- ID:
- ivo://CDS.VizieR/J/AJ/135/1334
- Title:
- Speckle interferometry at the USNO station
- Short Name:
- J/AJ/135/1334
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results are presented for 353 speckle interferometric observations of double stars, obtained in 2003 and 2004 at the USNO Flagstaff Station using the 1.55m Kaj Strand Astrometric Reflector. Separations range from 0.12" to 7.42", with a median of 0.42". These two observing runs concentrated on systems in need of improved orbital elements, and new solutions have been determined for 17 systems as a result.
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- ID:
- ivo://CDS.VizieR/J/AJ/156/117
- Title:
- Spectroscopic orbits for late-type stars. II.
- Short Name:
- J/AJ/156/117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined spectroscopic orbital elements for 13 systems - 10 single-lined binaries and three double-lined binaries. For the three binaries with previously published spectroscopic orbits, we have computed improved or comparable elements. While two systems have relatively short periods between 10 and 19 days, the remaining systems have much longer periods ranging from 604 to 9669 days. One of the single-lined systems, HD 142640, shows both short-period and long-period velocity variations and so is triple. For three systems - HD 59380, HD 160933, and HD 161163 - we have combined our spectroscopic results with Hipparcos astrometric observations to obtain astrometric orbits. For HD 14802 we have determined a joint orbital solution from spectroscopic velocities and interferometric observations. The orbits given here will be useful in combination with future interferometric and Gaia satellite observations.
- ID:
- ivo://CDS.VizieR/J/AJ/151/26
- Title:
- Spectroscopy of five {gamma} Dor variables
- Short Name:
- J/AJ/151/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined the spectroscopic orbits of five {gamma} Dor variables, HD776, HD6568, HD17310, HD19684, and HD62196. Their orbital periods range from 27.8 to 1163days and their eccentricities from 0.01 to 0.65. Of the five systems, only HD19684 shows lines of its binary companion, but those lines are always so weak and blended with the lines of the primary that we were unable to measure them satisfactorily. The velocity residuals of the orbital fits were searched for periodicities associated with pulsation. No clear, convincing case for velocity periodicities in the residuals was found in four of the five stars. However, for HD17310 we identified a period of 2.13434days, a value in agreement with the largest amplitude period previously found photometrically for that star. The velocity residuals of HD62196 have a long-term trend suggesting that it is a triple system.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A64
- Title:
- TESS time of eclipse of 15 eclipsing binaries
- Short Name:
- J/A+A/649/A64
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The change in the argument of periastron of eclipsing binaries, that is, the apsidal motion caused by classical and relativistic effects, can be measured from variations in the difference between the time of minimum light of the primary and secondary eclipses. Poor apsidal motion rate determinations and large uncertainties in the classical term have hampered previous attempts to determine the general relativistic term with sufficient precision to test general relativity predictions. As a product of the TESS mission, thousands of high-precision light curves from eclipsing binaries are now available. Using a selection of suitable well-studied eccentric eclipsing binary systems, we aim to determine their apsidal motion rates and place constraints on key gravitational parameters. We compute the time of minimum light from the TESS light curves of 15 eclipsing binaries with precise absolute parameters and with an expected general relativistic contribution to the total apsidal motion rate of greater than 60%. We use the changing primary and secondary eclipse timing differences over time to compute the apsidal motion rate, when possible, or the difference between the linear periods as computed from primary and secondary eclipses. For a greater time baseline we carefully combine the high-precision TESS timings with archival reliable timings. We determine the apsidal motion rate of 9 eclipsing binaries, 5 of which are reported for the first time. From these, we are able to measure the general relativistic apsidal motion rate of 6 systems with sufficient precision to test general relativity for the first time using this method. This test explores a regime of gravitational forces and potentials that had not been probed before. We find perfect agreement with theoretical predictions, and we are able to set stringent constraints on two parameters of the parametrised post-Newtonian formalism.
- ID:
- ivo://CDS.VizieR/V/39
- Title:
- 4th Catalog of Orbits of Visual Binaries
- Short Name:
- V/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Finsen-Worley Catalog (1970), supplemented by all subsequently published orbits known to Worley and Heintz as of 1 July 1982 formed the basis for the present compilation. Practically all stars having visual orbits were reobserved in the preceding decade, often repeatedly either with micrometers or with speckle interferometers. Astrometric solutions are included but only if they were judged to be relatively certain. Orbits with period greater than 4000 years and hyperbolic orbits were rejected as being unreliable. The catalog contains 928 orbits of 847 systems (counting triples as two systems). There are 23 orbits of unresolved systems. The catalog contains for each system the names of the star and the components involved, the 1900 position, the ADS number, the magnitude and spectral type for each component, the orbital elements, the equinox of the node, the quality of the orbit, the date of the last observation, the inclusive dates for which an ephemeris is given by the author, the computer of the orbit, and a reference.
- ID:
- ivo://CDS.VizieR/J/AJ/154/200
- Title:
- The nearby white dwarf/red dwarf pair 40 Eri BC
- Short Name:
- J/AJ/154/200
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new relative orbit solution with new dynamical masses is determined for the nearby white dwarf-red dwarf pair 40 Eri BC. The period is 230.29+/-0.68 years. It is predicted to close slowly over the next half-century, getting as close as 1.32" in early 2066. We determine masses of 0.573+/-0.018 M_{sun}_ for the white dwarf and 0.2036+/-0.0064 M_{sun}_ for the red dwarf companion. The inconsistency of the masses determined by gravitational redshift and dynamical techniques, due to a premature orbit calculation, no longer exists.
- ID:
- ivo://CDS.VizieR/J/AJ/156/144
- Title:
- The very high-eccentricity binary HR 7345
- Short Name:
- J/AJ/156/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- After an 11-year observing campaign, we present the combined visual-spectroscopic orbit of the formerly unremarkable bright star HR 7345 (HD 181655, HIP 94981, GJ 754.2). Using the Separated Fringe Packet method with the CHARA Array, we were able to determine a difficult-to-complete orbital period of 331.609+/-0.004 days. The 11-month period causes the system to be hidden from interferometric view behind the Sun for three years at a time. Due to the high-eccentricity orbit of about 90% of a year, after 2018 January the periastron phase will not be observable again until late 2021. Hindered by its extremely high eccentricity of 0.9322+/-0.0001, the double-lined spectroscopic phase of HR 7345 is observable for 15 days. Such a high eccentricity for HR 7345 places it among the most eccentric systems in catalogs of both visual and spectroscopic orbits. For this system, we determine nearly identical component masses of 0.941+/-0.076 M_{sun}_ and 0.926+/-0.075 M_{sun}_ as well as an orbital parallax of 41.08+/-0.77 mas.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A170
- Title:
- TRAPPIST-1 best-fit parameters
- Short Name:
- J/A+A/658/A170
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We analyze solutions drawn from the recently published posterior distribution of the TRAPPIST-1 system, which consists of seven Earth-size planets appearing to be in a resonant chain around a red dwarf. We show that all the planets are simultaneously in 2-planet and 3-planet resonances, apart from the innermost pair for which the 2-planet resonant angles circulate. By means of a frequency analysis, we highlight that the transit-timing variation (TTV) signals possess a series of common periods varying from days to decades, which are also present in the variations of the dynamical variables of the system. Shorter periods (e.g., the TTVs characteristic timescale of 1.3yr) are associated with 2-planet mean-motion resonances, while longer periods arise from 3-planet resonances. By use of N-body simulations with migration forces, we explore the origin of the resonant chain of TRAPPIST-1 and find that for particular disc conditions, a chain of resonances -- similar to the observed one -- can be formed which accurately reproduces the observed TTVs. Our analysis suggests that while the 4-yr collected data of observations hold key information on the 2-planet resonant dynamics, further monitoring of TRAPPIST-1 will soon provide signatures of three-body resonances, in particular the 3.3 and 5.1yr periodicities expected for the current best-fit solution. Additional observations would help to assess whether the innermost pair of planets is indeed resonant (its proximity to the 8:5 resonance being challenging to explain), and therefore give additional constraints on formation scenarios.
- ID:
- ivo://CDS.VizieR/J/A+A/369/249
- Title:
- T Tauri binary systems orbital motion
- Short Name:
- J/A+A/369/249
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using speckle-interferometry we have carried out repeated measurements of relative positions for the components of 34 T Tauri binary systems. The projected separation of these components is low enough that orbital motion is expected to be observable within a few years. In most cases orbital motion has indeed been detected. The observational data is discussed in a manner similar to Ghez et al. (1995AJ....110..753G). However, we extend their study to a larger number of objects and a much longer timespan. The database presented in this paper is valuable for future visual orbit determinations. It will yield empirical masses for T Tauri stars that now are only poorly known. The available data is however not sufficient to do this at the present time. Instead, we use short series of orbital data and statistical distributions of orbital parameters to derive an average system mass that is independent of theoretical assumptions about the physics of PMS stars. For our sample this mass is and thus in the order of magnitude one expects for the mass sum of two T Tauri stars. It is also comparable to mass estimates obtained for the same systems using theoretical PMS evolutionary models.
- ID:
- ivo://CDS.VizieR/J/A+A/589/A94
- Title:
- TU UMa light curves and maxima, CL Aur minima
- Short Name:
- J/A+A/589/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent statistical studies prove that the percentage of RR Lyrae pulsators that are located in binaries or multiple stellar systems is considerably lower than might be expected. This can be better understood from an in-depth analysis of individual candidates. We investigate in detail the light time effect of the most probable binary candidate TU UMa. This is complicated because the pulsation period shows secular variation. We model possible light time effect of TU UMa using a new code applied on previously available and newly determined maxima timings to confirm binarity and refine parameters of the orbit of the RRab component in the binary system. The binary hypothesis is also tested using radial velocity measurements. We used new approach to determine brightness maxima timings based on template fitting. This can also be used on sparse or scattered data. This approach was successfully applied on measurements from different sources. To determine the orbital parameters of the double star TU UMa, we developed a new code to analyse light time effect that also includes secular variation in the pulsation period. Its usability was successfully tested on CL Aur, an eclipsing binary with mass-transfer in a triple system that shows similar changes in the O-C diagram. Since orbital motion would cause systematic shifts in mean radial velocities (dominated by pulsations), we computed and compared our model with centre-of-mass velocities. They were determined using high-quality templates of radial velocity curves of RRab stars. Maxima timings adopted from the GEOS database (168) together with those newly determined from sky surveys and new measurements (85) were used to construct an O-C diagram spanning almost five proposed orbital cycles. This data set is three times larger than data sets used by previous authors. Modelling of the O-C dependence resulted in 23.3-year orbital period, which translates into a minimum mass of the second component of about 0.33Ms. Secular changes in the pulsation period of TU UMa over the whole O-C diagram were satisfactorily approximated by a parabolic trend with a rate of -2.2ms/yr. To confirm binarity, we used radial velocity measurements from nine independent sources. Although our results are convincing, additional long-term monitoring is necessary to unambiguously confirm the binarity of TU UMa.
