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Determination of C2 Production Rate in Comets from Visual Observations

Investigating the production rate of C2 molecules in selected comets using visual observations and theoretical background. Transforming visual magnitude to total C2 molecules and calculating production rates. Extrapolating data for distant comets and using amateur astronomers' magnitude estimates for rate calculations.

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Determination of C2 Production Rate in Comets from Visual Observations

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  1. DETERMINATION OF THE C2 PRODUCTION RATE FOR SELECTED COMET FROM VISUAL OBSERVATIONS Galin Borisov Institute of Astronomy, Bulgarian Academy of Sciences, E-mail: gborisov@astro.bas.bg

  2. Introduction • Comets: • C/1996 B2 (Hyakutake) • C/1999 S4 (LINEAR) • 153P/C1 (Ikeya-Zhang) • C/2001 A2 (LINEAR) • C/2000 WM1 (LINEAR) • Visual Observations – ICQ format British Astronomical Association – Comet Section (http://www.ast.cam.ac.uk/~jds/)

  3. Theoretical Background • Transformation from the Comet Visual Magnitude mc to Total Number of C2 Molecules mc – visual magnitude of comet mlx – 1Lx in magnitudes = -13.78 fc2 – oscillation force for Swan band (A3Pg – C3Pu) = 0.031 After replacing known quantities Churumov, K. 1980

  4. Theoretical Background • But this formalism gives “artificial” molecules when the comet is far away from the Sun (more than 1.5 AU) • The solution of this problem is extrapolating these distant “artificial” molecules to small heliocentric distances and subtracting them as a continuum • This idea will be presented in the next section for the fifth selected comets

  5. Theoretical Background • Transformation from Total Number of C2 molecules N to production rate QC2 N –total number of C2 molecules tC2 – lifetime of C2 molecule In literature the lifetime of C2 molecules is given for 1AU and should be correct for heliocentric distance dependence A’Hearn, M. et al. 1995

  6. C/1996 B2 (Hyakutake)

  7. C/1996 B2 (Hyakutake)

  8. C/1996 B2 (Hyakutake)

  9. C/1996 B2 (Hyakutake)

  10. C/1999 S4 (LINEAR)

  11. C/1999 S4 (LINEAR)

  12. C/1999 S4 (LINEAR)

  13. C/1999 S4 (LINEAR)

  14. 153P/C1 (Ikeya-Zhang)

  15. 153P/C1 (Ikeya-Zhang)

  16. 153P/C1 (Ikeya-Zhang)

  17. 153P/C1 (Ikeya-Zhang)

  18. C/2001 A2 (LINEAR)

  19. C/2001 A2 (LINEAR)

  20. C/2001 A2 (LINEAR)

  21. C/2001 A2 (LINEAR)

  22. C/2000 WM1 (LINEAR)

  23. C/2000 WM1 (LINEAR)

  24. C/2000 WM1 (LINEAR)

  25. C/2000 WM1 (LINEAR)

  26. Conclusions • When using this formalism for converting the visual magnitudes to the total number of C2 molecules we should subtract “artificial” molecules as a continuum • The visual comet magnitude estimated by amateur astronomers can be used for obtaining the C2 production rate for long range of heliocentric distances

  27. References • A’Hearn, M., Osip, D. & Birch, P., 1995, Icarus118, 223-270 • Churyumov, K., 1980, Nauka Moskva • Farnham, T., Schleicher, D., Woodney, L., Birch, P., Eberhardy, C. & Levy, L., 2001, Science292, 1348-1353 • Hicks, M. & Fink, U., 1997, Icarus127, 301-318 • Kiselev, N. & Velichko, F., 1998, Icarus133, 286-292 • Sanwal, B., Kumer, B. & Singh, M., 2002, Bull. Astr. Soc. India, in press

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