J/AJ/152/40 Spectroscopy of 341 bright A- and B-type stars (Gullikson+, 2016)
The close companion mass-ratio distribution of intermediate-mass stars.
Gullikson K., Kraus A., Dodson-Robinson S.
<Astron. J., 152, 40 (2016)>
=2016AJ....152...40G 2016AJ....152...40G (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, spectroscopic ; Stars, bright ; Stars, early-type ;
Stars, A-type ; Stars, B-type ; Spectroscopy ; Stars, masses ;
Effective temperatures ; Stars, ages ; Abundances, [Fe/H] ;
Rotational velocities ; Photometry, infrared
Keywords: binaries: spectroscopic - stars: early-type - stars: formation -
stars: statistics
Abstract:
Binary stars and higher-order multiple systems are a ubiquitous
outcome of star formation, especially as the system mass increases.
The companion mass-ratio distribution is a unique probe into the
conditions of the collapsing cloud core and circumstellar disk(s) of
the binary fragments. Inside a∼1000AU the disks from the two forming
stars can interact, and additionally companions can form directly
through disk fragmentation. We should, therefore, expect the
mass-ratio distribution of close companions (a≲100AU) to differ from
that of wide companions. This prediction is difficult to test using
traditional methods, in particular, with intermediate-mass primary
stars, for a variety of observational reasons. We present the results
of a survey searching for companions to A- and B-type stars using the
direct spectral detection method, which is sensitive to late-type
companions within ∼1'' of the primary and which has no inner working
angle. We estimate the temperatures and surface gravity of most of the
341 sample stars and derive their masses and ages. We additionally
estimate the temperatures and masses of the 64 companions we find, 23
of which are new detections. We find that the mass-ratio distribution
for our sample has a maximum near q∼0.3. Our mass-ratio distribution
has a very different form than in previous works, where it is usually
well-described by a power law, and indicates that close companions to
intermediate-mass stars experience significantly different accretion
histories or formation mechanisms than wide companions.
Description:
The sample is given in Table1. We use several high spectral
resolution, cross-dispersed echelle spectrographs for this survey. We
use the CHIRON spectrograph on the 1.5m telescope at Cerro Tololo
Inter-American Observatory (CTIO) for most southern targets. This
spectrograph is an R=λ/Δλ=80000 spectrograph with
wavelength coverage from 450-850nm, and is fed by a 2.7'' optical
fiber.
For the northern targets, we use a combination of the High Resolution
Spectrograph (HRS) on the Hobby-Eberly Telescope (HET), and the Tull
coude spectrograph (TS23) and Immersion Grating Infrared Spectrograph
(IGRINS), both on the 2.7m Harlan J. Smith Telescope. All three
northern instruments are at McDonald Observatory. For the HRS, we use
the R=60000 setting with a 2'' fiber, and with wavelength coverage
from 410-780nm. For the TS23 spectrograph, we use a 1.2'' slit in
combination with the E2 echelle grating (53 grooves/mm, blaze angle
65°), yielding a resolving power of R=60000 and a wavelength
coverage from 375-1020nm. IGRINS has a single setting with R=40000. It
has complete wavelength coverage from 1475-2480nm, except in the
telluric water band from 1810-1930nm. We give the spectroscopic
observation log in Table2.
As part of the follow-up effort, we used the NIRI instrument behind
the Altair adaptive optics system on the Gemini North Telescope. For
each star listed in Table3, we obtained 25 images in five dithering
positions. We used the K-continuum band centered on 2.2718µm and a
variety of exposure times and dates (listed in Table3). We list the
companion detections in Table4.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 107 340 Sample properties
table2.dat 36 499 Spectroscopic observation log
table3.dat 96 17 *NIRI observation log
table4.dat 72 64 Companion detections
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Note on table3.dat: The NIRI instrument behind the Altair adaptive optics system
on the Gemini North Telescope.
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See also:
B/sb9 : SB9: 9th Catalogue of Spectroscopic Binary Orbits (Pourbaix+ 2004-2014)
B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2014)
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
J/ApJ/804/146 : Atmospheric parameters for nearby B-F stars (David+, 2015)
J/MNRAS/437/1216 : VAST Survey. A-type stars multiplicity (De Rosa+, 2014)
J/A+A/537/A120 : Rotational velocities of A-type stars. IV. (Zorec+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Star name
13- 18 A6 --- SpT Spectral type (1)
20- 21 I2 h RAh Hour of Right Ascension (J2000) (1)
23- 24 I2 min RAm Minute of Right Ascension (J2000)
26- 32 F7.4 s RAs Second of Right Ascension (J2000)
34 A1 --- DE- Sign of the Declination (J2000) (1)
35- 36 I2 deg DEd Degree of Declination (J2000)
38- 39 I2 arcmin DEm Arcminute of Declination (J2000)
41- 46 F6.3 arcsec DEs Arcsecond of Declination (J2000)
48- 52 F5.3 mag Vmag [2/6]? The V-band magnitude (1)
54- 58 F5.2 mas plx [0.72/68.92]? Parallax (1)
60- 64 I5 K Teff [7594/26000]? Stellar effective temperature (2)
66- 69 I4 K e_Teff [258/2000]? Uncertainty in Teff
71- 73 F3.1 [cm/s2] logg [2.7/4.5]? Log surface gravity (2)
75- 78 F4.2 [cm/s2] e_logg [0.14/0.25]? Uncertainty in logg
80- 82 F3.1 Msun Mass [1.6/9.6]? Mass (2)
84- 87 F4.2 Msun E_Mass [0.06/0.77]? Upper uncertainty in Mass
89- 92 F4.2 Msun e_Mass [0.06/0.72]? Lower uncertainty in Mass
94- 97 I4 Myr Age [5/1064]? Age (2)
99-101 I3 Myr E_Age [3/807]? Upper uncertainty in Age
103-105 I3 Myr e_Age [1/412]? Low uncertainty in Age
107 I1 --- r_Age [1/2]? Reference for Teff, logg, Mass, and
Age (1, or 2=this study) (3)
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Note (1): From the SIMBAD database. The spectral type given is that of the
brightest star if part of a known multiple system.
Note (2): Discussed in Section 4.
Note (3): The reference codes are:
1 = David & Hillenbrand 2015 (Cat. J/ApJ/804/146);
2 = This study.
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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- 11 A11 --- Name Star name
13- 19 F7.2 d JD [6298.78/7288.82] Julian Date (JD-2450000)
21- 26 A6 --- Inst Spectroscopic instrument used (1)
28- 31 I4 s Exp [22/7386] Exposure time
33- 36 I4 --- S/N [20/2520] Spectroscopic signal to noise per
pixel (2)
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Note (1): The instruments used are:
CHIRON = CHIRON spectrograph on the 1.5m telescope at Cerro Tololo
Inter-American Observatory (CTIO);
HRS = High Resolution Spectrograph on the Hobby Eberly Telescope (HET);
IGRINS = Immersion Grating Infrared Spectrograph (IGRINS) on the 2.7m
Harlan J. Smith Telescope;
TS23 = Tull coude spectrograph on the 2.7m Harlan J. Smith Telescope.
Note (2): We calculate the S/N for the optical instruments (CHIRON, TS23, and
HRS) as the median of the extracted flux divided by its uncertainty for
each pixel from the echelle order nearest 675nm. For the IGRINS instrument,
we calculate the S/N from the order nearest 2200nm.
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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- 10 A10 --- Name Star name
12- 15 F4.2 mag Kmag [4.4/6.5] The K band magnitude
17 A1 --- f_Kmag Source of K magnitude (S=SIMBAD, or T=estimated
from the spectral type of the star and its
V-band magnitude)
19- 28 A10 "Y:M:D" Date Gemini/NIRI observation date (1)
30- 35 A6 --- Exp Exposure sequence
37- 42 F6.4 arcsec Sep [0.16/3.68]? Separation ρ
44- 49 F6.4 arcsec e_Sep [0.0007/0.003]? Uncertainty in Sep
51- 56 F6.2 deg PA [14.1/346.8]? Position angle θ
58- 61 F4.2 deg e_PA [0.02/0.92]? Uncertainty in PA
63- 66 F4.2 mag dKcmag [1.77/3.9]? The Δ K-continuum band
magnitude (2)
68- 71 F4.2 mag e_dKcmag [0.01/0.4]? Uncertainty in dKcmag
73- 75 F3.1 Msun Mass2 [0.7/1.5]? Mass of secondary
77- 80 F4.2 Msun E_Mass2 [0.14/0.39]? Upper uncertainty in Mass2
82- 85 F4.2 Msun e_Mass2 [0.1/0.28]? Lower uncertainty in Mass2
87- 91 F5.1 AU a [25.1/467.7]? Separation, in astronomical units
93- 96 F4.2 AU e_a [0.16/0.81]? Uncertainty in a
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Note (1): We used the NIRI instrument behind the Altair adaptive optics system
on the Gemini North Telescope.
Note (2): We used the K-continuum band centered on 2.2718µm.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Star Name
12- 16 A5 --- Comp Component (AB, AB?, AC, Aa,Ab, or Ba,Bb)
18 A1 --- f_Comp [d] Newly discovered companion (d=true)
20 I1 --- Nobs [1/3] Number of observations (1, 2, or 3)
22- 24 A3 --- Used Used in analysis (yes or no)
26- 30 I5 K Teff [3647/16000] Companion surface effective
temperature
32- 35 I4 K e_Teff [85/1000] Uncertainty in Teff
37- 39 I3 km/s vsini [1/120] Companion projected rotational velocity
41- 44 F4.1 [-] [Fe/H] [-0.5/0.5] Companion metallicity
46- 48 F3.1 Msun MassI [0.5/4.3] Companion mass from isochrones
50- 53 F4.2 Msun E_MassI [0.02/0.47] Upper uncertainty in MassI
55- 58 F4.2 Msun e_MassI [0.02/0.43] Lower uncertainty in MassI
60- 62 F3.1 Msun MassS [0.5/4.7] Companion mass from Spectral type
64- 67 F4.2 Msun E_MassS [0.01/0.76] Upper uncertainty in MassS
69- 72 F4.2 Msun e_MassS [0.01/0.67] Lower uncertainty in MassS
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 15-Sep-2016