J/A+A/631/A149 PHA contact-binary (85990) 1999 JV6 light curves (Rozek+, 2019)
Shape model and spin-state analysis of PHA contact-binary (85990) 1999 JV6 from
combined radar and optical observations.
Rozek A., Lowry S.C., Nolan M.C., Taylor P.A., Benner L.A.M.,
Fitzsimmons A., Zegmott T.J., Weissman P.R., Green S.F., Rozitis B.,
Snodgrass C., Smythe W.D., Hicks M.D., Howell E.S., Virkki A.K.,
Aponte-Hernandez B., Rivera-Valentin E.G., Rodriguez-Ford L.A.,
Zambrano-Marin L.F., Brozovic M., Naidu S.P., Giorgini J.D., Snedeker L.G.,
Jao J.S., Ghigo F.D.
<Astron. Astrophys. 631, A149 (2019)>
=2019A&A...631A.149R 2019A&A...631A.149R (SIMBAD/NED BibCode)
ADC_Keywords: Minor planets ; Photometry
Keywords: minor planets, asteroids: individual: (85990) 1999 JV6 -
methods: observational - methods: data analysis -
techniques: photometric - techniques: radar astronomy -
radiation mechanisms: thermal
Abstract:
The potentially hazardous asteroid (85990) 1999 JV6 has been a target
of previously published thermal-infrared observations, and optical
photometry. It has been identified as a promising candidate for
possible Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect
detection.
The YORP effect is a small thermal-radiation torque attributed to be a
key factor in spin-state evolution of small Solar System bodies. In
order to detect YORP on 1999 JV6 we develop a detailed shape model and
analyse the spin-state using both optical and radar observations.
For 1999 JV6, we collected optical photometry between 2007 and 2016.
Additionally, we obtained radar echo-power spectra and imaging
observations with Arecibo and Goldstone planetary radar facilities in
2015, 2016, and 2017. We combine our data with published optical
photometry to develop a robust physical model.
We determine that the rotation pole resides at negative latitudes in
an area with a 5° radius, close to the south ecliptic pole. The
refined sidereal rotation period is 6.536787±0.000007h. The radar
images are best reproduced with a bilobed shape model. Both lobes of
1999 JV6 can be represented as oblate ellipsoids with a smaller, more
spherical component resting at the end of a larger, more elongated
component. While contact binaries appear to be abundant in the
near-Earth population, there exists just a few published shape models
for asteroids in this particular configuration. By combining the
radar-derived shape model with optical light curves we determine a
constant-period solution that fits all available data well. Using
light curve data alone we determine an upper limit for YORP
8.5x10-8rad/day2.
The bifurcated shape of 1999 JV6 might be a result of two ellipsoidal
components gently merging with each other, or a deformation of a
rubble pile with a weak-tensile-strength core due to spin-up. The
physical model of 1999 JV6 presented here will enable future studies
of contact binary asteroid formation and evolution.
Description:
JV6 was one of our optical photometry targets at the ESO's 3.6m NTT
telescope in La Silla (Chile), using the EFOSC2. Strong winds imposed
pointing restrictions for the telescope and forced a break in the
observing, which resulted in obtaining two separate light curve
segments on 4 February 2013.
We monitored asteroid JV6 with the 2.5m INT in La Palma (Spain),
using the Wide-Field Camera (WFC). We observed the target on four
different nights in 2007, three in 2008, and another four in 2016,
giving a total of ten light curve data sets.
Between 23 and 25 January 2015, we observed JV6 with the Jet
Propulsion Laboratory's TMO's 0.6m telescope in California (USA).
Three light curves, covering just over one full rotation each, were
obtained.
The table also includes previously published photometry obtained at
the Palmer Divide Station. The processed light curves were retrieved
from the Asteroid Lightcurve Data Exchange Format (ALCDEF) database.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 9 28 List of light curves
tablea2.dat 35 1738 Measured optical light curves of (85990) 1999 JV6
used in the shape and spin-state analysis,
including published photometry
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 2 I02 --- LCNo [1/28] Light curve number (G1)
5- 7 I3 --- Npt Number of datapoints
9 A1 --- Filter [RrVc] Filter
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 2 I02 --- LCNo Light curve number (G1)
4- 17 F14.6 d JD Julian Date
20 A1 --- Filter [RrVc] Filter
22- 28 F7.3 mag mag Relative Magnitude
31- 35 F5.3 mag e_mag 1-sigma uncertainty in relative magnitude
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Global notes:
Note (G1): see Table 1 in paper for a details of which light curves are
published and the references below.
(1) Warner, 2014, Minor Planet Bulletin, 41, 157
(2) Warner, 2015, Minor Planet Bulletin, 42, 172
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Acknowledgements:
Agata Rozek, a.rozek(at)kent.ac.uk
(End) Patricia Vannier [CDS] 03-Oct-2019