CD-31 9113 / Gl 433

JPL, NASA



Larger image.



The internal composition of planet "b"
is not yet known, as it may rocky or
gaseous like Neptune.

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).

The Star

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.

Planet b

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.]

Trent Schindler, NSF


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.)