J/AJ/162/285 Parameters of 37 binaries in NGC2516 and NGC2422 (Lipartito+, 2021)
Orbital parameters and binary properties of 37 FGK stars in the cores of open
clusters NGC 2516 and NGC 2422.
Lipartito I., Bailey Iii J.I., Brandt T.D., Mazin B.A., Mateo M.,
Spencer M.E., Roederer I.U.
<Astron. J., 162, 285-285 (2021)>
=2021AJ....162..285L 2021AJ....162..285L (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open; Stars, double and multiple; Spectra, optical;
Radial velocities
Keywords: Radial velocity; Computational methods; Astronomical methods
Astronomy data analysis; Open star clusters; Spectroscopy
Binary stars; Orbits
Abstract:
We present orbits for 24 binaries in the field of open cluster NGC2516
(∼150Myr) and 13 binaries in the field of open cluster NGC2422
(∼130Myr) using results from a multiyear radial-velocity (RV) survey
of the cluster cores. Six of these systems are double-lined
spectroscopic binaries. We fit these RV variable systems with orvara,
a MCMC-based fitting program that models Keplerian orbits. We use
precise stellar parallaxes and proper motions from Gaia EDR3 to
determine cluster membership. We impose a barycentric RV prior on all
cluster members; this significantly improves our orbital constraints.
Two of our systems have periods between five and 15 days, the critical
window in which tides efficiently damp orbital eccentricity. These
binaries should be included in future analyses of circularization
across similarly-aged clusters. We also find a relatively flat
distribution of binary mass ratios, consistent with previous work.
With the inclusion of TESS light curves for all available targets, we
identity target 378-036252 as a new eclipsing binary. We also identify
a field star whose secondary has a mass in the brown dwarf range, as
well as two cluster members whose RVs suggest the presence of an
additional companion. Our orbital fits will help constrain the binary
fraction and binary properties across stellar age and across stellar
environment.
Description:
Bailey+ (2016AJ....152....9B 2016AJ....152....9B, hereafter B16) obtained multiepoch
spectroscopy in 2013 and 2014 for all photometric F5V-K5V members
(N∼125 each) in the core half degree of the open clusters NGC2516 and
NGC2422. They obtained ∼12 epochs (∼2hr exposures) in NGC2516 and ∼10
epochs (∼2.5hr exposures) in NGC2422. B16 used Michigan/Magellan Fiber
System (M2FS), a multiplexed high-resolution optical fiber-fed
spectrograph deployed at the Magellan/Clay 6.5m telescope at Las
Campanas Observatory in its cross-dispersed echelle mode for order 49
(7160-7290Å). B16 selected order 49 for its combination of stellar
and telluric absorption lines to provide a simultaneous RVel and
wavelength reference. Observations had a median R∼50000 and a mean
per-pixel signal-to-noise ratio (S/N) of 55. This configuration has a
limiting RVel precision of 25m/s, with a median per-epoch precision of
80m/s.
Here we incorporate an additional epoch for 36 stars in NGC2516
obtained from a 3hr exposure taken in February 2016 with a median S/N
of ∼107. This epoch benefits from a newer M2FS filter tailored to the
measured optical blaze, significantly improving throughput albeit with
a slightly different wavelength coverage of 7180-7360Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 553 27 *Binary solutions in the field of NGC 2516
table4.dat 553 16 *Binary Solutions in the Field of NGC 2422
figa1.dat 192 415 Radial velocity time series used in our MCMC fits
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Note on table3.dat and table4.dat: Errors correspond to the 68%
confidence intervals of the parameters. Quoted errors include all
modes. Vsini errors are from spectral fitting and are symmetric.
Eleven fits had orbital solutions consistent with periods exceeding
their observational baselines: their period posteriors lacked an upper
bound. We only report the 90% lower limits of the period and mass
ratio distributions for these systems (error columns are left blank),
as all their other orbital parameters (with the exception of the RV0)
are poorly constrained.
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See also:
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
J/A+A/558/A53 : Milky Way global survey star clusters. II. (Kharchenko+, 2013)
J/AJ/148/83 : Spectroscopy in NGC 2360, NGC 3680, and NGC 5822 (Sales+, 2014)
J/AJ/150/16 : Speckle-interferometry in Melotte 111 (Guerrero+, 2015)
J/ApJ/821/8 : Spectro. binary population of ONC and NGC2264 (Kounkel+, 2016)
J/A+A/616/A10 : 46 open clusters GaiaDR2 HR diagrams (Gaia Collaboration, 2018)
J/A+A/618/A93 : Gaia DR2 open clusters in the Milky Way (Cantat-Gaudin+, 2018)
J/AJ/156/18 : APOGEE DR14:Binary comp. of evolved stars (Price-Whelan+, 2018)
J/MNRAS/475/1609 : RV variability in NGC 2516 and NGC 2422 (Bailey+, 2018)
J/AJ/157/196 : Close companions around young stars (Kounkel+, 2019)
J/A+A/641/A51 : NGC 2516 membership list (Fritzewski+, 2020)
J/AJ/159/199 : OCCAM IV. Open cluster abundances APOGEE DR16 (Donor+, 2020)
J/AJ/160/169 : WOCS. LXXXII. Orbital parameters & RVs in NGC7789 (Nine+, 2020)
J/ApJ/903/55 : APOGEE parameters through 83 open clusters (Poovelil+, 2020)
J/AJ/161/190 : Radial Velocities of binary population in M67 (Geller+, 2021)
Byte-by-byte Description of file: table[34].dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- ID Target ID
13- 13 A1 --- Mem Member/ Non-Member
15- 33 F19.16 km/s vsini Line-of-sight stellar rotational velocity
35- 53 F19.17 km/s e_vsini Uncertainty in vsini
55- 75 F21.16 d Per ? Period, median fit value
77-100 F24.20 d e_Per ? Lower uncertainty on Per
102-124 F23.19 d E_Per ? Upper uncertainty on Per
126-146 F21.19 --- e ? Eccentricity, median fit value
148-168 F21.19 --- e_e ? Lower uncertainty on ecc
170-190 F21.19 --- E_e ? Upper uncertainty on ecc
192-209 F18.16 --- lambda ? mean anomaly at a reference epoch
211-230 F20.18 --- e_lambda ? Lower uncertainty on lambda
232-252 F21.19 --- E_lambda ? Upper uncertainty on lambda
254-274 F21.18 --- omega ? argument of periastron, median fit value
276-296 F21.19 --- e_omega ? Lower uncertainty on omega
298-317 F20.18 --- E_omega ? Upper uncertainty on omega
319-336 F18.15 km/s K ? RV semi-amplitude, median fit value
338-358 F21.18 km/s e_K ? Lower uncertainty on K
360-381 F22.18 km/s E_K ? Upper uncertainty on K
383-402 F20.16 km/s RVel ? barycenter radial velocity, median fit value
404-425 F22.19 km/s e_RVel ? Lower uncertainty on RVel
427-448 F22.19 km/s E_RVel ? Upper uncertainty on RVel
450-467 F18.16 Msun Mstar ? Primary mass, solar units
469-488 F20.18 --- q ? Mass ratio, Primary/Secondary mass
490-510 F21.19 --- e_q ? Lower uncertainty on q
512-532 F21.19 --- E_q ? Upper uncertainty on q
534-551 F18.16 --- sigmachi ? multiplicative constant (1)
553-553 A1 --- MM Multimodal targets (2)
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Note (1): Multiplicative constant applied to RV measurement errors to get a
reduced χ2 of ∼1
Note (2): Multimodal targets have an asterisk in the MM column
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Byte-by-byte Description of file: figa1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- ID Target ID
12- 29 F18.10 d JD Julian Date at observation midpoint, photon
weighted (1)
31- 52 F22.15 m/s RVel1 ? single stellar component best fit RV
54- 72 F19.14 m/s e_RVel1 ? Uncertainty in RVel1 (2)
74- 93 F20.13 m/s RVel12 ? two component best fit RV, first component
95-112 F18.14 m/s e_RVel12 ? Uncertainty in RVel12 (2)
114-133 F20.13 m/s RVel22 ? two component best fit RV, second component
135-153 F19.14 m/s e_RVel22 ? Uncertainty in RVel22 (2)
155-173 F19.16 --- Nres ? number of spectral resolution elements separating
the two component spectra
175-192 F18.16 --- eMUL error multiplier for each spectrum
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Note (1): Each row in the column corresponds to a single spectral epoch for a
single target.
Note (2): Error as used for MCMC fits, that is multiplied by the multiplier
in the eMUL column.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 08-Mar-2022