182 Elsa

182 Elsa (Template:IPAc-en) is a Massalia or background asteroid from the inner regions of the asteroid belt, approximately Template:Convert in diameter. It was discovered on 7 February 1878, by Austrian astronomer Johann Palisa at the Austrian Naval Observatory in today's Croatia.<ref name="MPC-object"/> The S-type asteroid has a very long rotation period of 80 hours and likely an elongated shape.<ref name="lcdb" /> The origin of its name is uncertain.<ref name="springer" />

Orbit and classification

Elsa is a member of the Massalia family (Template:Small),<ref name="Ferret" /> a very large inner belt asteroid family consisting of stony asteroids.<ref name="Nesvorny-2014" /> In a different HCM-study, however, it has been found to be a non-family asteroid from the main belt's background population.<ref name="AstDys-object" />

It orbits the Sun in the inner main-belt at a distance of 2.0–2.9 AU once every 3 years and 9 months (1,371 days; semi-major axis of 2.42 AU). Its orbit has an eccentricity of 0.19 and an inclination of 2° with respect to the ecliptic.<ref name="jpldata" />

Naming

The origin of this minor planet's name is uncertain.<ref name="springer" /> Originally, the asteroid was named "Elsbeth" – the Austrian variant of "Elisabeth" – and only later changed into a more lyrical "Elsa" with the consent of the discoverer, Johann Palisa.<ref name="springer" /> It may have been named after the character in the legend of Lohengrin perpetuated by Richard Wagner's opera of the same name.Template:Citation needed It may also refer to the Empress Elisabeth of Austria (1854–1898), or to a relative of Admiral Bourgignon, who requested the naming, as he was the military superior of the discoverer at the Naval Observatory at Pola. Finally, the name "Elsbeth" just might have been chosen generically as it is one of the most common feminine Christian names.<ref name="springer" />

Physical characteristics

Elsa has been characterized as a common, stony S-type asteroid in both the Tholen and SMASS classification.<ref name="jpldata" />

Rotation period

The asteroid is a relatively slow rotator.<ref name="lcdb" /> In 1980, its rotation period was estimated to be about 3.3 Earth days.<ref name="Harris-1980b" /> In 2008, a collaborative effort from three different sites under the lead of Frederick Pilcher was used to build a complete lightcurve for the asteroid, which showed a period of Template:Val hours with a brightness variation of Template:Val in magnitude. A possible companion has been proposed to explain the slow rotation.<ref name="Pilcher-2009e" /> Other period determinations gave similar results between 80.166 and 80.23 hours with an outlier by the Palomar Transient Factory.<ref name="Chang-2014a" /><ref name="Durech-2009" /><ref name="Gandolfi-2009" />Template:Efn

Elsa has very amplified lightcurve indicating an elongated or irregular body. It was one of five minor planets included in the 1993 study, Transition Comets -- UV Search for OH Emissions in Asteroids, which was research involving amateur astronomers who were permitted to make use of the Hubble Space Telescope.

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Elsa measures between 36 and 45.72 kilometers in diameter and its surface has an albedo between 0.196 and 0.2106.<ref name="Marchis-2006c" /><ref name="Masiero-2014" /><ref name="SIMPS" /><ref name="WISE" /><ref name="AKARI" /><ref name="Nugent-2016" />

During 2002, Elsa was also observed by radar from the Arecibo Observatory. The return signal matched an effective diameter of Template:Val.<ref name="Magri-2007" />

External links

• Asteroid Lightcurve Database (LCDB), query form (info Template:Webarchive)
• Dictionary of Minor Planet Names, Google books
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• Template:AstDys
• Template:JPL small body