J/ApJ/842/118 Brown dwarfs with spectral type later than T6 (Leggett+, 2017)
The Y-type brown dwarfs: estimates of mass and age from new astrometry,
homogenized photometry, and near-infrared spectroscopy.
Leggett S.K., Tremblin P., Esplin T.L., Luhman K.L., Morley C.V.
<Astrophys. J., 842, 118-118 (2017)>
=2017ApJ...842..118L 2017ApJ...842..118L (SIMBAD/NED BibCode)
ADC_Keywords: Photometry, infrared ; Stars, Y-type ; Spectral types ;
Parallaxes, trigonometric ; Stars, brown dwarf ; Stars, T-type
Keywords: brown dwarfs; molecular processes; stars: atmospheres
Abstract:
The survey of the mid-infrared sky by the Wide-field Infrared Survey
Explorer (WISE) led to the discovery of extremely cold, low-mass brown
dwarfs, classified as Y dwarfs, which extend the T class to lower
temperatures. Twenty-four Y dwarfs are known at the time of writing.
Here we present improved parallaxes for four of these, determined
using Spitzer images. We give new photometry for four late-type T and
three Y dwarfs and new spectra of three Y dwarfs, obtained at Gemini
Observatory. We also present previously unpublished photometry taken
from HST, ESO, Spitzer, and WISE archives of 11 late-type T and 9 Y
dwarfs. The near-infrared data are put onto the same photometric
system, forming a homogeneous data set for the coolest brown dwarfs.
We compare recent models to our photometric and spectroscopic data
set. We confirm that nonequilibrium atmospheric chemistry is important
for these objects. Nonequilibrium cloud-free models reproduce well the
near-infrared spectra and mid-infrared photometry for the warmer Y
dwarfs with 425≤Teff(K)≤450. A small amount of cloud cover may
improve the model fits in the near-infrared for the Y dwarfs with
325≤Teff(K)≤375. Neither cloudy nor cloud-free models reproduce
the near-infrared photometry for the Teff=250K Y dwarf
WISEJ085510.83-071442.5 (W0855). We use the mid-infrared region, where
most of the flux originates, to constrain our models of W0855. We find
that W0855 likely has a mass of 1.5-8 Jupiter masses and an age of
0.3-6Gyr. The Y dwarfs with measured parallaxes are within 20pc of the
Sun and have tangential velocities typical of the thin disk. The
metallicities and ages we derive for the sample are generally
solar-like. We estimate that the known Y dwarfs are 3 to 20
Jupiter-mass objects with ages of 0.6-8.5Gyr.
Description:
We present the new GNIRS and FLAMINGOS-2 spectra and the new NIRI
photometry in section 4 (see also table 1).
We obtained a 0.95≤λ(um)≤2.5 spectrum using GNIRS at Gemini
North on 2016 December 24 and 25 via program GN-2016B-Q-46 for
WISEAJ041022.75+150247.9 with R∼700.
We also obtained near-infrared spectra for WISEJ071322.55-291751.9 and
WISEAJ114156.67-332635.5 using FLAMINGOS-2 at Gemini South on 2017
February 3 and 7, via program GS-2017A-FT-2. The JH grism was used
giving R∼600.
We obtained photometry for WISE J085510.83-071442.5 on Gemini North
using NIRI at Y and CH4(short) via program GN-2016A-Q-50, and at M'
via program GN-2016A-FT-10 between 2015 December and 2016 March.
The M' data for a sample of T and Y dwarfs was obtained via program
GN-2016B-Q-46 using NIRI on Gemini North.
Finally, we obtained H data for the Y1 WISEA J064723.24-623235.4 using
FLAMINGOS-2 on Gemini South, which were presented in Leggett+
(2013ApJ...763..130L 2013ApJ...763..130L).
We also obtained new photometry from HST/WFC3, ESO VLT HAWK-I and
Spitzer/IRAC and WISE archives; see section 5 and tables 2 and 3.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 70 7 New Gemini NIRI photometry
table2.dat 147 7 New near-infrared photometry from WFC3 and
HAWK-I archives
table3.dat 107 14 New mid-infrared photometry from IRAC and
WISE archives
table7.dat 67 7 New astrometry
table8.dat 189 24 Y dwarf data set
table15.dat 424 97 Brown dwarfs or brown dwarf systems with
spectral types T6 and later
refs.dat 69 73 References
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See also:
V/144 : Near-IR spectroscopy of low-mass binaries and brown dwarfs (Mace, 2014)
J/ApJ/564/421 : Spectra of T dwarfs. I. (Burgasser+, 2002)
J/AJ/126/2487 : T dwarfs in the southern hemisphere (Burgasser+, 2003)
J/AJ/127/3553 : JHK photometry & spectroscopy for L and T dwarfs (Knapp+, 2004)
J/A+A/433/185 : Abundance analysis of 102 F and G dwarfs (Bensby+, 2005)
J/MNRAS/373/781 : JHK photometry of faint standard stars (Leggett+, 2006)
J/AJ/134/2398 : Stellar SEDs in SDSS and 2MASS filters (Covey+, 2007)
J/MNRAS/384/1399 : Proper motions of field L and T dwarfs (Jameson+, 2008)
J/AJ/137/1 : PMs and astrometry of late-type dwarfs (Faherty+, 2009)
J/ApJS/197/19 : First brown dwarfs discovered by WISE (Kirkpatrick+, 2011)
J/ApJ/753/156 : T/Y brown dwarfs with WISE photometry (Kirkpatrick+, 2012)
J/A+A/562/A71 : Abundances of solar neighbourhood dwarfs (Bensby+, 2014)
J/A+A/589/A49 : Photometric brown-dwarf classification (Skrzypek+, 2016)
J/ApJ/832/58 : IRAC monitoring of WISE J085510.83-071442.5 (Esplin+, 2016)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Name Brown dwarf designation
27 A1 --- l_SpT Limit flag on SpT
28- 31 A4 --- SpT Spectral type
33 A1 --- l_Ymag 3σ limit flag on Ymag
34- 37 F4.1 mag Ymag ? Gemini/NIRI Y magnitude in the MKO Y system
39- 43 F5.2 mag CH4s [23.38]? Gemini/NIRI CH4(short) magnitude
45- 48 F4.2 mag e_CH4s [0.2]? CH4s uncertainty
50- 54 F5.2 mag Hmag [23.11]? Gemini/NIRI H magnitude
56- 59 F4.2 mag e_Hmag [0.27]? Hmag uncertainty
61- 65 F5.2 mag M'mag [12/14]? Gemini/NIRI M' magnitude
67- 70 F4.2 mag e_M'mag [0.06/0.2]? M'mag uncertainty
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Name Borwn dwarf designation
27- 30 A4 --- SpT Spectral type
32- 36 F5.2 mag F105W [18/26]? HST/WFC3 F105W magnitude
38- 41 F4.2 mag e_F105W [0.03/0.2]? F105W uncertainty
43- 47 F5.2 mag F125W [17/26]? HST/WFC3 F125W magnitude
49- 52 F4.2 mag e_F125W [0.03/0.3]? F125W uncertainty
54- 58 F5.2 mag F127W [16/25]? HST/WFC3 F127W magnitude
60- 63 F4.2 mag e_F127W [0.02/0.3]? F127W uncertainty
65- 69 F5.2 mag F160W [17/25.5]? HST/WFC3 F160W magnitude
71- 74 F4.2 mag e_F160W [0.03/0.2]? F160W uncertainty
76- 80 F5.2 mag Jmag [18.7/19.7]? VLT/HAWK-I J magnitude (MKO system)
82- 85 F4.2 mag e_Jmag [0.02/0.03]? Jmag uncertainty
87- 91 F5.2 mag Hmag [19.2/20.2]? VLT/HAWK-I H magnitude (MKO system)
93- 96 F4.2 mag e_Hmag [0.02/0.03]? Hmag uncertainty
98-147 A50 --- PID WFC3 and HAWK-I PI and observation identifier
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Name Brown dwarf designation
26- 27 A2 --- m_Name Binary indicator
29 A1 --- f_Name [a] Flag on Name (1)
31 A1 --- l_SpT Limit flag on SpT
32- 36 A5 --- SpT Spectral type
38- 42 F5.2 mag [3.6] [14/17.8]? Spitzer/IRAC 3.6um magnitude
44- 47 F4.2 mag e_[3.6] [0.02/0.1]? [3.6] uncertainty
49- 53 F5.2 mag [4.5] [12.5/15.5]? Spitzer/IRAC 4.5um magnitude
55- 58 F4.2 mag e_[4.5] [0.02/0.03]? [4.5] uncertainty
60- 64 F5.2 mag W1mag [17.3/19.1]? WISE W1 (3.4um) band magnitude
66- 69 F4.2 mag e_W1mag [0.2/0.3]? W1mag uncertainty
71- 75 F5.2 mag W3mag [11.9/14]? WISE W3 (12um) band magnitude
77- 80 F4.2 mag e_W3mag [0.1/0.3]? W3mag uncertainty
82-107 A26 --- PID IRAC PI and observation ID
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Note (1):
a = For 2MASS J00345157+0523050, we also measured [5.8]=13.13±0.03 and
[8.0]=12.41±0.03mag.
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Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Name Brown dwarf designation
26- 27 A2 --- m_Name Binary indicator
29 A1 --- f_Name Flag on Name (1)
31- 35 F5.3 arcsec Plx [0.05/0.2] Parallax
37- 41 F5.3 arcsec e_Plx [0.005/0.02] Plx uncertainty
43- 48 F6.3 arcsec/yr pmRA [-2.4/0.8] Proper motion along RA
50- 54 F5.3 arcsec/yr e_pmRA [0.004/0.02] pmRA uncertainty
56- 61 F6.3 arcsec/yr pmDE [-1.3/0.3] Proper motion along DEC
63- 67 F5.3 arcsec/yr e_pmDE [0.004/0.01] pmDE uncertainty
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Note (1): Flag as follows:
a = Astrometric measurements are given in Table 11.
b = Parallax from Luhman & Esplin (2016AJ....152...78L 2016AJ....152...78L).
c = Astrometric measurements are given in Table 12.
d = Astrometric measurements are given in Table 13.
e = Astrometric measurements are given in Table 14.
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Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Name Y dwarf designation
26 A1 --- m_Name Binary indicator
28 A1 --- f_Name [abc] Flag on Name (1)
30- 31 A2 --- l_SpT [≥] Limit flag on SpT
32- 36 A5 --- SpT Spectral type
38- 42 F5.2 mag M-m [-1.5/3.3]? Distance modulus
44- 47 F4.2 mag e_M-m [0.04/0.3]? M-m uncertainty
49- 53 F5.2 mag Ymag [19.6/26.6]? MKO system Y-band magnitude
55- 58 F4.2 mag e_Ymag [0.03/0.3]? Ymag uncertainty
60- 64 F5.2 mag Jmag [19.4/25.5] MKO system J-band magnitude
66- 69 F4.2 mag e_Jmag [0.03/0.7] Jmag uncertainty
71- 75 F5.2 mag Hmag [19.9/25.3] MKO system H-band magnitude
77- 80 F4.2 mag e_Hmag [0.04/0.4] Hmag uncertainty
82- 86 F5.2 mag Kmag [19.9/23.5]? MKO system K-band magnitude
88- 91 F4.2 mag e_Kmag [0.06/0.4]? Kmag uncertainty
93- 97 F5.2 mag [3.6] [16/19.3]? Spitzer/IRAC 3.6um band magnitude
99-102 F4.2 mag e_[3.6] [0.02/0.2]? [3.6] uncertainty
104-108 F5.2 mag [4.5] [13.5/16.8]? Spitzer/IRAC 4.5um band magnitude
110-113 F4.2 mag e_[4.5] [0.02/0.05]? [4.5] uncertainty
115-119 F5.2 mag W1mag [16.4/19.1]? WISE W1 (3.4um) magnitude (2)
121-124 F4.2 mag e_W1mag [0.08/0.4]? W1mag uncertainty
126-130 F5.2 mag W2mag [13.5/17]? WISE W2 (4.6um) magnitude (2)
132-135 F4.2 mag e_W2mag [0.04/0.1]? W2mag uncertainty
137-141 F5.2 mag W3mag [11.7/14]? WISE W3 (12um) magnitude (2)
143-146 F4.2 mag e_W3mag [0.2/0.5]? W3mag uncertainty
148-154 A7 --- r_plx Plx reference (see refs.dat file)
156-167 A12 --- r_IRAC IRAC reference (see refs.dat file)
169-180 A12 --- r_YJHK YJHK reference (see refs.dat file)
182-189 A8 --- Ref Discovery reference (see refs.dat file)
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Note (1): Flag as follows:
a = WISE J014656.66+423410.0B and WISEPC J121756.91+162640.2B are in close
binary systems. Mid-infrared photometry is not available for the individual
components of the systems.
b = We have also measured for WISE J085510.83-071442.5 M'=13.95±0.20mag and
for WISEA J205628.88+145953.6 M'=14.00±0.15mag.
c = The brown dwarf WISE name is WISEA J163940.84-684739.4 (as in tables 3
and 8) and not, WISE J163940.86-684744.6. Corrected by CDS after
confirmation by the author (see the "Acknowledgements" section below);
flag added by CDS.
Note (2): From AllWISE catalog.
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Byte-by-byte Description of file: table15.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Name Star name (1)
26- 27 A2 --- m_Name Binary indicator (2)
29- 32 F4.1 --- SpT [6/12] Spectral type indicator e.g. 6=T6 12=Y2
34- 39 F6.2 mag M-m [-2.4/3.3]?=999 Distance modulus
(absolute magnitude - apparent magnitude)
41- 46 F6.2 mag JMag [14.2/28.8]?=999 Absolute MKO J (Vega)
magnitude
49- 54 F6.2 mag C2Mag [12/17.2]?=999 Absolute Spitzer/IRAC 4.5um
(Vega) magnitude
57- 62 F6.2 mag J-C2 [1.9/11.6]?=999 MKO J - Spitzer/IRAC C2 color
64- 69 F6.2 mag imag [22.5/26]?=99 SDSS i (AB) magnitude
71- 76 F6.2 mag zmag [18/22.8]?=199 SDSS z (AB) magnitude
78- 83 F6.2 mag Ymag [15/26.6]?=299 MKO Y (Vega) magnitude
85- 89 F5.2 mag Jmag [14.2/25.5] MKO J (Vega) magnitude
91- 96 F6.2 mag Hmag [14.6/25.3]?=300 MKO H (Vega) magnitude
98-103 F6.2 mag Kmag [15.2/23.5]?=399 MKO K (Vega) magnitude
105-110 F6.2 mag L'mag [12.3/14]?=499 MKO L' (Vega) magnitude
112-117 F6.2 mag M'mag [11.7/14]?=599 MKO M' (Vega) magnitude
119-124 F6.2 mag C1mag [13/19.3]?=699 Spitzer/IRAC 3.6um (Vega)
magnitude
127-132 F6.2 mag C2mag [11.6/16.8]?=799 Spitzer/IRAC 4.5um (Vega)
magnitude
135-140 F6.2 mag C3mag [12.3/15.4]?=899 Spitzer/IRAC 5.8um (Vega)
magnitude
142-147 F6.2 mag C4mag [11.7/14.6]?=999 Spitzer/IRAC 8.0um (Vega)
magnitude
149-155 F7.2 mag W1mag [14/19.1]?=1999 WISE W1 3.35um (Vega)
magnitude
158-164 F7.2 mag W2mag [11.6/17]?=2999 WISE W2 4.6um (Vega) magnitude
167-173 F7.2 mag W3mag [10.2/14]?=3999 WISE W3 11.6um (Vega) magnitude
175-178 F4.2 mag e_M-m [0.01/0.3]?=9 Uncertainty in M-m
180-183 F4.2 mag e_imag [0.09/0.7]?=9 Uncertainty in imag
185-188 F4.2 mag e_zmag [0.04/0.3]?=9 Uncertainty in zmag
190-193 F4.2 mag e_Ymag [0.01/0.3]?=9 Uncertainty in Ymag
195-198 F4.2 mag e_Jmag [0.01/0.3] Uncertainty in Jmag
200-203 F4.2 mag e_Hmag [0.01/0.4]?=9 Uncertainty in Hmag
205-208 F4.2 mag e_Kmag [0.02/0.4]?=9 Uncertainty in Kmag
210-213 F4.2 mag e_L'mag [0.04/0.08]?=9 Uncertainty in L'mag
215-218 F4.2 mag e_M'mag [0.06/0.2]?=9 Uncertainty in M'mag
220-223 F4.2 mag e_C1mag [0.02/0.2]?=9 Uncertainty in C1mag
225-228 F4.2 mag e_C2mag [0.01/0.05]?=9 Uncertainty in C2mag
230-233 F4.2 mag e_C3mag [0.03/0.2]?=9 Uncertainty in C3mag
235-238 F4.2 mag e_C4mag [0.03/0.2]?=9 Uncertainty in C4mag
240-243 F4.2 mag e_W1mag [0.03/0.5]?=9 Uncertainty in W1mag
245-249 F5.3 mag e_W2mag [0.02/0.2]?=9 Uncertainty in W2mag
251-254 F4.2 mag e_W3mag [0.07/0.5]?=9 Uncertainty in W3mag
256-286 A31 --- Ref1 Discovery reference (see refs.dat file)
288-306 A19 --- Comp Name if object is known to be part
of a multiple system
308-338 A31 --- Ref2 Spectral classification reference
(see refs.dat file)
340-361 A22 --- Ref3 Trigonometric parallax reference
(see refs.dat file)
363-424 A62 --- Ref4 Photometry reference (see refs.dat file)
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Note (1): Survey+position based identifiers are given for all sources and
have been verified with Simbad except for WISE J080715.26-661851.6. We give
this identifier to object WD 0806-661B to indicate the presence of a
faint but measurable source in the WISE images.
Note (2): Binary component indicators for systems with blended photometry in
one or more bands. The photometry of blended binary systems is given as
Binary=AB. Otherwise the photometry is of the individual component.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- Ref Reference code in table 8
6- 28 A23 --- Ref15 Reference code (First author's name and year)
in table 15
30- 48 A19 --- BibCode Bibcode of the reference
50- 69 A20 --- Comm Comment
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History:
From electronic version of the journal
Acknowledgements:
Sandy K. Leggett [Gemini Observatory]
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 31-Jan-2018