N2K Consortium
Encyclopedia
The N2K Consortium is a collaborative multinational effort by American
, Chile
an and Japan
ese astronomers to find additional extrasolar planet
s around stars that are
not already being surveyed. The N2K is shorthand for the set of roughly 2,000 of the nearest and most luminous main sequence stars that were selected to be newly surveyed. Target stars have a B - V
color index
value between 0.4 and 1.2, a visual magnitude brighter than 10.5, and a distance of less than 110 pc
from the Sun
. They were selected based upon their high metallicity
, which is the abundance of elements other than hydrogen and helium.
The observing campaign uses the Keck, Magellan
and Subaru telescopes, plus automated telescopes at Fairborn Observatory. Each star is observed three times over a period of several days, then checked for short period variations in radial velocity. This variation is a characteristic of gravitational perturbation caused by a hot Jupiter. Those stars showing radial velocity variations are then checked with the automated photometric telescopes from Fairborn Observatory.
During a two year run beginning in 2004, the N2K Consortium was predicted to detect about 60 new hot Jupiters. However, by 2009, only seven planets with orbital periods of up to five days had been discovered. They orbit the following stars:
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
an and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
ese astronomers to find additional 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...
s around stars that are
not already being surveyed. The N2K is shorthand for the set of roughly 2,000 of the nearest and most luminous main sequence stars that were selected to be newly surveyed. Target stars have a B - V
color index
Color index
In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature...
value between 0.4 and 1.2, a visual magnitude brighter than 10.5, and a distance of less than 110 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 ....
from 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...
. They were selected based upon their high metallicity
Metallicity
In astronomy and physical cosmology, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium...
, which is the abundance of elements other than hydrogen and helium.
The observing campaign uses the Keck, Magellan
Magellan telescopes
The Magellan Telescopes are a pair of 6.5 m diameter optical telescopes located at Las Campanas Observatory in Chile. The two telescopes are named after the astronomer Walter Baade and the philanthropist Landon T...
and Subaru telescopes, plus automated telescopes at Fairborn Observatory. Each star is observed three times over a period of several days, then checked for short period variations in radial velocity. This variation is a characteristic of gravitational perturbation caused by a hot Jupiter. Those stars showing radial velocity variations are then checked with the automated photometric telescopes from Fairborn Observatory.
During a two year run beginning in 2004, the N2K Consortium was predicted to detect about 60 new hot Jupiters. However, by 2009, only seven planets with orbital periods of up to five days had been discovered. They orbit the following stars:
- HD 33283HD 33283HD 33283 is an 8th magnitude star in the constellation Lepus. It is located 86.88 parsecs away from the solar system. HD 33283 is similar to our Sun in terms of spectral type [G4V]. However, the star dwarfs the Sun by 24% more massive, 20% larger, 217 K hotter, and 232% more metals...
- HD 86081HD 86081HD 86081 is a yellow-white dwarf star in the constellation Sextans south of the celestial equator. It is bigger and more massive at 1.22 and 1.21 solar units respectively. It has temperature of 6028 K and luminosity of 1.75 solar....
- HD 88133HD 88133HD 88133 is an 8th magnitude star in the constellation of Leo. It is classified as a yellow subgiant star . It is slightly more massive than our Sun, cooler and more luminous. As a subgiant, it has left the main sequence and started to evolve towards red gianthood...
- HD 109749HD 109749HD 109749 is a yellow subgiant star about 192 light years away in the constellation of Centaurus. Its mass is 1.2 solar and effective temperature 5610 kelvins. In 2005 a planet was discovered by Debra Fischer....
- HD 149026HD 149026HD 149026 is a yellow subgiant star approximately 257 light-years away in the constellation of Hercules. The star is thought to be much more massive, larger, and brighter than the Sun. , an extrasolar planet has been confirmed to be orbiting the star...
- HD 149143HD 149143HD 149143 is a star located in Ophiuchus constellation that has spectral type of G0 located at a distance of 207 ly from us. Its apparent magnitude is 7.9 and the absolute magnitude is 3.9....
- HD 224693HD 224693HD 224693 is a yellow subgiant star approximately 320 light-years away in the constellation Cetus.-Planetary system:...