Astronomy:(523764) 2014 WC510

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Short description: Binary trans-Neptunian object


(523764) 2014 WC510
Discovery[1]
Discovered byPan-STARRS 1
Discovery siteHaleakalā Obs.
Discovery date8 September 2011
(first imaged)
Designations
2014 WC510
Minor planet categoryplutino[2] · TNO[3]
distant[1] · binary[4]
Orbital characteristics[3]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 2
Observation arc7.49 yr (2,737 days)
|{{{apsis}}}|helion}}48.936 AU
|{{{apsis}}}|helion}}29.535
39.236
Eccentricity0.24724
Orbital period245.77 yr
Mean anomaly342.994°
Mean motion0° 0m 14.437s / day
Inclination19.542°
Longitude of ascending node194.464°
289.173°
Known satellites1
Physical characteristics
Mean diameter181±16 km (primary)[4]
138±32 km (secondary)[4]
Geometric albedo0.051±0.017[4]
Apparent magnitude22.0[1]
Absolute magnitude (H)7.2±0.3[4]


(523764) 2014 WC510 (provisional designation 2014 WC510) is a binary trans-Neptunian object discovered on 8 September 2011 by the Pan-STARRS survey at the Haleakalā Observatory in Hawaii. It was found by Pan-STARRS on 20 November 2014 and was announced later in July 2016 after additional observations and precovery identifications. It is in the Kuiper belt, a region of icy objects orbiting beyond Neptune in the outer Solar System. It is classified as a plutino, a dynamical class of objects in a 2:3 orbital resonance with Neptune. On 1 December 2018, a team of astronomers observed a stellar occultation by the object, which revealed that it is a compact binary system consisting of two separate components in close orbit around each other. The primary and secondary components are estimated to have diameters of around 180 km (110 mi) and 140 km (87 mi), respectively.

Observations

Discovery

Before the announcement of its discovery, 2014 WC510 had been observed by the Pan-STARRS survey from 2011 to 2015. All of these observations were made with the Pan-STARRS 1 1.8-meter Ritchey–Chrétien telescope, located at the Haleakalā Observatory atop the Hawaiian island of Maui. The accredited observers using the telescope were B. Gibson, T. Goggia, N. Primak, A. Schultz, and M. Willman.[5] The object was first identified on 20 November 2014, though it was announced later in a Minor Planet Electronic Circular published on 17 July 2016, after additional observations by Pan-STARRS had been found, preceding the team's original observation from 2014.[5] While 2014 WC510 is the object's first and only provisional designation assigned by the Minor Planet Center, the date of discovery is considered to be on 8 September 2011, which was the earliest known observation of the object before it was assigned a minor planet number.[1][6]

Occultation

On 1 December 2018, 2014 WC510 occulted a 15th-magnitude double star, blocking out its starlight for a maximal duration of approximately 11 seconds. The stellar occultation was observed by astronomers and citizen scientists across the West Coast of the United States and Canada. Of the 41 participating sites, six of them reported dimmings in the star's brightness, signifying likely positive detections of the occultation. Five of these sites reported two consecutive dimmings due to the occulted star's double nature; 2014 WC510 occulted one of the two stars being observed.[4] These observations were part of a campaign coordinated by the Research and Education Collaborative Occultation Network (RECON), a citizen science project dedicated to observing occultations by trans-Neptunian objects.[7][8]

Prior to the occultation, 2014 WC510 had only been observed by Pan-STARRS over an observation arc of 3 years. The calculated orbit from these Pan-STARRS observations had significant uncertainty, which would have been unreliable for predicting occultations.[5] In an effort to reduce the orbital uncertainty, the RECON project collaborated with the Pan-STARRS project to do a precovery search of archival Pan-STARRS images to gather extensive astrometric positions of 2014 WC510.[4] Follow-up observations by Pan-STARRS were also conducted through 2016–2018 and helped extend 2014 WC510's observation arc to 6.3 years.[1] Although an observation arc of this length is generally unreliable for predicting occultations especially by distant objects, this was compensated by Pan-STARRS's highly accurate astrometric system, allowing for 2014 WC510's orbital uncertainty to be significantly reduced.[4]

Orbit and classification

2014 WC510 is classified as a plutino, a subgroup of the resonant trans-Neptunian objects located in the inner region of Kuiper belt. Named after the group's largest member, Pluto, the plutinos are in a 2:3 mean-motion orbital resonance with Neptune. That is, they complete two orbits around the Sun for every three orbits that Neptune takes.[2] 2014 WC510 orbits the Sun at an average distance of 39.24 astronomical units (5.87×109 km; 3.65×109 mi), taking 245.8 years to complete a full orbit.[3] This is characteristic of all plutinos, which have orbital periods around 250 years and semi-major axes around 39 AU.[9]

Like Pluto, 2014 WC510's orbit is elongated and inclined to the ecliptic.[9] 2014 WC510 has an orbital eccentricity of 0.25 and an orbital inclination of 19.5 degrees with respect to the ecliptic. Over the course of its orbit, 2014 WC510's distance from the Sun varies from 29.5 AU at perihelion (closest distance) to 48.9 AU at aphelion (farthest distance).[3] 2014 WC510 has last passed aphelion in the early 20th century, and is now moving closer to the Sun, approaching perihelion by 2032.[3][10] Simulations by the Deep Ecliptic Survey show that 2014 WC510 can acquire a perihelion distance (qmin) as small as 28.7 AU over the next 10 million years.[2]

Binary system

Comparison of mean separation distances and diameters of tight trans-Neptunian binaries including 2014 WC510

Observations of the December 2018 occultation revealed that 2014 WC510 is a compact binary system consisting of two separate components in close orbit around each other. Of the six sites that reported positive detections of the occultation, one site located in Bishop, California, detected a shorter dimming event separate from the main detections by the other five sites located south of it. A 2020 study led by Rodrigo Leiva and Marc Buie analyzed the occultation data and determined that the detection from Bishop was most likely an occultation by a secondary component of 2014 WC510.[4][8]

Since the two components were only observed for a short period of time during the occultation, the binary system's orbital parameters have not been determined. The projected separation distance between the primary and secondary is 349 ± 29 km (217 ± 18 mi), derived from an angular separation of 16±1 milliarcseconds.[4] Assuming a density of 1 g/cm3 for both components, their mutual orbital period would likely be under one day.[11] 2014 WC510 has the third-smallest observed component separation of all known binary TNOs (As of 2021), after 2011 JY31 and 2014 OS393.[12] Such tight binary TNOs are difficult to resolve with direct imaging due to their characteristic small separation distances between their components.[4]

Most models of the formation of the Solar System indicate that most TNOs have formed as binaries, hence they are expected to be common especially in the Kuiper belt population.[8] While most known binary TNOs appear to have wide mutual orbits, tight binary TNOs similar to 2014 WC510 are thought to have a higher chance of survival after their formation. 2014 WC510 belongs to the population of smaller TNOs, which are expected to have a primordial origin similar to the classical Kuiper belt object 486958 Arrokoth.[4]

Physical characteristics

Assuming a circular projected shape for the components' occultation profiles, the diameters of the primary and secondary are estimated to be 181 ± 16 km (112.5 ± 9.9 mi) and 138 ± 32 km (86 ± 20 mi), respectively.[4] The diameter ratio of the secondary to the primary is 0.76:1.00—the secondary component is approximately 75% as large as the primary.[11] Since the mutual orbit of the components is undetermined, the mass and density of the 2014 WC510 system cannot be derived. The individual components of the 2014 WC510 system are among the smallest trans-Neptunian objects with sizes measured with stellar occultations, following the Kuiper belt object 486958 Arrokoth (~30 km).[4]

Given the components' estimated diameters and their combined absolute magnitude of 7.2, their calculated geometric albedos indicate that they have dark surfaces, reflecting about 5% of incident visible light. However, the estimated geometric albedo may be subject to a systematic error depending on the true shapes and photometric properties of the components, resulting in a significant uncertainty of ±2%. Nonetheless, 2014 WC510 is one of the darkest objects measured with stellar occultations, being darker than 486958 Arrokoth.[4]

Numbering and naming

This minor planet was numbered by the Minor Planet Center on 25 September 2018 and received the number 523764 in the minor planet catalog.[13] As of 2020, it has not been named.[1]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 "(523764) = 2014 WC510". International Astronomical Union. http://www.minorplanetcenter.net/db_search/show_object?object_id=523764. 
  2. 2.0 2.1 2.2 Buie, M. W.. "Orbit Fit and Astrometric record for 523764". Southwest Research Institute. http://www.boulder.swri.edu/~buie/kbo/astrom/523764.html. 
  3. 3.0 3.1 3.2 3.3 3.4 "JPL Small-Body Database Browser: 523764 (2014 WC510)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2523764. 
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 Leiva, Rodrigo et al. (September 2020). "Stellar Occultation by the Resonant Trans-Neptunian Object (523764) 2014 WC510 Reveals a Close Binary TNO". The Planetary Science Journal 1 (2): 48. doi:10.3847/PSJ/abb23d. Bibcode2020PSJ.....1...48L. 
  5. 5.0 5.1 5.2 Gibson, B.; Goggia, T.; Primak, N.; Schultz, A.; Willman, M.; Chambers, K.; Chastel, S.; Chen, Y. -T. et al. (2016-07-25). "MPEC 2016-O238: 2014 WC510". Minor Planet Electronic Circular (Minor Planet Center) 2016-O238. Bibcode2016MPEC....O..238G. https://minorplanetcenter.net/mpec/K16/K16ON8.html. 
  6. "How Are Minor Planets Named?". International Astronomical Union. https://www.minorplanetcenter.net/iau/info/HowNamed.html. 
  7. Gough, Evan (2020-09-29). "Astronomers Find a New Binary Object in the Kuiper Belt". Universe Today. https://www.universetoday.com/148082/astronomers-find-a-new-binary-object-in-the-kuiper-belt/. 
  8. 8.0 8.1 8.2 "SwRI study describes discovery of close binary trans-Neptunian object". Southwest Research Institute. 2020-09-28. https://www.swri.org/press-release/recon-close-binary-trans-neptunian-object. 
  9. 9.0 9.1 Johnston, W. R. (2020-08-18). "List of Known Trans-Neptunian Objects". Johnston's Archive. http://www.johnstonsarchive.net/astro/tnoslist.html. 
  10. "HORIZONS Web-Interface". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=523764. Retrieved 2020-09-30. 
  11. 11.0 11.1 Johnston, Wm. Robert (2020-10-11). "(523764) 2014 WC510". Asteroids with Satellites Database. Johnston's Archive. http://www.johnstonsarchive.net/astro/astmoons/am-523764.html. 
  12. Stern, Alan (2021-06-21). "New Horizons Kuiper Extended Mission Science Overview". Laboratory for Atmospheric and Space Physics. University of Colorado Boulder. https://lasp.colorado.edu/home/mop/files/2021/06/Stern.pdf. Retrieved 2021-11-13. 
  13. "M.P.C. 111781". Minor Planet Center. 2018-09-25. https://minorplanetcenter.net/iau/ECS/MPCArchive/2018/MPC_20180925.pdf. 

External links