C / 2004 Q2 (Machholz)

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C / 2004 Q2 (Machholz) [i]
C / 2004 Q2 in February 2005
C / 2004 Q2 in February 2005
Properties of the orbit ( animation )
Epoch:  March 27, 2005 ( JD 2,453,456.5)
Orbit type long-period
Numerical eccentricity 0.99950
Perihelion 1.205 AU
Aphelion 4805 AE
Major semi-axis 2403 AE
Sidereal period ~ 118,000 a
Inclination of the orbit plane 38.6 °
Perihelion January 24, 2005
Orbital velocity in the perihelion 38.4 km / s
history
Explorer Don Edward Machholz
Date of discovery August 27, 2004
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 2004 Q2 (Machholz) is a comet that could be observed with the naked eye at the turn of the year 2004/2005 .

Discovery and observation

The American amateur astronomer DE Machholz has been looking for comets regularly since 1975. By 1994 he had already discovered nine new comets. After that, he was unsuccessful until August 27, 2004, when he discovered his tenth comet at dawn in California with his 15 cm telescope . At that time, it had a brightness of about 11 mag and was just 2.5  AU from the sun and 2.2 AU from the earth . The first orbit calculations already indicated that the comet could be freely observed at the turn of the year 2004/2005.

Comet Machholz with Pleiades, January 8, 2005

For observers in the northern hemisphere , the comet was initially very low above the horizon, but it began to move rapidly northwards in late October 2004. At the beginning of November the brightness was still 8 mag, but in mid-November it already reached 6 mag, so that the comet could be seen with the naked eye during the second half of the night. At the end of the year the brightness was 4 mag and the comet could be observed during the whole night, its tail was rather inconspicuous. Around January 7th, the comet passed the star cluster of the Pleiades at a distance of less than 3 ° at its maximum brightness of 3.5–4 mag , at the end of January it passed with a brightness of 4 mag at a distance of about 5 ° the double cluster h and Chi Persei . On March 9, it approached the North Star to about 5 ° , but at that time the comet was barely visible to the naked eye. It could be observed telescopically until mid-August 2006.

Scientific evaluation

The production rate of C 2 and NH 2 could be determined from observations at the Lulin Observatory in Taiwan and at the La Silla Observatory in Chile between December 2004 and January 2005 . Two helical jets of gas were also observed, emitted from two active regions of the rotating comet. A period of rotation of the comet's nucleus could not be derived from the data. This was achieved in January 2005 during a targeted examination with a 1.2 m telescope at the Roque de los Muchachos observatory in the Canary Islands . A rotation period of the core of about 9.1 hours was derived (but double the value could not be excluded).

With the Near InfraRed echelle spectrograph (NIRSPEC) at 10 m telescope II of the Keck observatory on the Mauna Kea could in November 2004 and January 2005 infrared - spectral lines of the substances H 2 O , CH 4 , C 2 H 2 , C 2 H 6 , CO , H 2 CO , CH 3 OH , HCN and NH 3 are found and their mixing ratio evaluated. At the end of January, the same instrument was used to obtain additional spectra of the volatile substances H 2 O, HCN, C 2 H 2 , NH 3 , CH 4 , C 2 H 6 , CH 3 OH and H 2 CO, and their mixing ratio was determined relative to water has been. The results were compared with those of other comets from the Oort cloud . The comet Machholz could therefore have originated in the inner areas of the solar nebula . This was also confirmed by the estimation of the deuterium / hydrogen ratio in methane. The ammonia to water ratio and the production rate of NH 2 were also derived from the measurement results .

At the end of January, spectroscopic measurements in the infrared were also carried out with the 60 cm telescope of the Andruschiwka Astronomical Observatory in Ukraine . The emission lines of C 2 , C 3 , CN, NH 2 , CH, H 2 O + and CH + were found in the spectrum.

With the 10 m submillimeter telescope (SMT) at the Arizona Radio Observatory (ARO), the production rates of several volatile substances (CH 3 OH, HCN, H 13 CN, HNC, H 2 CO, CO and CS) in the cometary coma can be determined. Based on the measured values, it was assumed that the comet had already been near the sun at least once and was heated up in the process.

With the Galaxy Evolution Explorer (GALEX), a picture of the comet in the far ultraviolet (FUV ) was taken at the beginning of March and evaluated with regard to the resistance of atomic carbon to ionization by the solar wind and other causes. With the Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) on board the CHIPSat satellite , spectra of the comet in extreme ultraviolet could be obtained in January 2005 , from which conclusions could be drawn about the occurrence of O , C , N , Ne and Fe .

Orbit

An elliptical orbit could be determined for the comet from 3628 observation data over a period of 2 years , which is inclined by around 39 ° to the ecliptic . The comet's orbit is thus inclined to the orbits of the planets . At the point closest to the Sun ( perihelion ), which the comet passed on January 24, 2005, it was about 180.3 million km away from the Sun and was thus in the area between the orbits of Earth and Mars . It had already approached the earth on January 5th to about 51.9 million km (0.35 AU). There were no noteworthy approaches to the other small planets.

According to the orbital elements, which are afflicted with a certain uncertainty, as they are specified in the JPL Small-Body Database and which also take into account non-gravitational forces on the comet, the comet was still moving on an extremely elongated elliptical orbit long before its passage through the inner solar system with an eccentricity of around 0.99953 and a semi-major axis of around 2560 AU, so that its period of revolution was around 130,000 years. The comet came from the Oort cloud and possibly experienced one of its first passages through the inner solar system as a “dynamic young” comet. Due to the gravitational pull of the planets, especially due to the relatively close passages of Saturn on January 18, 2005 at a distance of just under 8 AU and at Jupiter on June 21, 2006 at a distance of about 2 ¾ AU, its orbital eccentricity became clear to about 0.99777 and its size Semi-axis reduced to about 538 AU, so that its orbital period is shortened to about 12,500 years.

See also

Web links

Commons : C / 2004 Q2 (Machholz)  - Collection of images, videos and audio files

Individual evidence

  1. ↑ D. Machholz: The Discovery of C / 2004 Q2 (Machholz). In: Astrosite GRONINGEN. RJ Bouma, E. van Dijk, accessed on August 13, 2020 .
  2. ^ Comet Machholz (C / 2004 Q2). In: kometen.info. Retrieved August 13, 2020 .
  3. ^ ZY Lin, M. Weiler, H. Rauer, WH Ip: Photometry and imaging of comet C / 2004 Q2 (Machholz) at Lulin and La Silla. In: Astronomy & Astrophysics. Volume 469, No. 2, 2007, pp. 771-776 doi: 10.1051 / 0004-6361: 20077286 . ( PDF; 836 kB )
  4. ↑ M. Reyniers, P. Degroote, D. Bodewits, J. Cuypers, C. Waelkens: The rotation and coma profiles of comet C / 2004 Q2 (Machholz). In: Astronomy & Astrophysics. Volume 494, No. 1, 2009, pp. 379-389 doi: 10.1051 / 0004-6361: 20079225 . ( PDF; 862 kB )
  5. ↑ BP Bonev, MJ Mumma, EL Gibb, MA DiSanti, GL Villanueva, K. Magee-Sauer, RS Ellis: Comet C / 2004 Q2 (Machholz): Parent Volatiles, a Search for Deuterated Methane, and Constraint on the CH 4 Spin Temperature. In: The Astrophysical Journal. Volume 699, No. 2, 2009, pp. 1-13 doi: 10.1088 / 0004-637X / 699/2/1563 . ( PDF; 1.24 MB )
  6. ^ H. Kobayashi, H. Kawakita: Formation Conditions of Icy Materials in Comet C / 2004 Q2 (Machholz). I. Mixing Ratios of Organic Volatiles. In: The Astrophysical Journal. Volume 703, No. 1, 2009, pp. 121-130 doi: 10.1088 / 0004-637X / 703/1/121 . ( PDF; 460 kB )
  7. ^ H. Kawakita, H. Kobayashi: Formation Conditions of Icy Materials in Comet C / 2004 Q2 (Machholz). II. Diagnostics Using Nuclear Spin Temperatures and Deuterium-to-Hydrogen Ratios in Cometary Molecules. In: The Astrophysical Journal. Volume 693, No. 1, 2009, pp. 388-396 doi: 10.1088 / 0004-637X / 693/1/388 . ( PDF; 497 kB )
  8. ↑ H. Kawakita, MJ Mumma: Fluorescence Excitation Models of Ammonia and Amidogen Radical (NH 2 ) in Comets: Application to Comet C / 2004 Q2 (Machholz). In: The Astrophysical Journal. Volume 727, No. 2, 2011, pp. 121-130 doi: 10.1088 / 0004-637X / 727/2/91 . ( PDF; 551 kB )
  9. ↑ O. Shubina, P. Korsun, Yu. Ivashchenko: Low-resolution spectrum of comet C / 2004 Q2 (Machholz). In: Advances in Astronomy and Space Physics. Volume 2, No. 2, 2012, pp. 173-176. ( PDF; 302 kB )
  10. ↑ M. de Val-Borro, P. Hartogh, C. Jarchow, M. Rengel, GL Villanueva, M. Küppers, N. Biver, D. Bockelée-Morvan, J. Crovisier: Submillimetric spectroscopic observations of volatiles in comet C / 2004 Q2 (Machholz). In: Astronomy & Astrophysics. Volume 545, A2, 2012, pp. 1–13 doi: 10.1051 / 0004-6361 / 201219172 . ( PDF; 468 kB )
  11. ↑ JP Morgenthaler, WM Harris, MR Combi, PD Feldman, HA Weaver: GALEX FUV observations of comet C / 2004 Q2 (Machholz): The ionization lifetime of carbon. In: The Astrophysical Journal. Volume 726, No. 1, 2010, pp. 1-10 doi: 10.1088 / 0004-637X / 726/1/8 . ( PDF; 1.58 MB )
  12. ↑ TP Sasseen, M. Hurwitz, CM Lisse, V. Kharchenko, D. Christian, SJ Wolk, MM Sirk, A. Dalgarno: A Search for Extreme-Ultraviolet Emission from Comets with the Cosmic Hot Interstellar Plasma Spectrometer (CHIPS). In: The Astrophysical Journal. Volume 650, No. 1, 2006, pp. 461-469 doi: 10.1088 / 0004-637X / 699/2/1563 . ( PDF; 298 kB )
  13. ↑ C / 2004 Q2 (Machholz) in the Small-Body Database of the Jet Propulsion Laboratory (English).Template: JPL Small-Body Database Browser / Maintenance / Alt
  14. ↑ A. Vitagliano: SOLEX 12.1. Retrieved July 9, 2020 .