Railway resonance
In celestial mechanics , orbit resonance (or resonance for short ) occurs when two or more celestial bodies are subject to periodically recurring gravitational influences . Causes of web resonances are the orbital periods of the heavenly bodies involved, their relationship to each other by low natural numbers can be described, for example, 2: 1 or 3: 2nd
There are harmonic relationships between the orbital times of some of our planets, described by Johannes Kepler in his “Harmonice mundi” .
Effects
Resonances can have both a disruptive and a stabilizing effect on the orbits of the heavenly bodies. This depends on the geometric constellation of the heavenly bodies involved. Path changes due to periodic disturbances (see resonance ) , which are always exerted at the same path position, add up in the case of an unstable, disruptive resonance or compensate each other in the case of a stable resonance.
Disruptive resonances
In the case of disruptive resonances, the periodically recurring disruptions lead to dramatic changes in the shape of the track over longer periods of time. The most common result is the increase in eccentricity until the celestial body is on a collision course with another object or is thrown out of the system in a nearby passage.
Examples of disruptive resonances are the divisions of Saturn's rings caused by Saturn's moons and the Kirkwood gaps in the asteroid belt . The latter is considered the most likely place of origin of the near-Earth asteroids .
Stabilizing resonances
With stabilizing resonances, the locations of the path disturbances are regularly distributed on the path of the disturbed object, so that their effects cancel each other out.
Examples
- The dwarf planet Pluto and numerous smaller objects in the Kuiper Belt known as Plutinos are in 3: 2 resonance with Neptune , i.e. H. during three orbits of Neptune they orbit the sun twice. Further outside there are other resonant Kuiper belt objects that are in 2: 1 resonance with the orbit of Neptune. There are also objects with other resonances, such as 5: 2, 3: 1 and 4: 1 (see below).
- The co-ordinate objects form a special form of orbit resonance with a ratio of 1: 1 . The best-known example of this are the so-called Trojans . You are at one of the L4 or L5 Lagrange points with respect to the sun and a planet (mostly Jupiter ).
- A large number of smaller asteroid groups outside the main belt between Mars and Jupiter are stabilized by resonances with Jupiter's orbit. Including the Hilda group at 3: 2 and the Cybele group at 7: 4.
- In the extrasolar planetary system around the star Ypsilon Andromedae A , the second innermost planet Ypsilon Andromedae d is in a 3: 1 resonance with the outermost planet Ypsilon Andromedae e .
Kuiper belt: orbit resonances to the outermost gas planet Neptune
A particularly stable orbit is when the minor planets of the Kuiper Belt are in a 3: 2 orbit resonance with Neptune, which means that they orbit the sun twice while Neptune makes 3 orbits. Since Pluto also has such an orbit, such Kuiper belt objects are called " Plutinos ", which with Orcus contain a second alleged dwarf planet and several dwarf planet candidates.
There are other orbital resonances that also provide stable orbits, such as 5: 2 orbital resonance, 3: 1 orbital resonance, and 4: 1 orbital resonance.
With the exception of the Kuiper belt objects 2004 XR 190 "Buffy" and (523635) 2010 DN 93 , all Kuiper belt objects with more than one and a half times the Neptune distance and moderately elliptical orbits have a stable 5: 2, 3: 1 or 4: 1 orbital resonance Neptune. - According to Kepler's 3rd law, these orbital resonances can be found out very easily, because they only depend on the semi-major axis of the orbits, especially not on their perihelion. Thus, a planetoid can get into such a stable orbit by making its orbit a little more or a little less elliptical.
Examples for 5: 2-resonant objects with high perihelion: 2015 KQ 174
Examples for 3: 1-resonant objects with high perihelion: 2015 FJ 345 , 2014 JM 80 , 2013 FQ 28 , 2013 SK 100
Examples for 4: 1-resonant objects with high perihelion: 2014 FZ 71 , 2014 FC 72 , (145480) 2005 TB 190
One can show, that if such asteroids have a medium-high orbit inclination from about 40 degrees orbit angle, their orbits are stable even with not so nice orbital resonances. Both "Buffy" and the dwarf planet candidate 2010 DN 93 have approximately an 8: 3 orbit resonance to Neptune and a sufficiently high orbital inclination that their orbits are also stable.
The orbits of these Kuiper belt objects, which have high perihelions up to over 55 AU, are thus very well understood and stable.
More types
Secular response
A secular resonance occurs when the movement of the perihelion or that of the knot of two or more heavenly bodies is synchronized with one another. In this case, the precession frequency of smaller bodies adapts to that of the disruptive, massive body.
Kozai mechanism
The Kozai mechanism is a periodic and synchronous change in the eccentricity and orbital inclination of a celestial body as a result of resonance effects.
Laplace resonance
In a Laplace resonance, the orbital times of three or more celestial bodies are in a low integer ratio to one another. The only two known examples are the three inner Galilean moons of Jupiter ( Io , Europa , Ganymede ) and the three outer planets of Gliese 876 ( Gliese 876 c , Gliese 876 b , Gliese 876 e ). The orbital frequencies of the three Jupiter moons are in a resonance of 4: 2: 1 - four Io orbits on two Europe orbits and one Ganymede orbit. In a comparable way, there are four circulations of Gliese 876 c, two of Gliese 876 b and one of Gliese 876 e.
See also
literature
- Joachim Krautter et al .: Meyers Handbuch Weltall . 7th edition. Meyers Lexikonverlag, 1994, ISBN 3-411-07757-3 , p. 144
Individual evidence
- ↑ Curiel et al. A fourth planet orbiting υ Andromedae . In: Astronomy & Astrophysics , Issue 525, 2011
- ^ Scott S. Sheppard, Chadwick Trujillo, David J. Tholen: Beyond the Kuiper Belt Edge: New High Perihelion Trans-Neptunian Objects With Moderate Semi-major Axes and Eccentricities . In: The Astrophysical Journal Letters . No. 825 (1) , 2015, arxiv : 1606.02294 .