DETERMINATION OF THE C 2 PRODUCTION RATE FOR SELECTED COMET FROM VISUAL OBSERVATIONS

DETERMINATION OF THE CDETERMINATION OF THE C22

PRODUCTION RATE FOR PRODUCTION RATE FOR SELECTED COMET FROM SELECTED COMET FROM VISUAL OBSERVATIONSVISUAL OBSERVATIONS

Galin Borisov

Institute of Astronomy, Bulgarian Academy of Sciences,

E-mail: gborisov@astro.bas.bg

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/)

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 (3g – 3u) = 0.031

After replacingknown quantities

Churumov, K. 1980

2

38

22)(4.0

1037.1

10

C

mm

f

rN

lxc

40

22)78.13(4.0

1025.4

10

r

Ncm

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

Theoretical Background Transformation from Total Number of C2 molecules

N to production rate QC2

N –total number of C2 moleculesC2 – lifetime of C2 molecule

In literature the lifetime of C2 molecules is given for 1AUand should be correct forheliocentric distance dependence

A’Hearn, M. et al. 1995

2

2

CC

NQ

2

41,

2

2sec106.6

rC

AUC

C/1996 B2 (Hyakutake)

C/1996 B2 (Hyakutake)

C/1996 B2 (Hyakutake)

C/1996 B2 (Hyakutake)

C/1999 S4 (LINEAR)

C/1999 S4 (LINEAR)

C/1999 S4 (LINEAR)

C/1999 S4 (LINEAR)

153P/C1 (Ikeya-Zhang)

153P/C1 (Ikeya-Zhang)

153P/C1 (Ikeya-Zhang)

153P/C1 (Ikeya-Zhang)

C/2001 A2 (LINEAR)

C/2001 A2 (LINEAR)

C/2001 A2 (LINEAR)

C/2001 A2 (LINEAR)

C/2000 WM1 (LINEAR)

C/2000 WM1 (LINEAR)

C/2000 WM1 (LINEAR)

C/2000 WM1 (LINEAR)

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

References

A’Hearn, M., Osip, D. & Birch, P., 1995, Icarus 118, 223-270

Churyumov, K., 1980, Nauka Moskva Farnham, T., Schleicher, D., Woodney, L., Birch, P.,

Eberhardy, C. & Levy, L., 2001, Science 292, 1348-1353

Hicks, M. & Fink, U., 1997, Icarus 127, 301-318

Kiselev, N. & Velichko, F., 1998, Icarus 133, 286-292 Sanwal, B., Kumer, B. & Singh, M., 2002, Bull. Astr. Soc.

India, in press