5477 Holmes, provisional designation , is a Hungaria asteroid and binary system from the innermost regions of the

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...

, approximately in diameter. It was discovered on 27 October 1989, by American astronomer Eleanor Helin at the

Palomar Observatory Palomar Observatory is an astronomical research observatory in San Diego County, California, United States, in the Palomar Mountain Range. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...

in California. The presumed

E-type asteroid E-type asteroids are asteroids thought to have enstatite (MgSiO3) achondrite surfaces. They form a large proportion of asteroids inward of the asteroid belt known as Hungaria asteroids, but rapidly become very rare as the asteroid belt proper is ...

is likely spherical in shape and has a short

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 2.99 hours. It was named for American amateur astronomer Robert Holmes. The discovery of its 1-kilometer-sized minor-planet moon was announced in November 2005.

Orbit and classification

''Holmes'' is a core member of the Hungaria family (), a large

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of bright asteroids that forms the innermost dense concentration of asteroids in the

Solar System The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...

, as the

Mars-crosser A Mars-crossing asteroid (MCA, also Mars-crosser, MC) is an asteroid whose orbit crosses that of Mars. Some Mars-crossers numbered below 100000 are listed here. They include the two numbered Mars trojans 5261 Eureka and . Many databases, for ...

and near-Earth populations are much more sparse. The family is part of the larger dynamical group with the same name. It orbits the Sun in the innermost asteroid belt at a distance of 1.8–2.1 AU once every 2 years and 8 months (970 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 lo ...

of 1.92 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- center, in geometry * Eccentricity (graph theory) of a ...

of 0.08 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 Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

of 23 ° with respect to the

ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic agai ...

. 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 with its official discovery observation at Palomar in October 1989.

Physical characteristics

''Holmes'' is an assumed

, which agrees with the overall

spectral type In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting th ...

for members of the Hungaria family.

Rotation period

Since 2005, several rotational

lightcurve In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequ ...

s of ''Holmes'' have been obtained from photometric observations by Brian Warner and

Petr Pravec Petr Pravec (born September 17, 1967) is a Czech astronomer and a discoverer of minor planets, born in Třinec, Czech Republic. Pravec is a prolific discoverer of binary asteroids, expert in photometric observations and rotational lightcurves ...

in collaboration with other astronomers. Analysis of the best-rated lightcurve gave a well-defined

of 2.9940 hours with a consolidated brightness amplitude between 0.10 and 0.12 magnitude, which indicates that the body has a nearly spherical shape (). The asteroid's short period is near that of a fast rotator.

Diameter and albedo

According to the survey carried out by the

NEOWISE Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and SMEX-6) is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 20 ...

mission of NASA's

Wide-field Infrared Survey Explorer Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and SMEX-6) is a NASA infrared astronomy space telescope in the Explorers Program. It was launched in December 2009, and placed in hibernation mode in February 2 ...

(WISE), ''Holmes'' measures 3.147 kilometers in diameter and its surface has an

albedo Albedo (; ) is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that refl ...

of 0.31, while the ''Collaborative Asteroid Lightcurve Link'' adopts

's revised WISE-data, that is, an albedo of 0.2849 and a diameter of 3.21 kilometers based on an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it we ...

of 14.445. Johnston's Archive derives a diameter of 2.95 and 3.15 kilometers for the primary only and for the combined system, respectively.

Satellite

The photometric observations obtained by Brian Warner and collaborators during 2–12 November 2005, revealed that ''Holmes'' is a synchronous

binary asteroid A binary asteroid is a system of two asteroid An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1 ...

with a minor-planet moon orbiting it every 24.4 hours at an estimated average distance of . The discovery was announced immediately on 15 November 2005. The mutual occultation events indicated the presence of a satellite 37% the size of its primary, which translates into an estimated diameter of kilometers depending on the underlying size estimate of the primary.

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 '' ...

was named after American amateur astronomer Robert E. Holmes Jr (born 1956), who directs the Astronomical Research Observatory in Westfield, Illinois. The official naming citation was suggested by

Sergio Foglia 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 obj ...

and published by the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function ...

on 18 February 2011 ().

Notes

References

External links

CBET 288
''

Central Bureau for Astronomical Telegrams The Central Bureau for Astronomical Telegrams (CBAT) is the official international clearing house for information relating to transient astronomical events. The CBAT collects and distributes information on comets, natural satellites, novae, su ...

'', 15 November 2005
Asteroids with Satellites
Robert Johnston, johnstonsarchive.net
Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Minor Planet Center * * {{DEFAULTSORT:Holmes 005477 Discoveries by Eleanor F. Helin Named minor planets 005477 19891027