1545 Thernöe ( ''prov. designation'': ) is an 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 central region 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 15 October 1941, by Finnish astronomer

Liisi Oterma Liisi Oterma (; 6 January 1915 – 4 April 2001) was a Finnish astronomer, the first woman to get a Ph.D. degree in astronomy in Finland. She studied mathematics and astronomy at the University of Turku, and soon became Yrjö Väisälä's assi ...

Turku Observatory Turku ( ; ; , ) is a city in Finland and the regional capital of Southwest Finland. It is located on the southwestern coast of the country at the mouth of the Aura River (Finland), River Aura. The population of Turku is approximately , while t ...

in Southwest Finland. The uncommon

K-type asteroid K-type asteroids are relatively uncommon asteroids with a moderately reddish spectrum shortwards of 0.75 μm, and a slight bluish trend longwards of this. They have a low albedo. Their spectrum resembles that of CV and CO meteorites. A larger K ty ...

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 16.1 hours and measures approximately in diameter. It was later named after Danish astronomer Karl August Thernöe.

Orbit

''Thernöe'' orbits the Sun in the central main-belt at a distance of 2.1–3.4 AU once every 4 years and 7 months (1,684 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 0.24 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 3 ° 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 ...

. It was first identified as 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 ...

in 1906, extending 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 ...

by 35 years prior to its official discovery observation at Turku.

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 Karl August Thernöe (1911–1987), Danish astronomer and celestial mechanic at

Østervold Observatory Østervold Observatory (or Copenhagen University Observatory; ) is a former astronomical observatory ( IAU code 035) in Copenhagen, Denmark owned and operated by the University of Copenhagen (Københavns Universitet). It opened in 1861 as a repla ...

in Copenhagen. He was also a popularizer of astronomy and director of

IAU The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

's ''

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

'' during 1950–1964. The official 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 20 February 1976 ().

Physical characteristics

Spectral type

In the SMASS taxonomy, ''Thernöe'' is classified as a rare

, a newly introduced subtype that belongs to the broader S-complex of stony bodies. Conversely, CALL groups ''Thernöe'' into the carbonaceous C-complex.

Rotation period and pole

In December 2006, 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 ''Thernöe'' was obtained from photometric observations by French amateur astronomer René Roy. Lightcurve analysis gave a well-defined

of 17.20 hours with a brightness variation of 0.76

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 ...

(). The high lightcurve-amplitude of 0.76 indicates that the body has a non-spheroidal shape. A 2016-published lightcurve, using modeled photometric data from the Lowell Photometric Database, gave a concurring period of 17.20321 hours, as well as a

spin axis 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 ...

of (164.0°, −5.0°) 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 surveys carried out by the Infrared Astronomical Satellite

IRAS The Infrared Astronomical Satellite (Dutch language, Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a astronomical survey, survey of the entire night sky at infrared wavelengths. Launched on 25 Janu ...

, the Japanese

Akari AKARI (ASTRO-F) was an infrared astronomy satellite developed by Japan Aerospace Exploration Agency, in cooperation with institutes of Europe and Korea. It was launched on 21 February 2006, at 21:28 UTC (06:28, 22 February JST) by M-V rocket ...

satellite, and 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 ...

with its subsequent

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, ''Thernöe'' measures between 16.12 and 19.37 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 ...

between 0.092 and 0.13. The ''Collaborative Asteroid Lightcurve Link'' (CALL) adopts the results obtained by IRAS, that is, an albedo of 0.0962 and diameter of 18.71 kilometers with an absolute magnitude of 11.8.

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:Thernoe 001545 Discoveries by Liisi Oterma Named minor planets 001545 19411015