J/AJ/157/196 Close companions around young stars (Kounkel+, 2019)
Close companions around young stars.
Kounkel M., Covey K., Moe M., Kratter K.M., Suarez G., Stassun K.G.,
Roman-Zuniga C., Hernandez J., Kim J.S., Ramirez K.P., Roman-Lopes A.,
Stringfellow G.S., O Jaehnig K., Borissova J., Tofflemire B.,
Krolikowski D., Rizzuto A., Kraus A., Badenes C., Longa-Pena P.,
Maqueo Chew Y.G., Barba R., Nidever D.L., Brown C., De Lee N., Pan K.,
Bizyaev D., Oravetz D., Oravetz A.
<Astron. J., 157, 196 (2019)>
=2019AJ....157..196K 2019AJ....157..196K (SIMBAD/NED BibCode)
ADC_Keywords: Star Forming Region ; Stars, pre-main sequence ;
Binaries, spectroscopic ; Radial velocities ; Proper motions ;
Rotational velocities ; Effective temperatures ; Models
Keywords: binaries: spectroscopic - stars: pre-main sequence
Abstract:
Multiplicity is a fundamental property that is set early during stellar
lifetimes, and it is a stringent probe of the physics of star formation.
The distribution of close companions around young stars is still poorly
constrained by observations. We present an analysis of stellar multiplicity
derived from Apache Point Observatory Galactic Evolution Experiment-2
spectra obtained in targeted observations of nearby star-forming regions.
This is the largest homogeneously observed sample of high-resolution
spectra of young stars. We developed an autonomous method to identify
double-lined spectroscopic binaries (SB2s). Out of 5007 sources spanning
the mass range of ∼0.05-1.5 M☉, we find 399 binaries, including
both radial velocity (RV) variables and SB2s. The mass ratio distribution
of SB2s is consistent with being uniform for q<0.95 with an excess of
twins for q>0.95. The period distribution is consistent with what has been
observed in close binaries (<10 au) in the evolved populations. Three
systems are found to have q∼0.1, with a companion located within the brown
dwarf desert. There are no strong trends in the multiplicity fraction
as a function of cluster age from 1 to 100 Myr. There is a weak dependence
on stellar density, with companions being most numerous at
Σ*∼30 stars/pc-2 and decreasing in more diffuse regions. Finally,
disk-bearing sources are deficient in SB2s (but not RV variables) by a
factor of ∼2; this deficit is recovered by the systems without disks.
This may indicate a quick dispersal of disk material in short-period
equal-mass systems that is less effective in binaries with lower q.
Description:
High-resolution near-infrared spectra of several nearby star-forming
regions and young clusters have been obtained by the APOGEE spectrograph,
which is mounted on the 2.5 m Sloan Digital Sky Survey (SDSS) telescope
(Gunn et al. 2006AJ....131.2332G 2006AJ....131.2332G; Blanton et al. 2017AJ....154...28B 2017AJ....154...28B).
The APOGEE spectrographs can observe up to 300 sources simultaneously
across a 1.5° field of view, and the instrument covers the spectral
range of 1.51-1.7 µm with a typical R∼22500 (although it may vary
between the individual fibers; Wilson et al. 2010SPIE.7735E..1CW;
Majewski et al. 2017AJ....154...94M 2017AJ....154...94M). The typical limiting magnitude for
the observations analyzed here is H∼13 mag.
The analysis in this work focuses on young stellar objects (YSOs) in
the Orion Complex (Da Rio et al. 2016, J/ApJ/818/59; 2017ApJ...845..105D 2017ApJ...845..105D;
Kounkel et al. 2018, J/AJ/156/84), NGC 1333 (Foster et al. 2015,
J/ApJ/799/136), IC 348 (Cottaar et al. 2015, J/ApJ/807/27), Taurus
Molecular Clouds, NGC 2264, α Per, and Pleiades. The observations
originally began as part of the SDSS-III IN-SYNC survey with APOGEE and
later transitioned into the SDSS-IV Young Clusters Survey with APOGEE-2
with an expanded list of regions, increased footprint on the sky, and
additional epochs covering a larger baseline for some of the existing
targets. Sources were selected for targeting using the presence of
infrared excess, optical variability, and when feasible, identification
as a YSO in the literature (Cottle et al. 2018, J/ApJS/236/27). In total,
53452 spectra were obtained for 14823 stars across a ∼150 deg2 field
of view over 6.5 yr, from 2011 September to 2018 March (Table 1).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 226 12832 Catalog of the sources observed by APOGEE-2 survey
towards the young clusters and star-forming
regions
table2.dat 136 39534 Stellar properties measured from the IN-SYNC
pipeline across the individual epochs
table3.dat 93 12 Observed clusters and star-forming regions
table4.dat 402 34915 Deconvolved cross-correlation functions (CCFs)
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See also:
J/AJ/121/2124 : λ Ori pre-main-sequence stars photometry (Dolan+, 2001)
J/ApJ/648/1090 : Radial velocities of NGC 2264 stars (Furesz+, 2006)
J/AJ/144/192 : Spitzer survey of Orion A and B. I. YSO catalog
(Megeath+, 2012)
J/ApJ/794/124 : Young star forming region NGC 2264 Spitzer sources
(Rapson+, 2014)
J/ApJ/794/125 : IN-SYNC. I. APOGEE stellar parameters (Cottaar+, 2014)
J/AJ/149/119 : Radial velocities of stars in NGC 2264 (Tobin+, 2015)
J/ApJ/799/136 : IN-SYNC. II. Candidate young stars in NGC 1333 (Foster+, 2015)
J/ApJ/807/27 : IN-SYNC. III. Radial velocities of IC348 stars
(Cottaar+, 2015)
J/ApJ/818/59 : IN-SYNC. IV. YSOs in Orion A (Da Rio+, 2016)
J/ApJ/821/8 : Spectroscopic binary population of ONC and NGC2264
(Kounkel+, 2016)
J/ApJ/821/52 : NIR survey of Spitzer YSOs in Orion Mol. Cloud
(Kounkel+, 2016)
J/ApJ/844/138 : Optical spectroscopy toward Orion B fields (Kounkel+, 2017)
J/A+A/609/A10 : NGC2264 structure and star formation history (Venuti+, 2018)
J/A+A/613/A63 : Lithium content for 148 Pleiades stars (Bouvier+, 2018)
J/AJ/156/18 : APOGEE DR14:Binary companions of evolved stars
(Price-Whelan+, 2018)
J/AJ/156/84 : APOGEE-2 survey of Orion Complex. II. (Kounkel+, 2018)
J/AJ/156/271 : The stellar membership of the Taurus SFR (Luhman, 2018)
J/ApJ/859/33 : GOBELINS. IV. VLBA obs. of Taurus (Galli+, 2018)
J/ApJS/236/27 : APOGEE-2 survey of Orion Complex (OSFC). I. (Cottle+, 2018)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- 2MASS 2MASS identifier
20- 31 F12.8 deg RAdeg Right Ascension in decimal degrees (J2000)
33- 44 F12.8 deg DEdeg Declination in decimal degrees (J2000)
46- 57 A12 --- Cluster Cluster identifier
59 I1 --- YSO [0/3]? YSO class (1)
61- 62 I2 --- Num [1/27] Number of epochs
64- 73 E10.3 km/s RV [-489/734.8]? Radial velocity
75- 83 E9.3 km/s e_RV [8.514e-05/8050]? Uncertainty in RV
85- 93 E9.3 km/s Vrot [0.008635/1976]? Rotational velocity times
sin(i)
95-103 E9.3 km/s e_Vrot [9.363e-07/5694]? Uncertainty in Vrot
105-113 E9.3 K Teff [2300/15000]? Effective temperature
115-123 E9.3 K e_Teff [1.477e-06/109700]? Uncertainty in Teff
125-134 E10.3 [cm/s2] log(g) [-0.5/6]? Log surface gravity
136-144 E9.3 [cm/s2] e_log(g) [8.342e-10/6.677]? Uncertainty in log(g)
146-154 E9.3 --- Veil [1.404e-07/22.36]? Veiling value (continuum
excess in the spectrum due to accretion)
156-164 E9.3 --- e_Veil [3.635e-07/1862]? Uncertainty in Veil
166 I1 --- SB2 [0/3]? Binary SB2 code (2)
168-176 E9.3 --- chi2 [5.21e-05/24790]? Binary χ2 value
178-186 E9.3 --- Slope [0.0002926/177.8]? Binary slope value
188-196 E9.3 --- Lchi2 [0.001515/16410]? Literature χ2 value
198-206 E9.3 --- LSlope [0.00122/177.8]? Literature slope value
208-216 E9.3 --- q [0.1039/0.9997]? Mass ratio
218-226 E9.3 --- e_q [0.008812/0.4503]? Uncertainty in q
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Note (1): YSO class as follows:
0 = Not a part of the curated sample;
2 = Class I/II YSO;
3 = Class III YSO.
Note (2): Binary SB2 code as follows:
0 = Undeconvolvable cross-correlation function (CCF);
1 = Only a single component in the CCF;
2 = Multiple components in the CCF with Flag 4;
3 = Not explained in this paper.
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- 2MASS 2MASS identifier
20- 24 I5 d MJD [55847/58179] Modified Julian Date of
the observation
26- 35 E10.3 km/s RV [-1534/1110]? Radial velocity
37- 45 E9.3 km/s e_RV [4.472e-05/28760]? Uncertainty in RV
47- 55 E9.3 km/s Vrot [0.008635/2933]? Rotational velocity times
sin(i)
57- 65 E9.3 km/s e_Vrot [9.363e-07/58980]? Uncertainty in Vrot
67- 75 E9.3 K Teff [2300/15000]? Effective temperature
77- 85 E9.3 K e_Teff [1.477e-06/266700]? Uncertainty in Teff
87- 96 E10.3 [cm/s2] log(g) [-0.5/6.491]? Log surface gravity
98-106 E9.3 [cm/s2] e_log(g) [8.342e-10/25.88]? Uncertainty in log(g)
108-116 E9.3 --- Veil [1.404e-07/1962]? Veiling value
118-126 E9.3 --- e_Veil [3.504e-07/12530]? Uncertainty in Veil
128-136 E9.3 --- S/N [0.118/941.1]? Signal-to-noise ratio
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Cluster Cluster identifier
14 A1 --- n_Cluster [b] Note on Cluster (1)
16- 18 I3 Myr Age [1/125] Age
20 A1 --- r_Age [abcdef] Reference for Age (2)
22- 25 I4 --- N* [132/1274] Number of stars
27- 29 I3 --- Nbin [7/137] Number of bins
31- 34 I4 K Teff-5 [2550/3324] 5th percentile of the effective
temperature
36- 39 I4 K Teff-50 [3770/4280] 50th percentile of the effective
temperature
41- 44 I4 K Teff-95 [4690/5770] 95th percentile of the effective
temperature
46- 48 F3.1 [cm/s2] log(g)-5 [3.2/4.8] 5th percentile of the surface
gravity
50- 52 F3.1 [cm/s2] log(g)-50 [4.3/5.2] 50th percentile of the surface
gravity
54- 56 F3.1 [cm/s2] log(g)-95 [4.7/5.5] 95th percentile of the surface
gravity
58- 61 I4 d Dt [357/2190] Time interval Δt
63 I1 --- Nv [2/6] Number of visits
65- 67 I3 km/s b_RV [-15/25] Lower value of radial velocity
69- 70 I2 km/s B_RV [15/36] Upper value of radial velocity
72- 73 I2 mas/yr b_pmRA [-8/15] Lower value of proper motion along
RA µα
75- 76 I2 mas/yr B_pmRA [2/35] Upper value of proper motion along
RA µα
78- 80 I3 mas/yr b_pmDE [-55/-5] Lower value of proper motion along
DE µδ
82- 84 I3 mas/yr B_pmDE [-35/5] Upper value of proper motion along
DE µδ
86- 88 F3.1 mas b_plx [0.8/6] Lower value of parallax π
90- 93 F4.1 mas B_plx [2.5/10] Upper value of parallax π
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Note (1): Note as follows:
b = Following the nomenclature from Kounkel et al. (2018, J/AJ/156/84);
sources without membership assignment were split on the basis of their
RVs.
Note (2): Reference as follows:
a = Luhman et al. (2016ApJ...827...52L 2016ApJ...827...52L);
b = Luhman (2018, J/AJ/156/271);
c = Venuti et al. (2018, J/A+A/609/A10);
d = Kounkel et al. (2018, J/AJ/156/84);
e = Balachandran et al. (2011MNRAS.410.2526B 2011MNRAS.410.2526B);
f = Bouvier et al. (2018, J/A+A/613/A63).
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- 2MASS 2MASS identifier
20- 24 I5 d MJD [55847/58179] Modified Julian Date of
the observation
26- 34 E9.3 km/s FWHM1 [0.2115/5478] First Gaussian full width at half
maximum
36- 44 E9.3 km/s e_FWHM1 [0/2.62e+15] Uncertainty in FWHM1
46- 54 E9.3 --- Amp1 [0/10.63] First Gaussian amplitude
56- 64 E9.3 --- e_Amp1 [0/2.219e+15]? Uncertainty in Amp1
66- 75 E10.3 km/s v1 [-11490/2750] First Gaussian mean position
77- 85 E9.3 km/s e_v1 [0/1.718e+16] Uncertainty in v1
87 I1 --- Flag1 [1/4] First Gaussian fit flag (1)
89- 97 E9.3 km/s FWHM2 [0.002546/17750000]? Second Gaussian full width
at half maximum
99-107 E9.3 km/s e_FWHM2 [0/1.648e+16]? Uncertainty in FWHM2
109-117 E9.3 --- Amp2 [0/13.13]? Second Gaussian amplitude
119-127 E9.3 --- e_Amp2 [0/9.159e+14]? Uncertainty in Amp2
129-138 E10.3 km/s v2 [-1250/16120000]? Second Gaussian mean position
140-148 E9.3 km/s e_v2 [0/1.058e+17]? Uncertainty in v2
150 I1 --- Flag2 [0/4] Second Gaussian fit flag (1)
152-160 E9.3 km/s FWHM3 [0.06381/6117]? Third Gaussian full width at half
maximum
162-170 E9.3 km/s e_FWHM3 [0/53060000000]? Uncertainty in FWHM3
172-180 E9.3 --- Amp3 [1.021e-13/22.94]? Third Gaussian amplitude
182-190 E9.3 --- e_Amp3 [0/53910]? Uncertainty in Amp3
192-201 E10.3 km/s v3 [-8530/8769]? Third Gaussian mean position
203-211 E9.3 km/s e_v3 [0/46390000000]? Uncertainty in v3
213 I1 --- Flag3 [0/4] Third Gaussian fit flag (1)
215-223 E9.3 km/s FWHM4 [4.428/1194]? Fourth Gaussian full width at half
maximum
225-233 E9.3 km/s e_FWHM4 [0/19950000000]? Uncertainty in FWHM4
235-243 E9.3 --- Amp4 [3.638e-11/0.1456]? Fourth Gaussian amplitude
245-253 E9.3 --- e_Amp4 [0/67370]? Uncertainty in Amp4
255-264 E10.3 km/s v4 [-273.8/3210]? Fourth Gaussian mean position
266-274 E9.3 km/s e_v4 [0/49720000000]? Uncertainty in v4
276 I1 --- Flag4 [0/1] Fourth Gaussian fit flag (1)
278-286 E9.3 km/s FWHM5 [6.318/350.3]? Fifth Gaussian full width at half
maximum
288-296 E9.3 km/s e_FWHM5 [0/430100]? Uncertainty in FWHM5
298-306 E9.3 --- Amp5 [0.01903/1.545]? Fifth Gaussian amplitude
308-316 E9.3 --- e_Amp5 [0/54450]? Uncertainty in Amp5
318-327 E10.3 km/s v5 [-883.8/195.7]? Fifth Gaussian mean position
329-337 E9.3 km/s e_v5 [0/1570000]? Uncertainty in v5
339 I1 --- Flag5 [0/1] Fifth Gaussian fit flag (1)
341-349 E9.3 km/s FWHM6 [13.3/184.6]? Sixth Gaussian full width at half
maximum
351-359 E9.3 km/s e_FWHM6 [0/68200000]? Uncertainty in FWHM6
361-369 E9.3 --- Amp6 [0.02759/2.093]? Sixth Gaussian amplitude
371-379 E9.3 --- e_Amp6 [0/20750000]? Uncertainty in Amp6
381-390 E10.3 km/s v6 [-438.7/691.4]? Sixth Gaussian mean position
392-400 E9.3 km/s e_v6 [0/300300000]? Uncertainty in v6
402 I1 --- Flag6 [0/1] Sixth Gaussian fit flag (1)
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Note (1): Gaussian fit flag as follows:
1 = Failed FWHM/amplitude test; could be noise;
2 = Fail the symmetry test; could be falsely multiply deconvolved;
3 = Inconclusive SB2/Spotted star pair;
4 = The primary peaks in all stars, and the secondary peaks of bona fide SB2s.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 06-Aug-2019