HD 147506
Encyclopedia
HD 147506 is a magnitude
8.7 F8 dwarf star that is somewhat larger and hotter than our sun
. The star is 440 light years
from Earth and is positioned near the keystone of Hercules
.
It is estimated to be 2 to 3 billion years old.
, the most massive transiting extrasolar planet
yet discovered. At 9.04 MJ and an estimated surface temperature of ~900 kelvin
s, on a 5.6 day orbit, this planet is unlike any previously discovered transiting
planet. The planet has a large mass
(nine times the mass of Jupiter
), and a surface gravity 25 times that exerted by the Earth. Its orbital eccentricity
is very large (e = 0.5). Since tidal forces should have reduced the orbital eccentricity of this planet it is speculated that another massive planet found outside the orbit of HAT-P-2b is in orbital resonance
with HAT-P-2b.
The planet was discovered by the HATNet Project
and the researchers there believed the planet to be 10-20% larger than Jupiter. This discovery is important as it provides further support for the existing theory of planetary structure.
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...
8.7 F8 dwarf star that is somewhat larger and hotter than our 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...
. The star is 440 light years
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"....
from Earth and is positioned near the keystone of 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...
.
It is estimated to be 2 to 3 billion years old.
Planetary system
Orbiting the star is HAT-P-2bHAT-P-2b
HAT-P-2b is an extrasolar planet detected by the HATNet Project in May 2007. It orbits a class F star, , located about 440 light-years away in the constellation Hercules...
, the most massive transiting extrasolar planet
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...
yet discovered. At 9.04 MJ and an estimated surface temperature of ~900 kelvin
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...
s, on a 5.6 day orbit, this planet is unlike any previously discovered transiting
Astronomical transit
The term transit or astronomical transit has three meanings in astronomy:* A transit is the astronomical event that occurs when one celestial body appears to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point...
planet. The planet has a large 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:...
(nine times the mass 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,...
), and a surface gravity 25 times that exerted by the Earth. Its orbital eccentricity
Orbital eccentricity
The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...
is very large (e = 0.5). Since tidal forces should have reduced the orbital eccentricity of this planet it is speculated that another massive planet found outside the orbit of HAT-P-2b is in orbital resonance
Orbital resonance
In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other, usually due to their orbital periods being related by a ratio of two small integers. Orbital resonances greatly enhance the mutual gravitational influence of...
with HAT-P-2b.
The planet was discovered by the HATNet Project
HATNet Project
The Hungarian Automated Telescope Network project is a network of six small fully automated "HAT" telescopes. The scientific goal of the project is to detect and characterize extrasolar planets using the transit method. This network is used also to find and follow bright variable stars...
and the researchers there believed the planet to be 10-20% larger than Jupiter. This discovery is important as it provides further support for the existing theory of planetary structure.