25 Phocaea (/foʊˈsiːə/) is a stony asteroid from the inner regions of the asteroid belt, approximately 75 kilometers in diameter. It is the parent body of the Phocaea family. Discovered by Jean Chacornac in 1853, it was named after the ancient Greek city of Phocaea.
Discovery and naming
Phocaea was discovered on 6 April 1853, by French astronomer Jean Chacornac at Marseille Observatory in southern France.[2] It was his first asteroid discovery out of a total of six.[citation needed] The asteroid was named after the ancient Ionian Greek city of Phocaea, modern-day Foça in Turkey, where the founders of Marseille came from.[4] The naming was proposed by French astronomer Benjamin Valz.[4]
It orbits the Sun at a distance of 1.8–3.0 AU once every 3 years and 9 months (1,358 days). Its orbit has an eccentricity of 0.25 and an inclination of 22° with respect to the ecliptic.[1] The body's observation arc begins at Vienna Observatory in March 1860, almost 7 years after its official discovery observation at Marseille.[2]
Photometric observations of this asteroid at the Organ Mesa Observatory in Las Cruces, New Mexico during 2010 gave a lightcurve with a period of 9.9341 ± 0.0002 hours. The brightness near the deepest minimum of the light curve showed changes with phase angle, which is the result of shadows extending across surface irregularities.[15] Several other lightcurves have also been obtained.[5]
The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.2310 and a diameter of 75.13 kilometers based on an absolute magnitude of 7.83.[5]
The asteroid has a mass of (5.99 ± 0.60) × 1017 kilograms and a mean density of 2.21±0.44 grams per cubic centimeters, which lies approximately in between the density of limestone and concrete/gravel.[11]
^ abcdUsui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)