 Comet 311P/PanSTARRS imaged by theHubble Space Telescope on 10–23 September 2013 | |
| Discovery[1] | |
|---|---|
| Discovered by | Bryce T. Bolin |
| Discovery site | Haleakala Observatory (Pan-STARRS) |
| Discovery date | 27 August 2013 |
| Designations | |
| P/2013 P5 | |
| Orbital characteristics[2] | |
| Epoch | 29 April 2017 (JD 2457872.5) |
| Observation arc | 20.29 years |
| Earliestprecovery date | 17 January 2005 |
| Number of observations | 272 |
| Aphelion | 2.442 AU |
| Perihelion | 1.936 AU |
| Semi-major axis | 2.189 AU |
| Eccentricity | 0.11567 |
| Orbital period | 3.238 years |
| Avg.orbital speed | 0.304°/d |
| Inclination | 4.966° |
| 279.26° | |
| Argument of periapsis | 143.99° |
| Mean anomaly | 337.88° |
| Last perihelion | 1 January 2024 |
| Next perihelion | 30 March 2027 |
| TJupiter | 3.661 |
| EarthMOID | 0.949 AU |
| JupiterMOID | 2.818 AU |
| Physical characteristics | |
Mean diameter | ~0.48 km (0.30 mi)[3] |
Meandensity | 3.3±0.2 g/cm3[3] |
| ~0.240 m/s[3] | |
| ≥ 5.4 hours[4] | |
| 0.29±0.09[5] | |
| Comet total magnitude (M1) | 18.98±0.10[5] |
311P/PanSTARRS, also known asP/2013 P5 (PanSTARRS), is anactive asteroid andEncke-type comet discovered byBryce T. Bolin using thePan-STARRS telescope on 27 August 2013.[1][6] Observations made by theHubble Space Telescope revealed that it had six comet-like tails.[7] The tails are suspected to be streams of material ejected by the asteroid as a result of arubble pile asteroid spinning fast enough to remove material from it.[3] This is similar to331P/Gibbs, which was found to be a quickly-spinning rubble pile as well.
Three-dimensional models constructed by Jessica Agarwal of theMax Planck Institute for Solar System Research in Lindau, Germany, showed that the tails could have formed by a series of periodic impulsive dust-ejection events,[a] radiation pressure from the Sun then stretched the dust into streams.[7]
Precovery images from theSloan Digital Sky Survey from 2005 were found, showing negligible cometary activity in 2005.[citation needed]
The asteroid has a radius of about 240 m (790 ft).[3] The first images taken by Pan-STARRS revealed that the object had an unusual appearance: asteroids generally appear as small points of light, but P/2013 P5 was identified as a fuzzy-looking object by astronomers.[6] The multiple tails were observed by theHubble Space Telescope on 10 September 2013, Hubble later returned to the asteroid on 23 September, its appearance had totally changed. It looked as if the entire structure had swung around.[6] The Hubble Space Telescope continued to track the object through 11 February 2014.[8] The comet-like appearance has resulted in the asteroid being named as a comet. The object has a loworbital inclination and always stays outside the orbit of Mars.[2]
On 19 April 2018, observations based on light curvature suggested a possible satellite around 311P/PANSTARRS approaching 200 meters.[9] If true this would be one of the few minor planets designated as a comet known to harbor a satellite.
TheTianwen-2 spacecraft is planned to get in orbit around 311P/PanSTARRS in the mid-2030s. It was launched on 28 May 2025 and it will first visit and take samples from asteroid469219 Kamoʻoalewa from late 2026 to early 2027.[10] After returning them to Earth, it will use its close encounter with Earth for agravity assist towards 311P/PanSTARRS. When it arrives there, it will get into orbit and conduct a remote sensing study.[11]
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