Edasich, Iota Draconis

Star 12 Iota Draconis (HR 5744, HD 137759, HIP 75458), in Draco


Right Ascension 15 : 24 : 55.8 (h:m:s)
Declination +58 : 57 : 58 (deg:m:s)
Distance 102.7 (ly)
Visual brightness 3.31 (mag)
Spectral type K2 III

Edasich (12 Iota Draconis) is an orange giant of spectral type K2 III in the constellation Draco. Its mass is little more than that of our sun (1.05 solar masses); therefore, it is probably quite similar to what our sun will look like in its "red giant" phase, in a couple of billion years. At its distant of 102.7 ly, its apparent brightness of 3.31 mag corresponds to a luminosity of 70 times that of our sun. Its diameter is about 11 to 13 times that of our sun, and its surface temperature is about 4490 K. It contains slightly more heavier elements than H and He; it "metallicity index" was determined at [Fe/H]=+0.03. It is approaching us at about 11 km/sec.

The name "Edasich" comes from Arabic and originally means Male Hyaena. A pale yellow star of ninth magnitude is only about 4' distant, but appears to be a physically unrelated background star.

On January 8, 2002, a team of astronomers from the University of California at San Diego announced the discovery of a "substellar companion" to Edasich, i.e., a planet or brown dwarf in orbit around that star. This was the first planet found in orbit around a giant star. The planet is orbiting the star in a highly-excentric orbit of semi-major axis of about 1.3 AU (195 million km), orbital period about 590 days (1.47 Earth years), and excentricity 0.71, which takes it from about 2.1 AU (315 million km) at its apastron to a mere 0.4 AU (60 million km) at its periastron. This companion makes it impossible that "inner planets" like Earth can orbit Edasich. As the orbital inclination is unknown, only a minimum for the mass of the companion can be estimated; it is more than 8.9 times the mass of Jupiter. Thus, it is unknown if the companion is a planet or a brown dwarf.

  • James Kaler's Edasich (and planet) info (Star of the Week)
  • Jean Schneider's Iota Draconis and planet data
  • Planet Around Iota Draconis = HIP 75458 (exoplanets.org)


    [Constellations] | [SEDS] | [MAA]

    Hartmut Frommert