J/ApJ/900/118 RSGs in the LMC & sp. follow-up for LMC & SMC (Neugent+, 2020)
The red supergiant binary fraction of the Large Magellanic Cloud.
Neugent K.F., Levesque E.M., Massey P., Morrell N.I., Drout M.R.
<Astrophys. J., 900, 118 (2020)>
=2020ApJ...900..118N 2020ApJ...900..118N
ADC_Keywords: Magellanic Clouds; Stars, supergiant; Stars, double and multiple;
Stars, B-type; Spectral types; Photometry, UBVRI; Colors;
Stars, diameters; Effective temperatures
Keywords: Red supergiant stars ; Massive stars ; Binary stars ;
Large Magellanic Cloud ; Close binary stars ; K supergiant stars
Abstract:
The binary fraction of unevolved massive stars is thought to be
70%-100% but there are few observational constraints on the binary
fraction of the evolved version of a subset of these stars, the red
supergiants (RSGs). Here we identify a complete sample of RSGs in the
Large Magellanic Cloud (LMC) using new spectroscopic observations and
archival UV, IR, and broadband optical photometry. We find 4090 RSGs
with logL/L☉>3.5, with 1820 of them having logL/L☉>4,
which we believe is our completeness limit. We additionally
spectroscopically confirmed 38 new RSG + B-star binaries in the LMC,
bringing the total known up to 55. We then estimated the binary
fraction using a k-nearest neighbors algorithm that classifies stars
as single or binary based on photometry with a spectroscopic sample as
a training set. We take into account observational biases such as
line-of-sight stars and binaries in eclipse while also calculating
model- dependent corrections for RSGs with companions that our
observations were not designed to detect. Based on our data, we find
an initial result of 13.5-6.67+7.56% for RSGs with O- or B-type
companions. Using the Binary Population and Spectral Synthesis models
to correct for unobserved systems, this corresponds to a total RSG
binary fraction of 19.5-6.7+7.6% . This number is in broad
agreement with what we would expect given an initial OB binary
distribution of 70%, a predicted merger fraction of 20%-30%, and a
binary interaction fraction of 40%-50%.
Description:
To calculate the binary fraction of the red supergiants (RSGs) in the
LMC, we first identified a complete sample of RSGs in the LMC
photometrically using 2MASS NIR colors and Gaia to confirm membership.
This process is described in Section 2. Table 2 contains the
coordinates, 2MASS J and K colors, and derived temperatures and
luminosities for the 4090 RSGs in the LMC.
We obtained spectra of 63 candidates in the LMC. Of these, 25 were
single RSGs and the remaining 38 were RSG+B binaries. We
additionally observed 22 new candidates in the SMC and confirmed 14 as
single RSGs and 8 as new RSG+B binaries.
Candidate RSG + B-star binaries were observed with the Magellan
Echellette instrument on the Baade 6.5m telescope at Las Campanas
Observatory over two dedicated observing runs in 2019 and 2020 and an
engineering run in 2019. See Section 3.2.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 86 4090 Red supergiant (RSG) content of the LMC
table3.dat 110 22 Spectroscopically observed SMC stars
table4.dat 60 1752 Percent likelihood of binarity from erratum
published in 2020, ApJ, 905, 83
table6.dat 103 63 Comparison of physical properties
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer- Jones+, 2018)
J/A+A/333/231 : O-M stars model atmospheres (Bessell+ 1998)
J/AJ/123/855 : Magellanic Clouds Photometric Survey: SMC (Zaritsky+, 2002)
J/AJ/128/1606 : Magellanic Clouds Photometric Survey: LMC (Zaritsky+, 2004)
J/AJ/133/2393 : UBVRI phot. in 7 Local Group dwarfs galaxies (Massey+, 2007)
J/ApJ/703/441 : Yellow supergiants in M31 (Drout+, 2009)
J/ApJ/703/420 : Red supergiants in M31 (Massey+, 2009)
J/AJ/140/416 : IR photometry of massive stars in the SMC (Bonanos+, 2010)
J/AJ/142/103 : Cool evolved stars in SAGE-SMC and SAGE-LMC (Boyer+, 2011)
J/A+A/537/A146 : Stellar models with rotation; 0.8<M<120. (Ekstrom+, 2012)
J/ApJ/759/11 : Wolf-Rayet content of M31 (Neugent+, 2012)
J/ApJ/749/177 : Yellow and red supergiants in the LMC (Neugent+, 2012)
J/other/Sci/337.444 : RV curves of Galactic massive O stars (Sana+, 2012)
J/ApJ/758/133 : Metallicity profile of M31 HII regions & PNe (Sanders+, 2012)
J/A+A/550/A107 : RV catalogue of O stars in 30 Doradus (Sana+, 2013)
J/A+A/580/A93 : VLTS. B stars multiplicity (Dunstall+, 2015)
J/A+A/586/A81 : High-mass X-ray binaries in the SMC (Haberl+, 2016)
J/A+A/618/A137 : MC cool supergiants spectra (Dorda+, 2018)
J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)
J/ApJ/863/181 : The fifth catalog of LMC Wolf-Rayet stars (Neugent+, 2018)
J/A+A/629/A134 : Radiative contribution from stripped stars (Goetberg+, 2019)
J/A+A/629/A91 : A source catalog for the SMC (Yang+, 2019)
J/ApJ/875/124 : Binary red supergiants. II. B-type companions (Neugent+, 2019)
J/ApJ/889/44 : UKIRT obs. of red supergiants in M31 (Neugent+, 2020)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 2MASS 2MASS Designation (HHMMSSss+DDMMSSs; J2000)
18- 19 I2 h RAh [4/5] Hour of Right Ascension (J2000)
21- 22 I2 min RAm Minute of Right Ascension (J2000)
24- 29 F6.3 s RAs Second of Right Ascension (J2000)
31- 31 A1 --- DE- [-] Sign of the Declination (J2000)
32- 33 I2 deg DEd [65/72] Degree of Declination (J2000)
35- 36 I2 arcmin DEm Arcminute of Declination (J2000)
38- 42 F5.2 arcsec DEs Arcsecond of Declination (J2000)
44- 49 F6.3 mag Ksmag [6.6/12] 2MASS Ks magnitude
51- 55 F5.3 mag e_Ksmag [0.016/0.06] Ksmag error
57- 61 F5.3 mag J-Ks [0.79/1.65] 2MASS J-Ks color index
63- 67 F5.3 mag e_J-Ks [0.025/0.092] J-Ks error
69- 69 I1 --- Fgaia [0/2]? Membership based upon Gaia (1)
71- 71 I1 --- Fsp [0/3]? Spectroscopy obtained (2)
73- 76 F4.2 mag Av [0.75/3.37] Adopted V-band extinction
78- 81 I4 K Teff [3450/4400] Effective temperature (3)
83- 86 F4.2 [Lsun] logLum [3.52/5.59] Log luminosity (4)
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Note (1): LMC membership flag based upon Gaia DR2 as follows:
0 = Probable member (3955 occurrences);
1 = Membership uncertain (81 occurrences);
2 = Incomplete or no Gaia data available (54 occurrences).
Note (2): Spectroscopic data used in this paper. Code as follows:
0 = no spectra (3974 occurrences).
1 = CTIO 4-m spectra (Levesque+ 2005ApJ...628..973L 2005ApJ...628..973L);
2 = Magellan spectra (Neugent+ 2019, J/ApJ/875/124);
3 = Magellan spectra (this paper; 59 occurrences).
Note (3): Typical uncertainty 150K.
Note (4): Typical uncertainty 0.05dex.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 2MASS 2MASS Designation (HHMMSSss+DDMMSSs; J2000)
18- 19 I2 h RAh [0/1] Hour of Right Ascension (J2000)
21- 22 I2 min RAm Minute of Right Ascension (J2000)
24- 29 F6.3 s RAs Second of Right Ascension (J2000)
31- 31 A1 --- DE- [-] Sign of the Declination (J2000)
32- 33 I2 deg DEd [71/73] Degree of Declination (J2000)
35- 36 I2 arcmin DEm Arcminute of Declination (J2000)
38- 42 F5.2 arcsec DEs Arcsecond of Declination (J2000)
44- 49 F6.3 mag Ksmag [8.3/10.4] 2MASS Ks magnitude
51- 55 F5.3 mag e_Ksmag [0.019/0.026] Ksmag error
57- 61 F5.3 mag J-Ks [0.85/1.15] 2MASS J-Ks color index
63- 67 F5.3 mag e_J-Ks [0.029/0.04] J-Ks error
69- 74 F6.3 mag Umag [13.46/16.07]? U band magnitude
(Zaritsky+ 2002, J/AJ/123/855)
76- 81 F6.3 mag Bmag [13.88/15.55]? B band magnitude
(Zaritsky+ 2002, J/AJ/123/855)
83- 88 F6.3 mag Vmag [11.87/14.06] V band magnitude
(Zaritsky+ 2002, J/AJ/123/855)
90- 95 A6 --- Class Classification
97-100 I4 K Teff [3525/4050] Effective temperature,
RSG component
102-104 I3 K e_Teff [25/100] Uncertainty in Teff
106-110 A5 --- SpT Type, RSG component
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 2MASS 2MASS Designation (HHMMSSss+DDMMSSs; J2000)
18- 22 F5.2 mag Umag [10.74/22.39]? U band magnitude
(Zaritsky+ 2004, J/AJ/128/1606)
24- 28 F5.2 mag Bmag [11.75/22.77]? B band magnitude
(Zaritsky+ 2004, J/AJ/128/1606)
30- 34 F5.2 mag Vmag [11.02/19.7] V band magnitude
(Zaritsky+ 2004, J/AJ/128/1606)
36- 40 F5.2 mag Imag [8.85/14.93]? I band magnitude
(Zaritsky+ 2004, J/AJ/128/1606)
42- 46 F5.2 mag U-B [-3.97/6.87]? U-B color index
48- 52 F5.2 mag B-V [-2.74/5.99]? B-V color index
54- 54 I1 --- Fnuv [0/4]? Galex NUV brightness flag (1)
56- 56 I1 --- Fsp [0/1] Spectra obtained (0=no spectra; 1=spectra)
58- 60 I3 % Bin [0/100] Percent Likelihood of Binarity
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Note (1): GALEX NUV brightness flag as follows:
0 = n/a;
1 = bright flux;
2 = medium flux;
3 = dim flux;
4 = no flux.
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Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 2MASS 2MASS Designation (HHMMSSss+DDMMSSs; J2000)
18- 19 I2 h RAh [4/5] Hour of Right Ascension (J2000)
21- 22 I2 min RAm Minute of Right Ascension (J2000)
24- 29 F6.3 s RAs Second of Right Ascension (J2000)
31 A1 --- DE- [-] Sign of the Declination (J2000)
32- 33 I2 deg DEd [65/71] Degree of Declination (J2000)
35- 36 I2 arcmin DEm Arcminute of Declination (J2000)
38- 42 F5.2 arcsec DEs Arcsecond of Declination (J2000)
44- 48 F5.2 mag Vmag [11.62/13.96] V band magnitude
(Zaritsky+ 2004, J/AJ/128/1606)
50- 53 F4.2 mag Ksmag [7.2/9.9] 2MASS Ks magnitude
55- 60 A6 --- Class Classification
62- 65 F4.2 mag Av1 [0.75/1.43]? V-band extinction derived from
photometry
67- 70 I4 K Teff1 [3450/4150]? Effective temperature derived
from photometry (1)
72- 75 F4.2 [Lsun] logLum1 [4.36/5.4]? Log luminosity, solar units,
derived from photometry
78- 81 F4.2 mag Av2 [0.01/1.43] V-band extinction adopted from
photometry for the binaries
83- 86 I4 K Teff2 [3475/4000] Effective temperature derived
from spectroscopy (2)
88- 91 F4.2 [Lsun] logLum2 [4.26/5.27] Log luminosity derived from
spectroscopy
93- 96 I4 Rsun Rstar [310/1160] Radius derived from spectroscopy
98- 103 A6 --- SpT Spectral type derived from spectroscopy
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Note (1): Typical uncertainty 150K.
Note (2): Typical uncertainty 25K.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 30-Dec-2021