CD-44 11909 / Gl 682
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CD-44 11909 is a dim red dwarf star, like Gliese
623 A (M2.5V) and B (M5.8Ve) at lower right.
This star is located about 16.4 +/-0.2 light-years (ly) away from our Sun, Sol. It can be found in the northern part (17:37:3.7-44:19:9.2, ICRS 2000.0) of Constellation Ara, the Altar, -- south of Girtab (Theta Scorpii), north of Alpha Arae, northwest of Theta Arae, and west of Alpha Tel (Alpha Telescopii). Much dimmer and smaller than Sol, it is not visible to the unaided Human eye from Earth's surface. On March 4, 2014, a team of astronomers announced that analysis of new and older radial-velocity data from nearby red dwarf stars revealed two super-Earths "b" and "c" with minimum earth-masses of 4.4 (+3.7/-2.4) and 8.7 (+5.8/-4.7), respectively, at average orbital distances of 0.080 (+0.014/-0.004) and 0.176 (+0.009/-0.030) AU, respectively, from host star Gl 682, with orbital eccentricities of 0.08 (+0.19/-.08) and 0.010 (+0.19/-0.10) and periods around 17.5 and 57.3 days, respectively (UH news release; and Tuomi et al, 2014).
Although the star is now commonly referred by some astronomers as GJ 682 or Gliese (or Gl) 682, it was probably first catalogued as CD-44 11909 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.
|Inner H.Z. Edge?||0.05||8.3||0.0||?||...||...||...||...||...|
|Outer H.Z. Edge?||0.09||20.1||0.0||?||...||...||...||...||...|
CD-44 11909 is a red dwarf star of spectral and luminosity type M3.5-4.5 V. This star has been estimated to have around 21 to 27 percent of Sol's mass (Tuomi et al, 2014; and Bonfils et al, 2013), 27 percent of its diameter (Pasinetti-Fracassini et al, 2001), and about 0.2 percent of its visual luminosity). The star is chromospherically inactive (Walkowicz and Hawley, 2009) and has a projected rotation period of 10.7 days (Reiners, 2007). It appears to have only around 1.29 times Sol's abundance of iron relative to hydrogen (Neves et al, 2013). Useful star catalogue numbers for -44 11909 include: Gl 632, Hip 86214, CD-44 11909, LHS 451, LTT 7000, LFT 1358, LPM 649, and 2MASS J17370367-4419088.
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 red dwarf star as cool and dim as CD-44 11909, even accounting for infrared heating. According to one type of model calculations, the inner edge of CD-44 11909's habitable zone should be located a quite close to the star, at an orbital distance of around 0.05 AU, while the outer edge is a a little farther out at around 0.09 AU (Tuomi et al, 2014), but another study found the HZ to range from 0.07 to 0.19 AU (Bonfils et al, 2013). The average orbital distance of planet "b" from this star is 0.080 AU and so it could have liquid water on its surface, although it moves arount its host star well within the orbital distance of Mercury in the Solar System. At that distance from the star, planet b has an orbital period of about 17.5 days, and it may develop a tidally locked, synchronous orbit around CD-44 11909.
On March 4, 2014, a team of astronomers announced that analysis of new and older radial-velocity data from nearby red dwarf stars revealed two super-Earths "b" and "c." Planet b has around 4.4 (+3.7/-2.4) Earth-masses and an average orbital distance of 0.080 (+0.014/-0.004) AU from host star Gl 682. The high circular orbit has an eccentricity of 0.08 (+0.19/-.08) and a period 17.5 days (UH news release; and Tuomi et al, 2014).
On March 4, 2014, a team of astronomers also revealed the detection of a larger super-Earth "c" with around 8.7 (+5.8/-4.7)Earth-masses at an average distance of 0.176 (+0.009/-0.030) AU from host star Gl 682. The outer planet's orbit has a low eccentricity of 0.010 (+0.19/-0.10) and its period takes 57.3 days to complete (UH news release; and Tuomi et al, 2014).
The following star systems are located within 10 light-years of CD-44 11909.
|Star System||Spectra &|
|CD-46 11540||K5-M3 V||1.8|
|L 205-128||M3.5-5 V||4.7|
|CD-32 13297||M2 V||5.4|
|L 347-14||M4.5 V||5.8|
|36 Ophiuchi 3?||K0-1.5 Ve |
|MLO 4 ABC||K3-4 V |
|CD-40 9712||M0-3 V||7.7|
|Ross 154||M3.5 Ve||8.7|
|BD-12 4523 AB||M3 Ve |
|CD-45 13677||M0 V||9.5|
|Delta Pavonis||G5-8 V-IV||10|
Up-to-date technical summaries on CD-44 11909 can be found at: the Astronomiches Rechen-Institut at Heidelberg's ARICNS, the SIMBAD Astronomical Database, and the Research Consortium on Nearby Stars (RECONS) list of the 100 Nearest Star Systems. Additional information may be available at Roger Wilcox's Internet Stellar Database.
Constellation Ara is a small constellation of the Southern Hemisphere, which was charted by Ptolemy in the Second Century. For Ancient Greeks, the constellatoin was usually identified with the altar upon which the gods swore their allegiance to Zeus before going to battle with the Titans, but it could also represents the altar on which the Arcadian king Lycaon sacrificed his grandson and served him as dish to Zeus, after which the angry god slaughtered Lycaon's 50 sons and turned him into a wolf (Constellation Lupus). Ancient Greek navigators believed that, if the Ara constellation was the only one visible in a cloudy sky, this was a sign of storm at sea. For an illustration, see David Haworth's Ara.
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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