(42355) Typhon

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Asteroid
(42355) Typhon
Properties of the orbit ( animation )
Epoch:  April 27, 2019 ( JD 2,458,600.5)
Orbit type centaur
Major semi-axis 38,055  AU
eccentricity 0.538
Perihelion - aphelion 17.58 AU - 58.529 AU
Inclination of the orbit plane 2.4 °
Length of the ascending node 352 °
Argument of the periapsis 159.4 °
Time of passage of the perihelion June 4, 2006
Sidereal period 234 a 9 M
Physical Properties
Medium diameter
Albedo 0.10 ± 0.02
Rotation period 3.66 h or 4.35 h
Absolute brightness 7.6 likes
history
Explorer NEAT
Date of discovery February 5, 2002
Another name 2002 CR 46
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . The affiliation to an asteroid family is automatically determined from the AstDyS-2 database . Please also note the note on asteroid items.

(42355) Typhon is an asteroid that belongs to the group of centaurs . On February 15, 2006, the discovery of a moon was announced - it is the first discovery of a binary system in the class of centaurs. Since Echidna is about half the diameter of Typhon, this system can also be understood as a double asteroid system.

Discovery and naming

Typhon was discovered on February 5, 2002 as part of the NEAT program at the Palomar Observatory . The asteroid was given the provisional designation 2002 CR 46 and the minor planet number 42355 on May 26, 2002 .

The asteroid was named after the giant Typhon from Greek mythology .

After its discovery, Typhon could be identified on photos from December 28, 1989, and thus its orbit calculated more precisely. Since then, the planetoid has been observed through the Herschel Space Telescope as well as Earth-based telescopes. In April 2017, a total of 295 observations were available over a period of 27 years.

Like all other Trans-Neptunian objects except Pluto , Typhon has no official or commonly used astronomical symbol . Typhon symbols circulating on the Internet such as B. Typhon symbol proposal.svgare designs from private individuals. An official symbol assignment is not to be expected, since astronomical symbols only play a subordinate role in modern astronomy.

properties

Typhon orbits the sun in a slightly elliptical orbit between 17.58  AU and 58.53 AU from its center. The perihelion of the minor planet is thus within the orbit of Uranus , while the aphelion is far outside of the orbit of Pluto - Typhon therefore crosses the orbits of two planets during its 234.76-year orbit. The orbit eccentricity is 0.538, the orbit is 2.43 ° inclined to the ecliptic .

There is still some uncertainty about the rotational behavior of Typhon. Different observations gave very different values ​​ranging from 3.66, 4.35, 5.00 to 9.67 hours.

Typhon has a diameter of about 162 km, an absolute brightness of 7.6 m and a geometric albedo of 0.1. Nothing is known about the mass at the moment.

Provisions of the diameter for Typhon
year Dimensions km source
2008 152.0 +28.0−32.0 Grundy et al. a.
2011 112.0 ± 26.0 Grundy et al. a.
2012 162.0 ± 7.0 Santos – Sanz et al. a.
2012 137.0 ± 30.0 Stansberry et al. a.
2014 <76.0 Thirouin et al. a.
2018 193.0 Brown
The most precise determination is marked in bold .

moon

(42355) Typhon I (Echidna) (provisional designation S / 2006 (42355) 1 ) was named after a figure from Greek mythology - Echidna . The moon was discovered as part of a program to determine the abundance of multiple systems in the outer solar system using the Hubble Telescope's HST camera and announced to the public on February 15, 2006. It has a diameter of 89 ± 6 km and a mean distance of about 1300 km. The masses of both bodies could not yet be determined.

The Typhon system at a glance:

Components Physical parameters Path parameters discovery
Surname Throughput
diameter
(km) 		Relative
size
% 		Mass
(kg) 		Major
semi-axis
(km) 		Orbital time
(d) 		eccentricity
 Inclination
to Typhon's
equator 		Date of discovery
Date of publication
(42355) Typhon
 162.0 100.00 ? - - - - February 5, 2002
2002
Echidna
(Typhon I) 		89.0 54.94 ? 1580 18,982 0.507 42.2 ° January 20, 2006
February 15, 2006

Consequences of the discovery of the moon

The centaurs are exposed to frequent close encounters with the large planets, so that until now the survival probability of multiple systems in this asteroid class was considered to be low. However, the moon was found during an investigation of only 8 centaurs - the actual frequency of multiple systems can, however, only be determined through further theoretical analyzes and an enlarged database through the more precise observation of further centaurs.

The common theories of comet formation see the centaurs of the outer planets Uranus and Neptune as the forerunners of the short-period comets. The discovery of a satellite in this asteroid class therefore raises the question of possible satellites of comets - however, no “cometary moon” has yet been discovered. If the frequency of multiple systems among the centaurs should actually be greater than previously assumed, a significant proportion of multiple systems can also be expected among the (short-period) comets.

See also

Web links

Individual evidence

  1. ↑ W. Grundy et al .: (42355) Typhon-Echidna: Scheduling observations for binary orbit determination (April 2008)
  2. ^ W. Grundy et al .: Five New and Three Improved Mutual Orbits of Transneptunian Binaries (March 2011)
  3. ↑ P. Santos – Sanz et al .: "TNOs are Cool": A Survey of the Transneptunian Region IV. Size / albedo characterization of 15 scattered disk and detached objects observed with Herschel Space Observatory-PACS (February 2012)
  4. ↑ J. Stansberry et al .: Physical properties of trans-neptunian binaries (120347) Salacia-Actaea and (42355) Typhon-Echidna (June 2012)
  5. ↑ A. Thirouin include: Rotational properties of the binary and non-binary populations in the Trans-Neptunian belt (July 2014)
  6. ↑ M. Brown : How many dwarf planets are there in the outer solar system? (November 2018)