J/AJ/155/51 Robo-AO binary star systems in 3 open clusters (Hillenbrand+, 2018)
Robo-AO discovery and basic characterization of wide multiple star systems in
the Pleiades, Praesepe, and NGC 2264 clusters.
Hillenbrand L.A., Zhang C., Riddle R.L., Baranec C., Ziegler C., Law N.M.,
Stauffer J.
<Astron. J., 155, 51 (2018)>
=2018AJ....155...51H 2018AJ....155...51H (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, double and multiple ; Photometry, VRI ;
Photometry, infrared ; Stars, masses
Keywords: binaries: visual - instrumentation: adaptive optics -
open clusters and associations: individual (NGC 2264, Pleiades,
Praesepe)
Abstract:
We identify and roughly characterize 66 candidate binary star systems
in the Pleiades, Praesepe, and NGC 2264 star clusters, based on robotic
adaptive optics imaging data obtained using Robo-AO at the Palomar 60"
telescope. Only ∼10% of our imaged pairs were previously known. We
detect companions at red optical wavelengths, with physical separations
ranging from a few tens to a few thousands of au. A three-sigma contrast
curve generated for each final image provides upper limits to the
brightness ratios for any undetected putative companions. The observations
are sensitive to companions with a maximum contrast of ∼6m at larger
separations. At smaller separations, the mean (best) raw contrast at 2"
is 3.8m (6m), at 1" is 3.0m (4.5m), and at 0.5" is 1.9m (3m).
Point-spread function subtraction can recover nearly the full contrast
in the closer separations. For detected candidate binary pairs, we report
separations, position angles, and relative magnitudes. Theoretical
isochrones appropriate to the Pleiades and Praesepe clusters are then
used to determine the corresponding binary mass ratios, which range
from 0.2 to 0.9 in q=m2/m1. For our sample of roughly solar-mass
(FGK type) stars in NGC 2264 and sub-solar-mass (K and early M-type)
primaries in the Pleiades and Praesepe, the overall binary frequency
is measured at ∼15.5%±2%. However, this value should be considered a
lower limit to the true binary fraction within the specified separation
and mass ratio ranges in these clusters, given that complex and uncertain
corrections for sensitivity and completeness have not been applied.
Description:
We obtained Robo-AO data for a total of 120 NGC 2264 members, 212 Pleiades
members, and 108 Praesepe members. Knowledge regarding stellar multiplicity
or lack thereof can inform the CoRoT and K2 lightcurve analysis.
Robo-AO (Baranec et al. 2014ApJ...790L...8B 2014ApJ...790L...8B) was mounted on the
Palomar 60 inch (1.5 m) telescope before being moved to the Kitt Peak
2.1 m telescope (Salama et al. 2016SPIE.9909E..1AS; Jensen-Clem et al.
2018AJ....155...32J 2018AJ....155...32J) in 2015. At Palomar, the instrument was capable
of imaging more than 200 objects per night. Images of 446 targets in
our three clusters were collected using the Robo-AO system on 2014
November 7-11 and 2015 March 3. Either an SDSS i' filter or an LP600
long pass filter with a 600 nm cut-on was used.
Objects:
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RA (ICRS) DE Designation(s)
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03 47 00 +24 07.0 Pleiades = Cl Melotte 22
08 40 24 +19 40.0 Praesepe = NGC 2632
06 40 58 +09 53.7 NGC 2264 = NAME XMAS TREE CL
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 124 440 Characteristics of Observed Targets
table2.dat 52 66 Basic Characteristics of Detected Binaries
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+A/320/74 : Radial velocities of Pleiades members (Mermilliod+ 1997)
J/A+A/323/139 : K magnitude of Pleiades low-mass binaries (Bouvier+ 1997)
J/A+A/329/101 : Masses of Pleiades members (Raboud+ 1998)
J/ApJ/521/682 : Binaries in the Praesepe and Coma clusters (Abt+, 1999)
J/A+A/375/989 : JHK photometry of Praesepe low-mass stars (Bouvier+, 2001)
J/AJ/123/1570 : alpha Persei and Praesepe Clusters (Patience+, 2002)
J/AJ/124/1570 : JHKs photometry in Praesepe (Adams+, 2002)
J/MNRAS/342/1241 : Low-mass stars in M45 and M44 (Pinfield+, 2003)
J/AJ/134/2340 : Membership of Praesepe and Coma Berenices clusters
(Kraus+, 2007)
J/ApJS/172/663 : Infrared observations of the Pleiades (Stauffer+, 2007)
J/MNRAS/380/712 : ZYJHK photometry in Pleiades (Lodieu+, 2007)
J/MNRAS/422/1495 : UKIDSS Galactic Clusters Survey Pleiades members
(Lodieu+ 2012)
J/MNRAS/426/3419 : UKIDSS GCS Praesepe members (Boudreault+, 2012)
J/MNRAS/430/1433 : NGC 2264 members periods with CoRoT (Affer+, 2013)
J/MNRAS/434/3236 : Masses of Praesepe members (Khalaj+, 2013)
J/A+A/563/A45 : Pleiades cluster membership probabilities (Sarro+, 2014)
J/ApJ/784/57 : Photometry and proper motions in Praesepe (Wang+, 2014)
J/A+A/577/A148 : The Seven Sisters DANCe. I. Pleiades (Bouy+, 2015)
J/ApJ/799/4 : Robo-AO observations of binary stars (Riddle+, 2015)
J/AJ/152/113 : Pleiades members with K2 light curves. I. Periods
(Rebull+, 2016)
J/ApJ/821/8 : Spectroscopic binary population of ONC and NGC2264
(Kounkel+, 2016)
J/AJ/153/66 : Robo-AO Kepler Planetary Candidate Survey. III.
(Ziegler+, 2017)
J/ApJ/839/92 : Praesepe members with K2 light curve data (Rebull+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Cluster Cluster identifier
10- 20 A11 --- Target Target identifier (1)
22- 30 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
32- 39 F8.5 deg DEdeg Declination in decimal degrees (J2000)
41- 45 F5.2 mag Vmag [11.74/17.45]? Apparent V band magnitude
47- 51 F5.2 mag Icmag [10.89/23.44]? Apparent IC band magnitude
53- 57 F5.2 mag Jmag [9.52/13.72] Apparent 2MASS J band magnitude
59- 63 F5.2 mag Ksmag [8.48/12.94] Apparent 2MASS Ks band magnitude
65- 99 A35 --- Multi Robo-AO multiplicity
101-104 F4.1 pix FWHM [2.2/52.8]? Adopted Full-Width at Half-Maximum
point-spread function (PSF) (2)
106-109 F4.2 mag C0.5 [0.31/3.07]? Robo-AO contrast differential
magnitude at 0.5" separation
111-114 F4.2 mag C1 [0.75/4.61]? Robo-AO contrast differential
magnitude at 1" separation
116-119 F4.2 mag C2 [1.21/6.04]? Robo-AO contrast differential
magnitude at 2" separation
121-124 F4.2 mag C3 [1.27/6.78]? Robo-AO contrast differential
magnitude at 3" separation
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Note (1): In the Pleiades, the naming convention follows that in Stauffer et al.
(2007, J/ApJS/172/663) for the stars from that list. For other stars from
Bouy et al (2015, J/A+A/577/A148), we generally chose to use the name from
the first published survey that included the star as a likely Pleiades member.
Names are SIMBAD-compliant if preceded by "Cl* Melotte 22" with the exception
of those noted as "s" which come from the catalog of Sarro et al. (2014,
J/A+A/563/A45).
In Praesepe, we attempted to follow the standard convention of referring to
the star by the name given to it in the first paper which ascribed cluster
membership. Names are SIMBAD-compliant if preceded by "Cl* NGC 2632" with the
exception of those noted as "AD", a nomenclature originating in
Kraus & Hillenbrand (2007, J/AJ/134/2340) to refer to stars first identified
as Praesepe members by Adams et al. (2002, J/AJ/124/1570).
In NGC 2264, the naming convention is that of the Stauffer et al. Spitzer
variability survey (https://irsa.ipac.caltech.edu/data/SPITZER/CSI2264/).
Names are SIMBAD-compliant as recorded.
Note (2): The Robo-AO platescale is sampled at 21.55 milli-arcsec/pixel.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Cluster Cluster identifier
10- 20 A11 --- Binary Binary identifier
22- 25 F4.1 --- sigma [3.5/30.5] Significance for companion detection
σ (1)
27- 30 F4.2 arcsec Sep [0.23/6.14] Projected separation
32- 36 F5.1 deg PA [0.4/356.1] Position angle
38- 41 F4.2 mag Br [0.27/4.62] Optical brightness ratio
43- 46 F4.2 mag e_Br [0.03/0.76] Uncertainty in Br
48 A1 --- l_M2/M1 [<] Limt flag on M2/M1
49- 52 F4.2 --- M2/M1 [0.17/0.93]? Mass ratio M2/M1
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Note (1): A significance for each companion detection was calculated using the
methods employed in Ziegler et al. (2017, J/AJ/153/66).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 01-Oct-2018