarfs has been made.

In addition we got the entire SEDs for 46 speckle-interferometric main sequences binaries. These data give an opportunity to improve statistical dependencies for the nearby stellar populations. The results can be used for the study of formation and evolution of binary and multiple systems.

The Appendix includes the tables of the spectral energy distributions for the 46 stars studied in chapter 3.

Publications of the author

1. Al-Wardat M.A., Al-Naimiy H.M., Barghouthi I.A., and Sabat H. New physical and geometrical elements of some x-ray binary stars, Astrophysics and Space Science, 260; 335-345, 1999.

2. Sabat H., Al-Naimiy H.M., Barghouthi I.A., and Al-Wardat M.A. Synthetic light curve of some X-ray binary stars, Astrophysics and Space Science, 260; 347-357, 1999.

3. Al-Wardat M.A., Balega LI., Balega Yu.Yu., Lueshin V.V., Pluzhnik E.A., Shkhago-sheva Z.U., The system 41 Draconis: approaching priastron on 2001, Proceedings of All-Russian Astronomical Conference (Saint Petersburg; 6-12 August 2001).

4. Al-Wardat M.A., Balega Yu.Yu., Leushin V.V., Monin D., Pluznik E.A. The Complex Study of the Quadruple System ADS11061, Proceedings of the IAU Symposium No. 210 Modelling of Stellar Atmospheres (Uppsala, Sweden; 17-21 June 2002).

5. Al-Wardat M.A. Spectral energy distributions and model atmosphere parameters of the quadruple system ADSl 1061, Bull. Spec. Astrophys. Observatory, 53, 51-57,2002.

6. Al-Wardat M.A. Spectrophotometry of speckle binary stars, Bull. Spec. Astrophys. Observatory, 53, 58-77, 2002.

7. Al-Wardat M.A. Spectrophotometry of speckle binary stars II, Bull. Spec. Astrophys. Observatory, 54, 29-45, 2002.

8. Al-Wardat M.A. Spectrophotometry of speckle binary stars III, Bull. Spec. Astrophys. Observatory, 55, 18-37, 2003.

9. Al-Wardat M.A. Spectral energy distributions and model atmosphere parameters of the binary systems COU1289 and CO U1291, Bull. Spec. Astrophys. Observatory, Preprint

#185

10. Al-Wardat M.A. Model atmosphere parameters of the binary systems 41Dra, Bull. Spec. Astrophys. Observatory, Preprint # 186

11. Al-Wardat M. A., Balega Yu.Yu., Pluznik E.A., Shkhagosheva Z.U. Speckle interfero-metric results and modified orbits of five binary systems, Spec. Astrophys. Observatory, Preprint #190  

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