HD 10647 / HR 506 / CP(D)-54 365 (q1 Eridani)
|Home | Stars | Orbits | Habitability | Life ||
This star is located about 56.6 light-years from Sol. It lies in the southwest corner of (1:42:29.3-53:44:27.0, ICRS 2000.0) of Constellation Eridanus, the River -- northeast of Achernar (Alpha Eridani) and southwest of Chi, Phi, Kappa, and Theta1,2 Eridani (Acamar). In 2003, astronomers announced the discovery of a Jupiter-class planet around this Sun-like star (Observatoire de Genève page on HD 10647 -- 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.) As HD 10647 has become one of the top 100 target stars for NASA's planned Terrestrial Planet Finder (TPF), images of this star and its position relative to the Milky Way in Earth's night sky are now available from the TPF-C team.
Although more recently designated as q1 Eridani, this star was first designated as CP(D)-54 365 (as in ChView data files) by the 1900 publication of the third part of the Cape Photographic Durchmusterung or CPD, based on photographic plates taken by David Gill (1843-1914) at the Royal Observatory on the Cape of Good Hope, South Africa, that were analyzed by Jacobus Cornelius Kapteyn (1851-1922). One of the first major photographic surveys of modern astronomy, the CPD was a continuation of older visual surveys descended from a 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") or BD. A complement to the BD was created with a visual survey of southern stars that was 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") or CD.
Today, many astronomers refer to this star as HD 10647, as designated in the Henry Draper (1837-82) Catalogue with 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. As a relatively bright star in Earth's night sky, HD 10647 is also catalogued as Harvard Revised (HR) 506, a numbering system derived from the 1908 Revised Harvard Photometry catalogue of stars visible to many Humans with the naked eye. The HR system has been preserved through its successor, the Yale Bright Star Catalogue -- revised and expanded through the hard work of E. Dorrit Hoffleit and others. (More discussion on star names and catalogue numbers is available from Alan MacRobert at Sky and Telescope and from Professor James B. Kaler's Star Names.)
HD 10647 is a yellowish main sequence dwarf star of spectral and luminosity type F8-9 V. The star has 1.1 times Sol's mass, a slightly larger diameter, and 1.5 to 1.6 times its luminosity. It appears to be around 83 to 94 percent or more as enriched as Sol with elements heavier than hydrogen ("metallicity"), based on its abundance of iron. Younger than Sol, it may be only around 1.75 billion years old (Donahue, 1993?). Useful catalogue numbers and designations for the star include: q1 Eri, HR 506, Hip 7978, HD 10647, CP(D)-54 365, SAO 232501, and N1 170.
In June 2003, a team of astronomers (including Dominique Naef, Francisco Pepe, Michel Mayor, Nuno C. Santos, Didier Queloz, and Stephane Udry) announced the discovery of a Jupiter-class planet around HR 10647 using radial-velocity methods (Observatoire de Genève page on HD 10647). Planet "b" is now thought to have at least 91 percent of Jupiter's mass. It moves around HD 10647 at an average distance of 2.1 AUs (a semi-major axis beyond the orbital distance of Mars in the Solar System) in a highly eccentric orbit (e= 0.18 +/- 0.08) that takes around 2.9 years to complete. The planet is probably similar to Jupiter in size.
The orbit of an Earth-like planet (with liquid water) around HD 10647 may be centered around 1.3 AU -- between the orbital distances of Earth and Mars -- with an orbital period around 1.4 years. However, the development of an Earth-like planet in this zone could have been disrupted by the eccentric orbit of planet b. Astronomers would find it very difficult to detect an Earth-type planet in the water zone of 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.)
Astronomers are hoping to use NASA's Terrestrial Planet Finder (TPF) and the ESA's Darwin planned groups of observatories to search for a rocky inner planet in the so-called "habitable zone" (HZ) around HD 10647. As currently planned, the TPF will include two complementary observatory groups: a visible-light coronagraph to launch around 2014; and a "formation-flying" infrared interferometer to launch before 2020, while Darwin will launch a flotilla of three mid-infrared telescopes and a fourth communications hub beginning in 2015.
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 HR 10647.
|Star System||Spectra &|
|Chi Eridani AB||G5-8 IV-II |
|L 221-60||M3 V||4.4|
|Hip 5812||M4 V||4.9|
|CD-58 538||M0 Ve||9.1|
|Iota Horologii||G0 Vp||9.|
|L 125-51||M V||9.6|
|* plus bright stars *||. . .|
|Nu Phoenicis||F8 V||11|
|HR 209||G1-5 IV||13|
|Alpha Hydri 2?||F0 V||17|
|K. Tucanae 2?||F6 IV||19|
The late John Whatmough created illustrated web pages on this system in Extrasolar Visions.
Up-to-date technical summaries on this star can be found at: Jean Schneiders's Extrasolar Planets Encyclopaedia; the Astronomiches Rechen-Institut at Heidelberg's ARICNS, and the Nearby Stars Database. Additional information may be available at Roger Wilcox's Internet Stellar Database.
Eridanus, the river, wends its way from the Hunter's foot of Orion then southwest to the southern circumpolar zone to enclose a larger area of sky than any other constellation. For more information on stars and other objects in Constellation Eridanus and an illustration, go to Christine Kronberg's Eridanus. Another illustration is available at David Haworth's Eridanus.
For more information about stars including spectral and luminosity class codes, go to ChView's webpage on The Stars of the Milky Way.
Note: Thanks to Mike Stevens for point out that HD 10647 has also been designated q1 Eridani.
© 2003-2005 Sol Company. All Rights Reserved.