2207 Antenor
Large Jupiter trojan, possibly the 5th known binary.
2207 Antenor is a sizable Jupiter trojan situated in the Trojan camp, with a diameter around 92 kilometers. It ranks among the 30 largest known Jupiter trojans and, if its suspected binary nature is verified, it would become only the fifth such binary system identified among these objects.
This dark D-type asteroid was discovered on August 19, 1977, by Soviet astronomer Nikolai Chernykh at the Crimean Astrophysical Observatory in Nauchnyj. It follows an orbit trailing Jupiter at the L5 Lagrangian point, roughly 60 degrees behind the gas giant, completing one revolution around the Sun every 11 years and 8 months from a distance of 5.1 to 5.2 AU. Its orbit has a low eccentricity of 0.02 and an inclination of 7 degrees to the ecliptic. Precovery images from Lowell Observatory date back to March 1959, though the official observation arc begins with its 1977 discovery.
The asteroid is named for Antenor, a wise elder and counselor to King Priam of Troy. In Greek mythology, he advocated returning Helen to Menelaus to avoid war, though later accounts portray him as a traitor who opened Troy's gates to the Greeks. The naming citation was issued by the Minor Planet Center on March 1, 1981. Related minor planets include 884 Priamus, 101 Helena, and 1647 Menelaus.
Photometric observations have yielded several rotation periods. The best-determined value, from April 1969 observations by Mottola, is 7.965 hours with a brightness variation of 0.09 magnitude. Later studies in 2012 by the Palomar Transient Factory found periods of 7.960 and 7.964 hours, while observations between 2016 and 2018 by Robert Stephens gave periods of 7.906 and 7.964 hours.
In October 2018, Stephens, along with Brian Warner and other European observers, reported evidence that Antenor is likely a binary system. No orbital period for the suspected moon could be determined. If confirmed, this would be the fifth known binary Jupiter trojan.
Size estimates vary by survey. IRAS, Akari, and NEOWISE data give diameters between 85.11 and 97.66 kilometers, with albedos from 0.051 to 0.0678. A stellar occultation directly measured the asteroid's dimensions at 108.6 km along its longest axis and 95.82 km along its shortest. The same event revealed an 11-kilometer gap, possibly a surface feature or evidence of a contact binary structure.
Quick Facts
- Minorplanet
- yes
- Background
- #C2FFFF
- Discovered
- 19 August 1977
- Discoverer
- N. Chernykh
- Discovery Site
- Crimean Astrophysical Obs.
- Mpc Name
- (2207) Antenor
- Adjective
- Antenorian
- Pronounced
- æ · n · ˈ · t · iː · n · ər
- Named After
- Antenor (Greek mythology)
- Mp Category
- Jupiter trojan / Trojanbackground
- Epoch
- 23 March 2018 (JD 2458200.5)
- Uncertainty
- 0
Facts from the source article.
Lore & Background
2207 Antenor was discovered on 19 August 1977 by Russian astronomer Nikolai Chernykh at the Crimean Astrophysical Observatory in Nauchnyj on the Crimean peninsula. It is a dark D-type asteroid orbiting in the trailing Trojan camp at Jupiter's L5 Lagrangian point, 60° behind Jupiter in a 1:1 resonance. The asteroid has a semi-major axis of 5.15 AU, an eccentricity of 0.02, and an inclination of 7° to the ecliptic. It takes 11 years and 8 months to orbit the Sun. The first precovery observation dates to March 1959 at Lowell Observatory.
The minor planet was named for Antenor, a wise elder and counselor of King Priam of Troy who advised returning Helen to Menelaus. The naming citation was published by the Minor Planet Center on 1 March 1981. Physical characteristics include a rotation period of 7.97 hours, with lightcurve observations from 1989, 1969, 2012, and 2016–2018 providing periods between 7.906 and 7.965 hours. Diameter estimates from IRAS, Akari, and NEOWISE range from 85.11 to 97.66 km, with albedo between 0.051 and 0.0678. A stellar occultation gave dimensions of 108.6 km by 95.82 km and revealed an 11 km gap, possibly a topographical feature or indication of a binary object.
Reader's Guide
2207 Antenor holds significance as one of the 30 largest Jupiter trojans, a population of asteroids that share Jupiter's orbit. Its classification as a dark D-type asteroid is typical of many trojans, which are thought to be primitive bodies from the early Solar System. The potential binary nature, reported in October 2018 by Robert Stephens and collaborators, would make it only the 5th known binary Jupiter trojan, adding to the understanding of satellite systems among these distant objects. The stellar occultation data, which revealed an 11 km gap, further supports the possibility of a binary or contact binary structure. The asteroid's naming after Antenor connects it to the Trojan War mythology, alongside other named minor planets such as 884 Priamus, 101 Helena, and 1647 Menelaus. The multiple lightcurve observations over decades have refined its rotation period, contributing to the broader study of trojan asteroid shapes and spin states. Its legacy lies in its role as a well-studied representative of the Jupiter trojan population, with ongoing observations that may confirm its binary status.
Did You Know?
- 2207 Antenor is one of the 30 largest Jupiter trojans.
- It was discovered by Russian astronomer Nikolai Chernykh on 19 August 1977.
- If confirmed as a binary, it would be the 5th known binary Jupiter trojan.
- A stellar occultation revealed an 11 km gap, possibly indicating a binary or contact binary object.
Frequently Asked Questions
What is 2207 Antenor?
2207 Antenor is a large D-type asteroid that shares Jupiter's orbit, trailing the gas giant at the L5 Lagrangian point roughly 60 degrees behind it. With a diameter of about 92 kilometers, it sits among the thirty biggest known Jupiter trojans in the so-called Trojan camp.
Who discovered 2207 Antenor and where?
Soviet astronomer Nikolai Chernykh spotted the object on 19 August 1977 from the Crimean Astrophysical Observatory in Nauchnyj, on the Crimean peninsula. It remained a single, unremarkable catalog entry for decades until its size and possible binary nature drew renewed attention.
How large is 2207 Antenor compared to other Jupiter trojans?
At roughly 92 kilometers (about 57 miles) across, Antenor comfortably ranks within the top thirty Jupiter trojans by diameter. Its rotation period is approximately 7.97 hours, giving it a slow, stately spin relative to many smaller asteroids.
Is 2207 Antenor a binary asteroid?
Observations suggest Antenor may consist of two bodies orbiting a common center of mass, though this has not yet been fully confirmed. If the binary classification is verified, it would become only the fifth known binary system among Jupiter's trojan population.
What makes 2207 Antenor important to asteroid researchers?
Its combination of large size, dark D-type surface composition, and suspected binary structure makes it a valuable reference point for understanding the formation and evolution of the Trojan swarms. Confirming a second companion would also tighten the small sample of known binaries in this region, helping refine models of early Solar System dynamics.
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