C / 2002 O4 (Hoenig)

from Wikipedia, the free encyclopedia
C / 2002 O4 (Hoenig) [i]
Properties of the orbit ( animation )
Epoch:  August 12, 2002 ( JD 2,452,498.5)
Orbit type hyperbolic
s. Cape. Orbit
Numerical eccentricity 1,00083
Perihelion 0.776 AU
Inclination of the orbit plane 73.1 °
Perihelion October 1, 2002
Orbital velocity in the perihelion 47.8 km / s
history
Explorer Sebastian Hönig
Date of discovery July 22, 2002
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 2002 O4 (Hoenig) was a comet that in 2002 could only be observed with optical aids. As he approached the sun , it began to dissolve.

Discovery and observation

The German amateur astronomer S. Hönig from Dossenheim had been looking for comets for almost 5 years. In the early morning of July 22, 2002, he was just about to observe the sky a little with his 25 cm telescope when he discovered a faint and diffuse object. He had no star maps with him and his telescope was not precisely aligned so he could only note an approximate position, but the object definitely seemed to be moving. He reported his discovery to the Central Bureau for Astronomical Telegrams and asked other comet hunters to review his observation. It was not until five days later that the comet was found again by a Japanese amateur astronomer and the discovery was officially confirmed. It was the first visual comet discovery in Germany since 1946 (Comet C / 1946 K1 (Pajdusakova-Rotbart-Weber) ).

At the time of its discovery, the comet had a brightness of about 12 mag and was still about 1.5  AU from the Sun and 0.8 AU from Earth . It was visible to observers in the northern hemisphere during the whole night. The brightness of the comet initially increased rapidly to about 8 mag, but from mid-August, when the comet passed the North Star at a small distance of about 10 °, it stopped increasing. Towards the end of September there were first reports that the comet appeared very diffuse and showed signs of dissolution. On October 10th only a faint remnant of the tail could be found, there were no more signs of the core . The same situation was shown by other recordings up to the beginning of November.

Scientific evaluation

With the 3 m telescope of the Infrared Telescope Facility (IRTF) on Mauna Kea , a spectrogram of the comet was recorded at the beginning of August and the emission lines of silicates were found.

After the observed disappearance of the comet, its fate was examined very intensively by Zdenek Sekanina . He came to the following interpretation of the observation results:

  • The comet had a nucleus less than 1 km in size.
  • The comet suffered a burst of brightness, likely covering the entire nucleus, beginning 2-3 days before its discovery and lasting at least 10 days, perhaps 3-4 weeks. At the peak, around 10 t of dust were emitted per second  . This could have been caused by an explosion of highly volatile substances, such as carbon monoxide , from a larger reservoir in the core. In total, the comet lost around 10–20 million t of dust in this phase, a significant part (up to 30%) of its total mass.
  • From the shape of its tail it can be deduced that active dust production was between the beginning of July and mid-August, i.e. it began before it was discovered.
  • The remaining mass of the core was so shaken by the previous explosion that it could not survive. It was subject to continued erosion , causing the comet to crumble into dust and smaller fragments near its perihelion. From the comet's light curve it can be deduced that the erosion of the comet's nucleus was not caused by the slow sublimation of water ice , but that its decay took place almost spontaneously.
  • This assumption is supported by the observed rapid decrease in brightness, the loss of condensation of the nucleus and the distinct non-gravitational perturbations on the motion of the comet (if the comet had remained intact and in a state of rest, its motion would have a much clearer correspondence with a pure obsessed with gravitational motion).

According to Sekanina, all the signs therefore indicate that the comet has completely dissolved.

Orbit

For the comet, a (temporary?) Hyperbolic orbit could be determined from 1205 observation data over a period of 58 days , which is inclined by around 73 ° to the ecliptic . The comet's orbit is steeply inclined to the orbits of the planets . At the point closest to the Sun (perihelion), which the comet passed on October 1, 2002, it was still about 116.1 million km from the Sun and was thus in the area between the orbits of Venus and Earth . The latter had already approached to about 97.2 million km (0.78 AU) on August 10 and it had come close to Venus to about 134.7 million km on September 2.

The orbital elements given in the JPL Small-Body Database, which do not take into account non-gravitational forces on the comet, are not suitable for deriving the comet's original orbit. Even before its discovery, the comet had already started to emit massive amounts of dust, so that the orbit observed was strongly influenced by non-gravitational effects until it finally dissolved. Hence, its orbit can not be determined with certainty before it approaches the inner solar system . It is almost as likely that it came out of interstellar space on a hyperbolic orbit as that it came out of the Oort cloud on a very elongated elliptical orbit .

See also

Web links

Individual evidence

  1. ↑ S. Hönig: Sebastian Hönig - C / 2002 O4. In: Comet discoverers & Comet discoveries by amateurs 2000 - 2009. S. Beck, March 18, 2017, accessed on August 14, 2020 (English).
  2. ↑ CW Hergenroth: IAUC 7939: 2002 O4. In: Central Bureau for Astronomical Telegrams. IAU, July 27, 2002, accessed August 14, 2020 .
  3. ↑ a b c Z. Sekanina: What Happened to Comet C / 2002 O4 (Hönig)? In: International Comet Quarterly. Vol. 24, 2002, pp. 223-236. ( PDF; 64.1 MB )
  4. ↑ ML Sitko, DK Lynch, RW Russell, MS Hanner: 3-14 Micron Spectroscopy of Comet C / 2002 O4 (honey), C / 2002 V1 (NEAT), C / 2002 X5 (Kudo-Fujikawa), C / 2002 Y1 (Juels-Holvorcem), and 69P / Taylor and the Relationships among Grain Temperature, Silicate Band Strength, and Structure among Comet Families. In: The Astrophysical Journal. Volume 612, No. 1, 2004, pp. 576-587 doi: 10.1086 / 421991 . ( PDF; 361 kB )
  5. ↑ C / 2002 O4 (Hoenig) in the Small-Body Database of the Jet Propulsion Laboratory (English).Template: JPL Small-Body Database Browser / Maintenance / Alt
  6. ↑ A. Vitagliano: SOLEX 12.1. Retrieved July 9, 2020 .