174567 Varda
A large, possibly dwarf, Kuiper belt object.
174567 Varda is a large object beyond Neptune, discovered on 21 June 2003 by American astronomer Jeffrey A. Larsen. He used survey images from the 0.9-meter Spacewatch telescope at Kitt Peak National Observatory. It belongs to the dynamically hot classical Kuiper belt, meaning it orbits within the Kuiper belt but on a tilted path. Stellar occultations in 2018 suggest Varda is likely an oblate spheroid with a flattening of 0.07 and an area-equivalent diameter of 740 ± 14 km; other triaxial ellipsoid models remain unconstrained. The total mass of the Varda system is about 2.675 +0.048 −0.049 × 10²⁰ kg, with Varda itself contributing 86 to 90 percent. Its bulk density is highly ambiguous. James Webb Space Telescope data show a surface temperature of 44 K, and abundant frozen carbon dioxide dominates the surface.
Because of its size, some astronomers—including Michael E. Brown and Noemi Pinilla-Alonso—have considered Varda a possible dwarf planet. However, it is hypothesized that trans-Neptunian objects in the 400–1000 km range, like Varda, may never have compressed into fully solid bodies or achieved hydrostatic equilibrium, so they are unlikely to be dwarf planets. The density calculations for Varda are too ambiguous to settle this.
Varda has one known moon, Ilmarë, with a diameter of approximately 403 ± 40 km. The two are likely mutually tidally locked, and the system has a very large mass ratio, comparable to that of Pluto and Charon.
**Observation history**
**Discovery:** Varda was discovered on 21 June 2003 by Jeffrey A. Larsen as part of a United States Naval Academy Trident Scholar project. The discovery used survey images from the 0.9-meter Spacewatch telescope at Kitt Peak National Observatory. Larsen's survey ran for 34 months, covering about 8,000 square degrees of sky to detect slow-moving trans-Neptunian objects. At its announcement, Varda was the only large object found by this program and was thought to be the tenth-largest known classical Kuiper belt object. The Minor Planet Center announced the discovery on 7 January 2006. The earliest known precovery images come from photographs taken at Siding Spring Observatory on 19 March 1980.
**Further observations:** After its initial tracking under the provisional designation 2003 MW₁₂, Varda was regularly observed to secure its orbit.
Quick Facts
- Symbol
- (astrological)
- Discoverer
- J. A. Larsen
- Discovery Site
- Kitt Peak National Obs.
- Discovered
- 21 June 2003
- Earliest Precovery Date
- 19 March 1980
- Mpc Name
- (174567) Varda
- Pronounced
- ˈ · v · ɑːr · d · ə
- Named After
- Varda / (figure by J. R. R. Tolkien)
- Mp Category
- TNO / classical (hot) / detached / distant / 15:8 resonance with Neptune10
- Epoch
- 31 May 2020 (JD 2459000.5)
- Uncertainty
- 2
- Observation Arc
- 39.12 yr (14,290 d)
Facts from the source article.
Lore & Background
Varda was discovered as part of a United States Naval Academy Trident Scholar project. Larsen's survey ran for 34 months and covered approximately 8,000 square degrees of the sky to detect slow-moving trans-Neptunian objects. At the time of its announcement, Varda was the only large object discovered through this specific program and was thought to be the tenth-largest known classical Kuiper belt object. The Minor Planet Center officially announced the discovery on 7 January 2006. Astronomers later identified the earliest known precovery images of Varda from photographs taken at the Siding Spring Observatory on 19 March 1980.
Stellar occultations in 2018 show that Varda is likely an oblate spheroid with a flattening of 0.07 and an area equivalent diameter of 740±14 km. Other triaxial ellipsoid shape models remain mathematically unconstrained. James Webb Space Telescope data shows a surface temperature of 44 K, and abundant frozen carbon dioxide dominates its surface. Varda has one known moon named Ilmarë, with a diameter of approximately 403±40 km. The binary system exhibits a very large mass ratio, comparable to that of Pluto and Charon.
Varda is named after the queen of the Valar in J. R. R. Tolkien's Middle-earth writings. Its moon was named Ilmarë, after a chief of the Maiar and Varda's handmaiden. The names were announced by the Minor Planet Center on 16 January 2014.
Reader's Guide
Varda is notable as a large trans-Neptunian object that straddles the boundary between dwarf planet candidates and smaller Kuiper belt objects. Its size, approximately 740 km in diameter, places it among the top 34 largest known trans-Neptunian objects. The object's status as a possible dwarf planet is disputed: some astronomers consider it a candidate, but it is hypothesized that objects in the 400–1000 km size range have probably never compressed into fully solid bodies or achieved hydrostatic equilibrium. Density calculations for Varda remain highly ambiguous, and it is not clear if its density is high enough to have compressed into a fully solid body. Its low albedo is consistent with a lack of geological activity typical of larger dwarf planets. The Varda–Ilmarë binary system has a very large mass ratio, comparable to Pluto–Charon, and the two bodies are likely mutually tidally locked. The system's total mass is precisely determined at 2.675+0.048−0.049×10^20 kg, with Varda contributing 86 to 90% of it.
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