 Chiminigagua (center) and its moon (bottom left), imaged by theHubble Space Telescope on 15 January 2018 | |
| Discovery[1][2] | |
|---|---|
| Discovered by | |
| Discovery site | Cerro Tololo Obs. (DECam) |
| Discovery date | 17 March 2013 |
| Designations | |
| (532037) Chiminigagua | |
| Pronunciation | /ˌʃɪmɪniˈɡɑːɡwə/ or/ˌtʃɪ-/ (with thePASTA vowel) |
Named after | Chiminigagua |
| 2013 FY27 | |
| Orbital characteristics (barycentric)[5] | |
| Epoch 25 February 2023 (JD 2460000.5) | |
| Uncertainty parameter 3[1] or 4[3] | |
| Observation arc | 13.94yr (5,093 d) |
| Earliestprecovery date | 15 March 2011 |
| Aphelion | 82.000AU |
| Perihelion | 35.572 AU |
| 58.786 AU | |
| Eccentricity | 0.3949 |
| 450.43yr (164,520d) | |
| 216.561° | |
| 0° 0m 7.878s /day | |
| Inclination | 33.121° |
| 187.053° | |
| ≈ 31 October 2202[6] ±10 days[3] | |
| 139.207° | |
| Knownsatellites | 1[4] |
| Physical characteristics[4] | |
| 742+78 −83 km[a] | |
| 0.170+0.045 −0.030[4] | |
| Temperature | 22 K (perihelion) to16 K (aphelion)[4]: 1 |
| |
| 22.5[7] | |
| 3.15±0.03[4] | |
532037 Chiminigagua (provisional designation2013 FY27) is a largetrans-Neptunian object in thescattered disc. It was discovered on 17 March 2013 byScott Sheppard andChad Trujillo atCerro Tololo Observatory inChile. Chiminigagua has a nominal diameter of about 740 km (460 mi), which is large enough that some astronomers consider it apossible dwarf planet. Chiminigagua has amoderately red color, which suggests it has an old, ice-poor surface that has been dulled bycosmic rays andmicrometeoroid bombardment. It has one unnamedmoon about 190 km (120 mi) in diameter, which is believed to have formed from a giantimpact on Chiminigagua.
Chiminigagua was discovered byScott Sheppard andChad Trujillo on 17 March 2013,[1] during a search for distanttrans-Neptunian objects (TNOs).[8][4] Their search was performed using the 4.0-meterVíctor M. Blanco Telescope'sDark Energy Camera (DECam) atCerro Tololo Observatory in Chile,[1] which repeatedly imaged large portions of the sky to reveal TNOs as slow-moving objects.[9]: 3 Sheppard and Trujillo had been searching for TNOs using other telescopes since 2007, but they switched to primarily using DECam when it became operational in 2012.[9]: 3
From May 2013 to March 2014, Sheppard and Trujillo reobserved Chiminigagua using DECam and the 6.5-meterMagellan–Baade Telescope inLas Campanas Observatory, Chile.[2] TheMinor Planet Center announced the discovery of Chiminigagua on 31 March 2014 and gave it theminor planetprovisional designation2013 FY27.[2]
Before Chiminigagua, Sheppard and Trujillo had discovered several large TNOs with DECam—namely, thesednoid2012 VP113 and thescattered disc object2013 FZ27, which were announced along with Chiminigagua within a week of one another in late March to early April 2014.[8][10] When Chiminigagua was discovered, it was nearly at its farthest point from the Sun (aphelion) in its orbit.[8][4] This made Chiminigagua appear dim with anapparent magnitude of 22 from Earth.[8] Because of its faintness, Chiminigagua likely evaded discovery by earlier, less sensitive TNO searches.[8] Chiminigagua has been identified inprecovery observations by thePan-STARRSsurvey from March 2011 to February 2013.[1]
.jpg)
The object is named afterChiminigagua,[b] thecreator god of theMuisca (Chibcha) people that inhabit theAndes mountains in the central part of Colombia.[12]: 11 The naming of this object was announced by theInternational Astronomical Union'sWorking Group for Small Body Nomenclature (WGSBN) on 11 August 2025.[12]: 11 The name follows the WGSBN's recommended naming theme of mythological creation figures for trans-Neptunian objects, which includesscattered disc objects like Chiminigagua.[13]: 8
Before Chiminigagua was officially named, it was known by itsprovisional designation2013 FY27,[1][4] which indicates the year and half-month of the object's discovery date.[14] The Minor Planet Center gave it theminor planet catalog number 532037 on 18 May 2019.[15]
Chiminigagua is atrans-Neptunian object (TNO) orbiting theSun at asemi-major axis or average distance of 58.9astronomical units (AU).[5][c] It follows a highly tilted andelliptical orbit with aneccentricity of 0.39 and inclination of 33.1° with respect to theecliptic.[5][4]: 1 During its 450-yearorbital period, Chiminigagua comes within 35.6 AU from the Sun atperihelion and up to 82.0 AU ataphelion.[5] This large variation in distance from the Sun means Chiminigagua experiences large variations in surface temperature over the course of its orbit: at perihelion Chiminigagua would be 22 K (−251.2 °C; −420.1 °F), whereas at aphelion it would be 16 K (−257.1 °C; −430.9 °F).[4]: 1
Chiminigagua belongs to thescattered disc, which is a population of TNOs that have distant, inclined, and eccentric orbits that come close toNeptune at perihelion.[8] The scattered disc population, which includes thedwarf planetsEris andGonggong, are strongly influenced by Neptune's gravitationalperturbations and consequently experiencegravitational scattering.[17]: 52
Chiminigagua passed aphelion in March–April 1978[18] and is now moving closer to the Sun until it will reach perihelion between October and November 2202.[6][d] Chiminigagua previously passed perihelion in April–May 1752.[19] Chiminigagua was 80.5 AU away from the Sun when it was discovered,[9]: 15 and it has since moved a few AU closer.[20] There are over 20 known TNOs that are located farther away from the Sun than Chiminigagua as of 2025[update].[21]
Chiminigagua has a diameter of about 742 km (461 mi) (full range 660 to 820 km or 410 to 510 mi when includinguncertainties), according toAtacama Large Millimeter Array measurements of itsthermal emission.[4]: 7 Chiminigagua has anabsolute magnitude of 3.15 invisible light,[4]: 4 which makes it the ninth intrinsically brightest TNO known as of 2025[update].[22] Chiminigagua is large and bright enough that someastronomers andplanetary scientists, including Scott Sheppard,Emily Lakdawalla, andMichael E. Brown, have called it alikely dwarf planet.[8][23][24]
Among TNO researchers, Chiminigagua is better known as belonging to the proposed class of "mid-sized" TNOs[25] between 400 and 1,000 km (250 and 620 mi) in diameter, which are believed to represent the transition between small, low-density TNOs and large, high-density dwarf planets.[26][4]: 1 Planetary scientists have hypothesized that mid-sized TNOs should have highlyporous and unheated interiors, because TNOs in this size range (namely55637 Uni and229762 Gǃkúnǁʼhòmdímà) have been found to have low densities around1 g/cm3.[26][25][27] The mass and density of Chiminigagua is unknown, however, because the orbit of its moon has not been determined yet.[25][27]Hubble Space Telescope observations in December 2025 and January 2026 will be able to determine Chiminigagua's mass and density, which will verify the aforementioned hypothesis on the interiors of mid-sized TNOs.[27]
Observations of Chiminigagua in differentlight filters show that it has amoderately red color, which is common among mid-sized TNOs.[4]: 3 The moderately red color of Chiminigagua suggests it has an old, ice-poor surface that has been dulled bycosmic rays andmicrometeoroid bombardment, in contrast to the fresh, icy surfaces of larger dwarf planets likePluto.[4]: 1, 3 Chiminigagua's brightness and diameter indicates it has a moderategeometric albedo of 0.17, which is on the high end for mid-sized TNOs with moderately red colors.[4]: 8, 10
The rotation period of Chiminigagua is unknown.[4] Observations of Chiminigagua's brightness over time in March and May 2016 showed no obvious variability beyond0.06±0.02 magnitudes over hours and days.[4]: 3 The lack of brightness variation suggests that Chiminigagua has either a very long rotation period, an approximately spheroidal shape with no significant albedo variation, or a rotation axis pointing towards Earth.[4]: 3, 11
 Timelapse animation of Chiminigagua's satellite (yellow arrow) orbiting back and forth, as seen by theHubble Space Telescope from January to July 2018 | |
| Discovery[4] | |
|---|---|
| Discovered by | Scott S. Sheppard[28] |
| Discovery site | Hubble Space Telescope |
| Discovery date | 15 January 2018 |
| Orbital characteristics[4] | |
| >9800±40 km | |
| ≈19 d (for assumed density1.6 g/cm3)[29] | |
| Satellite of | 532037 Chiminigagua |
| Physical characteristics | |
| 186+25 −26 km (assuming same albedo)[4] | |
| Albedo | 0.170+0.045 −0.030 (assumed)[4] |
| 25.5[7] | |
| 6.15[e] | |
Chiminigagua is a binary system with one knownnatural satellite, which as of 2025[update] has no officialdesignation or name.[3] The moon was discovered by Scott Sheppard using theHubble Space Telescope'sWide Field Camera 3 on 15 January 2018, whose high-resolution images revealed it as a faint dot next to Chiminigagua.[4]: 9 Sheppard reported the moon to theInternational Astronomical Union,[4]: 9 which announced the discovery on 10 August 2018 via theCentral Bureau for Astronomical Telegrams.[28]
The moon is3.0±0.2magnitudes fainter than Chiminigagua, which suggests it has a diameter between 160 and 210 km (99 and 130 mi) (about 1/4 of Chiminigagua's diameter), if the moon's albedo is the same as Chiminigagua's.[29][4]: 9 Compared to other mid-sized TNOs with moons, the secondary-to-primary diameter ratio of the Chiminigagua system is relatively small.[4]: 10 The relatively small size and orbit of Chiminigagua's moon suggests it likely formed from a giantimpact on Chiminigagua, similar to the small moons of the larger dwarf planets.[4]: 10
Although Chiminigagua's moon has been observed multiple times by the Hubble Space Telescope from January to July 2018, the exact details of its orbit are still unknown.[7][27] These Hubble observations from 2018 showed that the moon orbits relatively close to Chiminigagua, at least 9,800 km (6,100 mi) away (0.17arcseconds inangular separation)[4]: 9 but no farther than 0.25arcseconds.[25] The orbit of Chiminigagua's moon is oriented edge-on from Earth's perspective, which means that the moon can pass in front of or behind Chiminigagua and thus evade detection.[25][27] The Hubble Space Telescope is scheduled to observe Chiminigagua and its moon in December 2025 and January 2026, which should be able to determine the moon's orbit.[27]
Objects with distance from Sun over 79 AU
22 trans-Neptunian objects brighter than H = 3.8
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| Consensus | _(cropped).jpg)  | ||||||||||||
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| Candidate (for TNOs, D+1σ ≥ 700 km or H ≤ 4.0) |
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