J/ApJ/862/173 Nearby low-mass stars proper motions (Theissen, 2018)
Parallaxes of cool objects with WISE: filling in for Gaia.
Theissen C.A.
<Astrophys. J., 862, 173-173 (2018)>
=2018ApJ...862..173T 2018ApJ...862..173T (SIMBAD/NED BibCode)
ADC_Keywords: Stars, late-type ; Stars, nearby ; Parallaxes, trigonometric ;
Proper motions
Keywords: astrometry - brown dwarfs - parallaxes - proper motions -
stars: low-mass - techniques: miscellaneous
Abstract:
This paper uses the multi-epoch astrometry from the Wide-field
Infrared Survey Explorer (WISE) to demonstrate a method to measure
proper motions and trigonometric parallaxes with precisions of
∼4mas/yr and ∼7mas, respectively, for low-mass stars and brown dwarfs.
This method relies on WISE single exposures (Level 1b frames) and a
Markov Chain Monte Carlo method. The limitations of Gaia in observing
very low-mass stars and brown dwarfs are discussed, and it is shown
that WISE will be able to measure astrometry past the 95% completeness
limit and magnitude limit of Gaia (L, T, and Y dwarfs fainter than
G~=19 and G=21, respectively). This method is applied to WISE data of
20 nearby (≤17pc) dwarfs with spectral types between M6-Y2 and
previously measured trigonometric parallaxes. Also provided are WISE
astrometric measurements for 23 additional low-mass dwarfs with
spectral types between M6-T7 and estimated photometric distances
<17pc. Only nine of these objects contain parallaxes within Gaia Data
Release 2.
Description:
The MCMC routine described in the paper was applied to 20 known,
nearby, low-mass objects with generally well-determined parallaxes
(<15% uncertainty). Sources were chosen to cover a range of spectral
types, distances, and W2 magnitudes.
There are many known low-mass objects estimated to be within 20pc
based on spectrophotometric parallax relationships, that have either
no trigonometric parallax measurement, or measurements with large
uncertainties (>20%). Here, 23 such cases are investigated, sourced
from the literature to cover a range of spectral types, distances, and
W2 magnitudes, 9 of which have parallax measurements within Gaia DR2
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 56 43 Proper motion and parallaxes for low-mass stars
with estimated photometric distances ≤17pc
(tables 1 and 2 of the paper)
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/328 : AllWISE Data Release (Cutri+ 2013)
Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 26 A26 -- Name Identifier
28- 32 I5 mas/yr pmRA Proper motion in RA*cos(DE)
(pmRA*cos(DE)) from our best fit model
34- 35 I2 mas/yr e_pmRA Error in pmRA
37- 41 I5 mas/yr pmDE Proper motion in Declination
(pmDE) from our best fit model
43- 44 I2 mas/yr e_pmDE Error in pmDE
46- 50 F5.1 mas Plx Absolute trigonometric parallax
52- 56 F5.1 mas e_Plx Error in Plx
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Acknowledgements:
Christopher Theissen, ctheissen(at)ucsd.edu
(End) Patricia Vannier [CDS] 13-Sep-2018