826 Henrika

826 Henrika (prov. designation: Template:Mp or Template:Mp) is a background asteroid from the central regions of the asteroid belt. It was discovered by German astronomer Max Wolf at the Heidelberg-Königstuhl State Observatory on 28 April 1916. The carbonaceous C-type asteroid has a rotation period of 5.98 hours and measures approximately in diameter. Any reference to the origin of the asteroid's name is unknown.

Orbit and classification

Henrika is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements. It orbits the Sun in the central asteroid belt at a distance of 2.2–3.3 AU once every 4 years and 6 months (1,631 days; semi-major axis of 2.71 AU). Its orbit has an eccentricity of 0.21 and an inclination of 7° with respect to the ecliptic. The body's observation arc begins at Heidelberg Observatory on 2 July 1921, more than five years after its official discovery observation.

Naming

Any reference of this minor planet's name to a person or occurrence is unknown.

Unknown meaning

Among the many thousands of named minor planets, Henrika is one of 120 asteroids for which Template:MoMP has been published. All of these asteroids have low numbers, the first one being Template:Mp. The last asteroid with a name of unknown meaning is Template:Mp. They were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois, Johann Palisa, Max Wolf and Karl Reinmuth.

Physical characteristics

In the Bus–Binzel SMASS classification, Henrika is a common, carbonaceous C-type asteroid, with an untypically high albedo (see below) for such spectral class. In a taxonomic classification based on MOVIS near-infrared colors, Henrika could not be assigned a final class and was labelled as undefined (U).

Rotation period

In April 210, a rotational lightcurve of Henrika was obtained from six nights of photometric observations by Frederick Pilcher at the Organ Mesa Observatory Template:Obscode in New Mexico. Analysis of the classically shaped bimodal lightcurve gave a well-defined rotation period of hours with a brightness variation of magnitude (U=3).Template:Efn During the same apparition, a virtually identical period of hours with an amplitude of magnitude (U=3) was determined by Kenda Albers and colleges of the Rose-Hulman Institute of Technology at the Oakley Southern Sky Observatory Template:Obscode in Australia.

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, and the Japanese Akari satellite, and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), Henrika measures (), () and () kilometers in diameter and its surface has an albedo of (), () and (), respectively.

Alternative mean-diameters published by the WISE team include (), () and () with corresponding albedos of (), () and (). The Collaborative Asteroid Lightcurve Link derives an albedo of 0.1103 and a diameter of 19.15 kilometers based on an absolute magnitude of 11.6. An asteroid occultations of Henrika from 19 January 2010, gave a best-fit ellipse dimension of (). These timed observations are taken when the asteroid passes in front of a distant star.

External links

• Lightcurve Database Query (LCDB), at www.minorplanet.info
• Dictionary of Minor Planet Names, Google books
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• Template:AstDys
• Template:PAGENAMEBASE at the JPL Small-Body DatabaseTemplate:EditAtWikidata