3749 Balam is a stony Flora asteroid and rare trinary system orbiting in the inner regions of

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 ...

. It also forms a secured asteroid pair with sub-kilometer sized asteroid . ''Balam'' was discovered on 24 January 1982, by American astronomer

Edward Bowell Edward L. G. "Ted" Bowell (born 1943 in London), is an American astronomer. Bowell was educated at Emanuel School London, University College, London, and the University of Paris. He was principal investigator of the Lowell Observatory Near-Earth ...

at Lowell's

Anderson Mesa Station Anderson Mesa Station is an astronomical observatory established in 1959 as a dark-sky observing site for Lowell Observatory. It is located at Anderson Mesa in Coconino County, Arizona, about 12 miles southeast of Lowell's main campus on Mars ...

near Flagstaff, Arizona, and received the prov. designation . It was named after Canadian astronomer David Balam. ''Balam'' measures approximately in diameter. Its two

minor-planet moon A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. , there are 457 minor planets known or suspected to have moons. Discoveries of minor-planet moons (and binary objects, in general) are important ...

s have an estimated diameter of 1.66 and 1.84 kilometers, respectively.

Orbit and classification

''Balam'' is a member of the

Flora family The Flora family (''adj. Florian''; ; also known as ''Ariadne family'') is a prominent family of stony asteroids located in the inner region of the asteroid belt. It is one of the largest families with more than 13,000 known members, or approx ...

, a very large group of stony asteroids in the inner main-belt. It 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 2.0–2.5 AU once every 3 years and 4 months (1,222 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-center, in geometry * Eccentricity (graph theory) of a v ...

of 0.11 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 5 ° 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 again ...

Naming

It is named after the Canadian astronomer David Balam, principal observer at

Victoria Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seychelle ...

's Climenhaga Observatory in British Columbia. The approved naming citation was 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 31 May 1988 ().

Physical characteristics

The

S-type asteroid S-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 of this type, making it the second ...

has an

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, 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 ...

of 0.16. The body's

rotation Rotation, or spin, is the circular movement of an object around a '' central axis''. A two-dimensional rotating object has only one possible central axis and can rotate in either a clockwise or counterclockwise direction. A three-dimensional ...

around its axis has been measured several times by different lightcurve observations with a concurring period of 2.8 hours.

Trinary asteroid

Outer satellite

On 13 February 2002, the discovery of a

, provisionally designated , was announced by a team of researchers from SwRI, UA,

JPL The Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, United States. Founded in the 1930s by Caltech researchers, JPL is owned by NASA an ...

and OSUG, using the

Gemini North Telescope The Gemini Observatory is an astronomical observatory consisting of two 8.1-metre (26.6 ft) telescopes, Gemini North and Gemini South, which are located at two separate sites in Hawaii and Chile, respectively. The twin Gemini telescopes prov ...

Mauna Kea Mauna Kea ( or ; ; abbreviation for ''Mauna a Wākea''); is a dormant volcano on the island of Hawaii. Its peak is above sea level, making it the highest point in the state of Hawaii and second-highest peak of an island on Earth. The peak is ...

in Hawaii. It has an estimated diameter of 1.84 kilometers. It orbits km away in days, with a high

orbital eccentricity In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values betwee ...

of ~ 0.9. The distant and highly eccentric orbit of S/2002 (3749) 1 suggests that it was likely captured by Balam. Being such a small primary body in the inner

main 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 ...

with a separation of over 100 primary radii, S/2002 (3749) 1 is the most loosely bound binary known. Balam has a

Hill sphere The Hill sphere of an astronomical body is the region in which it dominates the attraction of satellites. To be retained by a planet, a moon must have an orbit that lies within the planet's Hill sphere. That moon would, in turn, have a Hill sp ...

with a radius of about 1,500 kilometers.

Inner satellite

In March 2008,

Franck Marchis Franck Marchis (born April 6, 1973 in Caen, France), astronomer and planetary scientist, is best known for his discovery and characterization of multiple asteroids, his study of Io volcanism and imaging of exoplanets, planets around other stars ...

discovered another companion, provisionally designated , making ''Balam'' a

trinary asteroid A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. , there are 457 minor planets known or suspected to have moons. Discoveries of minor-planet moons (and binary objects, in general) are important ...

. The inner satellite has a derived diameter of 1.66 kilometer, based on diameter-ratio of with its primary. Other known trinary asteroids include 45 Eugenia, 87 Sylvia, 93 Minerva, 107 Camilla, 130 Elektra and 216 Kleopatra.

Asteroid pair

''Balam'' also forms an asteroid pair with . Asteroid pairs are on highly similar

heliocentric orbit A heliocentric orbit (also called circumsolar orbit) is an orbit around the barycenter of the Solar System, which is usually located within or very near the surface of the Sun. All planets, comets, and asteroids in the Solar System, and the Sun i ...

s. At some point in the past, the pair of asteroids became gravitationally unbound due to ''rotational fission'' induced by the YORP-effect or from a collisional breakup of the parent body. After the discovery of ''Balam''s two satellites by Bill Merline (inner moon) and

(outer moon) in 2002 and 2008, respectively, Czech physicist David Vokrouhlický identified the unbound secondary in 2009. Based on backward orbit integrations, it is thought that ''Balam'' and ' form a secured asteroid pair that became separated approximately 400,000 years ago.

Notes

References

External links

IAUC 7827

Orbits of Binary Asteroids with Adaptive Optics
( VLT images)
Lightcurve Database Query
(LCDB), at ''www.minorplanet.info''

– ''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 numb ...

* * {{DEFAULTSORT:Balam 003749 Discoveries by Edward L. G. Bowell Named minor planets 003749 19820124