Orbital diagram of 2019 AQ3, as viewed from the ecliptic pole
|Discovered by||Zwicky Transient Facility|
|Discovery site||Palomar Obs.|
|Discovery date||4 January 2019|
(first observed only)
|MPC designation||2019 AQ3|
|NEO · Atira |
|Orbital characteristics |
|Epoch 27 April 2019 (JD 2458600.5)|
|Uncertainty parameter 3 · 4|
|Observation arc||3.23 yr (1,181 d)|
|2° 10m 56.28s / day|
|Earth MOID||0.2259 AU (87.9 LD)|
|Mercury MOID||0.0550 AU|
|Venus MOID||≤ 0.0384 AU|
|1+ km (est.)|
1.4 km(est. at 0.08)
2019 AQ3 is an inclined near-Earth object of the small Atira group from the innermost region of the Solar System, estimated to measure 1.4 kilometers (0.9 miles) in diameter. Among the hundreds of thousands known asteroids, 2019 AQ3's orbit has likely the smallest semi-major axis (0.589 AU) and aphelion (0.77 AU), that is, the orbit's average distance and farthest point from the Sun, respectively. The object was first observed on 4 January 2019, by astronomers at Palomar's Zwicky Transient Facility in California, with recovered images dating back to 2015.
Orbit and classification
2019 AQ3 orbits the Sun at a distance of 0.40–0.77 AU once every 5 months (165 days; semi-major axis of 0.589 AU). Its orbit has an eccentricity of 0.31 and an inclination of 47° with respect to the ecliptic. The body's observation arc begins with a precovery taken by Pan-STARRS at Haleakala Observatory in October 2015, more than 3 years prior to its official first observation at the Zwicky Transient Facility on 4 January 2019. It has a minimum orbit intersection distance with Earth of 0.22 AU or 88 lunar distances.
2019 AQ3's orbit has the smallest aphelion of any known asteroid in the Solar System, never distancing itself more than 0.774 AU from the Sun (77% of Earth's average orbital distance). Before its discovery, the record was held by (418265) 2008 EA32 at an aphelion of 0.804 AU, which is notably larger. 2019 AQ3's orbit also has a semi-major axis below that of Venus (0.723 AU) and an orbital period of 165 days, which is the second shortest among all asteroids. (The record 161-day orbit of 2016 XK24 is poorly defined and still may change considerably).
2019 AQ3 is a member of the small class of Atira asteroids, which are also known as Apoheles or interior-Earth objects, as their orbits are confined inside that of Earth's. This makes their discovery difficult, as they stay relatively close to the Sun when observed from Earth, never reaching a Solar elongation of more than 90°, often much less. Only 19 such asteroids are known, 14 of which still reach 90% Earth's distance from the Sun over the course of their orbit.
The asteroid's orbit is also highly inclined with respect to the plane of the Solar System, at more than 47°, the highest inclination of any known Atira asteroid, although there are many near-Earth asteroids with even higher inclinations.
On the long-term, 2019 AQ3 has a fairly quickly-changing orbit. Between 1600 AD and 2500 AD its aphelion distance lowers slightly from 0.7746 to 0.7725 AU, its perihelion distance increases slightly from 0.4025 to 0.4046 AU, and its inclination increases slightly from 47.19 to 47.25°. It is most likely in a Kozai resonance with Venus, affecting its eccentricity and inclination together over a period of thousands of years.
Numbering and naming
The object's diameter is estimated at 1.4 kilometers (0.87 miles), which corresponds to an assumed geometric albedo of 0.08 for an absolute magnitude of 17.6. The Minor Planet Center also considers 2019 AQ3 to be larger than 1 kilometer. However, these are estimates with apparently no published measurement confirming the body's diameter. Based on a generic magnitude-to-diameter conversion, the asteroid could measure anywhere between 500 meters and 2 kilometers for an extreme albedo of 0.45 (brighter than the E-types of the Hungaria population) and 0.04 (very dark carbonaceous D- and P-types of some members in the Hildian and Jupiter trojan population), respectively. As of 2019, less than 900 large (kilometer-sized) near-Earth asteroids have been discovered.
- "2019 AQ3". Minor Planet Center. Retrieved 8 January 2019.
- "MPEC 2019-A88 : 2019 AQ3". Minor Planet Electronic Circular. 6 January 2019. Retrieved 8 January 2019.
- "JPL Small-Body Database Browser: (2019 AQ3)" (2019-01-06 last obs.). Jet Propulsion Laboratory. Retrieved 8 January 2019.
- "2019AQ3 – Summary". ESA Space Situational Awareness – NEO Coordination Centre. Retrieved 8 January 2019.
- "Asteroid Size Estimator". CNEOS NASA/JPL. Retrieved 8 January 2019.
- "JPL Small-Body Database Search Engine: Q < 0.99 AU". Jet Propulsion Laboratory. Retrieved 8 January 2019.
- "JPL Small-Body Database Search Engine: asteroids and NEOs and period < 200 (d)". Jet Propulsion Laboratory. Retrieved 8 January 2019.
- "JPL Small-Body Database Search Engine: orbital class (IEO)". Jet Propulsion Laboratory. Retrieved 8 January 2019.
- "JPL Small-Body Database Search Engine: asteroids and NEOs and i > 47 (deg)". Jet Propulsion Laboratory. Retrieved 8 January 2019.
- "Discovery Statistics by Survey 1+ KM". CNEOS NASA/JPL. Retrieved 8 January 2019.
- 2019 AQ3 at NeoDyS-2, Near Earth Objects—Dynamic Site
- 2019 AQ3 at the JPL Small-Body Database