Conclusion - シューメーカー・レヴィー第9彗星と木星の衝突の近赤外線観測

The author observed the impact of comet Shoemaker-Levy 9 on Jupiter by near-infrared wavelength using the 188-cm telescope, with the near-IR camera OASIS, for Okayama Astrophysical Observatory during July 15-24, 1994, and succeeded the detections of the impacts of the fragments C, D, and K. The observational results with good time resolution showed the complicated behavior of the impact radiation and some stages of the impact phenomena; the two short precursors, PC1 and PC2, and the long lasting main event, and the shoulder.

Those phenomena were also observed for other impacts.

The author attempted to synthesize the overview of the impact phenomena.

The spacecraft Galileo detected the impacts of the SL9 fragments. Comparing ground-based observations with the detections by Galileo, it is shown that the PC1 is the radiation by entry of the fragment into the high altitude atmosphere.

The PC2 timings are related with the impact geometries. As a result of the explosion of the cometary fragment, the expanding and rising plume was ejected.

The vertical eject velocity of the plume was more 10 km s-1, and the plume rose to the height of Earth-line of sight within one minute. Thus thermal radiation from the hot plume was detected at some ground-based infrared observations as the PC2.

From 6 minutes after the impact, the main event started. The cause of the main event is debatable subject. Many researchers proposed the heating by the splash back of the plume as a cause of the main event. However the author do not sustain this theory by two reasons. The first reason is that the estimated temperatures of the impact radiator continued to decrease even in first half of the main event. The temperature increased from 10 minutes after the impact, which was after the peak of the main event. The second one is that the center position of the radiation did not change between before and after the main event start, but started to move southward at the speed of 4 km s-1 at 10 minutes after the impact again. Both the reasons mean that the splash back of the plume started at 10 minutes after the impact.

Therefore the author proposes dust grain formation theory as a cause of the main event. The formation of dust grain enhances the optical depth of the plume, and then enhances both the thermal radiation and the reflected sunlight.

The formation of dust grain in the plume at the start of the main event is consistent with the HST and other visible observations. The plume motion is modeled as simple ballistic motion. By comparing this ballistic model with the OAO observation of the K impact, the plume temperatures are estimated and shown to be consistent with other observations. The composition of the dust is probably silicate.

It is clear that more detailed analysis and precise modeling are needed in order to obtain the conclusion on the impact phenomena. It is left as a future work.

Acknowledgments

I am deeply grateful to Mr. Hitoshi Hasegawa of ASTEC, Inc., for co-research on the SL9 impact with him, without it I would never have achieved this study.

I would like to thank greatly to Dr. Jun-ichi Watanabe of the public information office, N AOJ for the organization of the OAO /OASIS observation and helpful discussions.

I express my thanks to Prof. Hideo Maehara, the director of the OAO, and all the staffs of OAO and the OASIS group for supports to the observation. In particular, fr. Atsushi Mori of Department of Astronomy, University of Tokyo, made some comments on reductions of the OASIS data, which are very valuable.

I am grateful to Prof. Kazuhiro Sekiguchi of NAOJ, who presented the data of the SAAO observations, and to Dr. David Crisp and Dr. Vikki Meadows of JPL, who presented the data of color temperature by AAT/IRIS, and to Mr. Naotaka Yamamoto of Department of Physics, Science University of Tokyo, for support on reductions and analyses. Thanks are due to Prof. Masahisa Yanagisawa of University of Electro-Communications, Dr. Toshiko Takata and Prof. Sho Sasaki of Geological Institute, University of Tokyo, and all the members of PLANET mailing-list and Planetary and Lunar Astronomical Network of Japan for helpful comments and discussions. I also thanks Miss Sumiko Harasawa for advices of English expressions.

Finally, I express my thanks deeply to Prof. Saburo Miyahara of Depart

ment of Earth and Planetary Sciences, Kyushu University for his guidances and critical readings of the manuscript, and to the members of the laboratory for supports on my study, in particular, to Dr. Takahiro Iwayama of Department of Control Engineering and Science, Kyushu Institute of Technology for many supports and courtesies.

References

[1] IA U (International Astronomical Union) Circular, No.5725, March 26, 1993.

[2] IA U _Circular,No.5730, March 29, 1993.

[3] IA U _Circular,No.5800, May 22, 1993.

(4] Jun-ichi Watanabe, 1994, KYODAI SUISEI GA MOKUSEI NI GEK

ITOTU SUTUTOKI, SEIBUNDOU-SHINKOUSYA Press, 191 pp, in Japanese; Jun-ichi Watanabe, 1995, SUISEI NO MOKUSEI SY OUTOTU WO OTTE, SEIBUNDOU-SHINKOUSYA Press, 175 pp, in Japanese.

[5] Bertrand M. Peek, 1958, The planet Jupiter, revised edition in 1981, Faber and Faber, 240 pp; Isamu Hirabayashi, 1981, Jupiter and its observations, in Guidebook for planetary observers 2

(

Planetary and Lunar Astronomi

cal Network of Japan, Eds.), 11-161, SEIBUNDOU-SHINKOUSYA Press, in Japanese; John H. Rogers, 1995, The giant planet Jupiter, Cambridge University Press, 418 pp.

[6] Sanjay S. Limaye, 1986, Jupiter: New estimates of the mean zonal flow at the cloud level, Icarus, 65, 335-352.

[7] D. Gautier, B. Conrath, M. Flasar, R. Hanel, V. Kunde, A. Chedin, and N.

Scott, 1981, The helium abundance of Jupiter from Voyager, J. Geophys.

Res., 86, 8713-8720; G. F. Linda!, and 11 others, 1981, The atmosphere of Jupiter: An analysis of the Voyager radio occultation measurements, J.

Geophys. Res., 86, 8721-8727.

[8] S. K. Atreya, T. M. Donahue, and M. C. Festou, 1981, Jupiter: Structure and composition of the upper atmosphere, Astrophys. J., 247, L43-L47;

Sushil K. Atreya, 1986, Atmospheres and ionospheres of the outer planets and their satellites, Springer-Verlag, 224 pp.

[9] Theodor Kostiuk, Fred Espenak, and Michael J. Mumma, 1989, Is ethane varying in the Jovian north polar "hot spot"?, in Time-variable phenomena in the Jovian system (Michael J. S. Belton, Robert A. West, and Ji.irgen Rahe, Eds.), 234-241, NASA SP-494.

[10] Richard A. Kerr, 1996, Galileo hits a strange spot on Jupiter, Science, 271, 593-594; David J. Stevenson, 1996, The subtle taste of Jupiter, Na

ture, 379, 495-496; Julio Magalhaes, February 6, 1996, Galileo Probe Mission "Quick-look" Science Summary, posted on the World Wide Web (http

:I I

ccf.arc.nasa.gov

I

galileo_probelhtmlslfirst...science...summary.html).

[11] John S. Lewis, 1969, The clouds of Jupiter and the NH3-H20 and NH3-H2S systems, Icarus, 10, 365-378 : S. J. Weidenschilling, and J. S. Lewis, 1973, Atmosphere and cloud structures of the Jovian planets, Icarus, 20, 465-476;

Sushi! K. Atreya, and P. N. Romani, 1985, Photochemistry and clouds of Jupiter, Saturn and Uranus, in Recent advances in planetary meteorology (Garry E. Hunt, Ed.), 17-68, Cambridge University Press.

[12] Kevin H. Baines, Robert A. West, Lawrence P. Giver, and Fernando Moreno, 1993, Quasi-random narrow-band model fits to near-infrared low

temperature laboratory methane spectra and derived exponential-sum ab

sorption coefficients, J. Geophys. Res., 98, 5517-5529.

[13] David Jewitt, Jane Luu, and Jun Chen, 1993, Physical properties of split comet Shoemaker-Levy 9, Bull. Am. Astron. Soc., 25, 1042.

[14] Z. Sekanina, P. W. Chodas, and D. K. Yeomans, 1994, Tidal disruption and the appearance of periodic comet Shoemaker-Levy 9, Astron. Astrophys., 289, 607-636.

[15] !AU Circular, No.5936, February 18, 1994.

[16] H. A. Weaver and 20 others, 1995, T he Hubble Space Telescope (HST ) observing campaign on comet Shoemaker-Levy 9, Science, 267, 1282-1288.

[17] IA U Circular, No.5973, April 12, 1994.

[18] H. A. Weaver and 18 others, 1994, Hubble Space Telescope observations of comet P /Shoemaker-Levy 9 ( 1993e), Science, 263, 787-791.

[19] Jun-ichi Watanabe, Yuka Hirota, and Masanao Abe, 1994, CCD imaging observation of periodic comet Shoemaker-Levy 9 1993e, Pub/. Astron. Soc.

Japan, 46, L1-L4.

[20] J. V. Scotti and H. J. Melosh, 1993, Estimate of the size of comet Shoemaker-Levy 9 from a tidal breakup model, Nature, 365, 733-735.

[21] P. W . Chodas, and D. K. Yeomans, Predicted impact parameters for frag

ments of P /Shoemaker-Levy 9 Last prediction before collisions, July 16, 1994, E-mail for International Jupiter Watch (Glenn Orton, Ed.).

[22] Zdenek Sekanina, 1993, Disintegration phenomena expected during colli

^A. ^J. Friedson and G. S. Orton, 1993, Effect of the collision of comet Shoemaker-Levy 9 on the appearance of Jupiter in the near and thermal IR, Bull. Am. Astron. Soc., 25, 1045; R. A. West and A. J. Friedson, 1993, Cometary particles as a tracer of Jupiter's stratospheric circulation, Bull.

Am. Astron. Soc., 25, 1047.

[33] Hitoshi Hasegawa, Satoru Takeuchi, and J un-ichi Watanabe, 1994, De

tectability of water-ice clouds expected after the P /Shoemaker-Levy 9 im

pact with Jupiter at near-infrared molecular bands, Planet. Space Sci., 41,

791-795, 1993.

[34] Wayne R. Pryor, C. Y. Na, and G. R. Gladstone, 1994, How will dust from Shoemaker-Levy 9 alter Jupiter's stratospheric aerosol populations?,

Geophys. Res. Letters, 21, 1079-1082.

[35] Joseph Harrington, Raymond P. LeBeau Jr. , Kari A. Backes, and Timothy E. Dowling, 1994, Dynamic response of Jupiter's atmosphere to the impact of comet Shoemaker-Levy 9, Nature, 368, 525-527.

[36] A. P. Ingersoll, H. Kanamori, and T. E. Dowling, 1994, Atmospheric gravity waves from the impact of comet Shoemaker-Levy 9 with Jupiter, Geophys.

Res. Letters, 21, 1083-1086.

[37] Takuya Yamashita, Eiji Nishihara, Shinichiro Okumura, Atsushi Mori, and Etsuji Watanabe, 1995, Development of OASIS and its first results, in Scientific and Engineering frontiers for ^8-10m telescopes (M. lye and T.

Nishimura, eds.), Universal Academy Press, Inc., Tokyo, 285-290.

[38] R. A. Hanel, B. J. Conrath, D. E. Jennings, and R. E. Samuelson, 1992, Exploration of the Solar System by infrared remote sensing, §7.6, Cambridge University Press, 458 pp.

[39] William C. Tittemore, and William M. Sinton, 1989, Near-infrared pho

tometry of the galilean satellites, Icarus, 77, 82-97.

[40] Muhammad Iqbal, 1983, An introduction to solar radiation, Academic press, 390 pp.

[41] Roger N. Clark, and Thomas B. Me Cord, 1980, The Galilean satellites:

New near-infrared spectral reflectance measurements (0.65-2.5p.m ) and a 0.325-5p.m summary, Icarus, 41, 323-339; Godfrey T. Sill, and Roger N. Clark, 1982, Composition of the surface of the galilean satellites, in Satellites of Jupiter(David Morrison, Ed.), 174-212, Univ. of Arizona Press.

[42] Vikki Meadows, David Crisp, Glenn Orton, Timothy Brooke, and John Spencer, 1995, AAT IRIS observations of the SL-9 impacts and initial fire

ball evolution, in Proceedings of European SL-9/ Jupiter Workshop (R. West and H. Bohnhardt, Eds.), 129-134; Vikki Meadows, and David Crisp, 1995, Impact plume composition from near-infrared spectroscopy, in Proceedings of European SL-9/ Jupiter Workshop (R. West and H. Bohnhardt, Eds.), 239-244.

(

₄₃

]

G. Orton, and 57 others, 1995, Collision of comet Shoemaker-Levy 9 with Jupiter observed by the NASA Infrared Telescope Facility, Science, 267, 1277-1282; Glenn S. Orton, and the IRTF SL9 Science Team, 1995, Some results from the NASA Infrared Telescope Facility Shoemaker-Levy 9 ob

serving campaign, in Proceedings of European SL-9

/

Jupiter Workshop

(R.

\Vest and H. Bohnhardt, Eds.

)

_,123-128; A. J. Friedson, W. F. Hoffmann, J. D. Goguen, L. K. Deutsch, G. S. Orton, J. L. Hora, A. Dayal, J. N. Spi

tale, W. K. Wells, and G. G. Fazio, 1995, Thermal infrared lightcurve of the impact of Comet Shoemaker-Levy 9 fragment R, Geophys. Res. Letters, 22, 1569-1572.

(

₄₄

]

J.-P. Maillard, P. Drossart, B. Bezard, C. de Bergh, E. Lellouch, A. Marten, J. Caldwell, J .-C. Hilico, and S. K. Atreya, 1995, Methane and carbon monoxide infrared emissions observed at the Canada-France-Hawaii Tele

scope during the collision of comet SL-9 with Jupiter, Geophys. Res. Let

ters, 22, 1573-1576.

(

₄₅

]

_TerryZ. Martin, Glenn S. Orton, Larry D. Travis, Leslie K. Tamppari, and Ian Claypool, 1995, Observation of Shoemaker-Levy impacts by the Galileo photopolarimeter radiometer, Science, 268, 1875-1879.

(

₄₆

]

(

_SAAO

)

. From 1995, Dr. Sekiguchi is at NAOJ, and the SAAO observations are analyzed by the author, Mr. Yamamoto of Science University of Tokyo, and others.

[52] P. ^0.Lagage, and 16 others, 1995, Collision of Shoemaker-Levy 9 fragments A, E, H, L, Q1 with Jupiter: Mid-Infrared light curves, Geophys. Res.

Letters, ^22,1773-1776.

[53) H. B. Hammel, and 16 others, 1995, HST imaging of atmospheric phe

nomena created by the impact of comet Shoemaker-Levy 9, Science, ^267, 1288-1296.

[54) C. W. Hord, and 12 others, 1995, Direct observations of the Comet Shoemaker-Levy 9 fragment G impact by Galileo UVS, Geophys. Res. Let

ters, ^22,1565-1568.

[55) R. W. Carlson, P.R. Weissman, M. Segura, J. Hui, W. D. Smythe, T.V. Johnson, K. H. Baines, P. Drossart, Th. Encrenaz, and F. E. Leader, 1995, Galileo infrared observations of the Shoemaker-Levy 9 G impact fireball:

A preliminary report, Geophys. Res. Letters, ^22,1557-1560; R. W. Car

son, and 10 others, 1995, Some timing and spectral aspects of the G and R collision events as observed by the Galileo near infrared mapping spec

trometer, in Proceedings of European SL-9/ Jupiter Workshop (R. West and H. Bohnhardt, Eds.), 69-73.

[56) F. Colas, D. Tiphe'ne, J. Lecacheux, P. Drossart, B. de Batz, S. Pau, D.

Rouan, F. Se'vre, 1995, Near-Infrared imaging of SL9 impacts on Jupiter from Pic-du-Midi Observatory, Geophys. Res. Letters, ^22,1765-1768.

[57] H. U. Kaufl, 1994, Imaging of the signatures of the impact events in the thermal infrared, ESO Messenger, No.77, 37-40, September 1994; T. A.

Livengood, H. ^U.Kaufl, T. Kostiuk, G. L. Bjoraker, P. N. Romani, G.

W iedemann, B. Mosser, and M. Sauvage, 1995, Multi-wavelength thermal

infrared imaging of SL9 impact phenomena, in Proceedings of European SL-9/ Jupiter Workshop (R. West and H. Bohnhardt, Eds.), 137-145.

(58) P. Drossart, T. Encrenaz, J. Lecacheux, F. Colas, and P. ^0.Lagage, 1995, The time sequence of SL9/impacts H and K from infrared observations,

Geophys. Res. Letters, ^22,1769-1772.

[59) H. Schleicher, H. Balthasar, M. Knolker, W. Schmidt, and K. Jockers, 1994, The impact of fragment "L" of comet SL-9 on Jupiter, Earth, Moon, and Planets, ^66,13-17; H. Scheleicher, H. Balthasar, K. Jockers, M. Knolker, and W. Schmidt, 1995, Observation at 892 nm of impact "L" with the Solar Vacuum Tower Telescope at Tenerife, in Proceedings of European SL-9/Jupiter Workshop (R. West and H. Bohnhardt, Eds.), 171-173.

[60) A. Fitzsimmons, J. E. Little, N. Walton, R. Catchpole, P. J. Andrews, I.

P. Williams, E. Harlaftis, and P.Rudd, 1995, Optical imaging and spec

troscopy of the impact plumes on Jupiter, in Proceedings of European SL-9/ Jupiter Workshop (R. West and H. Bohnhardt, Eds.), 197-201; A.

Fitzsimmons, P. J. Andrews, R. Catchpole, J. E. Little, N. Walton, and I.

P. Williams, 1996, Optical imaging of the impact plume on Jupiter from fragment L of comet D/Shoemaker-Levy 9, Mon. Not. R. Astron. Soc., 278, 781-786.

[61) Masahisa Yanagisawa, 1995, personal communication. The total Jovian flux at 0.89 J.lm is estimated by 1) the Jovian 0.55 J.lm magnitude of -2.2; 2) geo

metric albedo contrast between 0.55 and 0.89 pm to be 8.5 (M. G. Tomasko, 1976, Photometry and polarimetry of Jupiter, in Jupiter (T. Gehrels, Ed.), Univ. Arizona press, 486 pp.); and 3) the 5800K solar flux.

[62) James R. Graham, Imke de Pater, J. Garrett Jernigan, Michael C. Liu, and Michael E. Brown, 1995, The fragment R collision : W. M. Keck telescope observations of SL9, Science, 267, 1320-1323.

[63) P. D. Nicholson, and 12 others, 1995, Palomar observations of the R impact of comet Shoemaker-Levy 9: I. Light curves, Geophys. Res. Letters, 22,

1613-1616.; P. D. Nicholson, and 12 others, 1995, Palomar observations of the R impact of comet Shoemaker-Levy 9: II. Spectra, Geophys. Res.

Letters, 22, 1617-1620.

[64] J. T. Shy kula, D. Kilkenny, D. C. B. Whittet, and C. D. Laney, 1995, Infrared light curves of shoemaker-Levy 9 impacts H, Q1 and S, Mon. Not.

R. Astron. Soc., 272, L17-L20.

[65) fA U Circular, N o.6024, July 17, 1994.

[66) IA U Circular, No.6026, July 18, 1994.

[67) fA U Circular, N o.6030, July 20, 1994.

[68) fA U Circular, No.6032, July 21, 1994.

[69) fA U Circ·ular, N o.6034, July 22, 1994.

[70) Jun-ichi Watanabe, Takuya Yamashita, Hitoshi Hasegawa, Satoru Takeuchi, Masanao Abe, Yuka Hirota, Eiji Nishihara, Shin-ichi Okumura, and Atushi Mori, 1995, Near-IR observations of the cometary impacts to Jupiter: Brightness variation of impact plume of fragment K, Pub/. Astron.

Soc. Japan, 47, L21-L24 and Plate 5.

[71] Satoru Takeuchi, Hitoshi Hasegawa, Jun-ichi Watanabe, Takuya Ya

mashita, Masanao Abe, Yuka Hirota, Eiji Nishihara, Shin-ichi Okumura, and Atushi Mori, 1995, Near-IR imaging observations of the cometary im

pact into Jupiter, Geophys. Res. Letters, 22, 1581-1584.

[72] ^V.A. Bronshten, 1983, Physics of Meteoric Phenomena, D. Reidel Pub

lishing Co., Boston, 356 pp.

[73] Don Yeomans and Paul Chodas, 20 Apr 1995, Synthesis of fragment impact times, posted on the World Wide Web ( http:/ /newproducts.jpl.nasa.gov / sl9/impacts4.html ); Paul Chodas, Sky and Telescope, October 1995, 19.

[74) Naotaka Yamamoto, Satoru Takeuchi, Hitoshi Hasegawa, Kazuhiro Sekiguchi, and Jun-ichi Watanabe, 1995, SL9 impacts observed by near

IR: Comparison of timings of impact phenomena, in Proceedings of the 28th ISAS Lunar and Planetary Symposium, 5-8.

[75) Kevin Zahnle and Mordecai-Mark Mac Low, 1995, A simple model for the light curve generated by a Shoemaker-Levy 9 impact, J. Geophys. Res., 100, 16,885-16,894.

[76) Mark B. Boslough, David A. Crawford, Timithy G. Trucano, and Allen C. Robinson, 1995, Numerical modeling of Shoemaker-Levy 9 impacts as a framework for interpreting observations, Geophys. Res. Letters, 22, 1821-1824.

[77) Jun-ichi Watanabe, Satoru Takeuchi, and Hitoshi Hasegawa, 1995, Geo

metrical model for the plume evolution -Splash or grain formation?-, m

Proceedings of the 28th ISAS Lunar and Planetary Symposium, 17-20.

[78) Satoru Takeuchi, Hitoshi Hasegawa, and Jun-ichi Watanabe, 1995, Near

infrared brightness variation of the impact and plume evolution, in Pro

ceedings of European SL-9/ Jupiter Workshop (R. West and H. Bohnhardt, Eds.), 153-158.

[79) Hitoshi Hasegawa, Satoru Takeuchi, and J un-ichi Watanabe, 1996, Grains in the Shoemaker-Levy 9 impact plume: Formation and composition, Icarus, in press (appear in vol. 121, no. 2); Hitoshi Hasegawa, Satoru Takeuchi, and J un-ichi Watanabe, 1995, Grain formation in cometary im

pact plume, in Proceedings of European SL-9/ Jupiter Workshop (R. West and H. Bohnhardt, Eds.), 279-285.

[80) Ya. B. Zel'dovich and Yu. P. Raizer, 1967, Physics of Shock Waves and High- Temperature Hydrodynamic Phenomena, Academic Press, 916 pp.

[81) R. W. Carlson and 10 others, 1995, Galileo infrared observations of the Shoemaker-Levy 9 G and R fireballs and splash, in Abstracts for lA ^UCol

loquium 156: The Collision of Comet P /Shoemaker-Levy 9 and Jupiter, 15.

[82) Jean Meeus, 1988, Astronomical Formulae for Calculators, forth edition enlarged and revised, Willmann-Bell, Inc., 218 pp.

[83) D. Deming, J. Harrington, G. Bjoraker, and W. Maguire, 1995, Radiative

hydrodynamic modeling of the SL9 plume infall: The splash and the

bounce, Poster· presentation at IA U Colloquium 156: The Collision of Comet P /Shoemaker-Levy 9 and Jupiter, 133.

[84] Toshiko Takata, Thomas J. Ahrens, and Alan W. _Harris, 1995, Comet Shoemaker-Levy 9: Fragment and progenitor impact energy, Geophys. Res.

Letters, 22, 2433-2436.

ドキュメント内シューメーカー・レヴィー第9彗星と木星の衝突の近赤外線観測 (ページ 83-95)