TrES-4
Encyclopedia
TrES-4b is an extrasolar planet
discovered in 2006 and announced in 2007 by the Trans-Atlantic Exoplanet Survey
using the transit method. It is 1400 ly away in the constellation Hercules
.
TrES-4 orbits its primary star GSC 02620-00648
every 3.5 days and eclipses it when viewed from Earth
. It is 0.919 times as massive as Jupiter
but 1.799 times the diameter, the largest planet ever found (next to WASP-17b
, and that was on 1 May 2009), giving it an average density of only about 0.333 grams per cubic centimetre. This made TrES-4 both the largest known planet and the planet with the lowest known density at the time of its discovery.
TrES-4's orbital radius is 0.05091 AU
, giving it a predicted surface temperature of about 1782 K
. This by itself is not enough to explain the planet's low density, however. It is not currently known why TrES-4 is so large. The probable cause is the proximity to a parent star that is 3–4 times more luminous than the Sun
and the internal heat
within the planet.
A 2008 study concluded that the GSC 06200-00648 system (among others) is a binary star
system allowing even more accurate determination of stellar and planetary parameters.
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...
discovered in 2006 and announced in 2007 by the Trans-Atlantic Exoplanet Survey
Trans-Atlantic Exoplanet Survey
The Trans-atlantic Exoplanet Survey or TrES, uses three 4-inch telescopes located at Lowell Observatory, Palomar Observatory, and the Canary Islands to locate exoplanets. It was made using the network of small, relatively inexpensive telescopes designed to look specifically for planets orbiting...
using the transit method. It is 1400 ly away in the constellation Hercules
Hercules (constellation)
Hercules is a constellation named after Hercules, the Roman mythological hero adapted from the Greek hero Heracles. Hercules was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations today...
.
TrES-4 orbits its primary star GSC 02620-00648
GSC 02620-00648
GSC 02620-00648 A is a magnitude 12 star located approximately 1400 light-years away in the constellation of Hercules. This star is about 1.18 times as massive as the Sun.- Planetary system :...
every 3.5 days and eclipses it when viewed from Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
. It is 0.919 times as massive as 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,...
but 1.799 times the diameter, the largest planet ever found (next to WASP-17b
WASP-17b
WASP-17b is an exoplanet in the constellation Scorpius that is orbiting the star WASP-17. Its discovery was announced on 11 August 2009. It is the first planet discovered to have a retrograde orbit, meaning it orbits in a direction counter to the rotation of its host star. This discovery changed...
, and that was on 1 May 2009), giving it an average density of only about 0.333 grams per cubic centimetre. This made TrES-4 both the largest known planet and the planet with the lowest known density at the time of its discovery.
TrES-4's orbital radius is 0.05091 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
, giving it a predicted surface temperature of about 1782 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
. This by itself is not enough to explain the planet's low density, however. It is not currently known why TrES-4 is so large. The probable cause is the proximity to a parent star that is 3–4 times more luminous than the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
and the internal heat
Internal heat
Internal heat is the heat source from the interior of celestial objects, such as planets, brown dwarfs, and stars, caused by gravity, nuclear fusion and decaying radioactive materials. The amount of internal heating depends on mass; the more massive the object, the more internal heat it has...
within the planet.
A 2008 study concluded that the GSC 06200-00648 system (among others) is a binary star
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...
system allowing even more accurate determination of stellar and planetary parameters.
See also
- List of extrasolar planet extremes
- VY Canis MajorisVY Canis MajorisVY Canis Majoris is the largest known star and also one of the most luminous. Located in the constellation Canis Major, it is a red hypergiant, between 1800 and 2100 solar radii, 8.4–9.8 astronomical units in radius, about 3.0 billion km or 1.9 billion miles in diameter, and about 1.5 kiloparsecs ...
, the largest known star - WASP-17bWASP-17bWASP-17b is an exoplanet in the constellation Scorpius that is orbiting the star WASP-17. Its discovery was announced on 11 August 2009. It is the first planet discovered to have a retrograde orbit, meaning it orbits in a direction counter to the rotation of its host star. This discovery changed...
, another large exoplanet