CD-31 9113 / Gl 433
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Also known as Gl 433, this dim star lies around 29.5 light-years from Sol. It is located in the southwestern part (11:35:26.9-32:32:23.9, ICRS 2000.0) of Constellation Hydra, the Hydra -- west of Xi Hydrae, south of Chi Hydrae and Beta Crateris, southeast of Alpha Ant (Alpha Antliae), and northwest of Iota Antliae. Like other red dwarf stars, however, it is not visible to the naked eye. On October 19, 2009, a team of astronomers using the High Accuracy Radial Velocity Planet Searcher (HARPS) spectrograph with the European Southern Observatory's (ESO) 3.6-meter telescope announced the discovery of a super-Earth with at least 6.0 Earth-masses (0.019 Jupiter-Masses) that completes an orbit around Gl 433 in only seven days (at an ESO/CAUP conference on extra-Solar planets in Porto, Portugal -- ESO press release). [More to come with release of pre-prints: Forveille et al, 2010; and Delfosse et al, 2010.] (See an animation of the planetary and potentially habitable zone orbits of this system, with a table of basic orbital and physical characteristics.)
This star was probably given its first catalogue designation as CD-31 9113 during 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's high proper motion was probably noticed first and designated as Luyten (L) 907-1 by Willem Jacob Luyten (1899-1994). Luyten found the proper motions of over 520,000 stars despite the loss of sight in one eye since 1925 by building an automated photographic plate scanner and measuring machine. Today, however many astronomers refer to this star by its designation as Gliese (Gl) 433 in the first Gliese Catalogue of Nearby Stars (CNS, now ARICNS database) of Wilhelm Gliese (1915-93), who was a longtime astronomer at the Astronomiches Rechen-Institut at Heidelberg (even when it was at Berlin).
Gliese 433 is a cool and dim, main sequence red dwarf of spectral and luminosity type M1.5-2.5 Ve (Zechmeister et al, 2009). The star has almost a half (48 to 49 percent) of Sol's mass (Zechmeister et al, 2009, from Delfosse et al, 2000; and NASA Star and Exoplanet Database, derived from Henry and McCarthy, 1993), 48 to 57 percent of its diameter (NASA Star and Exoplanet Database, derived from Kenneth R. Lang, 1980; and Johnson and Wright, 1983, page 673), and percent of its visual and around 3.3 +/- 0.2 of its bolometric luminosity and McCarthy, 1993), 48 to 57 percent of its diameter (NASA Star and Exoplanet Database, derived from Kenneth R. Lang, 1980). It has magnetic activity and rotates on a -day period (). The star was once suspected of having a spectroscopic companion and later a brown dwarf companion (Bernstein ESA SP402-97). Some other useful star catalogue designations include: Gl 433, Hip 56528, CD-31 9113, SAO 202602, LHS 2429, LFT 825, LTT 4290, LPM 391, L 907-1, U 270, E439-237, 2MASS J11352695-3232232.
On October 19, 2009, a team of astronomers using the High Accuracy Radial Velocity Planet Searcher (HARPS) spectrograph with the European Southern Observatory's (ESO) 3.6-meter telescope announced the discovery of a super-Earth with at least 6.0 Earth-masses (0.019 Jupiter-Masses) that completes an orbit around Gl 433 in only seven days (at an ESO/CAUP conference on extra-Solar planets in Porto, Portugal -- ESO press release). [More to come with release of pre-prints: Forveille et al, 2010; and Delfosse et al, 2010.]
Larger and jumbo illustrations
(more images and videos of Gl 876).
Planet "b" may actually be a "Super-Earth"
that is similar to Gliese 876 d, which may
rocky and have an atmosphere, clouds, and
the glow of molten areas on its surface,
as imagined by Schindler (more).
Based on its bolometric luminosity, a planet may be able to hold water on its surface between 0.18 and 0.35 AUs of Gliese 433 (NASA Star and Exoplanet Database). Based on radial-velocity observations through 2009, no substellar companions were detected around Gl 433's habitable zone down to within a few Earth-masses (Zechmeister et al, 2009). (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 ly of Gliese 433.
|Star System||Spectra &|
|CD-32 8179 AB||K0 V |
|HR 4523 AB||G3-5 V |
|CD-26 8883 AB||K4-5 V |
|L 396-7||M3.5 V||6.7|
|CD-23 9765||M3 V||7.7|
|L 471-42||M4 V||8.6|
|L 399-68||M3.5 V||9.1|
|Ross 695||M4 V||9.2|
|CD-51 5974||K0-M0 V||9.6|
Up-to-date technical summaries on Gliese 433 can be found at: Jean Schneider's Extrasolar Planets Encyclopaedia; Astronomiches Rechen-Institut at Heidelberg's ARICNS, the NASA Star and Exoplanet Database, and the Research Consortium on Nearby Stars (RECONS). Additional information may be available at Roger Wilcox's Internet Stellar Database.
There are two ancient Greek myths involving Constellation Hydra. One involved an enormous water snake with nine heads that was killed by Hercules with the help of the Goddess Athena. Another referred to a water serpent brought by a pet Raven sent by the God Apollo for water, which the hungry Raven falsely claimed to have been attacked when it actually was delayed in waiting for a meal of ripening figs; both were flung into the Heavens by the angry God. For more information on this constellation, go to Christine Kronberg's Hydra. For illustrations, see Richard Dibon-Smith's Hydra and David Halworth's Hydra.
For more information about stars including spectral and luminosity class codes, go to ChView's webpage on The Stars of the Milky Way.
Notes: Thanks to Daniel Gonsalves for informing us of planet b's discovery and providing a link to its discovery paper.
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