39P/Oterma
Discovery | |
---|---|
Discovered by | Liisi Oterma |
Discovery date | 8 April 1943 |
Designations | |
1942 VII; 1950 III; 1958 IV; 39P/2001 P3 | |
Orbital characteristics | |
Epoch | 2023-06-25 |
Aphelion | 8.75 |
Perihelion | 5.707 |
Semi-major axis | 7.228 |
Eccentricity | 0.2105 |
Orbital period | 19.43 yr |
Max. orbital speed | 13.2 km/s[1] |
Min. orbital speed | 8.6 km/s (2013-Feb-15) |
Inclination | 1.5470° |
Last perihelion | 2023-Jul-13 (JPL)[2] 11 July 2023[3][4][5] 22 December 2002[4][5] |
Next perihelion | 2042-Jul-12[1] |
Physical characteristics | |
Dimensions | 4–5 km[6] |
39P/Oterma is a currently inactive periodic comet with an orbital period of nearly 20 years that stays outside the orbit of Jupiter. The nucleus has a diameter around 4–5 km.[6] It was last observed in August 2021 and came to perihelion in July 2023 while 1.2
Discovery
[edit]The comet was discovered by Liisi Oterma at Turku University Observatory, Finland on a photo plate on 8 April 1943 as a faint object of 15th magnitude in the constellation of Virgo. Its orbit was calculated by L. E. Cunningham and R. N. Thomas who derived an orbit with a small eccentricity, a perihelion distance of 3.4
The comet was continuously observed till after its next perihelia of 1950 and 1958, however a close approach (0.095
Orbit
[edit]Comet 39P/Oterma currently has a centaur-like orbit contained between Jupiter and Saturn. Since the orbit is outside the frost line which is located around 3
Orbital development
[edit]Perihelion distance at different epochs[3] | |||||||
Epoch | Perihelion ( | ||||||
---|---|---|---|---|---|---|---|
1958 | 3.39 | ||||||
1983 | 5.47 | ||||||
2023 | 5.71 | ||||||
2042 | 5.91[1] | ||||||
2246 | 6.15[11] |
Comet 39P/Oterma is an object with a rather unstable orbit in the long run because at irregular time intervals it undergoes very close approaches to the giant planets Jupiter and Saturn that severely influence and alter its orbit. This is also the reason why no definite statements can be made concerning the long-time development of its orbital characteristics for a period of more than a couple of hundred years in the past or in the future.
Apart from relatively precise statements for a few hundred years around our epoch, further conclusions can only be drawn by the use of statistical methods. By means of the software SOLEX 11.0[12] by A. Vitagliano and based on the values of the currently best known orbital elements of 39P/Oterma and their uncertainties from the JPL Small Body Database,[7] a set of 400 clones of the “mean” comet with randomly Gaussian distributed orbital elements (using their mean values and their sigma-values) was created and the orbital development of this bundle of objects with nearly identical orbits at the start epoch was calculated back in the past and forth in the future (neglecting non-gravitational effects). The result of these statistical calculations is presented in the following paragraphs.
Not much can be said about the orbit of 39P/Oterma before the 19th century. It could have been anywhere either inside the orbit of Jupiter (least probable), between the orbits of Jupiter and Saturn (most probable), or even a Saturn-crossing one. Anyhow, even if it had not been there before, with a probability of 20% a close encounter (< 2
Following a closer approach to Jupiter (1.44
-
Before 1930, the orbit of 39P/Oterma was situated between the orbits of Jupiter and Saturn
-
The orbit of 39P/Oterma between 1920 and 1950 shows the transition from a centaur-like orbit into a quasi-Hilda orbit
Already since the beginning of 1935, the comet was moving in an orbit nearly identical to Jupiter's with nearly the same angular velocity as the giant planet, i.e. 39P/Oterma underwent a temporary satellite capture (TSC) by Jupiter. However, this comet flew through the region near Jupiter over a rather short time, during which the comet did not complete a full revolution orbiting about the planet, instead already in the beginning of 1939 the comet could escape the planet's attraction.
However, the close encounter with Jupiter had altered the comet's orbital parameters severely. The semi-major axis was reduced from 6.9 to 4.0
-
The orbit of 39P/ between 1945 and 1983 shows the transition from a quasi-Hilda orbit back to a centaur-like orbit
-
After 1980, the orbit of 39P/Oterma is situated again between the orbits of Jupiter and Saturn
As the revolution period was reduced from a little more than 18 years to 7.9 years, it was now in an exact 3:2 mean motion resonance with Jupiter.[13] Such a Jupiter-family comet is called a “quasi-Hilda comet” (QHC)[14] and consequently after three revolutions the comet met again with the planet. From mid-1961 till the end of 1965 the comet again went through a temporary satellite capture (TSC) by Jupiter, while on 12 April 1963 an even closer approach to the planet at a distance of only 0.095
This led again to a transformation of the comet's orbit to an inactive centaur orbit with semi-major axis 7.2
Date & time of closest approach |
Jupiter distance ( |
Sun distance ( |
Velocity wrt Jupiter (km/s) |
Velocity wrt Sun (km/s) |
Uncertainty region (3-sigma) |
Reference |
---|---|---|---|---|---|---|
2025-Jan-15 12:56 ± 30 minutes | 0.8887 |
5.937 |
0.67 | 13.11 | ± 1500 km | Horizons |
And this will remain alike for quite a while. Although a couple of closer approaches to Saturn (1.015
However, this situation is going to change subsequently to a close encounter with Saturn during the second half of the year 2312 (0.8 ± 0.1
The currently known data about the comet 39P/Oterma do not permit to extrapolate its fate with sufficient certainty beyond this Jupiter rendezvous because shortly after, the comet's orbital parameters will be severely altered in a wide possible range. Only probabilities can be given.
Only 10 years after the encounter with Jupiter, the comet can be found with a probability of 11.5% inside the orbit of Jupiter as a “quasi-Hilda comet“ (which would reactivate it to become more easily observed again from Earth). There is even a (very small) probability that the comet gets caught by Jupiter in a satellite capture, but more likely the comet will remain an inactive centaur-like object. A larger probability of 63% sees it continuing in an orbit between Jupiter and Saturn, but there is also a probability of 25% that the comet will become a Saturn-crosser. The orbital eccentricity may be distributed in a wide range from 0.03 to 0.44, while the inclination may be anywhere between 1.6° and 8.5°.
References
[edit]- ^ a b c d "Horizons Batch for 39P/Oterma (90000469) on 2042-Jul-12" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Retrieved 2023-07-14. (JPL#19/Soln.date: 2022-May-09)
- ^ a b "Horizons Batch for 39P/Oterma (90000469) on 2023-Jul-13" (Perihelion occurs when rdot flips from negative to positive. Delta is set for distance from (599) Jupiter). JPL Horizons. Archived from the original on 2023-02-16. Retrieved 2023-07-06. (JPL#19/Soln.date: 2022-May-09)
- ^ a b "39P/Oterma Orbit". Minor Planet Center. Retrieved 2023-07-14.
- ^ a b Seiichi Yoshida (2004-02-21). "39P/Oterma". Seiichi Yoshida's Comet Catalog. Retrieved 2010-02-24.
- ^ a b Syuichi Nakano (2001-08-24). "39P/Oterma (NK 810)". OAA Computing and Minor Planet Sections. Retrieved 2010-02-24.
- ^ a b Schambeau, Charles; Fernandez, Yanga; De Pra, Mario (2019). "Cbet 4652: 20190717: Comet 39P/OTERMA". CBET. 4652: 1. Bibcode:2019CBET.4652....1S.
- ^ a b c d e f g h "JPL Small-Body Database Browser: 39P/Oterma" (2021-08-02 last obs. used). Archived from the original on 2012-12-13. Retrieved 2023-07-15.
- ^ "Horizons Batch for 39P/Oterma (90000469) on 2023-Nov-11". JPL Horizons. Retrieved 2023-08-16.
- ^ Kronk, Gary W. (2001–2005). "39P/Oterma". Retrieved 2014-04-28. (Cometography Home Page)
- ^ "Minor Planet Center MPEC 2001-Q35 : COMET 39P/2001 P3 (OTERMA)". Retrieved 2014-04-28.
- ^ a b "39P @ epoch 2246-Jan-01". JPL Horizons. Retrieved 2023-07-15.
- ^ Vitagliano, Aldo. "SOLEX & EXORB Orbits handling & determination software". Retrieved 2016-09-30.
- ^ Koon, W. S.; M. W. Lo; J. E. Marsden & S. D. Ross (2001). "Resonance and Capture of Jupiter Comets". Celestial Mechanics and Dynamical Astronomy. 81: 27–38. Bibcode:2001CeMDA..81...27K. doi:10.1023/A:1013398801813. S2CID 123044750.
- ^ Ohtsuka, Katsuhito; M. Yoshikawa; D. J. Asher & H. Arakida (2008). "Quasi-Hilda Comet 147P/Kushida-Muramatsu". Astronomy & Astrophysics. 489 (3): 1355. arXiv:0808.2277. Bibcode:2008A&A...489.1355O. doi:10.1051/0004-6361:200810321. S2CID 14201751.
External links
[edit]- 39P at Kronk's Cometography
- Orbital simulation from JPL (Java) / Ephemeris
- Centaurs with cometary designation
- SOLEX & EXORB Orbits handling & determination software by A. Vitagliano