HD 156668
Encyclopedia
HD 156668 is an orange dwarf
star
found in the Hercules constellation
which is approximately 78.4 light-year
s away from the earth. The star has only about 27% of the Sun’s
bolometric luminosity including a mass approximately 72% less and about 75% of its diameter. The star appears to have 85% enriched in iron
in relation to the abundance of hydrogen
as the Sun.
wife financed the study, it was also her husband who was responsible for the star’s designation in the Henry Draper Catalogue with subsequent extension (HD)
although it was first designated as BD+29 2979 in the original catalogue that was published in 1863 by Friedrich Wilhelm Argelander
due to its position and brightness of 324,198 stars between +90° and -2° declination in the span of an 11 year observation. A number of proper motion surveys
was published in 1957 where 9,867 stars in the Southern hemisphere where high proper motion was detected. The name BD was taken from a catalogue of the Bonner Durchmusterung (Bonn Survey)
where observations are abbreviated as BD. Latter study expansions were carried out by the Cape Photographic Durchmusterung observatory in Córdoba, Argentina
and further extensions by Henry Lee Giclas who designated the star as G 181-34 in the Giclas catalogues
. From 1990 to 1993, HD 156668 was observed at least twice and was featured at the 6th annual catalog of the Tokyo Photoelectric Meridian Circle (PMC) where it is one of 6649 stars observed.
in orbit around HD 156668. This planet is designated HD 156668 b. The announcement was made at the 215th American Astronomical Society meeting on January 4 to 7, 2010 in Washington D.C.. The planet orbits its star in only 4.6 days with a distance approximately 0.05 AU away from the parent star. The researchers used the wobble method
where the resulting spectrum showed color shifts which was used to approximate the mass of the astronomical object. The observation revealed data that the exoplanet was at least 4.15 Earth masses. Later observations revealed that the minimum mass
is now 3.1 Earth masses.
Orange dwarf
A K-type main-sequence star , also referred to orange dwarf, are main-sequence stars of spectral type K and luminosity class V. These stars are intermediate in size between red M-type main-sequence stars and yellow G-type main-sequence stars...
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...
found in the Hercules constellation
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...
which is approximately 78.4 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 away from the earth. The star has only about 27% of the Sun’s
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...
bolometric luminosity including a mass approximately 72% less and about 75% of its diameter. The star appears to have 85% enriched in iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
in relation to the abundance of 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...
as the Sun.
Observations
From 1911 to 1915, Photographic Stellar Spectrum surveys have been carried out by Annie Jump Cannon and Edward Charles Pickering. Anna Mary Palmer who was Henry Draper’sHenry Draper
Henry Draper was an American doctor and amateur astronomer. He is best known today as a pioneer of astrophotography.-Life and work:...
wife financed the study, it was also her husband who was responsible for the star’s designation in the Henry Draper Catalogue with subsequent extension (HD)
Henry Draper Catalogue
The Henry Draper Catalogue is an astronomical star catalogue published between 1918 and 1924, giving spectroscopic classifications for 225,300 stars; it was later expanded by the Henry Draper Extension , published between 1925 and 1936, which gave classifications for 46,850 more stars, and by the...
although it was first designated as BD+29 2979 in the original catalogue that was published in 1863 by Friedrich Wilhelm Argelander
Friedrich Wilhelm Argelander
Friedrich Wilhelm August Argelander was a German astronomer. He is known for his determinations of stellar brightnesses, positions, and distances.- Life and work :...
due to its position and brightness of 324,198 stars between +90° and -2° declination in the span of an 11 year observation. A number of proper motion surveys
Proper motion
The proper motion of a star is its angular change in position over time as seen from the center of mass of the solar system. It is measured in seconds of arc per year, arcsec/yr, where 3600 arcseconds equal one degree. This contrasts with radial velocity, which is the time rate of change in...
was published in 1957 where 9,867 stars in the Southern hemisphere where high proper motion was detected. The name BD was taken from a catalogue of the Bonner Durchmusterung (Bonn Survey)
Durchmusterung
In astronomy, Durchmusterung or Bonner Durchmusterung , is the usual name for three comprehensive astrometric star catalogues of the whole sky, processed by the Bonn Observatory from 1859 to 1903....
where observations are abbreviated as BD. Latter study expansions were carried out by the Cape Photographic Durchmusterung observatory in Córdoba, Argentina
Córdoba, Argentina
Córdoba is a city located near the geographical center of Argentina, in the foothills of the Sierras Chicas on the Suquía River, about northwest of Buenos Aires. It is the capital of Córdoba Province. Córdoba is the second-largest city in Argentina after the federal capital Buenos Aires, with...
and further extensions by Henry Lee Giclas who designated the star as G 181-34 in the Giclas catalogues
Star catalogue
A star catalogue, or star catalog, is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this article covers only some...
. From 1990 to 1993, HD 156668 was observed at least twice and was featured at the 6th annual catalog of the Tokyo Photoelectric Meridian Circle (PMC) where it is one of 6649 stars observed.
Super-Earth
Andrew Howard announced the discovery of a Super-EarthSuper-Earth
A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below the mass of the Solar System's gas giants. The term super-Earth refers only to the mass of the planet, and does not imply anything about the surface conditions or habitability...
in orbit around HD 156668. This planet is designated HD 156668 b. The announcement was made at the 215th American Astronomical Society meeting on January 4 to 7, 2010 in Washington D.C.. The planet orbits its star in only 4.6 days with a distance approximately 0.05 AU away from the parent star. The researchers used the wobble method
Doppler spectroscopy
Doppler spectroscopy, also known as radial velocity measurement, is a spectroscopic method for finding extrasolar planets. It involves the observation of Doppler shifts in the spectrum of the star around which the planet orbits....
where the resulting spectrum showed color shifts which was used to approximate the mass of the astronomical object. The observation revealed data that the exoplanet was at least 4.15 Earth masses. Later observations revealed that the minimum mass
Minimum mass
In astronomy, minimum mass is the lower-bound calculated mass of observed objects such as planets, stars and binary systems, nebulae, and black holes. Minimum mass is a widely cited statistic for extrasolar planets...
is now 3.1 Earth masses.