- ID:
- ivo://CDS.VizieR/J/A+A/654/A108
- Title:
- Triple-frequency meteor radar reflection coeff.
- Short Name:
- J/A+A/654/A108
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Radar scattering from meteor trails depends on several poorly constrained quantities, such as electron line density, q, initial trail radius, r0, and ambipolar diffusion coefficient, D. The goal is to apply a numerical model of full wave backscatter to triple frequency echo measurements to validate theory and constrain estimates of electron radial distribution, initial trail radius, and the ambipolar diffusion coefficient. A selection of 50 transversely polarized and 50 parallel polarized echoes with complete trajectory information were identified from simultaneous tri-frequency echoes recorded by the Canadian Meteor Orbit Radar (CMOR). The amplitude-time profile of each echo was fit to our model using three different choices for the radial electron distribution assuming a Gaussian, parabolic exponential, and 1-by-r^2^ electron line density model. The observations were manually fit by varying, q, r0, and D per model until all three synthetic echo-amplitude profiles at each frequency matched observation. The Gaussian radial electron distribution was the most successful at fitting echo power profiles, followed by the 1/r^2^. We were unable to fit any echoes using a profile where electron density varied from the trail axis as an exponential-parabolic distribution. While fewer than 5% of all examined echoes had self-consistent fits, the estimates of r0 and D as a function of height obtained were broadly similar to earlier studies, though with considerable scatter. Most meteor echoes are found to not be described well by the idealized full wave scattering model.
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- ID:
- ivo://CDS.VizieR/J/A+A/616/A75
- Title:
- Triple system HD150136 radial velocities
- Short Name:
- J/A+A/616/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The triple system HD 150136 is composed of an O3 V((f^*^))-O3.5 V((f^+^)) primary, of an O5.5-6 V((f)) secondary and of a more distant O6.5-7 V((f)) tertiary. The latter component went through periastron in 2015-2016, an event that will not occur again within the next eight years. We aim to analyse the tertiary periastron passage to determine the orbital properties of the outer system, to constrain its inclination and its eccentricity, and to determine the actual masses of the three components of the system. We conducted an intensive spectroscopic monitoring of the periastron passage of the tertiary component and combined them with new interferometric measurements. This allows us to derive the orbital solution of the outer orbit in three-dimensional space. We also obtained the light curve of the system to further constrain the inclination of the inner binary. We determine an orbital period of 8.61+/-0.02 years, an eccentricity of 0.682+/-0.002, and an inclination of 106.18+/-0.14{deg} for the outer orbit. The actual masses of the inner system and of the tertiary object are 72.32_-8.49_^+8.45^M_{sun}_ and 15.54_-4.97_^+4.96^M_{sun}_, respectively. From the mass of the inner system and accounting for the known mass ratio between the primary and the secondary, we determine actual masses of 42.81M_{sun}_ and 29.51M_{sun}_ for the primary and the secondary components, respectively. We infer, from the different mass ratios and the inclination of the outer orbit, an inclination of 62.4{deg} for the inner system. This value is confirmed by photometry. Grazing eclipses and ellipsoidal variations are detected in the light curve of HD 150136. We also compute the distance of the system to 1.096+/-0.274kpc. By combining spectroscopy, interferometry, and photometry, HD 150136 offers us a unique chance to compare theory and observations. The masses estimated through our analysis are smaller than those constrained by evolutionary models. The formation of this triple system suggests similar ages for the three components within the errorbars. Finally, we show that Lidov-Kozai cycles have no effect on the evolution of the inner binary, which suggests that the latter will experience mass transfer leading to a merger of the two stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/885/9
- Title:
- Triple system HD 28363; RVel and visual observations
- Short Name:
- J/ApJ/885/9
- Date:
- 15 Mar 2022 07:55:42
- Publisher:
- CDS
- Description:
- The star HD28363 in the Hyades cluster has been known for over a century as a visual binary with a period of 40yr. The secondary is, in turn, a single-lined spectroscopic binary with a 21day period. Here we report extensive spectroscopic monitoring of this hierarchical triple system that reveals the spectral lines of the third star for the first time. Combined with astrometric information, this makes it possible to determine the dynamical masses of all three stars. Only six other binaries in the Hyades have had their individual component masses determined dynamically. We infer the properties of the system by combining our radial-velocity measurements with visual observations, lunar occultation measurements, and with proper motions from the Hipparcos and Gaia missions that provide a constraint on the astrometric acceleration. We derive a mass of 1.341_-0.024_^+0.026^M{odot} for the visual primary, and 1.210{+/-}0.021 and 0.781{+/-}0.014 M{sun} for the other two stars. These measurements along with those for the other six systems establish an empirical mass-luminosity relation in the Hyades that is in broad agreement with current models of stellar evolution for the known age and chemical composition of the cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/127/2915
- Title:
- Triple systems (cool primary + hot binary)
- Short Name:
- J/AJ/127/2915
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the course of comparing parameters of evolved cool star plus hot main-sequence star binaries with theoretical isochrones, some discrepancies are found between implied stellar masses and the spectroscopic binary mass function or the measured angular separation. These are naturally explained if there is a third star in the system. Multiplicity is also required to explain some comparisons of "cool plus hot binary" IUE and optical spectral energy distribution analysis with measured flux ratios, especially Tycho's two-color photometry of separate components. Out of a sample of 136 cool-plus-hot binary star systems under study, measurements are now indicating several systems considered double (HD 5373, 23089, 26673, 29094, 49126, 71129, 149379, 179002, 187299), and probably a few others (including HD 136415), to have at least three stellar components. Several other cases of suspected triple systems are confirmed. For comparison, there are eight known triples included in the project. In all, about 25% of the systems contain three or more components within a few arcseconds. Estimated separations are provided, which may be of use when not known from interferometry. In general, the triple systems have one post-main-sequence component and two upper main-sequence components, usually revolving around each other. One new triple system, HD 149379, has as its middle component an F giant in the brief first crossing of the Hertzsprung gap.
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/1897
- Title:
- Triplets of galaxies in the SDSS-DR7
- Short Name:
- J/MNRAS/421/1897
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalogue of galaxy triplets derived from the Sloan Digital Sky Survey (SDSS) Data Release 7. The identification of systems was performed considering galaxies brighter than M_r_=-20.5 and imposing constraints over the projected distances, radial velocity differences of neighbouring galaxies and isolation. To improve the identification of triplets, we employed a data pixelization scheme, which allows us to handle large amounts of data as in the SDSS photometric survey. Using spectroscopic and photometric data in the redshift range 0.01<=z<=0.40, we obtain 5901 triplet candidates. We have used a mock catalogue to analyse the completeness and contamination of our methods.
- ID:
- ivo://CDS.VizieR/J/AJ/119/936
- Title:
- Triton stellar occultation candidates
- Short Name:
- J/AJ/119/936
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of our ongoing program of predictions and observations of stellar occultations by solar system bodies, we have completed a search for candidates for occultations by Triton over the decade 2000 to 2009. Star positions near Triton's projected orbit as determined by the DE405 ephemeris and NEP016 orbit model were measured on (unfiltered) CCD strip scans recorded with the 0.6 m telescope at the George R. Wallace Astrophysical Observatory to a depth of 16th to 18th magnitude, depending on the quality of individual strip scans. Within 1.0" of the predicted orbit of Triton during this period, 128 stars were found, including 12 stars brighter than 14th magnitude. Only appulses with geocentric minimum separations of less than about 0.37" will result in an occultation visible from Earth, but potential errors in the ephemeris and in the positions of our candidates preclude accurate prediction of actual occultation events without further astrometry.
- ID:
- ivo://CDS.VizieR/J/AJ/109/1352
- Title:
- Triton stellar occultation candidates
- Short Name:
- J/AJ/109/1352
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have completed a search for candidates for stellar occultations by Triton over the years 1995-1999 CCD strip scan images provided star positions in the relevant sky area to a depth of about 17.5Rmag. Over this time period, we find that Triton passes within 1.0arcsec of 75 stars. Appulses with geocentric minimum separations of less than 0.35arcsec will result in stellar occultations, but further astrometry and photometry is necessary to refine individual predictions for identification of actual occultations. Finder charts are included to aid in further studies and prediction refinement. The two most promising potential occultations, Tr176 and Tr180, occur in 1997.
- ID:
- ivo://CDS.VizieR/J/AJ/104/862
- Title:
- Triton stellar occultation candidates
- Short Name:
- J/AJ/104/862
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A search for Triton stellar occultation candidates for the period 1992-1994 has been completed with CCD strip-scanning observations. The search reached an R magnitude of about 17.4 and found 129 candidates within 1.5arcsec of Triton's ephemeris during this period. Of these events, we expect around 30 occultations to be visible from the Earth, indicating that a number of Triton occultation events should be visible from major observatories. Even the faintest of our candidate events could produce useful occultation data if observed with a large enough telescope. Our astrometric accuracy is inadequate to identify which of these appulse events will produce occultations on the Earth; further astrometry is needed to refine the predictions for positive occultation identification. To aid in selecting candidates for additional astrometric and photometric studies, we include finder charts and Earth-based visibility charts for each event.
- ID:
- ivo://CDS.VizieR/J/AJ/153/116
- Title:
- Trojan asteroids in the Kepler campaign 6 field
- Short Name:
- J/AJ/153/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a Kepler spacecraft survey during the K2 mission to characterize the rotational properties of 56 Trojan asteroids in the L4 cloud. More than one rotational period was observed for 51 of these targets, allowing for well constrained lightcurve rotation periods and amplitudes, five of which are found to be in conflict with previously published values. We find ~10% of objects have rotational periods longer than 100hr, an excess of slow rotators 10 times larger than suggested from the literature. Investigation of the rotational frequencies of our Kepler sample when combined with high-quality lightcurves in the literature reveals the distribution of rotational frequencies is non-Maxwellian even when consideration is given to size-dependent variations in rotational rate. From investigation of lightcurve shapes and amplitudes, we estimate the binary fraction within the Trojan population to be ~6%-36% depending on the methodology utilized to identify binary candidates.
22490. TROY project. I.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A96
- Title:
- TROY project. I.
- Short Name:
- J/A+A/609/A96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The detection of Earth-like planets, exocomets or Kuiper belts show that the different components found in the solar system should also be present in other planetary systems. Trojans are one of these components and can be considered fossils of the first stages in the life of planetary systems. Their detection in extrasolar systems would open a new scientific window to investigate formation and migration processes. In this context, the main goal of the TROY project is to detect exotrojans for the first time and to measure their occurrence rate (eta-Trojan). In this first paper, we describe the goals and methodology of the project. Additionally, we used archival radial velocity data of 46 planetary systems to place upper limits on the mass of possible trojans and investigate the presence of co-orbital planets down to several tens of Earth masses. We used archival radial velocity data of 46 close-in (P<5-days) transiting planets (without detected companions) with information from high-precision radial velocity instruments. We took advantage of the time of mid-transit and secondary eclipses (when available) to constrain the possible presence of additional objects co-orbiting the star along with the planet. This, together with a good phase coverage, breaks the degeneracy between a trojan planet signature and signals coming from additional planets or underestimated eccentricity. We identify nine systems for which the archival data provide >1-sigma evidence for a mass imbalance between L4 and L5. Two of these systems provide >2{sigma} detection, but no significant detection is found among our sample. We also report upper limits to the masses at L4/L5 in all studied systems and discuss the results in the context of previous findings.
