J/MNRAS/452/173 Nearby young stars in Northern hemisphere (Binks+, 2015)
A kinematically unbiased search for nearby young stars in the Northern
hemisphere based on SuperWASP rotation periods.
Binks A.S., Jeffries R.D., Maxted P.F.L.
<Mon. Not. R. Astron. Soc. 452, 173 (2015)>
=2015MNRAS.452..173B 2015MNRAS.452..173B
ADC_Keywords: Stars, pre-main sequence ; Stars, late-type
Keywords: stars: late-type - stars: pre-main sequence
Abstract:
We present a kinematically-unbiased search to identify young, nearby
low-mass members of kinematic moving groups (MGs). Objects with both
rotation periods shorter than 5 days in the SuperWASP All-Sky Survey
and X-ray counterparts in the ROSAT All-Sky Survey were chosen to
create a catalog of several thousand rapidly-rotating, X-ray active
FGK stars. These objects are expected to be either genuinely young
(<200Myr) single stars or tidally-locked spectroscopic binaries. We
obtained optical spectra for a sub-sample of 146 stars to determine
their ages and kinematics, and in some cases repeat radial velocity
(RV) measurements were used to identify binarity. Twenty-six stars are
found to have lithium abundances consistent with an age of 200Myr or
younger and show no evidence for binarity, and in most cases
measurements of Halpha and v sin i support their youthful status.
Based on their youth, their radial velocities and estimates of their
3-dimensional kinematics, we find 11 objects that may be members of
known MGs, 8 that do not appear associated with any young MG and a
further 7 that are close to the kinematics of the recently proposed
"Octans-Near" MG, and may be the first members of this MG found in the
northern hemisphere. The initial search mechanism was ∼18 per cent
efficient at identifying likely-single stars younger than 200Myr, of
which 80 per cent were early-K spectral types. A more complete survey
may result in the detection of new nearby MGs, particularly in the
comparatively little sampled northern hemisphere.
Description:
In the paper, we presented tabular data for all targets in our sample
that were measured to be younger than 200 Myr based on analysis of
their Li EWs and were unlikely to be tidally-locked short-period
binary (TLSPB) systems based on two or more RV measurements either
from our observations or previous measurements in the literature. In
these catalogs we present the equivalent data from tables 1, 3, 4, 5
and 6 for a) targets that were not measured as younger than 200 Myr,
but were not identified as TLSPBs and b) targets that were identified
as TLSPBs. For full details of this, see paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
mgs.dat 119 10 Moving Group data
age.dat 43 106 Ages for non-TLSPB young objects
age_b.dat 43 14 Ages for objects in TLSPB systems
params.dat 99 106 EWs, temperatures and abundances
params_b.dat 99 14 EWs, temperatures, abundances in TLSPB systems
kin.dat 108 106 Kinematics
kin_b.dat 60 14 Kinematics TLSPB systems
rvs.dat 49 120 Radial velocities (for the 106 sources)
rvs_b.dat 49 26 Radial velocities of TLSPB systems
(for the 14 sources)
p_xray.dat 89 106 Periods Xray
pxrayb.dat 89 14 Periods Xray TLSPB systems
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Byte-by-byte Description of file: mgs.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Moving group name
9- 10 I2 --- NObs [4/48] Number of observations
12- 13 I2 Myr Age [3/70] Lower value of Age interval
14 A1 --- --- [-]
15- 17 I3 Myr B_Age [5/120] Upper value of Age interval
18 A1 --- n_Age [*] * indicates ages calculated from the
lithium depletion boundary
19 A1 --- u_Dist [~] Uncertainty flag on Dist
20- 22 I3 pc Dist Lower value of distance interval
23 A1 --- --- [-]
24- 26 I3 pc B_Dist ? Upper value of distance interval
28- 33 F6.2 km/s Uvel ?=- U velocity
35- 40 F6.2 km/s Vvel ?=- V velocity
42- 47 F6.2 km/s Wvel ?=- W velocity
49- 52 F4.2 km/s e_Uvel rms uncertainty on Uvel
54- 57 F4.2 km/s e_Vvel rms uncertainty on Vvel
59- 62 F4.2 km/s e_Wvel rms uncertainty on Wvel
64- 69 F6.2 pc X ?=- X positions
71- 76 F6.2 pc Y ?=- Y positions
78- 83 F6.2 pc Z ?=- Z positions
85- 89 F5.2 pc e_X rms uncertainty on X
91- 95 F5.2 pc e_Y rms uncertainty on Y
97-101 F5.2 pc e_Z rms uncertainty on Z
103-110 F8.4 deg RAconv ?=- Convergent point in right ascension
112-119 F8.4 deg DEconv ?=- convergent point in declination
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Byte-by-byte Description of file: age.dat age_b.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Name of Target (SWHHMM+DDMM)
13 A1 --- l_AgeG Limit flag on AgeG (1)
14- 17 I4 Myr AgeG Age from gyrochronology
19 A1 --- l_AgeLi Limit flag on AgeLi (1)
20- 23 I4 Myr AgeLi Age from lithium, or lower value of interval
24 A1 --- --- [-]
25- 27 I3 Myr B_AgeLi ? Upper value of lithium age interval
30 A1 --- l_AgeHa Limit flag on AgeHa (1)
31- 33 I3 Myr AgeHa Age from Hα or lower value of interval
34 A1 --- --- [-]
35- 37 I3 Myr B_AgeHa ? Upper value of Hα age interval
39 A1 --- l_AgeR Limit flag on AgeR (1)
40- 43 I4 Myr AgeR Age from Rsini
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Note (1): Any ages measured as >1000 Myr are lower limits and are at least
older than the Hyades and for the purpose of this work the precision of
these ages are unimportant as they are not considered for further analysis.
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Byte-by-byte Description of file: params.dat params_b.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Name of Target (SWHHMM+DDMM)
13 A1 --- l_EWLi Limit flag on EWLi (2-σ upper limits)
14- 16 I3 0.1pm EWLi Lithium equivalent width before Fe correction
18- 21 I4 0.1pm EWLic ?=-999 Lithium equivalent width subsequent to
deblending the 6707.4 FeI line (mÅ) (2)
23- 25 I3 0.1pm e_EWLic ? Error on EWLic calculated using Cayrel de
Strobel (1988IAUS..132..345C 1988IAUS..132..345C) formulation
27- 32 F6.3 0.1nm EWHa Hα equivalent width (Å) (3)
34- 39 F6.3 mag Bmag B magnitude
41- 46 F6.3 mag e_Bmag ? rms uncertainty on Bmag
48- 53 F6.3 mag Vmag V magnitude
55- 59 F5.3 mag e_Vmag ? rms uncertainty on Vmag
61- 67 F7.3 mag Kmag ?=-99 K magnitude
69- 73 F5.3 mag e_Kmag ? rms uncertainty on Kmag
75- 78 I4 K Teff Effective temperature (4)
80- 81 A2 --- SpT Spectral type
83- 87 F5.2 [-] A(Li) ?=-9.99 Lithium abundance, calculated using
12+log(N(Li)/N(H))
89- 93 F5.2 [-] E_A(Li) ?=-9.99 1-σ upper error on A(Li)
95- 99 F5.2 [-] e_A(Li) ?=-9.99 1-σ lower error on A(Li)
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Note (2): using the prescription of Soderblom, 2010ARA&A..48..581S 2010ARA&A..48..581S.
Note (3): Positive/negative values represent absorption/emission.
Note (4): Effective temperature based on the 5th order V-K calibration in
Pecaut & Mamajek (2013ApJS..208....9P 2013ApJS..208....9P, Cat. J/ApJS/208/9).
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Byte-by-byte Description of file: kin.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Name of Target (SWHHMM+DDMM)
13- 18 F6.1 mas/yr pmRA Proper motion in right ascension
20- 23 F4.1 mas/yr e_pmRA rms uncertainty on pmRA
25- 30 F6.1 mas/yr pmDE Proper motion in declination
32- 35 F4.1 mas/yr e_pmDE rms uncertainty on pmDE
37- 41 F5.2 mas Plx Parallax calculated photometrically
42 A1 --- --- [-]
43- 47 F5.2 mas B_Plx ? Upper value of parallax when interval
49- 52 F4.2 mas e_Plx ? rms uncertainty on Plx
54- 59 F6.1 km/s Uvel ?=-999 U velocity
61- 63 F3.1 km/s e_Uvel ? First error bar on Uvel from the
uncertainties in proper motion and RV
65- 67 F3.1 km/s s_Uvel ? Second error bar on Uvel from the
distance uncertainty
69- 74 F6.1 km/s Vvel ?=-999 V velocity
76- 78 F3.1 km/s e_Vvel ? First error bar on Vvel from the
uncertainties in proper motion and RV
80- 82 F3.1 km/s s_Vvel ? Second error bar on Vvel from the
distance uncertainty
84- 89 F6.1 km/s Wvel ?=-999 W velocity
91- 93 F3.1 km/s e_Wvel ? First error bar on Wvel from the
uncertainties in proper motion and RV
95- 97 F3.1 km/s s_Wvel ? Second error bar on Wvel from the
distance uncertainty
98-103 F6.1 km/s Vsini ?=-999 Projected rotational velocity
105-108 F4.1 km/s e_Vsini ? rms uncertainty on Vsini
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Byte-by-byte Description of file: kin_b.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Name of Target (SWHHMM+DDMM)
13- 17 F5.1 mas/yr pmRA Proper motion in right ascension
19- 21 F3.1 mas/yr e_pmRA rms uncertainty on pmRA
23- 28 F6.1 mas/yr pmDE Proper motion in declination
30- 32 F3.1 mas/yr e_pmDE rms uncertainty on pmDE
34- 38 F5.2 mas Plx Parallax calculated photometrically
39 A1 --- --- [-]
40- 44 F5.2 mas B_Plx ? Upper value of parallax when interval
46- 49 F4.2 mas e_Plx ? rms uncertainty on Plx
51- 56 F6.1 km/s Vsini ?=-999 Projected rotational velocity
58- 60 F3.1 km/s e_Vsini ? rms uncertainty on Vsini
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Byte-by-byte Description of file: rvs.dat rvs_b.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Name of Target (SWHHMM+DDMM)
13- 20 F8.3 d HJD Heliocentric Julian Date (HJD-2450000)
23- 28 F6.1 km/s RVi ?=-999 Individual radial velocity measurement
31- 34 F4.1 km/s e_RVi ? rms uncertainty on RVi
35 A1 --- n_RVi [i] i indicates measurements made using the
Isaac Newton Telescope
36- 41 F6.1 km/s RVf ? Final radial velocity measurement
45- 47 F3.1 km/s e_RVf ? rms uncertainty on RVf
49 I1 --- Bin [1/5] Binary score (1)
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Note (1): Binary score used to distinguish likely single stars (1) from those
very likely to be binaries (5) as follows:
1 = likely single stars (consistent, low-uncertainty RV measurements for 2
or more spectra)
2 = objects which had a single spectrum, an RV uncertainty <5km/s and a
distinct single peak in the CCF
3 = status of the star from the CCF was unclear (presumably as a result of
poor SNR and/or large vsini), resulting in either an indeterminate RV
or a RV uncertainty >5km/s
4 = only one spectrum which results in (a) a clear, multipeaked CCF and (b)
an RV error <5km/s
5 = very likely to be binaries (detected RV differences >5km/s for a target
on separate nights or (if there was only one measurement) if there were
literature sources indicating that either the object is a close binary
or report a RV measurement >5km/s discrepant from our measurement
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Byte-by-byte Description of file: p_xray.dat pxrayb.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- 1SWASP Identification in the SuperWASP catalog
1SWASP J (HHMMSS.ss+DDMMSS.s)
20- 25 F6.3 mag Vmag1 V magnitude
27- 31 F5.3 mag V-K V-K colour index
33- 38 F6.3 d Per [0.7/20] Rotation period
40- 44 F5.3 d e_Per [0.002/3.5]? rms uncertainty on Per
46- 50 I5 --- Chisq Δχ2 value (section 2 of the paper)
52- 53 I2 --- Ns [1/7] Number of seasonal SuperWASP lightcurves
used in determining the rotation period
55 A1 --- q_Per [A-C] Quality of period measurement, A=best
(section 2 of the paper)
57- 59 A3 --- Date Month and year for which spectroscopy was
first obtained for the object,
J11 = June 2011, D12 = December 2012
61- 65 F5.3 s-1 CR [0.03/0.4] X-ray count rate
67- 71 F5.2 --- HR1 [-1/1] Hardness ratio 1
73- 77 F5.2 [-] logLx/b [-4/-2.9] Base 10 logarithm of the fractional
X-ray to bolometric luminosity
79- 89 A11 --- Name Name of Target (SWHHMM+DDMM)
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Acknowledgements:
Alex Binks, a.s.binks(at)keele.ac.uk
(End) Alex Binks [Univ. Keele], Patricia Vannier [CDS] 19-Aug-2015