Английская Википедия:319 Leona

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319 Leona (provisional designation Шаблон:Mp) is a dark, carbonaceous asteroid in the outer regions of the asteroid belt. It was discovered on 8 October 1891, by French astronomer Auguste Charlois at Nice Observatory in France. On 12 December 2023, Leona passed in front of the bright star Betelgeuse and occulted it, which caused the star to briefly dim from Central America, Europe, and east Asia. This occultation will reveal the shape of Leona and the surface of Betelgeuse in high detail.

Classification and orbit

Leona orbits the Sun in the outer main-belt at a distance of 2.7–4.1 AU once every 6 years and 3 months (2,295 days). Its orbit has an eccentricity of 0.22 and an inclination of 11° with respect to the ecliptic.

Physical characteristics

Spectral type

Leona has been characterized as a dark and reddish P-type asteroid by the Wide-field Infrared Survey Explorer (WISE), and as an X-type asteroid by Pan-STARRS photometric survey. The Collaborative Asteroid Lightcurve Link groups it to the carbonaceous C-type asteroids.

Slow rotator and tumbler

In October 2016, a rotational lightcurve of Leona was obtained from photometric observations by astronomers Frederick Pilcher (see naming cite for Шаблон:MoMP) at Organ Mesa Observatory (Шаблон:Small), United States, Lorenzo Franco at Balzaretto Observatory (Шаблон:Small), Italy, and Petr Pravec at the Ondřejov Observatory, Czech Republic. Lightcurve analysis gave a well-defined rotation period of Шаблон:Val hours with a brightness variation of 0.5 magnitude (Шаблон:Small).

This makes Leona one of the Top 100 slowest rotators known to exist. The astronomers also detected a non-principal axis rotation seen in distinct rotational cycles in successive order. This tumbling also gives an alternative candidate period solution of Шаблон:Val hours, one of the longest periods ever measured. It is the third-largest tumbler known to exist (also see List of tumblers).

Previous observations of Leona gave a much shorter period between 6 and 15 hours, which demonstrates the intricacy when observing slow rotators, especially those with a tumbling motion. A detailed description of the procedure of the photometric measurement is given by Pilcher.

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's WISE space-telescope, Leona measures between 49.943 and 89.00 kilometers in diameter and its surface has an albedo between 0.02 and 0.085. CALL derived an albedo of 0.0318 and a diameter of 67.97 kilometers based on an absolute magnitude of 10.2.

Naming

The origin of this minor planet's name is unknown.

Among the many thousands of named minor planets, Leona is one of 120 asteroids for which no official naming citation has been published. All of these low-numbered asteroids have numbers between Шаблон:Mp and Шаблон:Mp and were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois, Johann Palisa, Max Wolf and Karl Reinmuth.

2023 occultation of Betelgeuse

• Predicted path of the occultation of Betelgeuse by (319) Leona on 12 December 2023, using the SOLEX software

  Predicted path of the occultation of Betelgeuse by (319) Leona on 12 December 2023, using the SOLEX software

On 12 December 2023 at about 01:09–01:27 UT, Leona occulted Betelgeuse as seen from southern Europe, Turkey, Greece and Sicily. The 14th magnitude asteroid was predicted to occult Betelgeuse approximately 12 seconds; Betelgeuse was expected to dim by about 3 magnitudes. Totality was at first uncertain, visible on a very narrow path on Earth's surface, the exact width and location being uncertain due to lack of precise knowledge of the size and path of the asteroid). Projections were later refined as more data were analyzed for a totality ("ring of fire") of approximately five seconds on a 60 km wide path stretching from China, Tajikistan, Armenia, Turkey, Greece, Italy, Spain, the Atlantic Ocean, Miami, Florida and the Florida Keys to parts of Mexico. Among other programmes 80 amateur astronomers in Europe alone have been coordinated by astrophysicist Miguel Montargès, et al. of the Paris Observatory for the event. Light curve studies of the event may help to understand the distribution of brightness down to the granular level of Beltegeuse's convection cells, thus providing detailed data on the giant star heretofor inaccessible.

Observations of a September 2023 occultation showed that the asteroid was slightly elliptical; a preliminary 3D model of Leona was able to be constructived. Leona is approximately 80 by 55 kilometres, hence is projected to have a silhouette of roughly 46 by 41 milliarcseconds (mas). Betelgeuse has an apparent size in the sky of about 40 mas, but its diffuse atmosphere may make it appear 50 mas in size. Шаблон:UpdateIf Betelgeuse appears to be that much larger than Leona, then its light won't be completely obscured. If the eclipse is complete there will be a narrow strip of several kilometres wide wherein the star will completely disappear for 5–15 seconds.

External links

• Asteroid Lightcurve Database (LCDB), query form (info Шаблон:Webarchive)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• Шаблон:AstDys
• Шаблон:JPL small body