background asteroid
An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions. An ...
from the central regions of the
asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...
. It was discovered on 13 January 1929, by Belgian astronomer
Sylvain Arend
Sylvain Julien Victor Arend (6 August 1902 – 18 February 1992) was a Belgian astronomer born in Robelmont, Luxembourg province, Belgium. His main interest was astrometry.
Together with Georges Roland, he discovered the bright comet C/1956 ...
at the
Royal Observatory of Belgium
The Royal Observatory of Belgium (; ; ) has been situated in the Uccle municipality of Brussels since 1890. It is part of the institutions of the Belgian Federal Science Policy Office (BELSPO).
The Royal Observatory was first established in S ...
in Uccle. The carbonaceous
C-type asteroids
C-type (carbonaceous ) asteroids are the most common variety, forming around 75% of known asteroids. They are volatile-rich and distinguished by a very low albedo because their composition includes a large amount of carbon, in addition to rocks ...
(CX) has a
rotation period
In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...
of 12.7 hours and measures approximately in diameter. Through a glitch in the naming process, the asteroid received the name "Mimi" instead of "Robelmonte" as originally intended by the discoverer.
Orbit and classification
''Mimi'' is a non-
family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
hierarchical clustering method
An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions. An ...
to its
proper orbital elements
__NOTOC__
The proper orbital elements or proper elements of an orbit are constants of motion of an object in space that remain practically unchanged over an astronomically long timescale. The term is usually used to describe the three quantities ...
. It orbits the Sun in the central asteroid belt at a distance of 1.9–3.3 AU once every 4 years and 2 months (1,528 days). Its orbit has an
eccentricity
Eccentricity or eccentric may refer to:
* Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal"
Mathematics, science and technology Mathematics
* Off-Centre (geometry), center, in geometry
* Eccentricity (g ...
of 0.26 and an
inclination
Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object.
For a satellite orbiting the Eart ...
ecliptic
The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making.
Fr ...
. The asteroid was first observed as at
Heidelberg Observatory
Heidelberg (; ; ) is the List of cities in Baden-Württemberg by population, fifth-largest city in the States of Germany, German state of Baden-Württemberg, and with a population of about 163,000, of which roughly a quarter consists of studen ...
in July 1906. The body's
observation arc
In observational astronomy, the observation arc (or arc length) of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly use ...
begins at Uccle in May 1934, more than 5 years after its official discovery observation.
Naming
This
minor planet
According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
was named after "Mimi" the wife of Belgian astronomer
Eugène Delporte
Eugene is a common male given name that comes from the Greek εὐγενής (''eugenēs''), "noble", literally "well-born", from εὖ (''eu''), "well" and γένος (''genos''), "race, stock, kin".1145 Robelmonte (birthplace of Arend) had been switched, and each name had been proposed by the discoverer of the other asteroid. The was mentioned in ''
The Names of the Minor Planets
Paul Herget (January 30, 1908 – August 27, 1981) was an American astronomer and director of the Cincinnati Observatory, who established the Minor Planet Center after World War II.
Career
Herget taught astronomy at the University of Cincinna ...
'' by
Paul Herget
Paul Herget (January 30, 1908 – August 27, 1981) was an American astronomer and director of the Cincinnati Observatory, who established the Minor Planet Center after World War II.
Career
Herget taught astronomy at the University of Cincinna ...
in 1955 ().
Physical characteristics
''Mimi'' has been characterized as a dark
P-type asteroid
P-type (primitive-type) asteroids have low albedo and a featureless reddish spectrum. It has been suggested that they have a composition of organic-rich silicates, carbon and anhydrous silicates, possibly with water ice in their interior. P-type ...
by the
Wide-field Infrared Survey Explorer
Wide-field Infrared Survey Explorer (WISE, List of observatory codes, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy Space observatory, space telescope in the Explorers Program launched in December 2009.. . WISE L ...
(WISE). In the
Tholen classification
An asteroid spectral type is assigned to asteroids based on their reflectance spectrum, color, and sometimes albedo. These types are thought to correspond to an asteroid's surface composition. For small bodies that are not internally different ...
, no unambiguous type could by assigned. Numerical color analysis showed that it is closest to the
C-type asteroids
C-type (carbonaceous ) asteroids are the most common variety, forming around 75% of known asteroids. They are volatile-rich and distinguished by a very low albedo because their composition includes a large amount of carbon, in addition to rocks ...
and somewhat similar to the
X-type asteroid
The X-group of asteroids collects together several types with similar spectra, but probably quite different compositions.
Tholen classification
In the Tholen classification, the X-group consists of the following types:
* E-type – with high ...
s (CX).
Rotation period and pole
In January 2004, the best-rated rotational
lightcurve
In astronomy, a light curve is a graph (discrete mathematics), graph of the Radiance, light intensity of a celestial object or region as a function of time, typically with the magnitude (astronomy), magnitude of light received on the ''y''-axis ...
of ''Mimi'' was obtained from photometric observations by astronomer John Menke at his Menke Observatory in Barnesville, Maryland (no obs. code). Lightcurve analysis gave a well-defined
rotation period
In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...
of 12.749 hours with a brightness amplitude of 0.72
magnitude
Magnitude may refer to:
Mathematics
*Euclidean vector, a quantity defined by both its magnitude and its direction
*Magnitude (mathematics), the relative size of an object
*Norm (mathematics), a term for the size or length of a vector
*Order of ...
(). Two other lightcurves gave a shorter period of 8.541 hours with an amplitude of 0.93 and 0.95 magnitude, respectively ().
A 2016-published lightcurve, using modeled photometric data from the Lowell Photometric Database (LPD), gave a concurring period of 12.74557 hours, as well as a spin axis of (224.0°, −57.0°) in
ecliptic coordinates
In astronomy, the ecliptic coordinate system is a celestial coordinate system commonly used for representing the apparent positions, orbits, and pole orientations of Solar System objects. Because most planets (except Mercury) and many small So ...
(λ, β).
Diameter and albedo
According to the surveys carried out by the Infrared Astronomical Satellite
IRAS
The Infrared Astronomical Satellite (Dutch language, Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a astronomical survey, survey of the entire night sky at infrared wavelengths. Launched on 25 Janu ...
NEOWISE
Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy space telescope in the Explorers Program launched in December 2009.. . WISE discovered thousands of minor planets and nu ...
mission of NASA's WISE telescope, ''Mimi'' measures between 46.006 and 50.67 kilometers in diameter and its surface has an
albedo
Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
between 0.031 and 0.04.
The ''Collaborative Asteroid Lightcurve Link'' adopts the results obtained by IRAS, that is, an albedo of 0.0336 and a diameter of 46.84 kilometers based on an absolute magnitude of 10.95.
Raoul Behrend
This is a list of minor-planet discoverers credited by the Minor Planet Center with the discovery of one or several minor planets (such as near-Earth and main-belt asteroids, Jupiter trojans and distant objects). , the discovery of 612,011 nu ...