889 Erynia is a highly elongated
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 inner 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 5 March 1918, 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� ...
at the
Heidelberg-Königstuhl State Observatory
Heidelberg-Königstuhl State Observatory () is a historic astronomical observatory located near the summit of the Königstuhl hill in the city of Heidelberg in Germany. It is operated by the ''Center for Astronomy (ZAH)'' at the University of He ...
, and given the
provisional designations and .
The stony
S-type asteroid
S-type (stony-type or silicaceous-type) asteroids are asteroids with a spectral type that is indicative of a siliceous (i.e. stony) mineralogical composition, hence the name. They have relatively high density. Approximately 17% of asteroids are ...
(Sl) 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 9.89 hours and measures approximately in diameter. It was named from Greek mythology, after the
Erinyes
The Erinyes ( ; , ), also known as the Eumenides (, the "Gracious ones"), are chthonic goddesses of vengeance in ancient Greek religion and mythology. A formulaic oath in the ''Iliad'' invokes them as "the Erinyes, that under earth tak ...
, also known as Furies.
Orbit and classification
''Erynia'' 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 ...
asteroid of the main belt's
background population when applying the
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
inner asteroid belt at a distance of 2.0–2.9
AU once every 3 years and 10 months (1,398 days;
semi-major axis
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...
of 2.45 AU). 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 0.20 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 ...
of 8
° with respect to the
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 the
Johannesburg Observatory
Union Observatory, also known as Transvaal Observatory, Republic Observatory and Johannesburg Observatory ( 078), is a defunct astronomical observatory in Johannesburg, South Africa that operated from 1903 to 1971. It is located on Observatory R ...
on 7 August 1912. 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
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 ...
on 16 March 1918, or eleven nights 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 one of the
Erinyes
The Erinyes ( ; , ), also known as the Eumenides (, the "Gracious ones"), are chthonic goddesses of vengeance in ancient Greek religion and mythology. A formulaic oath in the ''Iliad'' invokes them as "the Erinyes, that under earth tak ...
from Greek mythology, also known as Furies in Roman mythology. The female deities of vengeance have snakes for hair, dog's heads, coal black bodies, bat's wings, and blood-shot eyes. They tortured their victims with brass-studded scourges and inflicted plagues. 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
In the Tholen-like taxonomy of the
Small Solar System Objects Spectroscopic Survey (S3OS2), ''Erynia'' is a common stony
S-type asteroid
S-type (stony-type or silicaceous-type) asteroids are asteroids with a spectral type that is indicative of a siliceous (i.e. stony) mineralogical composition, hence the name. They have relatively high density. Approximately 17% of asteroids are ...
, while in the SMASS-like taxonomic variant of the survey, it is an Sl-subtype, which transitions from the S- to the uncommon
L-type.
Rotation period and poles
In January 2002, a 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 ''Erynia'' was obtained from
photometric observations by French astronomer
Laurent Bernasconi
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 object, near-Earth and main-belt asteroids, Jupiter trojans and Distant minor planet, distant ob ...
. Lightcurve analysis gave 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 hours with a high brightness variation of
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 ...
, indicative of a non-spherical, elongated shape ().
A concurring period of hours and an amplitude 0.47 magnitude was obtained by astronomers at the
Palomar Transient Factory
The Palomar Transient Factory (PTF, obs. code: I41), was an astronomical survey using a wide-field survey camera designed to search for optical transient and variable sources such as variable stars, supernovae, asteroids and comets. The projec ...
in April 2010 ().
In 2011, a modeled lightcurve using data from the Uppsala Asteroid Photometric Catalogue (UAPC) and other sources gave a sidereal period hours, as well as two
spin axes at (187.0°, −60.0°) and (335.0°, −74.0°) 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 survey carried out by the
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
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) and the Japanese
Akari satellite, ''Erynia'' measures () and () 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 ...
of () and (), respectively.
The ''Collaborative Asteroid Lightcurve Link'' assumes a standard albedo for a stony asteroid of 0.20 and calculates a diameter of 18.75 kilometers based on an
absolute magnitude of 11.
The WISE team also published a mean-diameter of () with a corresponding albedo of ().
References
External links
Lightcurve Database Query(LCDB), at ''www.minorplanet.info''
Dictionary of Minor Planet Names Google books
– ''Geneva Observatory'',
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 ...
Discovery Circumstances: Numbered Minor Planets (1)-(5000)– Minor Planet Center
*
*
{{DEFAULTSORT:Erynia
000889
Discoveries by Max Wolf
Named minor planets
19180305