3749 Balam is a stony

Flora asteroid The Flora family (''adj. Florian''; ; also known as the 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 ...

and rare trinary system orbiting in the inner regions of

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 also forms a secured

asteroid pair An asteroid pair, or (if more than two bodies) an asteroid cluster, are asteroids which at some point in the past had very small relative velocities, and are typically formed either by a collisional break-up of a parent body, or from binary asteroid ...

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, died August 21 2023 in Flagstaff, Arizona), was an American astronomer. Bowell was educated at Emanuel School London, University College, London, and the University of Paris. He was principal invest ...

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 southeast of Lowell's main campus on Mars Hill in F ...

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 the 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 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-Centre (geometry), center, in geometry * Eccentricity (g ...

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 reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of 5 ° 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 ...

Naming

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

Victoria Victoria most commonly refers to: * Queen Victoria (1819–1901), Queen of the United Kingdom and Empress of India * Victoria (state), a state of Australia * Victoria, British Columbia, Canada, a provincial capital * Victoria, Seychelles, the capi ...

'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. Funct ...

on 31 May 1988 ().

Physical characteristics

The

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 ...

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 0.16. The body's

rotation Rotation or rotational/rotary motion is the circular movement of an object around a central line, known as an ''axis of rotation''. A plane figure can rotate in either a clockwise or counterclockwise sense around a perpendicular axis intersect ...

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

Triple 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 (FFRDC) in La Cañada Flintridge, California, Crescenta Valley, United States. Founded in 1936 by California Institute of Technology (Caltech) researche ...

and OSUG, using the Gemini North Telescope on

Mauna Kea Mauna Kea (, ; abbreviation for ''Mauna a Wākea''); is a dormant Shield volcano, shield volcano on the Hawaii (island), island of Hawaii. Its peak is above sea level, making it the List of U.S. states by elevation, highest point in Hawaii a ...

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 be ...

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, 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 ...

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 is a common model for the calculation of a Sphere of influence (astrodynamics), gravitational sphere of influence. It is the most commonly used model to calculate the spatial extent of gravitational influence of an astronomical ...

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 star ...

discovered another satellite from eclipses seen in Balam's

light curve 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 ...

, 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, which does not have a provisional designation, has a derived diameter of 1.66 kilometers, 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 forms an

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 ...

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 nu ...

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