J/AJ/159/15 Binary stars in Upper Scorpius (Tokovinin+, 2020)
Binary stars in Upper Scorpius.
Tokovinin A., Briceno C.
<Astron. J., 159, 15 (2020)>
=2020AJ....159...15T 2020AJ....159...15T (SIMBAD/NED BibCode)
ADC_Keywords: Star Forming Region ; Stars, double and multiple ;
Parallaxes, trigonometric ; Proper motions ; Magnitudes ;
Stars, masses
Keywords: Binary stars - Star-forming regions - Visual binary stars -
Multiple stars
Abstract:
To address the statistics of binary stars in the 8 Myr old Upper Scorpius
(USco) star formation region, we conducted a speckle interferometric survey
of 614 association members more massive than 0.4 M☉ (spectral types
earlier than M3V) based on the list of Luhman et al. (2018, J/AJ/156/271).
We resolved 187 pairs, 55 of which are new discoveries. Also using the
published data and the Gaia DR2 (Cat. I/345), a catalog of 250 physical
binaries was produced. We carefully estimated detection limits for each
target and studied binary statistics in the separation range from 0.06"
to 20" (9-2800 au), as well as clustering at larger separations. The
frequency of companions with mass ratios q>0.3 in this separation range
is 0.33±0.04 and 0.35±0.04 for early M- and solar-type stars,
respectively, larger by 1.62±0.22 and 1.39±0.18 times compared to field
stars of similar masses. The excess is produced mostly by pairs closer
than 100 au. At separations from 100 to 104 au, the separation
distribution and companion fraction resemble those of solar-type stars
in the field. However, unlike in the field, we see a relative deficit
of equal-mass binaries at separations of ∼500 au, compared to smaller and
larger separations. The distribution of q depends on the separation, with
a preference of larger q and a larger fraction of twins with q>0.95 at
smaller separations. The binary population of USco differs from binaries
in the field in several ways and suggests that binary statistics is
not universal.
Description:
For the binary survey, it was used the large sample of USco members
featured in the papers by Esplin et al. (2018, J/AJ/156/75) and Luhman
et al. (2018, J/AJ/156/76) - in short, Luhman's sample.
The stars were observed using the high-resolution camera (HRCam) on
the 4.1 m Southern Astrophysical Research Telescope (SOAR) located at
Cerro Pachon in Chile. The instrument, observing procedure, and data
reduction are covered in Tokovinin (2018PASP..130c5002T 2018PASP..130c5002T). The survey
has been done in the I filter of HRCam (824/170 nm). The observations
started in 2018 March (these data are partly published in Tokovinin &
Briceno 2018AJ....156..138T 2018AJ....156..138T) and continued in 2019. Overall, we used
about 2 nights of telescope time. For each target, two data cubes of
400 frames each were recorded using the 2x2 binning (effective pixel
scale 31.5 mas) and 200x200 binned pixels region of interest (6.30" on
the sky).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 75 614 Filtered Luhman's sample
table2.dat 80 719 Results of SOAR observations
table3.dat 97 1020 Detection limits
table5.dat 77 250 List of binaries in Upper Scorpius
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See also:
B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2014)
I/345 : Gaia DR2 (Gaia, 2018)
J/A+A/356/541 : T Tauri stars in the Sco-Cen OB association (Koehler+, 2000)
J/A+A/430/137 : Close visual companions in Scorpius OB2 (Kouwenhoven+, 2005)
J/ApJS/181/62 : Survey of young solar analogs (Metchev+, 2009)
J/ApJ/757/141 : Companion IR detection limits in young associations
(Kraus+, 2012)
J/ApJ/785/47 : Sources around target stars in Upper Scorpius
(Lafreniere+, 2014)
J/AJ/155/196 : Analysis of K2 LCs for members of USco & ρ Oph
(Rebull+, 2018)
J/AJ/156/75 : Circumstellar disks in the Upper Sco association
(Esplin+, 2018)
J/AJ/156/76 : New young stars and brown dwarfs in Upper Sco (Luhman+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- USn Number in Esplin et al. (2018, J/AJ/156/75)
6- 14 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
16- 24 F9.5 deg DEdeg Declination in decimal degrees (J2000)
26- 30 F5.2 mas Plx [5.12/11.04]? Parallax from Gaia DR2 (Cat. I/345)
32- 37 F6.2 mas/yr pmRA [-24.6/3.77]? Proper motion in RA (pmRA*cosDE)
39- 44 F6.2 mas/yr pmDE [-41.1/-11.33]? Proper motion in DE
46- 50 F5.2 mag Vmag [2.3/17.16] V-band magnitude
52- 56 F5.2 mag Gmag [2.27/15.16] Gaia DR2 G-band magnitude
58- 62 F5.2 mag V-K [-0.76/7.26] V-K color index
64- 67 F4.2 mag Av [0/0.29] Extinction from Esplin et al. (2018,
J/AJ/156/75)
69- 73 F5.2 Msun Mstar [0.32/16.29] Estimated mass
75 I1 --- Fsec [0/1] Flag for secondary component (0=Primary;
1=Secondary)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- WDS WDS code (HHMMm+DDMM, J2000) (G1)
12- 15 A4 --- USn Number in Esplin et al. (2018, J/AJ/156/75)
17- 23 A7 --- Disc Discoverer designation from WDS or from USn
number
25- 29 A5 --- Comp Components designation
31- 38 F8.3 yr Epoch [2008.535/2019.613] Epoch of observation,
Julian year
40 A1 --- Filt [Iy] Filter used
42- 46 F5.1 deg PA [-0/358.9]?=0 Position angle (1)
48- 52 F5.3 arcsec Sep [0/5.462]?=0 Separation (1)
54- 58 F5.1 mas e_Sep [0.1/781.8]?=0 The 1σ uncertainty in Sep
(1)
60- 64 F5.2 mag Dm [-0.17/7.45]?=0 Magnitude difference of pair
(1)
66- 70 F5.3 arcsec MinSep [0.028/0.767] Minimum detectable resolution
limit
72- 75 F4.2 mag Dm0.15 [0/5.44] 5σ magnitude difference
at 0.15 arcsecond
77- 80 F4.2 mag Dm1 [0/6.91] 5σ magnitude difference
at 1 arcsecond
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Note (1): For unresolved objects these parameters are null.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- USn Number in Esplin et al. (2018, J/AJ/156/75)
6- 12 A7 --- Ref Reference (1)
14- 15 A2 --- Meth Method (2)
17- 20 F4.2 um lambda [0.5/2.2] Imaging wavelength λ
22- 26 F5.3 arcsec Sep1 [0.031/7.143] Minimum separation, first value
28- 33 F6.3 arcsec Sep2 [0.046/28.436] Minimum separation, second value
35- 40 F6.3 arcsec Sep3 [0.062/28.436] Minimum separation, third value
42- 47 F6.3 arcsec Sep4 [0.2/28.436] Minimum separation, forth value
49- 54 F6.3 arcsec Sep5 [1/28.436] Minimum separation, fifth value
56- 61 F6.3 arcsec Sep6 [1.523/28.436] Minimum separation, sixth value
63- 67 F5.2 mag Dm1 [0/13.5] Maximum magnitude difference at Sep1
69- 73 F5.2 mag Dm2 [0.02/18.5] Maximum magnitude difference at Sep2
75- 79 F5.2 mag Dm3 [0.02/20.3] Maximum magnitude difference at Sep3
81- 85 F5.2 mag Dm4 [0.02/20.7] Maximum magnitude difference at Sep4
87- 91 F5.2 mag Dm5 [0.02/20.7] Maximum magnitude difference at Sep5
93- 97 F5.2 mag Dm6 [0.02/20.7] Maximum magnitude difference at Sep6
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Note (1): Reference as follows:
HIP = Hipparcos;
KOH2000 = Koehler et al. (2000, J/A+A/356/541);
KOU05 = Kouwenhoven et al. (2005, J/A+A/430/137);
KRS12 = Kraus & Hillenbrand (2012, J/ApJ/757/141);
LAF14 = Lafreniere et al. (2014, J/ApJ/785/47);
MH09 = Metchev & Hillenbrand (2009, J/ApJS/181/62);
SOAR = This work.
Note (2): Mehods:
AO = Adaptive optics;
SI = Speckle interferometry;
q = Mass ratios are given instead of magnitude differences.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- WDS WDS code (HHMMm+DDMM, J2000) (G1)
12- 15 A4 --- USn Number in Esplin et al. (2018, J/AJ/156/75)
17- 23 A7 --- Disc Discoverer designation
25- 29 A5 --- Comp Components designation
31- 37 F7.2 yr Epoch [2000.4/2019.61] Epoch of observation, Julian year
39- 43 F5.1 deg PA [1.2/359.9] Position angle
45- 50 F6.3 arcsec Sep [0.017/20.128] Separation
52- 56 F5.2 mag Dm [0/11.66] Magnitude difference of pair at λ
(1)
58- 61 F4.2 um lambda [0.5/2.2] Imaging wavelength λ
63- 67 F5.2 Msun M1 [0.19/16.29] Primary mass
69- 74 F6.3 --- q [-0.02/1] Mass ratio
76- 77 I2 ---- Lev [1/12] Hierarchical level (2)
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Note (1): 0.6µm for Gaia, 0.8µm for SOAR in the I filter.
Note (2): Hierarchical level as follows:
1 = Outer systems;
11 = Inner subsystems around primary;
12 = Secondary subsystems.
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Global notes:
Note (G1): For objects not in the WDS these codes were created.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 14-Feb-2020