2015 ER61
| Discovery | |
|---|---|
| Discovered by | Pan-STARRS 1 (F51) |
| Discovery date | 15 March 2015 |
| Designations | |
| Amor, NEO, damocloid, scattered disc object, centaur | |
| Orbital characteristics | |
| Epoch 2015-Jun-27 (JD 2457200.5) | |
| Observation arc | 1 yr |
| Aphelion |
2456 ± 62 AU 1425/854 AU |
| Perihelion | 1.059306 ± 0.000046 AU |
|
1229 ± 31 AU 715/428 AU | |
| Eccentricity | 0.999138 ± 0.000022 |
| 43060 ± 1620 years (1.6x10^7 ± 5.9x10^5 days | |
| 359.98435 ± 0.00059° | |
| Inclination | 6.129721 ± 0.000071° |
| 238.8124 ± 0.0022° | |
| 64.0806 ± 0.0020° | |
| Earth MOID | 0.1035 AU |
| Mars MOID | less than 0.01 AU |
| Jupiter MOID | 0.0287 AU |
| Physical characteristics | |
| Dimensions |
9–22 km[1] 20 km |
| Albedo | ~0.05 (assumed) |
|
20.5 (Jan 2016) 14.74 (peak 1 May 2017) | |
| 12.2 | |
|
| |
2015 ER61 is a comet, centaur, inner Oort cloud object, Amor near-Earth asteroid, and possibly a damocloid. It has the fourth-largest aphelion of any known minor planet in the Solar System, after 2005 VX3, 2012 DR30, and 2013 BL76. It additionally has the most eccentric orbit of any known minor planet, with its distance from the Sun varying by about 99.9% during the course of its orbit, followed by 2005 VX3 with an eccentricity of 0.9973. On January 30, 2016, it was classified as a comet when it was 5.7 AU from the Sun.[2]
It comes close to Jupiter, and a close approach in the past threw it on the distant orbit it is on now. It also has a small MOID to Mars of less 0.01 AU
2017 Perihelion
2015 ER61 was discovered on March 15, 2015 when it was 8.44 AU from the Sun, and magnitude 21.5. As of September 2015, it is magnitude 21.2, and slowly increasing in brightness. In early February 2016, the object reached magnitude 20, and will make a close approach to Jupiter on March 28, 2016 of 0.9245 AU.[3] This will change its orbit, significantly decreasing its aphelion distance from 1430 AU to ~1200 AU, and as it passes through the inner Solar System its aphelion decreases to 160 AU, and by 2020 will have an aphelion of 854 AU.
On April 4, 2017, 2015 ER61 will reach its closest point to the Earth, at ~1.42 AU. At this point, it will be magnitude 14.8, and, assuming a size of 20 km, have an apparent size of 19 mas. It will not be 50 AU from the Sun until 2045.
Orbital elements table
| Distance from Sun |
Event | Epoch | Aphelion (Q) |
Perihelion (q) |
Semi-major axis (a) |
Eccentricity (e) |
Period (p) |
Inclination (i) |
Longitude ascending node (Ω) |
Mean anomaly (M) |
Argument of perihelion (ω) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| AU | (years) | (°) | |||||||||
| 36.5 AU | 2000/01/01 | 1423.4 | 1.05378 | 712.2 | 0.99852 | 18,990 | 6.12745 | 239.06 | 359.671 | 63.99 | |
| 20.2 AU | 2010/01/01 | 1435.4 | 1.05377 | 718.2 | 0.99853 | 19,240 | 6.12732 | 239.03 | 359.862 | 64.01 | |
| 9.01 AU | 2015/01/01 | 1430.8 | 1.05347 | 715.9 | 0.99853 | 19,140 | 6.12819 | 238.97 | 359.956 | 64.08 | |
| 8.44 AU | discovery | 2015/03/15 | 1436.1 | 1.05313 | 718.6 | 0.99853 | 19,250 | 6.12879 | 238.95 | 359.960 | 64.11 |
| 6.008 AU | 2016/01/01 | 1667.3 | 1.04763 | 834.2 | 0.99874 | 24,080 | 6.15827 | 238.25 | 359.980 | 64.92 | |
| 5.204 AU | Jupiter approach | 2016/03/28 | 1291.9 | 1.04030 | 646.5 | 0.99839 | 16,420 | 6.24250 | 236.73 | 359.976 | 66.64 |
| 2.242 AU | 2017/01/01 | 324.6 | 1.03505 | 162.8 | 0.99364 | 2,080 | 6.34928 | 235.27 | 359.939 | 68.46 | |
| 1.079 AU | Earth approach | 2017/04/04 | 164.3 | 1.03830 | 82.7 | 0.98744 | 750 | 6.34595 | 235.27 | 359.953 | 68.30 |
| 1.0397 AU | Perihelion | 2017/05/10 | 210.0 | 1.03973 | 105.5 | 0.99015 | 1,080 | 6.34423 | 235.25 | 000.0004 | 67.92 |
| 3.437 AU | 2018/01/01 | 1091.1 | 1.04449 | 546.1 | 0.99809 | 12,750 | 6.34438 | 235.23 | 000.018 | 68.27 | |
| 9.78 AU | 2020/01/01 | 857.8 | 1.04583 | 429.4 | 0.99756 | 8,890 | 6.34009 | 235.21 | 000.107 | 68.29 | |
| 56.03 AU | 2050/01/01 | 854.6 | 1.04649 | 427.8 | 0.99755 | 8,840 | 6.33543 | 235.18 | 001.329 | 68.34 | |
Comparison
See also
Notes
^ assuming a comet-like albedo of 0.05
^ ^ Because 2015 ER61's orbit takes it so far from the Sun, a more accurate value for its orbit is a barycentric solution. Additionally, a close approach to Jupiter in 2016, and a travel through the inner solar system in 2017 drastically changes its orbit. Therefore, orbits for 2000-2016 and 2018-2100 are provided, respectively.
References
- ↑ "Glossary: Absolute Magnitude (H)". JPL. NASA. Retrieved 14 September 2015.
- ↑ "MPEC 2016-C01 : COMET C/2015 ER61 (PANSTARRS)". IAU Minor Planet Center. 2016-02-01. Retrieved 2016-02-01. (CK15E61R)
- ↑ "JPL Small-Body Database Browser: (2015 ER61)" (last observation: 2016-01-23; arc: 1 yr). Jet Propulsion Laboratory.
External links
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