47 Ursae Majoris c
Encyclopedia
47 Ursae Majoris c (sometimes abbreviated 47 Uma c) is an extrasolar planet
approximately 46 light-year
s from Earth in the constellation
of Ursa Major
. The planet was discovered located in a long-period
around the star 47 Ursae Majoris
. Its orbit lasts 6.55 years and the planet has a mass at least 0.540 times that of Jupiter
.
Like the majority of known extrasolar planets, 47 Ursae Majoris c was discovered by detecting changes in its star's radial velocity caused by the planet's gravity. This was done by measuring the Doppler shift of the star's spectrum
.
At the time of discovery in 2001, 47 Ursae Majoris was already known to host one extrasolar planet, designated 47 Ursae Majoris b
. Further measurements of the radial velocity revealed another periodicity in the data unaccounted for by the first planet. This periodicity could be explained by assuming that a second planet, designated 47 Ursae Majoris c, existed in the system with an orbital period
close to 7 years. Observations of the photosphere
of 47 Ursae Majoris suggested that the periodicity could not be explained by stellar activity, making the planet interpretation more likely. The planet was announced in 2002.
Further measurements of 47 Ursae Majoris failed to detect the planet, calling its existence into question. Furthermore, it was noted that the data used to determine its existence left the planet's parameters "almost unconstrained". A more recent study with datasets spanning over 6,900 days came to the conclusion that while the existence of a second planet in the system is likely, periods around 2,500 days have high false-alarm probabilities, and gave a best-fit period of 7,586 days (almost 21 years).
In 2010, a study was published that determined that there are three giant planets orbiting 47 Ursae Majoris, including one at 2,391 days that corresponds well with the original claims for 47 Ursae Majoris c.
, composition, and temperature
are unknown. Based on its high mass, the planet is likely to be a gas giant
with no solid
surface.
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
approximately 46 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s from Earth in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
of Ursa Major
Ursa Major
Ursa Major , also known as the Great Bear, is a constellation visible throughout the year in most of the northern hemisphere. It can best be seen in April...
. The planet was discovered located in a long-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...
around the star 47 Ursae Majoris
47 Ursae Majoris
47 Ursae Majoris is a solar analog, yellow dwarf star approximately 46 light-years away from Earth in the constellation of Ursa Major. , it has been confirmed that three Jupiter-like extrasolar planets orbit the star...
. Its orbit lasts 6.55 years and the planet has a mass at least 0.540 times that of Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
.
Discovery
Spectrum
A spectrum is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. The word saw its first scientific use within the field of optics to describe the rainbow of colors in visible light when separated using a prism; it has since been applied by...
.
At the time of discovery in 2001, 47 Ursae Majoris was already known to host one extrasolar planet, designated 47 Ursae Majoris b
47 Ursae Majoris b
47 Ursae Majoris b is an extrasolar planet approximately 46 light-years from Earth in the constellation of Ursa Major. The planet was discovered located in a long-period orbit around the star 47 Ursae Majoris in January 1996 and as of 2011 is the innermost of three known planets in its planetary...
. Further measurements of the radial velocity revealed another periodicity in the data unaccounted for by the first planet. This periodicity could be explained by assuming that a second planet, designated 47 Ursae Majoris c, existed in the system with an orbital 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...
close to 7 years. Observations of the photosphere
Photosphere
The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, φῶς, φωτός/phos, photos meaning "light" and σφαῖρα/sphaira meaning "sphere", in reference to the fact that it is a spheric surface perceived...
of 47 Ursae Majoris suggested that the periodicity could not be explained by stellar activity, making the planet interpretation more likely. The planet was announced in 2002.
Further measurements of 47 Ursae Majoris failed to detect the planet, calling its existence into question. Furthermore, it was noted that the data used to determine its existence left the planet's parameters "almost unconstrained". A more recent study with datasets spanning over 6,900 days came to the conclusion that while the existence of a second planet in the system is likely, periods around 2,500 days have high false-alarm probabilities, and gave a best-fit period of 7,586 days (almost 21 years).
In 2010, a study was published that determined that there are three giant planets orbiting 47 Ursae Majoris, including one at 2,391 days that corresponds well with the original claims for 47 Ursae Majoris c.
Physical characteristics
Since 47 Ursae Majoris c was detected indirectly, properties such as its radiusRadius
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...
, composition, and temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
are unknown. Based on its high mass, the planet is likely to be a gas giant
Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...
with no solid
Solid
Solid is one of the three classical states of matter . It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a...
surface.
See also
- 47 Ursae Majoris in fiction