TX UMa Research Articles

TX UMa: new orbit, spin rotation and chemical composition of components

High-resolution echelle spectra have been obtained of the semi-detached Algol-type eclipsing binary system, TX UMa with the high-resolution echelle spectrographs of the 1.8 m telescope at Bohyunsan Optical Astronomy Observatory in Korea and of the 2.0 m telescope of Peak Terskol Observatory in Russia. New accurate radial velocities of its components have been measured. With the new measurements, we have been able to infer an improved orbital solution and the masses of the components of the system. For the first time, we have measured the rotational velocity for the Roche lobe filling secondary component. We have concluded that it rotates synchronously, while the rotation of the mass-accreting primary component is 1.5 times faster than synchronous. TX UMa confirms the previous conclusion that the strong lines of the light elements (N, O, Mg) in the atmospheres of mass-accreting components in Algol-type systems are stronger and wider than in single stars of the same spectral class and luminosity. Stronger lines also imply higher elemental abundances than weak lines, but this can also be explained if the former have greater microturbulent velocities. We have suggested that such an excess enhancement of the strong lines may be explained in terms of a distended pseudo-atmosphere of the mass-accreting component, engendered by gas flowing in via the L1 Lagrange point. We have found the chemical abundances of 12 elements in the atmosphere of the primary component of TX UMa. Si and Ni were found to show significant deficiencies while the abundance measures of C varied (within the uncertainties of the model atmosphere parameters) from solar to noticeably deficient. Other elements, including He, have solar abundance. The abundances of the secondary component are likely solar, as its spectrum is represented well by a synthetic spectrum with solar abundance and Teff= 5500 K and log g = 3.3.

Orbital Period Studies of Two Algol‐Type Eclipsing Binary Systems: TY Pegasi and X Trianguli

ABSTRACTO - C curves of two EA‐type eclipsing binaries, TY Peg and X Tri, are formed and studied in detail based on all available times of light minimum. For TY Peg, it was discovered that the general trend of the O - C curve showed a downward parabolic variation, which indicates a secular period decrease with rate at dP/dt = -1.16 × 10-6 days yr−1. When the secular decrease is removed from the O - C curve, the residuals can be described by several linear ephemerides, suggesting several sudden period jumps. For the other one, X Tri, it is found that the general O - C trend also indicates a secular period decrease (dP/dt = -1.42 × 10-7 days yr−1), and several irregular period jumps are found to superpose on the long‐time period decrease. This kind of period change, irregular sudden jumps superposed on secular decrease, is typical for many other Algol‐type binary systems such as TU Her, UU And, Z Per, Y Psc, BO Mon, FH Ori, RT Per, and TX UMa. The period changes of these systems may be caused by orbital angular momentum loss via variable magnetic coupling and gravity coupling between the components.

Possible Mass and Angular Momentum Loss in Algol-Type Binaries. V. RT Persei and TX Ursae Majoris

The changes in the orbital periods of two EA-type eclipsing binaries, RT Per and TX UMa, are studied in detail, based on the analysis of their times of minimum light. For RT Per, it is shown that the trend of the O-C curve can be described by a parabola opening at the bottom, which indicates a secular period decrease at the rate dP/dt -9.29 x 10(-8) days yr(-1). By subtracting the secular decrease in the O-C curve, the residuals display an oscillatory variation that can either be described by a continuous periodic change, indicating the presence of a third body, or by several linear ephemerides, indicating several sudden period jumps. Since the oscillatory change is not strictly periodic, the latter is more plausible, which suggests that several irregular period jumps are superposed on the long-term period decrease. For the other object, TX UMa, it is discovered that the O-C trend also suggests a secular period decrease (dP/dt = -7.13 x 10(-7) days yr(-1)), and five irregular period jumps are found superposed on the secular period decrease. This kind of period is not unique for Algol-type binary systems. The period changes, both the secular decrease and the sudden jumps, can be plausibly explained by orbital angular momentum loss via magnetic coupling and gravity coupling between the components.

Morphologies of Hα Accretion Regions in Algol Binaries

We have investigated a group of 18 Algol-type binaries to determine the general morphologies and physical properties of the accretion regions in these systems. The systems studied were V505 Sgr, RZ Cas, AI Dra, TV Cas, TW Cas, δ Lib, RW Tau, TW Dra, β Per, TX UMa, U Sge, S Equ, U CrB, RS Vul, SW Cyg, CX Dra, TT Hya, and AU Mon, in order of increasing orbital period P = 1.18-11.11 days. In addition, the RS CVn-type binary HR 1099 (V711 Tau) was observed to illustrate the appearance of chromospheric Hα emission. Nearly 2200 time-resolved Hα spectra were collected from 1992 March to 1994 December with the McMath-Pierce Solar Telescope at NSO and mostly with the Coude Feed Telescope at KPNO. The spectra were obtained at phases around the entire orbit of each binary and were closely spaced to permit the detection of transitions in the profiles. Moreover, the spectra were obtained typically within three orbital cycles to reduce the influence of secular variations. Difference profiles were calculated by subtracting a composite theoretical photospheric spectrum from the observed spectrum. The analysis of the Hα difference profiles demonstrates that the accretion structures in Algol binaries have four basic morphological types: (1) double-peaked emission systems in which the accretion structure is a transient or classical accretion disk; (2) single-peaked emission systems in which the accreted gas was found along the trajectory of the gas stream and also between the two stars in an accretion annulus; (3) alternating single- and double-peaked emission systems, which can change between a single-peaked and a double-peaked type within an orbital cycle; and (4) weak spectrum systems in which there was little evidence of any accretion structure since the difference spectra are weak at all phases. The first two types are the dominant morphologies. The first type can be interpreted physically as a disklike distribution, while the second is a gas stream-like distribution. The most common type in short-period Algols with 2.7 days 6 days) were found to have slightly variable but permanent accretion disks at all epochs (i.e., CX Dra, TT Hya, and AU Mon), similar to those found in cataclysmic variables. SW Cyg (P = 4.57 days) was found to be an intermediate case between the shorter period systems with P 6 days. Two systems, U Sge and U CrB, displayed alternating single- and double-peaked emission at different epochs (Type 3), and changes from one type to another were detected within a 12 hour time interval. Observations at multiple epochs suggest that four members of the single-peaked emission group, namely RW Tau, TX UMa, S Equ, and RS Vul, may actually belong to the alternating group. So, the complete group of alternating systems covers periods of 2.7 days < P < 4.5 days. Finally, the systems V505 Sgr, δ Lib, AI Dra, TW Cas, and TV Cas had weak difference spectra or uninteresting observed spectra at most phases (Type 4). All of these systems have orbital periods P < 2.4 days and are high in the r-q diagram. In these cases, the mass-gaining star is very large relative to the binary separation, and the path of the gas stream path is very short, so there is very little room to form any substantial accretion structures as found in the other systems.

ITAL]ORFEUS-SPAS II[/ITAL] Observations of Algol-type Interacting Binaries

The first results from ORFEUS-SPAS II observations of five Algol-type binary systems obtained during the shuttle mission STS-80 in 1996 November/December are reported. Single spectra covering 900-1220 Å of AU Mon, Z Vul, U CrB, and TX UMa were acquired with the Berkeley spectrograph. TT Hya was observed at three phases (0.19, 0.63, and 0.95) to study mass flow and to investigate asymmetry in the circumstellar material in the system. O VI was not detected in any of the binaries, which allows us to place an upper limit on Tion in the high-temperature plasma seen in Algol-type binaries. Circumstellar material, presumably associated with the accretion disk, was detected in Fe III (UV1) in AU Mon. We estimate a particle density in the range 108-109 cm-3 for the region of the disk sampled during the observations. Evidence for mass infall was found in the phase 0.95 spectrum of TT Hya. From the additional (redshifted) absorption in N II (1085 Å) and N I (1135 Å), we find evidence for superionization in this plasma and estimate a lower limit of 10-12 M☉ yr-1 for the current infall rate.

Doppler tomography of chromospheres and accretion regions in Algol binaries

The technique of back-projection Doppler tomography has been used to produce the first set of reconstructed images of chromospheric emission sources in the class of Algol-type binaries. The Hα emission sources in the Doppler tomograms include the gas stream, a sub-Keplerian accretion annulus, a quasi-stable accretion disk, and the chromosphere of the cool secondary star. The chromospheric images of several Algol secondaries (e.g., RS Vul, β Per, TX UMa, RW Tau) are consistent with that of the RS CVn binary V711 Tau.

The chemical composition of Algol systems - V. Confirmation of carbon deficiencies in the primaries of eight systems

We use low-noise CCD spectra of the 4267-A C II line in the spectra of eight Algol-type eclipsing binaries to measure the C abundances of their primaries. A differential LTE analysis of the Algol binaries with respect to single standard stars of the same spectral type shows marginal, to moderate deficiencies of C in the primaries of the binaries. We find [C/H] abundances of −0.62 for U CrB, −0.34 for u Her, ≤+0.24 for δ Lib, −0.22 for β Per, −0.18 for U Sge, −0.48 for λ Tau, −0.35 for TX UMa and −0.16 for RS Vul with respect to the average C abundance of single B-type standard stars. These results confirm those of Cugier and Hardorp, who have used IUE observations of the 1300-A C II lines to determine C abundances in the same stars

Circumstellar material in TX Ursae Majoris

The analysis of the H-alpha difference profiles of TX UMa has revealed deep redshifted absorption during primary eclipse, weaker redshifted absorption at other phases, and strong blueshifted and redshifted emission outside primary eclipse. The absorption seen during primary eclipse is produced by circumstellar gas extending above and below the orbital plane and between us and the partially eclipsed primary star. The circumstellar material is in the form of an asymmetric rotating disk. There is evidence that the circumstellar gas varied between 1991 and 1992, but the profiles were relatively unchanged during intervals less than four orbital cycles. Our results also support previous reports that the primary star rotates up to four times the synchronous rate. This high rotational velocity is most likely due to the impact of the high-velocity gas stream on the star. In TX UMa, most of the circumstellar gas is observed between phases 0.65 and 0.11 and is found primarily in the region between the two stars, symmetrically located at about the point of the impact between the gas stream and the primary. With these results, TX UMa is now only the second partially eclipsing Algol-type system, after Beta Per, in which there is convincing evidence of a transient accretion disk.

Simultaneous solutions for photometric and spectroscopic observations of TX UMa

B andV light curves for one epoch and radial velocity curves of three different epochs have been analyzed to revise the solution of TX UMa. The solution has been adjusted simultaneously in the light curves and radial velocity curves by the method of Wilson and Devinney's differential correction. The primary star's surface rotation rate to synchronous rate is determined as 1.768 from one of the radial velocity curves. The absolute dimension of the system has been deduced based on the simultaneous solution. The primary star is well fitted to the evolutionary track for a single star while the secondary star, while filling its Roche lobe, is fitted to the evolutionary track for a close binary system.

Spectroscopic and photometric detection of interacting processes and their evolution in the eclipsing binary TX UMa

Nearly one century of spectroscopic and photometric observations of eclipsing binary TX UMa offer a good opportunity for studying evolutionary processes in this system. Extensive spectroscopic observations carried out with the D.A.O. high-dispersion spectrographs in 1969–70 and at the Ondřejov Observatory in 1972–80 cover all radial velocity curve with particular emphasis on phases within primary minimum of the light curve. The manifestations of interacting processes as well as the presence of the spectrum of secondary component are examined in the ever changing line spectra. Photometric observations having been collected at the Skalnate Pleso Observatory since 1966 display orbital period changes. Evolution of period changes using this photometric material in connection with the published data is presented.

Direct detection of the secondary spectrum of the interacting eclipsing binary TX UMa

Eclipsing binary TX UMa was observed with the D.A.O. high-dispersion spectrographs in 1969–1970, with emphasis on the detailed coverage of the primary minimum. One spectrum was taken exclusively within totality, thus exhibiting an uncontaminated spectrum of the secondary component. This leads to spectral reclassification of the secondary (F6 IV). The narrowing of the line profile of the Hγ-line in totality is interpreted in terms of synchronous rotation of the secondary (v sini∼80 km s−1) while the primary rotates faster (v sini∼130 km s−1) than synchronously (v sini∼50 km s−1). Although the secondary does not fill in its Roche lobe fully, the system exhibits pronounced indications of rather strong physical interaction. This is now supported also by the profound changes of the line profiles of the Hγ-line with phase.

Spectral behaviour of the eclipsing binary TX UMa around primary minimum

Sixty-one blue spectrograms of TX UMa were obtained in the years 1969–1970, mainly in phases close to the primary minimum of the eclipsing system. The radial velocity curve displays clear rotational effect from which much higher than synchronous rotational velocity of the blue (B8V) component has been formally derived. However, this discrepancy is probably due to the presence of the tenous accretion disk around the primary. The disk is apparently fed by the intermittent mass transfer as indicated by the occasional changes of orbital period of the system. From all available radial velocity data an improved set of spectroscopic orbital elements is derived. The behaviour of the spectral lines in and out of the primary minimum is compared. Metallic lines of the cold (F7IV) secondary component are clearly seen exclusively in phases 0.988 to 0.012.

Measurement of spin in twenty binary systems

The spin velocities of 20 primaries and 5 secondaries in 20 binary systems were measured with the Condé Reticon on the McDonald 2.1 m telescope. 14 of the primaries and all 5 of the secondaries measured show synchronous rotation. The star, 62 Per, previously thought to have V sin i = 0,, turned out to have V sin i = 200 km/ s. Results for other stars are in basic agreement with previous measurements ( 0 Per has not been measured before). For TX UMa, the NaI D-line was found to be stronger in the secondary than in the primary, from which fact a mass-ratio of 0.32 was deduced.

A photometric study of TX Ursae Majoris

view Abstract Citations (12) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A photometric study of TX Ursae Majoris. Oh, K. -D. ; Chen, K. -Y. Abstract Photoelectric observations of the eclipsing binary, TX UMa, in two colors are presented. Solutions of the light curves based on the Russell model were obtained and they are in good agreement with the published solutions for the observations by Koch (1961). Discrete change in period was noticed around JD 2438856. A transfer of 1.1×10-5M_sun; from the cooler star to the B8 companion could account for the period change. Publication: The Astronomical Journal Pub Date: January 1984 DOI: 10.1086/113490 Bibcode: 1984AJ.....89..126O Keywords: Eclipsing Binary Stars; Light Curve; Stellar Spectrophotometry; Variable Stars; Electrophotometry; Minima; Astronomy; Eclipsing Binaries:Light Curves; Eclipsing Binaries:Period Changes; Eclipsing Binaries:Photometric Elements; Light Curves:Eclipsing Binaries; Period Changes:Eclipsing Binaries; Photometric Elements:Eclipsing Binaries full text sources ADS | data products SIMBAD (1)

Observations of Mass Flow, Disks, and Accretion Processes in Algol Binary Systems

As part of a multi-faceted study of gas streams, disks, and accretion processes in Algol type binaries, R.S. Polidan and I have obtained high resolution IUE observations of seven systems. Perhaps one of the most interesting results from these observations was the discovery of strong, variable absorption lines of N V, C IV, and Si IV in the spectra of stars whose photospheres are much too cool to form these ions. N V (1239,1243) and C IV (1548,1551) have been observed in AU Mon (B5V, 11ḍ1), CX Dra (B3V, 6ḍ7), and U CrB (B4V, 3ḍ5) while Si IV (1394, 1403) was found in TX UMa (B8V, 3ḍ1). The systems in which these ions have been observed generally contain primaries whose dimensions are greater than the Lubow and Shu (1975) parameter ϖmin.Radial velocity measurements of the N V, C IV, and Si IV features suggest that the line formation region is associated with the primary star and small in size. The strengths of the N V, C IV features appear to be variable on a time scale of several orbital periods and may be determined by the instantaneous rate of mass transfer. However, when the high ionization features are observed, their presence appears to be global and not restricted to the domain of gas stream impact.

Frequency domain analysis of the light changes of the close eclipsing systems TX ursae majoris and S cancri

The aim of this paper has been to carry out an analysis of the light curves of two eclipsing systems TX UMa and S Cnc by Kopal's new method of the analysis of the light curves of eclipsing systems in the frequency domain. The elements of these systems are evaluated and the results are discussed.

The Monochromatic Reflection Effect. II. The Monochromatic Reflection Coefficient.

A comparison of the observed values of A1 and computed values of the reflection coefficients for Al Dra, Z Her, CM Lac, Per, RZ Tau, TX UMa, and RS Vul is used to evaluate a model based on the solution of the transfer equation for an irradiated, plane-parallel atmosphere in radiative and local thermodynamic equilibrium. Solutions are made for gray and non-gray atmospheres at XX = 0.4, 0.5, and 0.6 microns. No hydrodynamic effects are considered. The model used is essentially that given in Paper I but allowing for the effects of secondary reflection. Lack of agreement with obse,rvational data for several systems considered is taken to corroborate a hypothesis advanced by Hosokawa in which non-radial energy transfer plays a fundamental role. Photometric effects and, in particular, a possible modification to the phase law arising out of non-radial energy transfer are described.