J/AJ/153/116 Trojan asteroids in the Kepler campaign 6 field (Ryan+, 2017)
Trojan asteroids in the Kepler campaign 6 field.
Ryan E.L., Sharkey B.N.L., Woodward C.E.
<Astron. J., 153, 116-116 (2017)>
=2017AJ....153..116R 2017AJ....153..116R (SIMBAD/NED BibCode)
ADC_Keywords: Minor planets ; Photometry ; Solar system
Keywords: minor planets, asteroids: general
Abstract:
We report on a Kepler spacecraft survey during the K2 mission to
characterize the rotational properties of 56 Trojan asteroids in the
L4 cloud. More than one rotational period was observed for 51 of these
targets, allowing for well constrained lightcurve rotation periods and
amplitudes, five of which are found to be in conflict with previously
published values. We find ∼10% of objects have rotational periods
longer than 100hr, an excess of slow rotators 10 times larger than
suggested from the literature. Investigation of the rotational
frequencies of our Kepler sample when combined with high-quality
lightcurves in the literature reveals the distribution of rotational
frequencies is non-Maxwellian even when consideration is given to
size-dependent variations in rotational rate. From investigation of
lightcurve shapes and amplitudes, we estimate the binary fraction
within the Trojan population to be ∼6%-36% depending on the
methodology utilized to identify binary candidates.
Description:
To obtain high-precision (i.e., differential micro-magnitude)
photometric measurements of Trojan asteroids, we utilized the Kepler
spacecraft during Campaign 6 of the K2 Mission (Howell et al. 2014,
Cat. IV/34).
The Kepler spacecraft imager has a 110 square degree Field Of View (FOV)
with 4 arcsec pixels. The Kepler FOV is covered by 21 camera modules,
each of which is comprised of two CCDs, wherein each CCD is read from
two amplifiers which are labelled as Kepler channels. During Campaign 6
the center of the Kepler FOV was centered at R.A. (J2000)=13:39:28 and
decl. (J2000)=-11:17:43 which overlapped with the Trojan L4 cloud.
This field was observed from 2015 July 14 to September 30.
A list of observing circumstances for all of the observed Trojan
asteroids over the ∼80 day campaign is given in Table1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 104 56 Trojan Observing Circumstances
table2.dat 91 56 Trojan fitted lightcurve properties
table3.dat 123 51 Trojan fitted lightcurve components
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See also:
B/astorb : Orbits of Minor Planets (Bowell+ 2014)
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
J/AJ/134/1133 : Fraction of contact binary trojan asteroids (Mann+, 2007)
J/ApJ/742/40 : Jovian Trojans asteroids with WISE/NEOWISE (Grav+, 2011)
J/ApJ/759/49 : Jovian Trojan asteroids with WISE/NEOWISE: taxonomy
(Grav+, 2012)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Ast [1143/353363] Asteroid number
8- 19 A12 --- Name Asteroid name
21- 29 F9.1 d JD0 Starting Julian Date
31- 39 F9.1 d JD1 Ending Julian Date
41- 45 F5.3 AU HDist0 [4.713/5.955] Lower range of heliocentric distance
46 A1 --- --- [-]
47- 51 F5.3 AU HDist1 [4.72/5.958] Upper range of heliocentric distance
53- 57 F5.3 AU KDist0 [3.955/5.513] Lower range of Kepler-centric
distance
58 A1 --- --- [-]
59- 63 F5.3 AU KDist1 [4.1/5.717] Upper range of Kepler-centric distance
65- 70 F6.3 deg Angle0 [7.021/12.19] Lower range of phase angle
71 A1 --- --- [-]
72- 77 F6.3 deg Angle1 [8.516/12.274] Upper range of phase angle
79- 84 F6.3 deg bPAB [-7.631/6.197] Mean PAB ecliptic latitude
βPAB
86- 92 F7.3 deg lPAB [204.975/218.819] Mean PAB ecliptic longitude
λPAB
94-104 A11 --- Ch Kepler channel(s)
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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 A1 --- Type [WS] Type of light curve (1)
3- 8 I6 --- Ast [1143/353363] Asteroid number
10- 21 A12 --- Name Asteroid name
23 A1 --- f_Name [a] Flag on Name (2)
25- 36 F12.4 d T0 Epoch T0 in Julian Date
38- 44 F7.3 h Per [5.4/562.134] Period
46- 51 F6.3 h e_Per [0.021/36] Error in Per
53- 57 F5.3 mag EAmp [0.068/0.873]? Extrema amplitude
59- 63 F5.3 mag e_EAmp [0.01/0.267]? Error in EAmp
65- 69 F5.3 deg MAmp [0.039/0.47] Mean to peak amplitude
71- 75 F5.2 mag Mag [7.93/12.7] Minor Planet Center (MPC) absolute
magnitude
77- 83 F7.3 km Diam [13.386/114.624] Effective diameter
85 A1 --- f_Diam [b] Flag on Diam (3)
87- 91 F5.3 km e_Diam [0.307/6.581]? Error in Diam
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Note (1): Type as follows:
W = Well constrained lightcurve;
S = Slow rotator.
Note (2): Flag as follows:
a = These objects have lightcurves with inverted U-V-shaped lightcurves
characteristic of eclipsing contact binary systems.
Note (3): Flag as follows:
b = These objects have diameters estimated utilizing the MPC derived absolute
magnitude and a mean albedo of 0.06 derived from WISE results of
Grav et al. (2011, J/ApJ/742/40; 2012, J/ApJ/759/49).
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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- 6 I6 --- Ast [1143/353363] Asteroid number
8- 13 F6.3 mag KpMag [8.4/13] Fitted absolute Kepler magnitude
15- 19 F5.3 mag e_KpMag [0.002/0.024] Uncertainty in KpMag
21- 26 F6.3 mag A1 [-0.045/0.056] Amplitude of first fitted
Fourier cosine term
28- 32 F5.3 mag e_A1 [0.003/0.036] Uncertainty in A1
34- 39 F6.3 mag B1 [-0.053/0.041] Amplitude of first fitted
Fourier sine term
41- 45 F5.3 mag e_B1 [0.002/0.032] Uncertainty in B1
47- 52 F6.3 mag A2 [-0.28/0.201] Amplitude of second fitted
Fourier cosine term
54- 58 F5.3 mag e_A2 [0.003/0.034] Uncertainty in A2
60- 65 F6.3 mag B2 [-0.406/0.362] Amplitude of second fitted
Fourier sine term
67- 71 F5.3 mag e_B2 [0.002/0.035] Uncertainty in B2
73- 78 F6.3 mag A3 [-0.048/0.034] Amplitude of third fitted
Fourier cosine term
80- 84 F5.3 mag e_A3 [0.003/0.032] Uncertainty in A3
86- 91 F6.3 mag B3 [-0.03/0.028] Amplitude of third fitted
Fourier sine term
93- 97 F5.3 mag e_B3 [0.002/0.035] Uncertainty in B3
99-104 F6.3 mag A4 [-0.055/0.045] Amplitude of fourth fitted
Fourier cosine term
106-110 F5.3 mag e_A4 [0.003/0.036] Uncertainty in A4
112-117 F6.3 mag B4 [-0.072/0.036] Amplitude of fourth fitted
Fourier sine term
119-123 F5.3 mag e_B4 [0.003/0.032] Uncertainty in B4
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 10-Jul-2017