391 Ingeborg ('' prov. designation:'' ''or'' ) is an

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

and second-largest Mars-crosser on an eccentric orbit from the asteroid belt. It was discovered by German astronomer

Max Wolf Maximilian Franz Joseph Cornelius Wolf (21 June 1863 – 3 October 1932) was a German astronomer and a pioneer in the field of astrophotography. He was the chairman of astronomy at the University of Heidelberg and director of the Heidelberg-K� ...

on 1 November 1894, at the

Heidelberg Observatory Heidelberg (; Palatine German: ') is a city in the German state of Baden-Württemberg, situated on the river Neckar in south-west Germany. As of the 2016 census, its population was 159,914, of which roughly a quarter consisted of students. ...

in southwest Germany. When discovered, it was observed for a couple of weeks, and follow-up observations were made in 1901 and 1904. The stony S-type asteroid has a

rotation period The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the ...

of 26.4 hours and measures approximately in diameter. Any reference of the asteroid's name to a person is unknown.

Orbit and classification

''Ingeborg'' orbits the Sun in the

inner Interior may refer to: Arts and media * ''Interior'' (Degas) (also known as ''The Rape''), painting by Edgar Degas * ''Interior'' (play), 1895 play by Belgian playwright Maurice Maeterlinck * ''The Interior'' (novel), by Lisa See * Interior de ...

main-belt at a distance of 1.6–3.0 AU once every 3 years and 6 months (1,291 days). Its orbit has an eccentricity of 0.31 and an inclination of 23 ° with respect to the ecliptic.

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 Named may refer to something that has been given a name. Named may also refer to: * named (computing), a widely used DNS server * Naming (parliamentary procedure) * The Named (band), an American industrial metal group In literature: * ''The Na ...

, ''Ingeborg'' is one of 120 asteroids, for which no official naming citation has been published. All of these low-numbered asteroids have numbers between and and were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois,

Johann Palisa Johann Palisa (6 December 1848 – 2 May 1925) was an Austrian astronomer, born in Troppau, Austrian Silesia, now Czech Republic. He was a prolific discoverer of asteroids, discovering 122 in all, from 136 Austria in 1874 to 1073 Gel ...

and Karl Reinmuth.

Physical characteristics

Diameter and albedo

According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, ''Ingeborg'' measures between 15.75 and 18.15 kilometers in diameter and its surface has an albedo between 0.282 and 0.495. The ''Collaborative Asteroid Lightcurve Link'' assumes an albedo of 0.20 and calculates a diameter of 19.63 kilometers based on an absolute magnitude of 10.9. Other large Mars crossing minor planets include

132 Aethra Aethra ( minor planet designation: 132 Aethra) is a metallic asteroid and Mars-crosser on an eccentric orbit from the asteroid belt. It measures approximately 40 kilometers in diameter. It was discovered by James Craig Watson in 1873 and is the ...

(43 km),

323 Brucia Brucia (minor planet designation: 323 Brucia) is a stony Phocaea asteroid and former Mars-crosser from the inner regions of the asteroid belt, approximately in diameter. It was the first asteroid to be discovered by the use of astrophotography. ...

(36 km), and

2204 Lyyli 2204 Lyyli ( ''prov. designation'': ) is a dark asteroid and very eccentric Mars-crosser from the middle region of the asteroid belt, approximately in diameter. It was discovered on 3 March 1943 by Finnish astronomer Yrjö Väisälä at Turku O ...

(25 km).

Orbit and classification

Naming

Unknown meaning

Physical characteristics

Diameter and albedo

References

External links