Delta Trianguli 2

Delta Trianguli A

Delta Trianguli A is a yellow-orange main sequence dwarf star of spectral and luminosity type G0.5 Ve. It may have as much as 109 percent of Sol's mass, 98 percent of its diameter (Johnson and Wright, 1983, page 649), and as much as 1.1 times its visual luminosity. The star may be only 13 to 31 percent as enriched as Sol with elements heavier than hydrogen ("metallicity"), based on its abundance of iron (Cayrel de Strobel et al, 1991, page 279). It is known to have a double-lined, spectroscopic stellar companion "B" of lower mass. Useful catalogue numbers and designations for the star include: 8 Tri A, Del Tri A, HR 660*, Gl 92 A, Hip 10644, HD 13974, BD+33 395, SAO 55420, LHS 154, LTT 10770, LFT 198, and ADS 1739 A.

According to the new Sixth Catalog of Visual Orbits of Binary Stars, Stars A and B are separated on average by less than 0.11 AU (a= 0.0098" at a HIPPARCOS distance estimate of 35.4 ly). Their highly circular orbit (e= 0.020) takes only about 10.02 days (0.02743 years) to complete and is inclined around 167° from Earth's perspective (Hummel et al, 1995, pp. 389 to 390). According to calculations available from the Flagstaff Station of the U.S. Naval Observatory, orbit elements derived from possibly more recent MARK III observational data are slightly different: a = 0.00993"; e=0.012; i= 157 +/- 2 degrees; and P= 10.02 days. (See also "Delta Tri" in the Eighth Catalogue of the Orbital Elements of Spectroscopic Binary Systems.)

Delta Trianguli B

© Torben Krogh & Mogens Winther,



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



Star B may be an orange-red
dwarf star, somewhat similar to
Epsilon Eridani at left center of
meteor.

According to Hummel et al (1995, page 390), the companion object may be a star as orange in color as a spectral and luminosity type of K4 V, but error margins in their calculations "prevent any meaningful physical discussion of Delta Trianguli until better interferometric measurements are available." Useful catalogue numbers and designations for the star include: Del Tri B, Gl 92 B, and ADS 1739 B.

The orbit of an Earth-like planet (with liquid water) around close-orbiting Stars A and B may be centered as close as 1.06 AU -- between the orbital distances of Earth and Mars in the Solar System -- with an orbital period of over 384 days (1.05 years). Astronomers would find it very difficult to detect an Earth-type planet in the water zone of this star using present methods. (See an animation of the stellar and potentially habitable zone orbits of this system, with a table of basic orbital and physical characteristics.)