J/ApJS/231/15 Astrometric monitoring of ultracool dwarf binaries (Dupuy+, 2017)
Individual dynamical masses of ultracool dwarfs.
Dupuy T.J., Liu M.C.
<Astrophys. J. Suppl. Ser., 231, 15-15 (2017)>
=2017ApJS..231...15D 2017ApJS..231...15D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Spectral types ; Photometry, HST ;
Photometry, infrared ; Stars, late-type ; Stars, masses
Keywords: astrometry; binaries: close; brown dwarfs; fundamental parameters;
parallaxes; stars: evolution
Abstract:
We present the full results of our decade-long astrometric monitoring
programs targeting 31 ultracool binaries with component spectral types
M7-T5. Joint analysis of resolved imaging from Keck Observatory and
Hubble Space Telescope and unresolved astrometry from CFHT/WIRCam
yields parallactic distances for all systems, robust orbit
determinations for 23 systems, and photocenter orbits for 19 systems.
As a result, we measure 38 precise individual masses spanning
30-115MJup. We determine a model-independent substellar boundary
that is ∼70MJup in mass (∼L4 in spectral type), and we validate
Baraffe et al. evolutionary model predictions for the
lithium-depletion boundary (60MJup at field ages). Assuming each
binary is coeval, we test models of the substellar mass-luminosity
relation and find that in the L/T transition, only the Saumon & Marley
(2008ApJ...689.1327S 2008ApJ...689.1327S) "hybrid" models accounting for cloud clearing
match our data. We derive a precise, mass-calibrated spectral
type-effective temperature relation covering 1100-2800K. Our masses
enable a novel direct determination of the age distribution of field
brown dwarfs spanning L4-T5 and 30-70MJup. We determine a median age
of 1.3Gyr, and our population synthesis modeling indicates our sample
is consistent with a constant star formation history modulated by
dynamical heating in the Galactic disk. We discover two
triple-brown-dwarf systems, the first with directly measured masses
and eccentricities. We examine the eccentricity distribution,
carefully considering biases and completeness, and find that
low-eccentricity orbits are significantly more common among ultracool
binaries than solar-type binaries, possibly indicating the early
influence of long-lived dissipative gas disks. Overall, this work
represents a major advance in the empirical view of very low-mass
stars and brown dwarfs.
Description:
In Table 1 we list all 33 binaries in our Keck+CFHT astrometric
monitoring sample, along with three other binaries that have published
orbit and parallax measurements. We began obtaining resolved Keck AO
astrometry in 2007-2008, and we combined our new astrometry with
available data in the literature or public archives (e.g., HST and
Gemini) to refine our orbital period estimates and thereby our
prioritization for Keck observations.
We present here new Keck/NIRC2 AO imaging and non-redundant
aperture-masking observations, in addition to a re-analysis of our own
previously published data and publicly available archival data for our
sample binaries. Table 2 gives our measured astrometry and flux ratios
for all Keck AO data used in our orbital analysis spanning 2003 Apr 15
to 2016 May 13. In total there are 339 distinct measurements (unique
bandpass and epoch for a given target), where 302 of these are direct
imaging and 37 are non-redundant aperture masking. Eight of the
imaging measurements are from six unpublished archival data sets. See
section 3.1.1 for further details.
In addition to our Keck AO monitoring, we also obtained data for three
T dwarf binaries over a three-year HST program using the Advanced
Camera for Surveys (ACS) Wide Field Camera (WFC) in the F814W bandpass.
See section 3.1.2 for further details.
Many of our sample binaries have HST imaging data in the public
archive. We have re-analyzed the available archival data coming from
the WFPC2 Planetary Camera (WFPC2-PC1), ACS High Resolution Channel
(ACS-HRC), and NICMOS Camera 1 (NICMOS-NIC1). See section 3.1.3 for
further details.
We present here an updated analysis of our data from the Hawaii
Infrared Parallax Program that uses the CFHT facility infrared camera
WIRCam. Our observing strategy and custom astrometry pipeline are
described in detail in Dupuy & Liu (2012, J/ApJS/201/19). See section
3.2 for further explanations.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 126 36 Orbit monitoring sample
table2.dat 104 339 Relative astrometry from Keck/NIRC2 adaptive optics
imaging and masking
table3.dat 144 77 Relative astrometry from HST imaging and
the literature
table4.dat 96 580 Integrated-light astrometry from CFHT/WIRCam
table5.dat 197 739 Markov Chain Monte Carlo (MCMC) posteriors for the
orbit and parallax of all sources
table9.dat 112 212 Apparent magnitudes for the sample
table10.dat 162 31 Summary of key parameters from orbit analysis
table11.dat 147 22 Summary of properties for dynamical mass sample
table13.dat 90 2327 Observed and model-derived properties of all systems
refs.dat 73 73 References
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See also:
B/cfht : Log of CFHT Exposures (CADC, 1979-)
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/AJ/103/638 : USNO Photographic Parallaxes. I. (Monet+, 1992)
J/AJ/106/773 : Mass-luminosity relation (Henry+, 1993)
J/A+A/327/1039 : Structure and evolution of low-mass stars (Chabrier+ 1997)
J/A+A/367/111 : A Hipparcos study of the Hyades cluster (de Bruijne+, 2001)
J/AJ/126/1526 : IR photometry of ultracool dwarfs (Bouy+, 2003)
J/AJ/126/2421 : 2MASS-Selected sample of ultracool dwarfs (Cruz+, 2003)
J/AJ/125/3302 : HST binary very low mass stars and brown dwarfs (Gizis+, 2003)
J/AJ/127/3553 : JHK photom. and spectroscopy for L and T dwarfs (Knapp+, 2004)
J/ApJ/637/1067 : Near-IR spectral classification of T dwarfs (Burgasser+, 2006)
J/AJ/131/2722 : New L and T dwarfs from the SDSS (Chiu+, 2006)
J/AJ/132/891 : Binaries among nearby L dwarfs (Reid+, 2006)
J/AJ/133/439 : Luminosity function of M7-L8 ultracool dwarfs (Cruz+, 2007)
J/AJ/134/1162 : 11 new T dwarfs in 2MASS (Looper+, 2007)
J/AJ/133/2258 : Activity and kinematics of ultracool dwarfs (Schmidt+, 2007)
J/ApJ/689/1295 : Lithium test implications for BDs (Kirkpatrick+, 2008)
J/AJ/136/1290 : Ultracool dwarfs from the 2MASS (Reid+, 2008)
J/AJ/135/785 : SDSS-DR5 low-mass star spectroscopic sample (West+, 2008)
J/AJ/137/1 : PMs and astrometry of late-type dwarfs (Faherty+, 2009)
J/ApJ/705/1416 : Volume-limited sample of M7-M9.5 dwarfs <20pc (Reiners+, 2009)
J/A+A/510/A99 : Epsilon Indi Ba and Bb IR spectra (King+, 2010)
J/ApJS/190/1 : A survey of stellar families (Raghavan+, 2010)
J/ApJ/725/331 : Astrometry in the Galactic Center (Yelda+, 2010)
J/ApJS/201/19 : Hawaii Infrared Parallax Program. I. (Dupuy+, 2012)
J/ApJ/752/56 : BDKP. III. Parallaxes for 70 ultracool dwarfs (Faherty+, 2012)
J/ApJ/753/156 : T/Y brown dwarfs with WISE photometry (Kirkpatrick+, 2012)
J/A+A/545/A85 : LHS1070 photometry and spectroscopy (Rajpurohit+, 2012)
J/MNRAS/433/457 : 76 T dwarfs from the UKIDSS LAS (Burningham+, 2013)
J/AJ/147/94 : Solar neighborhood. XXXII. L and M dwarfs (Dieterich+, 2014)
J/AJ/147/146 : Spectroscopy of Tuc-Hor candidate members (Kraus+, 2014)
J/A+A/581/A73 : Luhman 16AB X-shooter spectra (Lodieu+, 2015)
J/AJ/152/141 : Solar neighborhood. XXXVII. RVs for M dwarfs (Benedict+, 2016)
J/AJ/152/24 : Trigonometric plx of 134 low-mass stars (Weinberger+, 2016)
http://www.as.utexas.edu/~tdupuy/plx/Database_of_Ultracool_Parallaxes.html :
Database of Ultracool Parallaxes
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- f_Name o: other ultracool visual binaries with
published orbits and parallaxes
3- 29 A27 --- Name Identifier
31- 35 F5.3 arcsec Sep [0.04/0.8] Binary separation
37- 47 A11 "Y/M/D" Date UT date of binary discovery
49- 55 A7 --- Ref Reference
57- 67 A11 --- SpT Integrated-light spectral type: Optical/IR
69- 84 A16 --- r_SpT SpT reference(s)
86- 98 A13 --- CSpT Component spectral types A+B based on
NIR spectra (unless flagged) (1)
100 A1 --- f_CSpT [a] Flag on CSptT (2)
102-108 A7 --- r_CSpT CSpT reference
110-126 A17 --- ID Abbreviated identifier as in other tables;
column added by CDS
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Note (1): All component types (unless flagged) are based on near-IR spectra,
either resolved or deconvolved from the integrated-light near-IR
spectrum using near-IR resolved photometry.
Note (2):
a = The component spectral types in these cases come from resolved optical
spectroscopy.
For LHS 2397aAB, the primary spectral type is assumed to be the same
as the optical integrated-light type given the large contrast ratio
in the optical.
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Byte-by-byte Description of file: table[23].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- ID Identifier (G1)
20- 21 I2 --- Nep [1/17] Number of epochs observed
23- 27 F5.2 yr Delt [0/12]? Time between first and last observations
(only for table 2)
29- 39 A11 "Y/M/D" Date UT date of the observation
41- 48 F8.2 d MJD ? Modified Julian Date of the observation
(only for table 2)
50- 55 F6.2 mas Sep [25/389] Separation
57- 61 F5.2 mas e_Sep [0.06/20] Uncertainty in Sep
63- 68 F6.2 deg PA Position angle
70- 74 F5.2 deg e_PA [0.01/30] Uncertainty in PA
76- 81 F6.3 mag Delmag [-0.7/4.2]? Magnitude difference between
components in Filt
83- 87 F5.3 mag e_Delmag [0.001/0.8]? Uncertainty in Delmag
89- 96 A8 --- Filt Filter used in the observation
98- 99 I2 --- Nf [3/62]? Number of frames obtained
in the observation (only for table 2)
101-136 A36 --- Note Additional notes (1)
138-144 A7 --- r_Note Reference for measurements coming from
other paper (see refs.dat file) (2)
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Note (1):
I = an observation done with direct imaging;
M = non-redundant aperture masking.
* = This denotes a previously published data set that we obtained from
the public NIRC2 archive.
** = This denotes a previously unpublished data set that we obtained from
the public NIRC2 archive.
Note (2): The measurements reported in table 3 are from our own analysis
of archival data in this paper, unless another reference is given
in the Notes column.
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- ID Identifier (G1)
20- 21 I2 --- Nep [12/31] Number of epochs observed
23- 26 F4.2 yr Delt [2/10] Time between first and last observations
28- 38 A11 "Y/M/D" Date UT date of the observation
40- 49 F10.4 d MJD Modified Julian Date of the observation
51- 62 F12.8 deg RAdeg Right Ascension in decimal degrees (J2000)
64- 75 F12.8 deg DEdeg Declination in decimal degrees (J2000)
77- 80 F4.1 mas e_RAdeg [0.9/19] Uncertainty in RAdeg; times cos(DE)
82- 85 F4.1 mas e_DEdeg [1/17] Uncertainty in DEdeg
87- 91 F5.3 --- Air [1/1.9] Airmass
93- 96 F4.2 arcsec See [0.3/1.3] Seeing
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- ID Identifier (G1)
20 A1 --- Type [DF] Property type (F=Fitted parameter;
D=Derived property)
22- 88 A67 --- Prop Property description
90-101 F12.4 --- Median Median value for Prop
103-112 F10.4 --- e_Median Lower 1σ error on Median
114-123 F10.4 --- E_Median Upper 1σ error on Median
125-136 F12.4 --- Best Best fit for Prop
138-149 F12.4 --- LConf Lower 95.4% confidence boundary for Prop
151-162 F12.4 --- UConf Upper 95.4% confidence boundary for Prop
164-197 A34 --- Note Prior value or additional notes
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table9.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- ID Identifier (G1)
20- 28 A9 --- Filt Filter used in the observation
30- 35 F6.3 mag mag [9/19.7] Apparent integrated magnitude in Filt
37- 41 F5.3 mag e_mag [0.01/0.2] Uncertainty in mag
43- 48 F6.3 mag Delmag [-0.6/3.4] Difference in system magnitudes in Filt
50- 54 F5.3 mag e_Delmag [0.003/0.4] Uncertainty in Delmag
56- 61 F6.3 mag Amag [9.7/20.3] Primary apparent magnitude in Filt
63- 67 F5.3 mag e_Amag [0.01/0.2] Uncertainty in Amag
69- 74 F6.3 mag Bmag [9.9/20.7] Secondary apparent magnitude in Filt
76- 80 F5.3 mag e_Bmag [0.01/0.3] Uncertainty in Bmag
82-112 A31 --- Ref Reference(s) (see refs.dat file)
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Byte-by-byte Description of file: table10.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- ID Identifier (G1)
19- 23 F5.1 Mjup Mtot [38/270] Total mass
25- 28 F4.1 Mjup e_Mtot [1.7/50] Negative uncertainty in Mtot
30- 33 F4.1 Mjup E_Mtot [1.8/40] Positive uncertainty in Mtot
35 A1 --- f_Mtot Flag on Mtot
37- 41 F5.3 --- q [0.5/1.7]? M2/M1 ratio
43- 47 F5.3 --- e_q [0.02/0.2]? Negative uncertainty in q
49- 53 F5.3 --- E_q [0.02/0.2]? Positive uncertainty in q
55- 60 F6.4 --- e [0.002/0.9] Eccentricity
62- 67 F6.4 --- e_e [0.0003/0.3] Negative uncertainty in e
69- 74 F6.4 --- E_e [0.001/0.3]? Positive uncertainty in e
76 A1 --- f_e Flag on e
78- 85 F8.2 d Per [865.8/78000] Period
87- 94 F8.2 d e_Per [0.2/22000] Negative uncertainty in Per
96-103 F8.2 d E_Per [0.2/15000] Positive uncertainty in Per
105 A1 --- f_Per Flag on Per
107-112 F6.3 AU a [0.9/20] True semimajor axis
114-118 F5.3 AU e_a [0.009/4] Positive uncertainty in a
120-124 F5.3 AU E_a [0.009/3] Positive uncertainty in a
126 A1 --- f_a Flag on a
128-133 F6.3 --- aph/a [-0.9/0.9]? Ratio aphot/a (1)
135-139 F5.3 --- e_aph/a [0.006/2.1]? Uncertainty in aph/a
141-146 F6.4 --- beta [0.06/0.7]? Ratio of F2/(F1+F2)
148-153 F6.4 --- e_beta [0.001/0.03]? beta uncertainty
155-158 F4.1 mas Plx [31/89]? Absolute parallax from this work;
column added by CDS from table 8
160-162 F3.1 mas e_Plx [0.6/2.2]? Plx uncertainty
--------------------------------------------------------------------------------
Note (1): Where aphot is the constrained photocenter orbit semimajor axis.
See Section 5.2.
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Byte-by-byte Description of file: table11.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- ID Identifier (G1)
19 A1 --- f_ID Flag on ID
21- 25 F5.1 Mjup M1 [51/156] Primary component mass
27- 30 F4.1 Mjup e_M1 [1/18] Negative uncertainty in M1
32- 35 F4.1 Mjup E_M1 [1/17] Positive uncertainty in M1
37- 42 F6.3 [Lsun] Lbol1 [-5/-3] log of bolometric luminosity for
the primary component
44- 48 F5.3 [Lsun] e_Lbol1 [0.02/0.07] Negative uncertainty in Lbol1
50- 54 F5.3 [Lsun] E_Lbol1 [0.02/0.07] Positive uncertainty in Lbol1
56- 59 A4 --- SpT1 MK spectral type for the primary component
61- 63 F3.1 --- e_SpT1 [0.5/1.5] SpT1 uncertainty
65- 68 I4 K Teff1 [1150/2844]? Effective temperature of the
primary component
70- 71 I2 K e_Teff1 [16/60]? Negative uncertainty in Teff1
73- 74 I2 K E_Teff1 [16/70]? Positive uncertainty in Teff1
76- 80 F5.1 Mjup M2 [31.8/116] Secondary component mass
82- 85 F4.1 Mjup e_M2 [1.4/18] Negative uncertainty in M2
87- 90 F4.1 Mjup E_M2 [1.4/16] Positive uncertainty in M2
92- 97 F6.3 Lsun Lbol2 [-5/-3] log of bolometric luminosity for
the secondary component
99-103 F5.3 Lsun e_Lbol2 [0.02/0.07] Negative uncertainty in Lbol2
105-109 F5.3 Lsun E_Lbol2 [0.02/0.08] Positive uncertainty in Lbol2
111-114 A4 --- SpT2 MK spectral type for the secondary component
116-118 F3.1 --- e_SpT2 [0.5/1.5]? SpT2 uncertainty
120-123 I4 K Teff2 [1100/2820]? Effective temperature of the
secondary component
125-126 I2 K e_Teff2 [10/70]? Negative uncertainty in Teff2
128-129 I2 K E_Teff2 [20/60]? Positive uncertainty in Teff2
131-135 F5.3 Gyr Age [0.2/3.4]? Age
137-141 F5.3 Gyr e_Age [0.02/2.1]? Negative uncertainty in Age
143-147 F5.3 Gyr E_Age [0.02/2.8]? Positive uncertainty in Age
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Byte-by-byte Description of file: table13.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- ID Identifier (G1)
18 A1 --- f_ID [*] *: not explained in the paper
20- 24 A5 --- Type1 First type (1)
26- 28 A3 --- Type2 Second type (2)
30- 47 A18 --- Prop Property
49- 58 A10 --- x_Prop Units for Prop
60 A1 --- l_Value Limit flag on Prop
61- 70 F10.5 --- Value ? Value of Prop
72- 80 F9.5 --- e_Value [0/110]? Lower uncertainty in Value
82- 90 F9.5 --- E_Value [0/100]? Upper uncertainty in Value
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Note (1):
INPUT = input parameter;
B_TOT = result from total-mass analysis using BHAC models;
B_IND = result from individual-mass analysis using BHAC models;
C_TOT = result from total-mass analysis using Cond models;
C_IND = result from individual-mass analysis using Cond models;
S_TOT = result from total-mass analysis using SM08 models;
S_IND = result from individual-mass analysis using SM08 models
Note (2):
SYS = property of combined system;
PRI = property of primary;
SEC = property of secondary;
DEL = difference in primary and secondary properties.
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Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Ref Reference code
9- 27 A19 --- BibCode Bibcode of the reference
29- 53 A25 --- Auth First author's name
55- 73 A19 --- Comm Comment
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Global notes:
Note (G1): 2MASS J1047+4026AB is also known as LP 213-68.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Sep-2017