16974 Iphthime
A large binary Jupiter trojan from the Greek camp.
16974 Iphthime is a Jupiter trojan from the Greek camp, located at the L4 Lagrangian point 60° ahead of Jupiter. It is notable as a binary system, with a companion discovered by the Hubble Space Telescope, and ranks among the 80 largest Jupiter trojans.
Quick Facts
- Minorplanet
- yes
- Background
- #C2FFFF
- Discoverer
- LINEAR
- Discovery Site
- Lincoln Lab's ETS
- Discovered
- 18 November 1998
- Mpc Name
- (16974) Iphthime
- Adjective
- Iphthimean
- Pronounced
- ɪ · f · ' · θ · aɪ · m · iː
- Named After
- Iphthime Iphthīmē/Ἰφθῑμη / (Greek mythology)
- Mp Category
- Jupiter trojan / Greekbackground
- Epoch
- 23 March 2018 (JD 2458200.5)
- Uncertainty
- 0
Facts from the source article.
Lore & Background
Iphthime orbits the Sun at a distance of 4.8–5.6 AU every 11 years and 10 months, with a semi-major axis of 5.19 AU, an eccentricity of 0.07, and an inclination of 15° to the ecliptic. It is a non-family asteroid in the Jovian background population. Its observation arc began with a first observation as 1974 WX at Crimea-Nauchnij in November 1974, 24 years before its official discovery at Socorro.
The minor planet was named after Iphthime from Greek mythology, the sister of Penelope and daughter of Icarius, who appears in her sister's dream to comfort her. The naming citation was published by the Minor Planet Center on 3 December 2017. Physically, Iphthime is an assumed C-type asteroid, though its V–I color index of 0.96 is typical for D-type asteroids, the most common spectral type among larger Jupiter trojans. A rotational lightcurve obtained in October 2009 at Calar Alto Observatory gave a long rotation period of 78.9±0.4 hours with a brightness amplitude of 0.25 magnitude.
Reader's Guide
Iphthime's significance lies in its membership among the 80 largest Jupiter trojans and its status as a binary system, with the companion's discovery announced in March 2016 using the Hubble Space Telescope. The asteroid's slow rotation period of 78.9 hours is notably long, and its dark surface, with an albedo between 0.065 and 0.069, is consistent with the primitive composition typical of many trojans. Measurements from IRAS, Akari, and NEOWISE surveys give a diameter range of 55.43 to 57.341 kilometers. The object's orbit at Jupiter's L4 point places it in the leading Greek camp, and its naming from Greek mythology ties it to the epic tradition of the Odyssey. As a background population asteroid, it is not part of any known collisional family, suggesting it may be a primordial body from the early Solar System. The binary nature adds to its scientific interest for studying satellite formation around trojans.
Did You Know?
- Iphthime has a rotation period of 78.9 hours, or about 3.3 days.
- It is a binary system; its companion was discovered by the Hubble Space Telescope in March 2016.
- The asteroid was named after Iphthime, sister of Penelope in Greek mythology.
- It belongs to the 80 largest Jupiter trojans, with a diameter of approximately 57 kilometers.
Frequently Asked Questions
What is 16974 Iphthime?
Iphthime is a large Jupiter trojan asteroid that belongs to the Greek camp, orbiting at the L4 Lagrangian point about 60 degrees ahead of Jupiter. At roughly 57 kilometers in diameter, it ranks among the 80 largest known Jupiter trojans.
Who discovered 16974 Iphthime and when?
The asteroid was detected on 18 November 1998 by the Lincoln Near-Earth Asteroid Research team at the ETS Test Site in Socorro, New Mexico. It was first logged under the provisional designation 1998 WR21 before being given its permanent number and mythological name.
Why is 16974 Iphthime called a binary asteroid?
Observations with the Hubble Space Telescope revealed a smaller companion orbiting the primary body, confirming that Iphthime is a two-member asteroid system. This makes it a notable outlier, since the vast majority of Jupiter trojans are single, unaccompanied objects.
How long does it take Iphthime to rotate once?
The asteroid completes a full spin in approximately 78.9 hours, or a little over three and a quarter days. That is a comparatively sluggish pace relative to many smaller asteroids that rotate in under ten hours.
Where does 16974 Iphthime sit in Jupiter's orbit?
Iphthime shares Jupiter's orbital path but lags at the L4 point, which sits 60 degrees ahead of the planet in its circuit around the Sun. This positioning places it squarely in the so-called Greek camp of the Jupiter trojan population.
More in Notable Asteroids, Part 4 1-24
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