scholarly journals Updated astrometry and masses of the LUH 16 brown dwarf binary

2018 ◽  
Vol 618 ◽  
pp. A111 ◽  
Author(s):  
P. F. Lazorenko ◽  
J. Sahlmann
Keyword(s):  
High Precision ◽  
Photographic Plate ◽  
Brown Dwarf ◽  
Precision Data ◽  
Orbital Parameters ◽  
Very Large Telescope ◽  
High Precision Data ◽  
The Absolute ◽  
The Individual

The nearest known binary brown dwarf WISE J104915.57–531906.1AB (LUH 16) is a well-studied benchmark for our understanding of substellar objects. Previously published astrometry of LUH 16 obtained with FORS2 on the Very Large Telescope was affected by errors that limited its use in combination with other datasets, thereby hampering the determination of its accurate orbital parameters and masses. We improve upon the calibration and analysis of the FORS2 astrometry with the help of Gaia DR2 to generate a high-precision dataset that can be combined with present and future LUH 16 astrometry. We demonstrate its use by combining it with available measurements from the Hubble Space Telescope (HST) and Gemini/GeMS and deriving updated orbital and mass parameters. Using Gaia DR2 as astrometric reference field, we derived the absolute proper motion and updated the absolute parallax of the binary to 501.557 ± 0.082 mas. We refined the individual dynamical masses of LUH 16 to 33.5 ± 0.3 M Jup (component A) and 28.6 ± 0.3 M Jup (component B), which corresponds to a relative precision of ∼1% and is three to four times more precise than previous estimates. We found that these masses show a weak dependence on one datapoint extracted from a photographic plate from 1984. The exact determination of a residual mass bias, if any, will be possible when more high-precision data can be incorporated in the analysis.

A Simple Method for Determination of the Elastic Modulus of Thin Films on a Substrate

1993 ◽  
Vol 308 ◽  
Author(s):  
M.V. Swain ◽  
E.R. Weppelmann
Keyword(s):  
Thin Films ◽  
High Precision ◽  
Elastic Contact ◽  
Precision Data ◽  
Simple Method ◽  
Tin Film ◽  
High Precision Data ◽  
Properties Of Materials ◽  
Force Displacement

ABSTRACTHigh precision force displacement indenting instruments are now widely used for the determination of the mechanical properties of materials. However, for thin films attached to a substrate, the basis of any analysis of such high precision data is still limited. In this study the force displacement data has been generated using spherically tipped indenters of radii from 5 to 150 μm loaded onto a 2.74 μm thick TiN film on a silicon substrate as well as onto the substrate directly. Data have been generated using two loading procedures, continuous and load partial-unloading, almost entirely within the elastic contact regime. The results are analysed to determine the modulus of the TiN film.

scholarly journals High-Precision AMS 14C Results on TIRI/FIRI Turbidite

Radiocarbon ◽  
2003 ◽  
Vol 45 (1) ◽  
pp. 75-80 ◽  
Author(s):  
Thomas P Guilderson ◽  
John R Southon ◽  
Thomas A Brown
Keyword(s):  
Standard Deviation ◽  
High Precision ◽  
Weighted Average ◽  
Precision Data ◽  
Average Fraction ◽  
High Precision Data ◽  
Fractional Error ◽  
Counting Statistics

Unleached aliquots of TIRI/FIRI turbidite were analyzed by accelerator mass spectronomy (AMS) over a timespan of 18 months. Individual analyses ranged from 18,090–18,245 yr BP with reported errors between 30–50 yr. The weighted average fraction modern (FM) of these 28 measurements is 0.10378 ± 0.00008 (which equates to 18,199 ± 8 yr BP) and the measurements show a 1 standard deviation scatter of 0.00044 (±35 yr). The fractional error of these results indicates reproducibility of individual measurements at the 4 (1σ) level, which is consistent with the quoted counting-statistics-based errors. Laboratories engaged in the determination of 14C results at reasonably high precision should consider taking advantage of the TIRI and FIRI sample materials in the role of process standards. Additional suites of high-precision data are necessary to refine the accuracy of these sample materials.

scholarly journals Transit-period search from single-event space-based data: the role of wide-field surveys

2019 ◽  
Vol 625 ◽  
pp. A145
Author(s):  
Geza Kovacs
Keyword(s):  
High Precision ◽  
Wide Field ◽  
Precision Data ◽  
Frequency Spectra ◽  
Transiting Planets ◽  
High Precision Data ◽  
Space Data ◽  
Signal Search

We investigate the optimization of dataset weighting in searching for the orbital period of transiting planets when high-precision space-based data with a single transit event are combined with (relatively) low-precision ground-based (wide-field) data. The optimization stems from the lack of multiple events in the high-precision data and the likely presence of such events in the low-precision data. With noise minimization, we combined two types of frequency spectra: (i) spectra that use two fixed transit parameters (moment of the center of the transit and duration of the event) derived from the space data alone; (ii) spectra that result from the traditional weighted box signal search with optimized transit parameters for each trial period. We used many mock signals to test the detection power of the method. Marginal or no detections in the ground-based data may lead to secure detections in the combined data with the above weighting. Depending on the coverage and quality of the ground-based data, transit depths of ~0.05% and periods up to ~100 days are accessible by the suggested optimum combination of the data.

scholarly journals Constraining the properties of HD 206893 B

2019 ◽  
Vol 627 ◽  
pp. L9 ◽  
Author(s):  
A. Grandjean ◽  
A.-M. Lagrange ◽  
H. Beust ◽  
L. Rodet ◽  
J. Milli ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Semimajor Axis ◽  
High Contrast ◽  
Brown Dwarf ◽  
Contrast Imaging ◽  
Dynamical Mass ◽  
Orbital Parameters ◽  
High Contrast Imaging ◽  
Very Large Telescope ◽  
Astrometric Data

Context. High contrast imaging enables the determination of orbital parameters for substellar companions (planets, brown dwarfs) from the observed relative astrometry and the estimation of model and age-dependent masses from their observed magnitudes or spectra. Combining astrometric positions with radial velocity gives direct constraints on the orbit and on the dynamical masses of companions. A brown dwarf was discovered with the VLT/SPHERE instrument at the Very Large Telescope (VLT) in 2017, which orbits at ∼11 au around HD 206893. Its mass was estimated between 12 and 50 MJ from evolutionary models and its photometry. However, given the significant uncertainty on the age of the system and the peculiar spectrophotometric properties of the companion, this mass is not well constrained. Aims. We aim at constraining the orbit and dynamical mass of HD 206893 B. Methods. We combined radial velocity data obtained with HARPS spectra and astrometric data obtained with the high contrast imaging VLT/SPHERE and VLT/NaCo instruments, with a time baseline less than three years. We then combined those data with astrometry data obtained by HIPPARCOS and Gaia with a time baseline of 24 yr. We used a Markov chain Monte Carlo approach to estimate the orbital parameters and dynamical mass of the brown dwarf from those data. Results. We infer a period between 21 and 33 yr and an inclination in the range 20−41° from pole-on from HD 206893 B relative astrometry. The RV data show a significant RV drift over 1.6 yr. We show that HD 206893 B cannot be the source of this observed RV drift as it would lead to a dynamical mass inconsistent with its photometry and spectra and with HIPPARCOS and Gaia data. An additional inner (semimajor axis in the range 1.4–2.6 au) and massive (∼15 MJ) companion is needed to explain the RV drift, which is compatible with the available astrometric data of the star, as well as with the VLT/SPHERE and VLT/NaCo nondetection.

scholarly journals The Variation of UT from 700 BC to the Present

1995 ◽  
Vol 10 ◽  
pp. 258-258
Author(s):  
F.R. Stephenson ◽  
L.V. Morrison
Keyword(s):  
High Precision ◽  
Arab World ◽  
Precision Data ◽  
High Precision Data ◽  
Answering Questions

AbstractRecords of solar and lunar eclipses in the period 700 BC to AD 1600 originating from the ancient and medieval civilisations of Babylon, China, Europe and the Arab world are amassed and critically appraised for their usefulness in answering questions about the long-term variability of the Earth’s rate of rotation. Results from previous analyses of lunar occultations in the period AD 1600-1955.5 and from high-precision data in AD 1955.5-1990 are included in the dataset considered in this paper.

Sign in / Sign up

Export Citation Format

Share Document