Inner solar system material discovered in the Oort cloud

We have observed C/2014 S3 (PANSTARRS), a recently discovered object on a cometary orbit coming from the Oort cloud that is physically similar to an inner main belt rocky S-type asteroid. Recent dynamical models successfully reproduce the key characteristics of our current solar system; some of these models require significant migration of the giant planets, whereas others do not. These models provide different predictions on the presence of rocky material expelled from the inner solar system in the Oort cloud. C/2014 S3 could be the key to verifying these predictions of the migration-based dynamical models. Furthermore, this object displays a very faint, weak level of comet-like activity, five to six orders of magnitude less than that of typical ice-rich comets on similar Orbits coming from the Oort cloud. For the nearly tailless appearance, we are calling C/2014 S3 a Manx object. Various arguments convince us that this activity is produced by sublimation of volatile ice, that is, normal cometary activity. The activity implies that C/2014 S3 has retained a tiny fraction of the water that is expected to be present at its formation distance in the inner solar system. We may be looking at fresh inner solar system Earth-forming material that was ejected from the inner solar system and preserved for billions of years in the Oort cloud.

Simulation Nongravitational Dynamic of Cometary Orbit

The tail formation of a comet near the sun leads to the situation in which the comet continually losses a part of its masses so that the mass of the comet decreases monotonically. A comet may also accrete the material encountered along its orbit so that its mass increases. Therefore, the mass of a comet can be regarded as a function of time. In this work we study simulation the dynamics of the orbit of a comet due to the lost of its mass along the formation of its tail and the material accretion along its orbit. Here, we assume that the comet under consideration is of the form of a ball and rotates so rapidly that the whole of its surface catches the radiation of the sun equally.

From Jupiter-family comets to objects in Encke-like orbits

Numerical integrations of the orbital evolution of objects in orbits resembling the peculiar cometary orbit of 2P/Encke have allowed the identification of the dynamical paths connecting these orbits to the possible source regions and to the possible end states. A certain degree of concentration of the longitudes of perihelion of objects in Encke-like orbits has led to the idea that 2P/Encke and the asteroidal objects in nearby orbits all come from the recent fragmentation of a giant progenitor. However, the fact that the majority of Earth-crossing asteroids are discovered when passing near the Earth induces a correlation between the date of discovery and a range of possible longitudes of perihelion. By combining this correlation with the variable rate of asteroid discoveries over the year, it is possible to show that the discovery of asteroids on orbits of given semimajor axis and eccentricity is favoured if their longitudes of perihelion fall within certain intervals. A question still open is the efficiency of the dynamical path linking the Jupiter family to Encke-like orbits; nongravitational forces seem to play an important rôle in this respect.

Detection of a high density meteoroid on cometary orbit

We report a detection of a unique fireball photographed at three Czech stations of the European Fireball Network on June 1, 1997. The main exceptionality of this fireball is given by its retrograde heliocentric orbit (i= 138°) typical for comets and, at the same time, a behavior in the Earth’s atmosphere typical for the hardest component of the interplanetary matter. The spectrum of the fireball is unique by the absence of the sodium line. With the entry velocity of 65 km s−1, the meteoroid of an estimated initial mass of 0.2 kg (diameter of several centimeters) penetrated down the altitude 65 km, i.e. significantly deeper (about 25 km) than cometary meteoroids of a comparable velocity and mass. A comparison with a typical cometary meteoroid is demonstrated on anηAquarid fireball photographed one month before.The event reported is unique in decades-long records of the fireball networks. The origin of the meteoroid in the asteroid belt is highly improbable owing to the orbit. The possibility that comets contain centimeter sized compact stones is therefore suggested.

Early Observations of the Leonids in East Asia

The parent comet of the Leonids, 55P/Tempel-Tuttle, was recovered in 1997. An improved orbit for the interval 1366 to 1997 together with predictions before 1366 were calculated by Nakano (1997). These orbital elements are used to determine the longitude of the descending node of the cometary orbit so that this can be compared with the solar longitude of meteors found in historic records. A number of catalogues listing the appearances of meteors showers have already been published. Most notable of these are Imoto and Hasegawa (1958), Zhuang (1977), Mason (1995), Rada and Stephenson (1992), Kidger (1993) and Hasegawa (1996). Nearly fifty records of the Leonids from AD855 to the end of the 19th century are found in these catalogues.