11118 Modra (

provisional designation Provisional designation in astronomy is the naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calcu ...

) is a Flora

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

of uncertain composition from the inner 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 5 kilometers in diameter. It was discovered on 9 August 1996, by Slovak astronomers

Adrián Galád Adrián Galád (born 1970) is a Slovak astronomer and a discoverer of minor planets. He is credited by the Minor Planet Center with the discovery and co-discovery of 81 numbered minor planets between 1995 and 2009, most of them in collaboratio ...

and

Dušan Kalmančok Dušan Kalmančok (born 1945) is a Slovak astronomer and co-discoverer of minor planets. He is credited by the Minor Planet Center with the discovery of 7 asteroids between 1996 and 2000, and significantly contributed to the establishment of th ...

at the

Modra Observatory The Astronomical Observatory of Modra ( sk, Astronomické observatórium Modra), also known as Modra Observatory or the Astronomical and Geophysical observatory in Modra, is an astronomical observatory located in Modra, Slovakia. It is owned and o ...

in Slovakia, and named for the town

Modra Modra (german: Modern, hu, Modor, Latin: ''Modur'') is a city and municipality in the Bratislava Region in Slovakia. It has a population of 9,042 as of 2018. It nestles in the foothills of the Malé Karpaty (Little Carpathian mountains) and is ...

where the discovering observatory is located.

Classification and orbit

Modra 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 ...

, one of the largest families of stony asteroids. 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 2.1–2.5 AU once every 3 years and 6 months (1,286 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 0.08 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 3 ° 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 ...

. A first

precovery In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of an object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This happens mos ...

was taken at ESO's

La Silla Observatory La Silla Observatory is an astronomy, astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory (ESO). Several other telescopes are located at the site and are partly maintained by ESO. The obse ...

in 1991, extending the asteroid'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 ...

by 5 years prior to its discovery.

Rotation period

In September 2010, a photometric

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 ...

analysis of Modra by American astronomer Brian Warner at his Palmer Divide Observatory, Colorado, rendered an unambiguous

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

of hours with a brightness variation of 0.53 in

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 ...

(). A second lightcurve obtained during the wide-field survey at the U.S.

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 August 2010, and gave a period of hours with an amplitude of 0.42 ().

Diameter and albedo

According to the survey carried out by 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 2011, ...

and its subsequent

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 2011, ...

mission, the asteroid has a low

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 0.05. In agreement, the large-scale survey by

Pan-STARRS The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1; List of observatory codes, obs. code: IAU code#F51, F51 and Pan-STARRS2 obs. code: IAU code#F52, F52) located at Haleakala Observatory, Hawaii, US, consists of astronomical c ...

(PS1) rates it as a dark

carbonaceous Carbon () is a chemical element with the chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—its atom making four electrons available to form covalent bond, covalent chemical bonds. It belongs to gro ...

body. However, the ''Collaborative Asteroid Lightcurve Link'' (CALL) assumes a much higher albedo of 0.24 – derived from

8 Flora Flora (minor planet designation: 8 Flora) is a large, bright main-belt asteroid. It is the innermost ''large'' asteroid: no asteroid closer to the Sun has a diameter above 25 kilometres (20% that of Flora), and not until 20-km 149 Medusa was dis ...

, the orbital family's largest member and namesake – and groups it to 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 ...

. The different albedos of the two

spectral classes 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 the ...

also translate into divergent estimates for the body's diameter. While CALL calculates 3.7 kilometers, NASA's space-based survey inferred a much larger diameter of 8.7 kilometers.

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 both the small historical town of

, located in the Bratislava Region of Slovakia, and the

of the Institute of Astronomy at Comenius University, where this asteroid had been discovered. 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 28 September 1999 ().

Classification and orbit

Rotation period

Diameter and albedo

Naming

References

External links