J/MNRAS/507/4914 Contact-binary (68346) 2001 KZ66 light curves (Zegmott+, 2021)
Detection of the YORP Effect on the contact-binary (68346) 2001 KZ66 from
combined radar and optical observations.
Zegmott T.J, Lowry S.C., Rozek A., Rozitis B., Nolan M.C., Howell E.S.,
Green S.F., Snodgrass C., Fitzsimmons A., Weissman P.R.
<Mon. Not. R. Astron. Soc. 507, 4914-4932 (2021)>
=2021MNRAS.507.4914Z 2021MNRAS.507.4914Z (SIMBAD/NED BibCode)
ADC_Keywords: Minor planets ; Photometry
Keywords: radiation mechanisms: thermal - methods: data analysis -
methods: observational - techniques: photometric -
techniques: radar astronomy -
minor planets, asteroids: individual: (68346) 2001 KZ66
Abstract:
The YORP effect is a small thermal-radiation torque experienced by
small asteroids, and is considered to be crucial in their physical and
dynamical evolution. It is important to understand this effect by
providing measurements of YORP for a range of asteroid types to
facilitate the development of a theoretical framework. We are
conducting a long-term observational study on a selection of
near-Earth asteroids to support this. We focus here on
(68346) 2001 KZ66, for which we obtained both optical and radar
observations spanning a decade. This allowed us to perform a
comprehensive analysis of the asteroid's rotational evolution.
Furthermore, radar observations from the Arecibo Observatory enabled
us to generate a detailed shape model. We determined that (68346) is a
retrograde rotator with its pole near the southern ecliptic pole,
within a 15-degree radius of longitude 170 degrees and latitude
-85-degrees. By combining our radar-derived shape model with the
optical light curves we developed a refined solution to fit all
available data, which required a YORP strength of
(8.43±0.69)x10-8rad/day/day. (68346) has a distinct bifurcated
shape comprising a large ellipsoidal component joined by a sharp
neckline to a smaller non-ellipsoidal component. This object likely
formed from either the gentle merging of a binary system, or from the
deformation of a rubble pile due to YORP spin-up. The shape exists in
a stable configuration close to its minimum in topographic variation,
where regolith is unlikely to migrate from areas of higher potential.
Description:
(68346) was one of our optical photometry targets at ESO's 3.6m NTT in
La Silla (Chile), using the EFOSC2 instrument. All observations of
(68346) were performed in imaging mode using 2x2 binning on the
detector, and with the Bessel R filter in 2010 and 2012, and the
Bessel V filter in 2014 and 2019. The object was detected at the NTT
on two different nights in 2010, three in 2012, two in 2014, and two
in 2019; a total of nine light curves were obtained.
We also monitored (68346) with the 2.5m INT in La Palma (Spain), using
the Wide-Field Camera (WFC). The observations were performed using the
Harris R filter. The object was observed over one night one the 24
February 2012 for 3.1 hours.
The table also includes previously published photometry obtained at
the Palmer Divide Station. These processed light curves were obtained
from the Asteroid Lightcurve Data Exchange Format (ALCDEF) database.
objects:
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Planet Name H i e a
mag deg AU
--------------------------------------------------------------
68346 2001 KZ66 16.80 16.693773 0.41658317 1.50747568
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 59 17 A log of optical photometry datasets of
asteroid (68346) 2001 KZ66 used in this study
lc.dat 42 950 List of light curves
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- LCNo [1/17] Light curve number
4- 13 A10 "date" Obs.date UT date of observation
15- 19 F5.3 AU rh Heliocentric distance
21- 25 F5.3 AU De Geocentric distance
27- 31 F5.2 deg alpha Solar phase angle
33- 37 F5.1 deg ELON Observer-centred ecliptic longitude
39- 43 F5.1 deg ELAT Observer-centred ecliptic latitude
45- 47 F3.1 h Total Total observation time
49- 53 A5 --- Filter [R V Clear] Filter
55- 57 A3 --- Obs Observing facility used to obtain the
light curve (1)
59 I1 --- Ref [1/2]? Reference (2)
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Note (1): Observing facility key as follows:
INT = 2.5m Isaac Newton Telescope (La Palma, Spain)
NTT = European Southern Observatory 3.5m New Technology Telescope (Chile)
PDS = Palmer Divide Station (California, USA)
Note (2): References as follows:
1 = Warner B. D., 2016, Minor Planet Bulletin, 43, 311
2 = Warner B. D., 2017, Minor Planet Bulletin, 44, 22
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Byte-by-byte Description of file: lc.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- LCNo [1/17] Light curve number (1)
4- 20 F17.9 d JD Julian Date
23- 27 A5 --- Filter [R V Clear] Filter
30- 35 F6.3 mag mag Relative magnitude in Filter
38- 42 F5.3 mag e_mag 1-sigma uncertainty in relative magnitude
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Note (1): see Table 1 for details.
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Acknowledgements:
Tarik J. Zegmott, tjz2(at)kent.ac.uk
(End) Patricia Vannier [CDS] 21-Sep-2021