CD-66 2307 / HD 181433
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© Torben Krogh & Mogens Winther,
(Amtsgymnasiet and EUC Syd Gallery,
student photo used with permission)
HD 181433 is an orange-red star (similar to
Epsilon Eridani at left center of meteor) that
may have already evolved into a subgiant, but
is probably not yet a giant, star. (A 2MASS
Survey image of HD 181433 at the NASA Star
and Exoplanet Database may become available.)
HD 181433 is located around 85.3 +/- 3.3 light-years (ly)
from Sol. The star lies near the center
(19:25:9.6-66:28:7.7, ICRS 2000.0) of Constellation
the Peacock -- slight southeast of
Delta Pavonis, west of
Beta Pavonis, southwest of
(Alpha Pavonis), and northeast of Epsilon Pavonis. On
June 16, 2008, a team of astronomers announced at the 2008
Solar Super-Earths Workshop in France their discovery of a
class planet in a tight orbit around this star with with two other
gas planets in outer orbits (ESO
Bouchy et al, 2009 -- more
details below). (See an animation of the
planetary and potentially
habitable zone orbits of this system, with a table of
basic orbital and physical characteristics.)
Today, many astronomers refer to this star as HD 181433, as designated in the Henry Draper (1837-82) Catalogue with subsequent extension (HDE), a massive photographic stellar spectrum survey carried out by Annie Jump Cannon (1863-1941) and Edward Charles Pickering (1846-1919) from 1911 to 1915 under the sponsorship of a memorial fund created by Henry's wife, Anna Mary Palmer. However, it was probably first designated as CD-66 2307 in a visual survey of southern stars begun in 1892 at the Astronomical Observatory of Cordoba in Argentina under the direction of its second director John M. Thome (1843-1908). Thome died before the completion of this southern sky atlas in 1914, when 578,802 stars from declination -22° to -90° were published as the Cordoba Durchmusterung ("Survey"). The "CD" is an extension of an older catalogue by Friedrich Wilhelm August Argelander (1799-1875) in 1863 on the position and brightness of 324,198 stars between +90° and -2° declination that were measured over 11 years from Bonn, Germany, made with his assistants Eduard Schönfeld (1828-1891) and Aldalbert Krüger (1832-1896), which became famous as the Bonner Durchmusterung ("Bonn Survey") abbreviated as BD. The BD and CD were greatly expanded and extended into the modern age of photographic surveys with the subsequent creation of the Cape Photographic Durchmusterung from South Africa.
HD 181433 may be a subgiant rather than a main-sequence, orange-red dwarf star (Sousa et al, 2008; and ARICNS), but is probably not an giant, star (SIMBAD) of spectral and luminosity type K3-5 V-III. The star probably has a mass somewhat smaller (around 78 percent) than Sol's (Sousa et al, 2008; and NASA Star and Exoplanet Database, derived from Kenneth R. Lang, 1980), and it appears to have only around 78.7 percent of its diameter (Masana et al, 2006). Most revealing, HD 181433 only has around 25 percent of Sol's visual and around 31 to 34 percent of its bolometric luminosity (Sousa et al, 2008; and Nordström et al, 2004; NASA Star and Exoplanet Database, derived from Kenneth R. Lang, 1980; and ARICNS). It appears to be around 1.8 to 2.1 times as enriched as Sol in iron relative to the abundance of hydrogen and nearly 3.2 times as enriched as Sol in elements other than hydrogen, helium, and iron (Sousa et al, 2008; Gray et al, 2006; and Kotoneva et al, 2002). If HD 181433 has a mass less than Sol's but is more evolved (i.e., where it may have already shut down hydrogen fusion in its helium-rich core), then it may be significantly older than Sol's 4.6 billion years. Useful catalogue numbers and designations for the star include: Gl/GJ 756.1, Hip 95467, HD 181433, CD-66 2307, CPD-66 3431, SAO 254563, LTT 7669, and 2MASS J19250951-6628075.
Larger and jumbo illustrations
(more images and videos).
Planetary candidate "b" is a "super-Earth"
class planet with 7.5 Earth-masses in a
tight orbit. It may be rocky and have
atmospheres with clouds, like Gliese 876 d,
as imagined by Schindler (more).
On June 16, 2008, a team of astronomers announced at the 2008 Extra Solar Super-Earths Workshop in France their discovery of one "super-Earth" type planet in a tight orbit around this star with two other gas giant planets in outer orbits (ESO press release and Bouchy et al, 2009). Planet "b" has 7.5 Earth-masses at an average orbital distance of 0.08 with a period of only 9.5 days and an orbital eccentricity near 0.40. Moving outwards from host star, planet "c" has 72 percent of Jupiter's mass and an orbital period of 2.8 years (1,024 days) with an average orbital distance of 1.76 AUs and eccentricity around 0.28. Lastly, there may be an additional third planet "d," which may have around 54 percent of Jupiter's mass and an average orbital distance of around 3 AUs with a period of around 6 years (2,172 +/- 158 and an eccentricity near 0.48. (Bouchy et al, 2009).
If you include infrared radiation, the orbit of an Earth-like planet with surface water would be centered around 0.57 AU -- between the orbital distances of Mercury and Venus in the Solar System. Such an orbit would take around six months to complete. It is possible, however, that the presence of massive planetary candidate c at an orbital distance around two AUs could disrupt the orbital stability of an Earth-mass planet in the habitable zone. Astronomers would find it very difficult to detect an Earth-sized planet around this star using present methods. (See an animation of the planetary and potentially habitable zone orbits of this system, with a table of basic orbital and physical characteristics.)
The following table includes all star systems known to be located within 10 light-years (ly), plus more bright stars within 10 to 20 ly, of HD 181433.
|Star System||Spectra &|
|L 79-24||M V||8.8|
|* plus bright stars *||. . .|
|HR 7012||A5-7 V-IV||12|
|CD-63 1343||F9 V||15|
|Phi1 Pavonis||F1 III||16|
|Phi2 Pavonis||F8 V||16|
|HR 7674||F8 V||20|
Up-to-date technical data on these stars may be found at: Jean Schneider's Extrasolar Planets Encyclopaedia; the Astronomiches Rechen-Institut at Heidelberg's ARICNS, the NASA Star and Exoplanet Database, the HIPPARCOS Catalogue; NASA's ADS Abstract Service for the Astrophysics Data System; and the SIMBAD Astronomical Database.
Constellation Draco is associated with the dragon slain by Cadmus, Observable only in the southern hemisphere, Constellation Pavo is located between Telescopium to the north and Octans to the south. For more information about the stars and objects in this constellation, go to Christine Kronberg's Pavo. For an illustration, see David Haworth's Pavo.
For more information about stars including spectral and luminosity class codes, go to ChView's webpage on The Stars of the Milky Way.
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