J/ApJS/213/34 Velocities of Cygnus OB2 massive binaries (Kobulnicky+, 2014)
Toward complete statistics of massive binary stars: penultimate results from
the Cygnus OB2 radial velocity survey.
Kobulnicky H.A., Kiminki D.C., Lundquist M.J., Burke J., Chapman J.,
Keller E., Lester K., Rolen E.K., Topel E., Bhattacharjee A., Smullen R.A.,
Vargas Alvarez C.A., Runnoe J.C., Dale D.A., Brotherton M.M.
<Astrophys. J. Suppl. Ser., 213, 34 (2014)>
=2014ApJS..213...34K 2014ApJS..213...34K
ADC_Keywords: Stars, double and multiple ; Radial velocities ; Spectral types ;
Binaries, spectroscopic; Surveys
Keywords: binaries: close; binaries: general; binaries: spectroscopic;
stars: early-type; stars: kinematics and dynamics; stars: massive;
techniques: radial velocities
Abstract:
We analyze orbital solutions for 48 massive multiple-star systems in
the Cygnus OB2 association, 23 of which are newly presented here, to
find that the observed distribution of orbital periods is
approximately uniform in log P for P<45days, but it is not scale-free.
Inflections in the cumulative distribution near 6days, 14days, and
45days suggest key physical scales of ≃0.2, ≃0.4, and ≃1A.U. where
yet-to-be-identified phenomena create distinct features. No single
power law provides a statistically compelling prescription, but if
features are ignored, a power law with exponent β≃-0.22 provides
a crude approximation over P=1.4-2000days, as does a piece-wise linear
function with a break near 45days. The cumulative period distribution
flattens at P>45days, even after correction for completeness,
indicating either a lower binary fraction or a shift toward low-mass
companions. A high degree of similarity (91% likelihood) between the
Cyg OB2 period distribution and that of other surveys suggests that
the binary properties at P≲25days are determined by local physics of
disk/clump fragmentation and are relatively insensitive to
environmental and evolutionary factors. Fully 30% of the unbiased
parent sample is a binary with period P<45days. Completeness
corrections imply a binary fraction near 55% for P<5000days. The
observed distribution of mass ratios 0.2<q<1 is consistent with
uniform, while the observed distribution of eccentricities 0.1<e<0.6
is consistent with uniform plus an excess of e≃0 systems. We identify
six stars, all supergiants, that exhibit aperiodic velocity variations
of ∼30km/s attributed to atmospheric fluctuations.
Description:
Paper I (Cat. J/ApJ/664/1102) describes instrumental setups and dates
of observation for observing runs using the Keck+HIRES spectrograph
(1999-2001), the Lick+Hamilton echelle spectrograph (1999-2000), and
the WIYN+Hydra spectrograph (2001-2008). Results presented here
principally use spectra obtained at the Wyoming Infrared Observatory
(WIRO) 2.3m telescope+Longslit optical spectrograph during the
2011-2013 observing seasons, with a small number of observations
obtained in 2014 May. Resolutions of R∼4500 were achieved in the
wavelength range 5400-6700Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 49 543 Ephemerides for new binary systems
table7.dat 32 173 Velocities of stars showing aperiodic variations
table8.dat 128 50 OB binaries in Cyg OB2
table9.dat 48 207 Reanalyzed ephemerides for systems from
Paper II (2008ApJ...679.1478K 2008ApJ...679.1478K) and
Paper III (2009AJ....137.4608K 2009AJ....137.4608K)
apvar.dat 22 6 O-star sample exhibiting irregular velocity
variations (table added by CDS following
Section 3.2 data)
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See also:
III/195 : Atlas of Optical Spectral Classification OB Stars (Walborn+ 1990)
J/A+A/550/A107 : RV catalogue of O stars in 30 Doradus (Sana+, 2013)
J/A+A/543/A101 : OB stars in Cygnus OB2 association (Comeron+, 2012)
J/MNRAS/424/1925 : Spectrocopic Binarity of O and B type stars (Chini+, 2012)
J/other/Sci/337.444 : RV curves of Galactic massive O stars (Sana+, 2012)
J/ApJ/751/4 : Paper V. RVs of massive stars in Cyg OB2 (Kiminki+, 2012)
J/AJ/137/3358 : Speckle interferometry of massive stars (Mason+, 2009)
J/A+A/479/541 : VLT-FLAMES survey of massive stars (Hunter+, 2008)
J/MNRAS/386/447 : RV catalogue of O-type stars in NGC 6231 (Sana+, 2008)
J/ApJ/664/1102 : Paper I. RV survey of Cyg OB2 association (Kiminki+, 2007)
J/MNRAS/298/753 : Variables in Cygnus OB2 (Pigulski+ 1998)
J/AJ/101/1408 : Massive stars in Cyg OB2. (Massey+ 1991)
Byte-by-byte Description of file: table[19].dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Source identifier
12- 13 A2 --- m_ID [ab c12] Component identifier
16- 24 F9.3 d HJD Heliocentric Julian Date; HJD-2400000
26- 30 F5.3 --- Phase Orbital phase
32- 37 F6.1 km/s RVel [-220/197] Radial velocity
39- 42 F4.1 km/s e_RVel [1.1/32] The 1σ uncertainty in RVel
44- 49 F6.2 km/s O-C [-47/47] The observed-minus-computed velocity
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Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- ID Source identifier
11 A1 --- f_ID [a] Flag on ID (1)
13- 21 F9.3 d HJD Heliocentric Julian Date; HJD-2400000
23- 27 F5.1 km/s RVel [-37.1/18] Radial velocity
29- 32 F4.1 km/s e_RVel [1.3/11.5] The 1σ uncertainty in RVel
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Note (1):
a = Velocities measured from HeII λ5411 assuming a rest
wavelength of 5411.45 Angstroms.
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Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- ID Star identifier
12- 13 A2 --- m_ID [c12] Component identifier
16- 18 A3 --- ID2 Other identifier (S=Schulte)
20- 26 A7 --- Type Spectroscopic binary type (1)
28- 47 A20 --- SpT MK spectral types for the components
49- 58 F10.5 d Per [1.4/4996] Orbital period
60- 68 F9.5 d e_Per [0/330]? Per uncertainty
70 A1 --- f_Per [fy] f=fixed; y=6.19yr
72- 76 F5.1 km/s K1 [3.4/257]? Primary semi-amplitude
78- 81 F4.1 km/s e_K1 [0.3/15]? K1 uncertainty
83- 87 F5.3 --- e [0/0.75]? Eccentricity
89- 93 F5.3 --- e_e [0.01/0.3]? e uncertainty
95 A1 --- f_e [f] f=fixed eccentricity
97-101 F5.3 --- q1 [0/1] Mass ratio (q=M2/M1): lower limit (2)
102-104 A3 --- n_q2 [~:f ±] How to interpret q2 (2)
105-109 F5.3 --- q2 [0/1]? Mass ratio (q=M2/M1): upper limit or error
111-123 A13 --- Ref Reference(s) to published orbital solutions (3)
125-128 A4 --- Note [a-f,? ] Additional note(s) (4)
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Note (1): Photometric types EW/KE, EA, and EB stand for eclipsing system of
the W UMa type (ellipsoidal; P<1day), Algol type (near spherical), and
β Lyr type (ellipsoidal; P>1day), respectively.
Note (2): The mass ratio for MT91 421 is calculated using the O star masses
of Martins et al. (2005A&A...436.1049M 2005A&A...436.1049M) and interpolated AB masses of
Drilling & Landolt (2000asqu.book..381D 2000asqu.book..381D).
q1 may be a lower limit (n_q2=-) or approximate lower limit (n_q2≃-);
q2 may be an error (n_q2=±) or an upper limit (n_q2=-);
n_q2=f indicates a fixed valeur for q, and n_q2=: a value with a large
uncertainty.
Note (3): Reference as follows:
0 = This work
1 = Paper VI (Kobulnicky et al. 2012ApJ...756...50K 2012ApJ...756...50K)
2 = Paper II (Kiminky et al. 2008ApJ...679.1478K 2008ApJ...679.1478K)
3 = Paper III (Kiminky et al. 2009AJ....137.4608K 2009AJ....137.4608K)
4 = Paper IV (Kiminky et al. 2012ApJ...747...41K 2012ApJ...747...41K)
5 = Wozniak et al. 2004AJ....127.2436W 2004AJ....127.2436W
6 = Pigulski & Kolaczkowski 1998, Cat. J/MNRAS/298/753
7 = Rios & DeGioia-Eastwood 2004AAS...205.0905R 2004AAS...205.0905R
8 = Kiminki & Kobulnicky 2012, Cat. J/ApJ/751/4 (Paper V)
9 = Wilson 1948PASP...60..385W 1948PASP...60..385W
10 = Wilson & Abt 1951ApJ...114..477W 1951ApJ...114..477W
11 = Miczaika 1953PASP...65..141M 1953PASP...65..141M
12 = Walborn 1973ApJ...180L..35W 1973ApJ...180L..35W
13 = Contreras et al. 1997ApJ...488L.153C 1997ApJ...488L.153C
14 = Rauw et al. 1999ApJ...517..416R 1999ApJ...517..416R
15 = Hall 1974AcA....24...69H 1974AcA....24...69H
16 = Romano 1969MmSAI..40..375R 1969MmSAI..40..375R
17 = De Becker et al. 2004A&A...424L..39D 2004A&A...424L..39D
18 = Naze et al. 2008A&A...483..543N 2008A&A...483..543N
19 = Naze et al. 2012A&A...546A..37N 2012A&A...546A..37N
20 = Otero 2008OEJV...83....1O 2008OEJV...83....1O
21 = Hanson 2003ApJ...597..957H 2003ApJ...597..957H
22 = Stroud et al. 2010A&A...511A..84S 2010A&A...511A..84S
23 = Otero 2008OEJV...91....1O 2008OEJV...91....1O
Note (4): Note as follows:
a = Probable triple system.
b = Re-analyzed and updated from Paper II (Kiminky et al. 2008,
Cat. J/ApJ/679/1478).
c = Re-analyzed and updated from Paper III (Kiminky et al.
2009AJ....137.4608K 2009AJ....137.4608K).
d = An alternative period of 5.998 days is also possible, but less likely.
e = Preliminary updates on published orbital parameters presented here. A more
complete analysis will be presented in Paper 8.
f = Exhibits irregular velocity variations in addition to the listed orbital
motion.
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Byte-by-byte Description of file: apvar.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- ID Star identifier
11- 14 A4 --- ID2 Other identifier (S=Schulte)
16- 22 A7 --- SpT MK spectral type
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History:
From electronic version of the journal
References:
Kiminki et al. Paper I. 2007ApJ...664.1102K 2007ApJ...664.1102K Cat. J/ApJ/664/1102
Kiminki et al. Paper II. 2008ApJ...679.1478K 2008ApJ...679.1478K
Kiminki et al. Paper III. 2009AJ....137.4608K 2009AJ....137.4608K
Kiminki et al. Paper IV. 2012ApJ...747...41K 2012ApJ...747...41K
Kiminki & Kobulnicky Paper V. 2012ApJ...751....4K 2012ApJ...751....4K Cat. J/ApJ/751/4
Kobulnicky et al. Paper VI. 2012ApJ...756...50K 2012ApJ...756...50K
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 11-Sep-2014