41 Arae 2

41 Arae A

The star is a main sequence, yellow-orange dwarf (G8-K0 V). It has about 58 percent of Sol's diameter and around 42 percent of its luminosity. The star does not appear to be as enriched as Sol in elements heavier than hydrogen ("metals") because it has only 45 percent of Sol's abundance of iron (Cayrel de Strobel et al, 1991, page 301). Thus, 41 Arae A may be a relatively old star. In addition to Star B, 41 Arae A may also have two optical companions. Some useful star catalogue numbers for 41 Arae A are: 41 Ara, HR 6416, Gl 666 A, Hip 84720, HD 156274, CD-46 11370, CP(D)-46 8513, SAO 227816, BSO 13 A, LHS 444, LTT 6886, LPM 636, LFT 1334, and Brs 13.

The new Sixth Catalog of Orbits of Visual Binaries provides two very old estimates of orbital elements for 41 Arae A and its companion. According to Roland Wielen (1962; see Brs 13 on page 603), who used a computer to mathematically iterate (photographic observations in both coordinates and visual observations of the position angle) to "best fit" estimates, AB travel in an extremely eccentric orbit (e= 0.901) that takes 2,200 years to complete, with a semi-major axis of 210 AUs (23.900", using HIPPARCOS parallax of 0.11381 +/- 0.00136") when viewed at an inclination of 44.88° from the perspective of Earth. On the other hand, N. Wieth-Knudsen (Inf. Circ. 13, 1957) found that the orbit of the AB pair took only 693 years to complete, given a semi-major axis of 91.5 AUs (10.415", same parallax), an eccentricity of 0.779, and an inclination of 35.64°. Wieth-Knudsen's estimates were used in Poveda et al (1994, pages 32 to 33). (See an animation of the orbits of Stars A and B and their potentially habitable zones, with a table of basic orbital and physical characteristics.)

41 Arae B

This star is a main sequence, orange-red or red dwarf (K7-M0 Vp), with peculiar metal-weak spectrum for CA I, CA II, and CR triplet (Christopher J. Corbally, S.J., 1984). Some useful star catalogue numbers for 41 Arae B are: Gl 666 B, BSO 13 B, and LHS 445.

NASA -- larger image

41 Arae B is an orange-red or red dwarf star, somewhat brighter
than Gliese 623 A (M2.5V) and B (M5.8Ve) at lower right.

Hunt for Substellar Companions

The distance from 41 Arae A where an Earth-type planet would be "comfortable" with liquid water is centered around only 0.64 AU -- between at about the orbital distances of Mercury and Venus in the Solar System. However, an Earth-type planet around Star B would have to be centered around only 0.15 AU. Astronomers would find it very difficult to detect such planets using present methods.