J/MNRAS/481/3548 Parallaxes of Southern Extremely Cool objects (Smart+, 2018)
Parallaxes of Southern Extremely Cool objects. III: 118 L and T dwarfs.
Smart R.L., Bucciarelli B., Jones H.R.A., Marocco F., Andrei A.H.,
Goldman B., Mendez R.A., d'Avila V.A., Burningham B., Camargo J.I.B.,
Crosta M.T., Dapra M., Jenkins J.S., Lachaume R., Lattanzi M.G.,
Penna J.L., Pinfield D.J., da Silva Neto D.N., Sozzetti A., Vecchiato A.
<Mon. Not. R. Astron. Soc., 481, 3548-3562 (2018)>
=2018MNRAS.481.3548S 2018MNRAS.481.3548S (SIMBAD/NED BibCode)
ADC_Keywords: Parallaxes, trigonometric ; Proper motions ; Stars, brown dwarf
Keywords: parallaxes - proper motions - brown dwarfs - stars: low-mass
Abstract:
We present new results from the Parallaxes of Southern Extremely Cool
dwarfs program to measure parallaxes, proper motions and multiepoch
photometry of L and early T dwarfs. The observations were made on 108
nights over the course of 8yr using the Wide Field Imager on the ESO
2.2m telescope. We present 118 new parallaxes of L and T dwarfs of
which 52 have no published values and 24 of the 66 published values
are preliminary estimates from this program. The parallax precision
varies from 1.0 to 15.5mas with a median of 3.8mas. We find evidence
for two objects with long term photometric variation and 24 new moving
group candidates. We cross-match our sample to published photometric
catalogues and find standard magnitudes in up to 16 pass-bands from
which we build spectral energy distributions and H-R diagrams. This
allows us to confirm the theoretically anticipated minimum in radius
between stars and brown dwarfs across the hydrogen burning minimum
mass. We find the minimum occurs between L2 and L6 and verify the
predicted steep dependence of radius in the hydrogen burning regime
and the gentle rise into the degenerate brown dwarf regime. We find a
relatively young age of ∼2Gyr from the kinematics of our sample.
Description:
The PARSEC observations were made on the Wide Field Imager (WFI; Baade
et al. 1999Msngr..95...15B 1999Msngr..95...15B) of the ESO MPIA 2.2m telescope. This is a
mosaic of 8 EEV CCD44 chips with 2kx4k 15µm pixels, for the results
presented here we only used observations from the top half of CCD#7
(Priscilla). Limiting our reductions to this region was a balance
between simplicity of the required astrometric transforms - the larger
the adopted area being modelled the more complicated transforms were
required - and number of anonymous reference stars for which we
required a minimum of 12.
We observed all objects in the z band (Z+/61 ESO#846, central
wavelength 964.8µm, FWHM 61.6µm) which provided the best ratio
of exposure time and signal to noise for these very red targets. The
target lists had to meet a number of practical and scientific
considerations. In Table 1, we list the 118 targets published here
including a short name for each object used throughout this paper, the
discovery name, the z-band magnitude adopted at the beginning of the
program and, when they exist, published values of optical/NIR spectral
types, radial velocities, and parallaxes. In Table 2, we present the
astrometric results for the 118 targets, listed are positions at epoch
2010, epoch of the base frame, parallaxes, proper motions, relative to
absolute corrections applied (COR), number of observations used in the
final solution, number of anonymous objects used as references in
the transformation of sequence frames to the base frame, epoch
coverage of the frames in the final solution.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 112 118 Targets, published magnitudes, spectral types,
radial velocities, and parallaxes
refs.dat 77 88 References
table2.dat 104 118 Astrometric parameters of PARSEC targets
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Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Short name for each object
12- 37 A26 --- Name Discovery Name of the source
39- 40 I2 --- r_Name Reference for Name, in refs.dat file
42- 45 F4.1 mag zmag z-band magnitude
47- 53 A7 --- SpTypeOp ? Optical spectral type
55- 56 I2 --- r_SpTypeOp ? Reference for SpTypeOp, in refs.dat file
58- 66 A9 --- SpTypeNIR ? NIR spectral type
68- 69 I2 --- r_SpTypeNIR ? Reference for SpTypeNIR, in refs.dat file
71- 75 F5.1 km/s RV ? Radial velocity
77- 80 F4.1 km/s e_RV ? Error on RV
82- 86 A5 --- r_RV ? Reference for RV, in refs.dat file
88- 92 F5.1 mas plx ? Parallax
94- 97 F4.1 mas e_plx ? Error on plx
99-100 I2 --- r_plx ? Reference for plx, in refs.dat file
102-106 A5 --- Mult Published indications of multiplicity (1)
108-112 A5 --- r_Mult Reference for Mult, in refs.dat file
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Note (1): Multiple code as follows:
VB = Visual binary
UR = Unresolved binary
MG = Moving group
Bi = Binary
SB = Spectral binary
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Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode Bibcode
24- 56 A33 --- Aut Author's name
57- 77 A21 --- Com Comments
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- ID Short name for each object
12- 22 F11.7 deg RA Right ascension (ICRS) at Ep=2010
24- 34 F11.7 deg DE Declination (ICRS) at Ep=2010
36- 42 F7.2 yr Epoch Epoch of base frame
44- 49 F6.2 mas plx Parallax (1)
51- 55 F5.2 mas e_plx Error on plx
57- 64 F8.2 mas/yr pmRA Proper motion in right ascension (1)
66- 70 F5.2 mas/yr e_pmRA Error on pmRA
72- 80 F9.2 mas/yr pmDE Proper motion in declination (1)
82- 86 F5.2 mas/yr e_pmDE Error on pmDE
88- 92 F5.2 mas COR Corrections estimated from the average
magnitude of the common reference stars and
the Galaxy model of Mendez & van Altena
(1996AJ....112..655M 1996AJ....112..655M) in the z-band
94- 96 I3 --- Nobs Number of observations used in the final
solution
98- 99 I2 --- Nobj Number of anonymous objects used as references
in the transformation of sequence frames to
the base frame
101-104 F4.2 yr DeltaT Epoch coverage of the frames in the final
solution
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Note (1): Parallaxes and proper motions, relative to absolute corrections
applied (COR)
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History:
From electronic version of the journal
References:
Andrei et al., Paper I 2011AJ....141...54A 2011AJ....141...54A
Marocco et al., Paper II 2013AJ....146..161M 2013AJ....146..161M
(End) Ana Fiallos [CDS] 10-Jun-2022