CD-23 17699 / Gl 884

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© Torben Krogh & Mogens Winther,

(Amtsgymnasiet and EUC Syd Gallery,
student photo used with permission)

CD-23 17699 is an orange-red
dwarf star, like Epsilon Eridani
at left center of meteor. (See
a Digitized Sky Survey image
of CD-23 17699 from the
Nearby Stars Database.)

System Summary

CD-23 17699 is located about 26.6 light-years (ly) away from our Sun, Sol, in the southwest corner (23:00:16.1-22:31:27.6, ICRS 2000.0) of Constellation Aquarius, the Water Bearer -- southwest of Skat (Delta Aquarii), northwest of Fomalhaut (Alpha Piscis Austrini), north of Epsilon Piscis Austrini, and east of the Helix Nebula. The star is not visible to most Humans without a telescope.

Its designation as CD-23 17699 came from 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.

The Star

CD-23 17699 is a orange-red dwarf star of uncertain spectral type K5 to M0 (NStars), but there seems to be agreement that it is a main-sequence dwarf of luminosity type of V. The star's spectral type has been classed as red as M1 (Mount Wilson Observatory). It may have around 63 percent of Sol's mass, 67 percent of its diameter (Johnson and Wright, 1983, page 703), and 4.0 percent of its luminosity. Useful star catalogue numbers for CD-23 17699 include: M1-Wil, Gl 884, Hip 113576, HD 217357, CP(D)-23 8259, SAO 191563, LHS 3885, LTT 9308, LFT 1754, LPM 846, and Vys/McC 339.

Hunt for Substellar Companions

The distance from CD-23 17699 where an Earth-type planet would be "comfortable" with liquid water is centered around only 0.202 AU -- within the orbital distance of Mercury in the Solar System. An Earth-type in such a water-zone orbit would probably would have a period of around 42 days. At such a close distance to CD-23 17699, astronomers would have great difficulty in detecting such a planet using present methods.

Closest Neighbors

The following star systems are located within 10 light-years of CD-23 17699.

Star System	Spectra & Luminosity	Distance (light-years)
FK Aquarii AabB	M0-2 Ve ? M4 Ve	3.0
Fomalhaut	A3 V	3.5
TW Piscis Australis	K4-5 Vpe	4.4
L 788-34	M4.5 V	5.5
LP 823-4	M V	6.6
LP 701-29	DZ9 /VII	7.2
LHS 1070	M5.5 V	9.0

Other Information

Up-to-date technical summaries on these stars can be found at: 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.