C / 2007 N3 (Lulin)

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C / 2007 N3 (Lulin) [i]
C / 2007 N3 on February 5, 2009
C / 2007 N3 on February 5, 2009
Properties of the orbit ( animation )
Epoch:  December 6th, 2008 ( JD 2,454,806.5)
Orbit type long-period
Numerical eccentricity 0.999983
Perihelion 1.21 AU
Aphelion 144,800 AU
Major semi-axis 72,400 AU
Sidereal period 19.5 mill. A
Inclination of the orbit plane 178.4 °
Perihelion January 10, 2009
Orbital velocity in the perihelion 38.3 km / s
history
Explorer Qǐshēng Lín, Quánzhì Yè, Lulin Observatory
Date of discovery July 11, 2007
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 2007 N3 (Lulin) is a comet that could be observed with the naked eye in 2009 .

Discovery and observation

The astronomer Qǐshēng Lín (林啟生) took several pictures on July 11, 2007 with a 41 cm telescope at the Lulin Observatory in Taiwan . Quánzhì Yè (葉 泉 志) at the Sun-Yat-sen University in Guangzhou identified an object with a brightness of about 19 mag on 3 images , which was initially described as an asteroid . Several observations confirmed the discovery, but it was not until July 17 that the object was recognized as a comet by J. Young at the Table Mountain Observatory in California , which is why the comet was not named after its discoverer.

The object was more than 6.4 AU from the Sun at the time of its discovery  , but initial orbital calculations by Brian Marsden indicated that the comet would come relatively close to Earth . One year after its discovery, the brightness had already increased to 10 mag, in October 2008 it could be observed in Australia and Spain at a brightness of about 8 mag at dusk .

After its conjunction with the Sun, the comet was found again in the morning sky in Spain in December. It was first observed with the naked eye in Australia in early February. By the end of February 2009 it had reached its greatest brightness of 4 mag. The comet was rapidly approaching the earth, and by moving in the opposite direction, it was moving very quickly across the sky. It glowed intensely green and, in addition to its main tail, also developed a counter-tail, a phenomenon that can be observed when a comet moves almost in the plane of the earth's orbit. Its brightness had fallen back to about 6 mag at the beginning of March because it was again moving away from the sun and earth, and was still 8 mag at the end of March. The comet could be observed telescopically until the end of 2010.

Scientific evaluation

The physical properties of the cometary dust could be determined by optical observations with the 2.3 m Bok telescope of the Kitt Peak National Observatory and polarimetric measurements at the Mount Lemmon Observatory in February / March 2008, as well as observations in the infrared with the Infrared Spectrograph ( IRS) on the Spitzer Space Telescope in October 2008.

The unusual appearance of the comet gave rise to particularly extensive observations with the 1.1 m telescope at the Lowell Observatory in Arizona from July 2008 to May 2009. The production rates of OH , NH, CN, C 3 , C 2 and H 2 O derived. The images of the comet's comet showed an elongated extension and two corkscrew-shaped rays, caused by two active zones near the comet's pole that emit gas and sometimes dust. From this, the orientation of the axis of rotation and a period of rotation of the comet of around 41.5 hours could be derived. A radius of the comet's nucleus of up to 8 km was derived from the production rate of water . The early discovery date of the comet, the isolated gas sources and the properties of the dust were interpreted more as signs of a "dynamically old" comet.

The chemical composition of the comet was investigated in January / February 2009 with the Near Infra-Red Spectrograph (NIRSPEC) at the Keck Observatory on Mauna Kea . 9 volatile substances (H 2 O, C 2 H 6 , CH 3 OH , H 2 CO , CH 4 , HCN , C 2 H 2 , NH 3 and CO ), as well as OH * and NH 2 were detected. In relation to water, C 2 H 2 and H 2 CO in particular had a below-average occurrence, while CH 3 OH was enriched above average.

From January to March 2009, the comet was observed several times with the Ultraviolet and Optical Telescope (UVOT) on the Swift satellite. With two observations in the ultraviolet at the end of January, the production rates of OH, CS, NH, CN, C 3 , C 2 and dust could be determined. The rate of production of water could also be determined. In three further observations, the comet's morphology was measured simultaneously in the X-ray range and in the ultraviolet and compared with one another.

In February 2009, the comet was observed with the 22 m radio telescope of the Crimean Observatory at a wavelength of 18 cm and the production rate of OH was estimated.

The comet was the end of March 2009, with the infrared - Space Telescope Akari observed. The ratio of CO and CO 2 to water was determined and was relatively low for this comet.

Orbit

For the comet, a long-period elliptical orbit could be determined from 3855 observation data over a period of three and a half years , which is inclined by around 178 ° to the ecliptic . The comet's orbit thus runs almost in the same plane as that of the planets , but its orbit runs in the opposite direction ( retrograde ) to them. At the point closest to the Sun ( perihelion ), which the comet passed on January 10, 2009, it was about 181.4 million km from the Sun and was thus between the orbits of Earth and Mars . As early as November 22, 2008, the comet had come very close to Mars, up to around 14.8 million km. On February 2, 2009, Mercury was approached to about 130.9 million km and on February 24, the closest distance to Earth was reached with about 61.5 million km (0.41 AU). On March 2, there was another passage of Venus at a distance of about 111.0 million km.

The comet moves in an extremely elongated elliptical orbit around the sun. According to the orbital elements, which are afflicted with a certain uncertainty, as they are specified in the JPL Small-Body Database and which do not take into account non-gravitational forces on the comet, its orbit would still have an eccentricity of around 0.99996 long before it passed through the inner solar system and had a semi-major axis of about 34,000 AU, so that its orbital period would have been about 6.3 million years. Due to the gravitational pull of the planets, in particular due to the relatively close passages of Jupiter on June 23, 2008 in about 2 ½ AU distance, on Saturn on March 13, 2009 in about 8 AU distance and again on Jupiter on November 13, 2011 approximately 6 AU distance, its orbital eccentricity would be reduced to about 0.99900 and its semi-major axis to about 1200 AU, so that its orbital period would be shortened to about 42,000 years.

In a study from 2013, Królikowska and Dybczyński were able to show, using a total of 3951 observations of the comet over a period of three and a half years, that the best correspondence with the observed positions of the comet can be obtained through a purely gravitational orbit and a separate evaluation of the Obtain observation results before and after the perihelion passage. They used 1594 observations to determine a set of orbit elements to describe the comet's orbit up to perihelion, and 515 observations to determine a set of orbit elements to describe the comet's orbit after perihelion. They also determined values ​​for the original and future shape of the orbit long before and after the passage through the inner solar system. As a result, they obtained that the comet, before approaching the sun, was on an elliptical orbit with an eccentricity of about 0.99996, a semi-major axis of about 34,000 AU (uncertainty ± 2.0%) and an orbital time of about 6, 3 million years ago. For the future orbit, they determined an elliptical characteristic with an eccentricity of around 0.99900, a semi-major axis of around 1214 AU (uncertainty ± 0.3%) and an orbital period of around 42,300 years.

In a further study from 2015, they were able to optimize the data somewhat by simulating the cometary dynamics with statistical methods while also taking into account the forces of attraction of the galactic disc and the galactic center, as well as gravitationally disruptive stars in the solar environment, but these additional effects only had one very little influence, so that the aforementioned numerical values ​​could also be confirmed here almost identically. They also classified the comet as "dynamic new" because it did not come close to the Sun during its previous orbit.

See also

Web links

Commons : C / 2007 N3 (Lulin)  - collection of images, videos and audio files

Individual evidence

  1. ^ GW Kronk: C / 2007 N3 (Lulin). In: Gary W. Kronk's Cometography. Retrieved July 27, 2020 (English).
  2. ^ Comet Lulin (C / 2007 N3). In: kometen.info. March 29, 2009, accessed July 27, 2020 .
  3. ↑ CE Woodward, TJ Jones, B. Brown, EL Ryan, M. Krejny, L. Kolokolova, MS Kelley, DE Harker, ML Sitko: Dust in Comet C / 2007 N3 (Lulin). In: The Astronomical Journal. Volume 141, No. 6, 2011, pp. 1-9 doi: 10.1088 / 0004-6256 / 141/6/181 . ( PDF; 1.11 MB )
  4. ^ AN Bair, DG Schleicher, MM Knight: Coma Morphology, Numerical Modeling, and Production Rates for Comet C / Lulin (2007 N3). In: The Astronomical Journal. Volume 156, No. 4, 2018, pp. 1–22 doi: 10.3847 / 1538-3881 / aad549 . ( PDF; 4.05 MB )
  5. ↑ EL Gibb, BP Bonev, G. Villanueva, MA DiSanti, MJ Mumma, E. Sudholt, Y. Radeva: Chemical Composition of Comet C / 2007 N3 (Lulin): Another Atypical Comet. In: The Astrophysical Journal. Volume 750, No. 2, 2012, pp. 1-14 doi: 10.1088 / 0004-637X / 750/2/102 . ( PDF; 1.71 MB )
  6. ↑ D. Bodewits, GL Villanueva, MJ Mumma, WB Landsman, JA Carter, AM Read: Swift-UVOT grism spectroscopy of comets: A first application to C / 2007 N3 (Lulin). In: The Astronomical Journal. Volume 141, No. 1, 2011, pp. 1-13 doi: 10.1088 / 0004-6256 / 141/1/12 . ( PDF; 1.70 MB )
  7. ↑ JA Carter, D. Bodewits, AM Read, S. Immler: Simultaneous Swift X-ray and UV views of comet C / 2007 N3 (Lulin). In: Astronomy & Astrophysics. Volume 541, A70, 2012, pp. 1–10 doi: 10.1051 / 0004-6361 / 201117950 . ( PDF; 1.53 MB )
  8. ↑ А. Е. Вольвач, А. А. Бережной, Л. Н. Вольвач, И. Д. Стрепка, Е. А. Вольвач: Наблюдения на РТ-22 КрАО мазерных линий ОН на длине волны 18 см в кометах 9P / Temple 1 и Lulin C / 2007 N3. In: Известия Крымской астрофизической обсерватории. Volume 107, No. 1, 2011, pp. 178-182 doi: 10.3103 / S0190271711010165 . ( PDF; 186 kB )
  9. ↑ T. Ootsubo, F. Usui, H. Kawakita, M. Ishiguro, R. Furusho, S. Hasegawa, M. Ueno, J. Watanabe, T. Sekiguchi, T. Wada: Detection of parent H 2 O and CO 2 molecules in the 2.5-5 μm spectrum of comet C / 2007 N3 (Lulin) observed with AKARI. In: The Astrophysical Journal Letters. Volume 717, No. 1, 2010, pp. L66-L70 doi: 10.1088 / 2041-8205 / 717/1 / L66 . ( PDF; 254 kB )
  10. ↑ C / 2007 N3 (Lulin) in the Small-Body Database of the Jet Propulsion Laboratory (English).Template: JPL Small-Body Database Browser / Maintenance / Alt
  11. ↑ A. Vitagliano: SOLEX 12.1. Retrieved July 9, 2020 .
  12. ↑ C / 2007 N3 Lulin. Solar System Dynamics & Planetology Group, 2013, accessed July 27, 2020 .
  13. ↑ M. Królikowska, PA Dybczyński: Near-parabolic comets observed in 2006–2010. The individualized approach to 1 / a-determination and the new distribution of original and future orbits. In: Monthly Notices of the Royal Astronomical Society. Volume 435, No. 1, 2013, pp. 440–459 doi: 10.1093 / mnras / stt1313 . ( PDF; 1.77 MB )
  14. ↑ PA Dybczyński, M. Królikowska: Near-parabolic comets observed in 2006–2010 - II. Their past and future motion under the influence of the Galaxy field and known nearby stars. In: Monthly Notices of the Royal Astronomical Society. Volume 448, No. 1, 2015, pp. 588-600 doi: 10.1093 / mnras / stv013 . ( PDF; 967 kB )