OGLE-TR-123
Encyclopedia
|-
! style="background-color: #FFFFC0;" colspan="2" | Characteristics
|-
| Spectral type
| F (primary)/M (b)
|- style="vertical-align: top;"
| Apparent magnitude
(infrared, I band)
| 15.40 (system)
|- style="vertical-align: top;"
| Variable type
| Eclipsing binary
|-
! style="background-color: #FFFFC0;" colspan="2" | Astrometry
|- style="vertical-align: top;"
| Distance
| 5000 ± 1000 ly
(1600 ± 400 pc
)
|-
! style="background-color: #FFFFC0;" colspan="2" | Binary orbit
|- style="vertical-align: top;"
| Period
(P)
| 1.804 day
s
|- style="vertical-align: top;"
| Eccentricity (e)
| 0
|- style="vertical-align: top;"
| Semi-major axis
| 0.031 ± 0.002 AU
|- style="vertical-align: top;"
| Inclination
(i)
| 86–90°
OGLE-TR-123 is a binary
stellar system containing one of the smallest main-sequence star
s whose radius
has been measured. It was discovered when the Optical Gravitational Lensing Experiment
(OGLE) survey observed the smaller star eclipsing the larger primary. The orbital period is approximately 1.80 days.
The smaller star, OGLE-TR-123b, is estimated to have a radius
around 0.13 solar radii, and a mass
of around 0.085 solar mass
es, or approximately 90 times Jupiter's. OGLE-TR-123b's mass is close to the lowest possible mass, estimated to be around 0.07 or 0.08 solar masses, for a hydrogen
-fusing star. OGLE-TR-123b is the second star with mass less than 0.1 solar mass
whose radius has been directly measured; the first such star was the similar OGLE-TR-122b
.
! style="background-color: #FFFFC0;" colspan="2" | Characteristics
|-
| Spectral type
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
| F (primary)/M (b)
|- style="vertical-align: top;"
| Apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
(infrared, I band)
| 15.40 (system)
|- style="vertical-align: top;"
| Variable type
Variable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
| Eclipsing binary
|-
! style="background-color: #FFFFC0;" colspan="2" | Astrometry
|- style="vertical-align: top;"
| Distance
Cosmic distance ladder
The cosmic distance ladder is the succession of methods by which astronomers determine the distances to celestial objects. A real direct distance measurement of an astronomical object is possible only for those objects that are "close enough" to Earth...
| 5000 ± 1000 ly
Light Years
Light Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....
(1600 ± 400 pc
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
)
|-
! style="background-color: #FFFFC0;" colspan="2" | Binary orbit
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
|- style="vertical-align: top;"
| Period
Orbital period
The orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of...
(P)
| 1.804 day
Day
A day is a unit of time, commonly defined as an interval equal to 24 hours. It also can mean that portion of the full day during which a location is illuminated by the light of the sun...
s
|- style="vertical-align: top;"
| Eccentricity (e)
| 0
|- style="vertical-align: top;"
| Semi-major axis
Semi-major axis
The major axis of an ellipse is its longest diameter, a line that runs through the centre and both foci, its ends being at the widest points of the shape...
| 0.031 ± 0.002 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
|- style="vertical-align: top;"
| Inclination
Inclination
Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...
(i)
| 86–90°
OGLE-TR-123 is a binary
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
stellar system containing one of the smallest main-sequence star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
s whose radius
Radius
In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...
has been measured. It was discovered when the Optical Gravitational Lensing Experiment
Optical Gravitational Lensing Experiment
The Optical Gravitational Lensing Experiment or OGLE is a Polish astronomical project based at the University of Warsaw that is chiefly concerned with discovering dark matter using the microlensing technique. Since the project began in 1992, it has discovered several extrasolar planets as a side...
(OGLE) survey observed the smaller star eclipsing the larger primary. The orbital period is approximately 1.80 days.
The smaller star, OGLE-TR-123b, is estimated to have a radius
Radius
In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...
around 0.13 solar radii, and a mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
of around 0.085 solar mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
es, or approximately 90 times Jupiter's. OGLE-TR-123b's mass is close to the lowest possible mass, estimated to be around 0.07 or 0.08 solar masses, for a hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
-fusing star. OGLE-TR-123b is the second star with mass less than 0.1 solar mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
whose radius has been directly measured; the first such star was the similar OGLE-TR-122b
OGLE-TR-122b
|-! style="background-color: #FFFFC0;" colspan="2" | Characteristics|-| Spectral type | ? /M |- style="vertical-align: top;"| Apparent magnitude '| 15.61 |- style="vertical-align: top;"...
.