5751 Zao
Encyclopedia
5751 Zao also designated 1992 AC is an Amor asteroid
discovered on January 5, 1992 by M. Koishikawa at the Ayashi Station of the Sendai Astronomical Observatory.
was observed by Pravec
, et al. between 1992 and 1995 with the intention of determining its rotational period. From its nearly constant brightness it was determined that the asteroid is roughly spherical and has a rotational period of ≥ 21.7 hr
. Another group led by Wisniewski conducted an approximately 5 hour observation and were unable to conclude a rotational period. 5751 Zao was again observed in 2001 by Delbó, et al. using the Keck telescope. They were able to determine the asteroid's albedo of 0.36 and re-classify the asteroid from X-type
to E-type
. Using the asteroid's albedo and the Near Earth Asteroid Thermal Model (NEATM) the asteroid's diameter
was estimated to be 2.3 km. Further study of the asteroid by the Ondrejov Asteroid Photometry Project concludes that a rotational period of 76 hour
s is consistent with earlier measurements.
Amor asteroid
The Amor asteroids are a group of near-Earth asteroids named after the asteroid 1221 Amor. They approach the orbit of the Earth from beyond, but do not cross it. Most Amors do cross the orbit of Mars...
discovered on January 5, 1992 by M. Koishikawa at the Ayashi Station of the Sendai Astronomical Observatory.
Physical properties
5751 Zao has been observed by several groups to determine its rotational period. Its light curveLight curve
In astronomy, a light curve is a graph of light intensity of a celestial object or region, as a function of time. The light is usually in a particular frequency interval or band...
was observed by Pravec
Petr Pravec
Petr Pravec is a Czech astronomer, born in Třinec, a prolific discoverer of binary asteroids using lightcurve photometric studies. He is leading the effort of a large consortium of stations called BinAst to look for multiplicity in the NEA and inner main-belt populations...
, et al. between 1992 and 1995 with the intention of determining its rotational period. From its nearly constant brightness it was determined that the asteroid is roughly spherical and has a rotational period of ≥ 21.7 hr
Hour
The hour is a unit of measurement of time. In modern usage, an hour comprises 60 minutes, or 3,600 seconds...
. Another group led by Wisniewski conducted an approximately 5 hour observation and were unable to conclude a rotational period. 5751 Zao was again observed in 2001 by Delbó, et al. using the Keck telescope. They were able to determine the asteroid's albedo of 0.36 and re-classify the asteroid from X-type
X-type asteroid
The X-group of asteroids collects together several types with similar spectra, but probably quite different compositions.-Tholen classification:In the Tholen classification the X-group contains the types:* E-type* M-type, the largest grouping* P-type...
to E-type
E-type asteroid
E-type asteroids are asteroids thought to have enstatite achondrite surfaces. They form a large proportion of asteroids inward of the main belt known as Hungaria asteroids, but rapidly become very rare as the main belt proper is entered. There are, however, some that are quite far from the inner...
. Using the asteroid's albedo and the Near Earth Asteroid Thermal Model (NEATM) the asteroid's diameter
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
was estimated to be 2.3 km. Further study of the asteroid by the Ondrejov Asteroid Photometry Project concludes that a rotational period of 76 hour
Hour
The hour is a unit of measurement of time. In modern usage, an hour comprises 60 minutes, or 3,600 seconds...
s is consistent with earlier measurements.