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Opposition polarimetry and photometry of S- and E-type asteroids |
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| Authors: | Irina N Belskaya Vasilij G Shevchenko Yurij N Krugly Yurij S Efimov Alberto Cellino |
| Institution: | a Astronomical Observatory of Kharkiv National University, Sumska str. 35, Kharkiv 61022, Ukraine b Crimean Astrophysical Observatory, Nauchny, Crimea, Ukraine c Osservatorio Astronomico di Torino, Via Osservatorio, 20, 10025 Pino Torinese, Italy d Félix Aguilar Observatory, 5431 San Juan, Argentina |
| Abstract: | The first results of the observational program devoted to simultaneous investigation of asteroid polarimetric and photometric opposition phenomena are presented. UBVRI polarimetric and V-band photometric observations of the S-type Asteroid 20 Massalia and the E-type Asteroids 214 Aschera and 620 Drakonia were carried out in 1996-1999 down to phase angles of 0.08°, 0.7°, and 1.2°, correspondingly. The S-type Asteroid 20 Massalia is characterized by the pronounced brightness opposition surge with an amplitude larger than that observed for the E-type asteroids. A sharp peak of negative polarization at small phase angles was not observed for this asteroid. The value of polarization degree at phase angle α<1° is less than 0.5% for both S and E types. The negative polarization branches of S and especially E-asteroids have an asymmetrical shape. The phase angle at which the polarization minimum occurs is close to the angle at which non-linear increase begins in the asteroid magnitude phase curves. A relation of the observed effects to the mechanism of coherent backscattering is discussed. |
| Keywords: | Asteroids Photometry Polarimetry Opposition effect Backscattering |
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