C/2015 ER61 (PanSTARRS)

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2015 ER61 (PANSTARRS)
Discovery
Discovered byPan-STARRS 1 (F51)
Discovery date15 March 2015
Designations
Comet, Amor,[1] NEO, damocloid, scattered disc object, centaur
Orbital characteristics[2]
Epoch 2017-May-07 (JD 2457880.5)
Observation arc1.96 yr
Aphelion2456 ± 62 AU
1425/854 AU[1]
Perihelion1.0421 AU
1229 ± 31 AU
715/428 AU[2]
Eccentricity0.99730
7591 years[2]
9000 years (epoch 2050)
359.99°
Inclination6.3490°
235.21°
68.197°
Earth MOID0.10 AU[3]
Mars MOIDless than 0.01 AU[citation needed]
Jupiter MOID0.06 AU[3]
Physical characteristics
Dimensions8–20 km[4]
20 km[3]
Albedo~0.05 (assumed)
20.5 (Jan 2016)
14.74 (peak 1 May 2017)
12.3[1]

C/2015 ER61 (PANSTARRS) is a comet, inner Oort cloud object, Amor near-Earth asteroid, and possibly a damocloid. When classified as a minor planet, it had the fourth-largest aphelion of any known minor planet in the Solar System, after 2005 VX3, 2012 DR30, and 2013 BL76. It additionally had 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.[5] It comes close to Jupiter, and a close approach in the past threw it on the distant orbit it is on now.

Though the comet nucleus was probably mildly active, early asteroidal estimates gave an absolute magnitude (H) of 12.3,[1] which would suggest a nucleus as large as 8–20 km in diameter. But it could easily be half that size due to activity brightening the nucleus.

2017 perihelion

2015 ER61 was discovered on March 15, 2015 when it was 8.44 AU from the Sun,[6] and magnitude 21.5.[5] By early February 2016, the object reached magnitude 20, and made a close approach to Jupiter on March 28, 2016 of 0.9245 AU.[3] This changed 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 770 AU, and by 2020 will have an aphelion of 854 AU.

The barycentric orbital period will decrease from 19000 years (epoch 1950) to 9000 years (epoch 2050).

As of January 2017, it was magnitude 13, and increasing in brightness. On April 4, 2017, it was detected outbursting to magnitude 6.5. On April 19, 2017, it will reach its closest point to Earth of ~1.2 AU. At this point, it will be about apparent magnitude 8,[7] and, assuming a size of 20 km, have an apparent size of 19 mas. It will come to perihelion (closest approach to the Sun) on May 10, 2017.[2] 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

Sedna compared to some other very distant orbiting bodies including 2015 DB216 (orbit wrong), 2000 OO67, 2004 VN112, 2005 VX3, 2006 SQ372, 2007 TG422, 2007 DA61, 2009 MS9, 2010 GB174, 2010 NV1, 2010 BK118, 2012 DR30, 2012 VP113, 2013 BL76, 2013 AZ60, 2013 RF98, 2015 ER61

See also

Notes

^ assuming an inactive nucleus and 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

  1. ^ a b c Archive of JPL 13 (2015-Jun-04) as Amor near-Earth object
  2. ^ a b c "C/2015 ER61 (PANSTARRS) Orbit". Minor Planet Center. Archived from the original on 2017-03-02. Retrieved 2017-03-02. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  3. ^ a b c "JPL Small-Body Database Browser: (2015 ER61)" (last observation: 2016-01-23; arc: 1 yr). Jet Propulsion Laboratory. Archived from the original on 2015-06-24. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  4. ^ "Glossary: Absolute Magnitude (H)". JPL. NASA. Retrieved 14 September 2015.
  5. ^ a b "MPEC 2016-C01 : COMET C/2015 ER61 (PANSTARRS)". IAU Minor Planet Center. 2016-02-01. Retrieved 2016-02-01. (CK15E61R)
  6. ^ "Watching a Long Period Comet Turn On - C/2015 ER61 (PANSTARRS)". Bibcode:2016DPS....4830806M. {{cite journal}}: Cite journal requires |journal= (help)
  7. ^ Seiichi Yoshida (2007-02-27). "C/2015 ER61 ( PanSTARRS )". Seiichi Yoshida's Comet Catalog. Retrieved 2017-03-02.

External links

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