BD-05 5715 / Gl 849
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NASA -- larger image
BD-05 5715 is a dim red dwarf star, like Gliese
623 A (M2.5V) and B (M5.8Ve) at lower right.
(See a Digitized Sky Survey field image of
BD-05 5715 from the Nearby Stars Database.)
This star is located about 28.6 light-years (ly) away from our Sun, Sol, in the north central part (22:9:40.3-4:38:26.6, ICRS 2000.0) of Constellation Aquarius, the Water Bearer. Much dimmer and smaller than Sol, it is not visible to the unaided Human eye from Earth's surface. Between October 6 and 26, 2006, a team of astronomers submitted a paper on the discovery of a Jupiter-class planet in a 5.2-year orbit around this dim star, with indications of a second planetary companion (Butler et al, 2006 -- more below). (See an animation of the planetary and potentially habitable zone orbits of this system, with a table of basic orbital and physical characteristics.)
Although the star is now commonly referred by some astronomers as GJ 849 or Gliese (or Gl) 849, it was probably first designated as BD-05 5715, in a catalogue that was originally published in 1863 by Friedrich Wilhelm August Argelander (1799-1875) on the position and brightness of 324,198 stars between +90° and -2° declination that were measured over 11 years from Bonn, Germany with his assistants Eduard Schönfeld (1828-1891) and Aldalbert Krüger (1832-1896). The catalogue became famous as the Bonner Durchmusterung ("Bonn Survey") and is typically abbreviated as BD. It was later expanded and extended during the early 20th Century with the Cordoba (observed from Argentina) then the Cape Photographic Durchmusterung (observed from South Africa).
Due to BD-05 5715's relative proximity to Sol and the discovery of a planetary companion, the system has been suggested for selection as a target star for NASA's optical Space Interferometry Mission (SIM). The mission will attempt to detect planets as small as three Earth-masses within two AUs of each star.
BD-05 5715 is a red dwarf star of spectral and luminosity type M3.5 V. This star has been estimated to have around 49 +/- 5 percent of Sol's mass (Butler et al, 2006; Delfosse et al, 2000; and Henry and McCarthy, 1993), 45 percent of its diameter (Pasinetti-Fracassini et al, 2001; and Johnson and Wright, 1983), and about 0.43 percent of its visual luminosity. It may be more enriched than Sol, with 1.4 +0.8/-0.5 times Sol's abundance of iron relative to hydrogen (Butler et al, 2006; Bonfils et al, 2005a; and Sandy K. Leggett, 1992). The star's low chromospheric activity and slow rotation are consistent with a middle–age dwarf that is older than three billions (Butler et al, 2006; and Andrew West, private communication with Bulter et al). Useful star catalogue numbers for BD-05 5715 include: Gl 849, Hip 109388, G 27-16, LHS 517, LTT 8889, LFT 1689, LPM 814, Vys/MCC 73, and Wolf 1329.
Between October 6 and 26, 2006, a team of astronomers submitted a paper on the discovery of a Jupiter-class planet in a 5.2-year orbit around this dim star, with indications of a second planetary companion (Butler et al, 2006 -- more below). The planetary companion has at least 82 percent of Jupiter's mass. Moving around BD-05 5715 at an average distance (semi-major axis) of 2.35 AUs, planet b's highly circular orbit (e= 0.06 +/- 0.09) takes 5.16 +/- 0.36 years to complete.
In order to be warmed sufficiently have liquid water at the surface, an Earth-type rocky planet would have to be located very close to such a cool and dim red dwarf star like BD-05 5715, at around 0.066 AU) -- not accounting for infrared heating. At such a close distance, such a planet can easily become tidally locked -- with one side in perpetual day -- and race around the star in less than 8.8 days. (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 star systems are located within 10 light-years of BD-05 5715.
|Star System||Spectra &|
|Wolf 1561 Ab||M4.5 Ve |
|LP 701-29||DZ9 / VII||5.6|
|Wolf 922 AB||M4.5 Ve |
|BD+00 4810||K8-M0.5 V||6.1|
|L 788-34||M4.5 V||7.0|
|GJ 1265||M V||8.2|
|LP 760-3||M6.5 V||8.4|
|FK Aquarii AabB||M0-2-Ve |
Up-to-date technical summaries on these stars can be found at: Jean Schneider'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.
Aquarius was "Latinized" by the Romans from Ganymede in Greek mythology, who was "cup-bearer to the gods." For more information on stars and other objects in Constellation Aquarius and an illustration, go to Christine Kronberg's Aquarius. For another illustration, see David Haworth's Aquarius.
For more information about stars including spectral and luminosity class codes, go to ChView's webpage on The Stars of the Milky Way.
Note: Special thanks to Daniel Gonsalves for informing us of planet b's discovery and providing a link to its discovery paper.
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