Visible Lightcurve Observations of Comet 19p/Borrelly
Tóm tắt
The final Deep Space 1 (DS1) mission target, comet 19P/Borrelly, was observedfrom July 28–August 1, 2000 at the CTIO-1.5 m telescope in the R filter. Theobserved lightcurve has a large peak to peak variation between 0.84 mag and1.0 mag. A period of 26.0 ± 1 hr (assuming a double-peaked lightcurve)was found using all five nights. This is in good agreement with the period of25.02 ± 0.5 hr quoted by Lamy et al. (1998) using only 6 points ofHST data and is also consistent with HST data taken around the DS1 encountertime by Weaver et al. (2002).Using the mean magnitude R = 20.8 mag and assuming a 4% albedo, we derivean effective nuclear radius of 2.6 km. The large lightcurve amplitude translates toa long to intermediate axial ratio a/b ≥ 2.2, in excellent agreement with theHST result of a/b ≥ 2.4 (Lamy et al., 1998) and with DS1 images (Soderblom et al., 2002).
Tài liệu tham khảo
Belton, M. J. S. and Gandhi, A.: 1988, ‘Application of the CLEAN Algorithm to Cometary Light Curves’, Bull. Am. Astron. Soc. 20, 836.
Belton, M. J. S., Julian, W. H., Anderson, A. J., and Mueller, B. E. A.: 1991, ‘The Spin State and Homogeneity of Comet Halley's Nucleus’, Icarus 93, 183–193.
Lamy, P. L., Toth, I., and Weaver, H. A.: 1998, ‘Hubble Space Telescope Observations of the Nucleus and Inner Coma of Comet 19P/1904 Y2 (Borrelly)’, Astrophys. J. 337, 945–954.
Meech, K. J., Belton, M. J. S., Mueller, B. E. A., Dicksion, M. W., and Li, H. R.: 1993, ‘Nucleus Properties of P/Schwassmann-Wachmann 1’, Astron. J. 106, 1222–1236.
Mueller, B. E. A. and Ferrin, I.: 1996, ‘Change in the Rotational Period of Comet P/Tempel 2 between the 1988 and 1994 Apparitions’, Icarus 123, 463–477.
Mueller, B. E. A., Samarasinha, N. S., and Belton, M. J. S.: 2002, ‘The Diagnosis of Complex Rotation in the Lightcurve of 4179 Toutatis and Potential Applications to Other Asteroids and Bare Cometary Nuclei’, Icarus 158, 305–311.
Samarasinha, N. H. and Mueller, B. E. A.: 2002, ‘Spin Axis Direction of Comet 19P/Borrelly Based on Observations from 2000 and 2001’, these proceedings.
Sekanina, Z.: 1979, ‘Fan-Shaped Coma, Orientation of Rotation Axis, and Surface Structure of a Cometary Nucleus. I. Test of a Model on Four Comets’, Icarus 37, 420–442.
Soderblom, L. A., Becker, T. L., Bennett, G., Boice, D. C., Britt, D. T., Brown, R. H., Buratti, B. J., Isbell, C., Giese, B., Hare, T., Hicks, M. D., Howington-Fraus, E., Kirk, R. L., Lee, M., Nelson, R. M., Oberst, J., Owen, T. C., Rayman, M. D., Sandel, B. R., Stern, S. A., Thomas, N. and Yelle, R. V.: 2002, ‘Observations of Comet 19P/Borrelly by the Miniature Integrated Camera and Spectrometer aboard Deep Space 1’, Science 296, 1087–1091.
Suntzeff, N. B., Phillips, M. M., Covarrubias, R., Navarrete, M., Pérez, J. J., Guerra, A., Acevedo, M. T., Doyle, L. R., Harrison, T., Kane, S., Long, K. S., Maza, J., Miller, S., Piatti, A. E., Clariá, J. J., Ahumada, A. V., Pritzel, B., and Winkler, P. F.: 1999, ‘Optical Light Curve of the Type Ia Supernova 1998bu in M96 and the Supernova Calibration of the Hubble Constant’, Astron. J. 117, 1175–1184.
Weaver, H. A., Stern, S. A., and Parker, J. Wm.: 2002, ‘HST/STIS Observations of 19P/Borrelly during the Deep Space 1 Encounter’, Astron. J., in revision.