Zeta Tucanae 2?

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NASA

Zeta Tucanae is a yellowish star that is
brighter than our Sun, Sol. (See a
Digitized Sky Survey image of Zeta
Tucanae from the Nearby Stars Database.)

System Summary

Zeta Tucanae is located about 28.0 light-years from Sol. It lies in the central part (00:20:04.26-64:52:29.25,ICRS 2000.0) of Constellation Tucana, the Toucan -- south of the multiple star Beta Tucanae and east of Epsilon Tucanae. As Zeta Tucanae has become one of the top 100 target stars for NASA's planned Terrestrial Planet Finder (TPF), images of this star and its position relative to the Milky Way in Earth's night sky are now available from the TPF-C team.

JPL, CalTech, NASA

Larger illustration

Astronomers have identified Zeta
Tucanae as a prime target for the
Terrestrial Planet Finder (TPF),
now planned for launch between
2014 and 2020.

The Star

Zeta Tucanae is a yellowish main sequence dwarf of spectral and luminosity type F8-G0 V, with about 98 percent of Sol's mass, 1.1 times its diameter, and 1.3 times its luminosity. The star may be only 44 to 79 percent as enriched as Sol with elements heavier than hydrogen ("metallicity"), based on its abundance of iron (Cayrel de Strobel et al, 1991, page 4). Useful star catalogue numbers for the star include: Zet Tuc, HR 77, Gl 17, AC+48 1595, Hip 1599, HD 1581, CP(D)-65 13, SAO 248163, FK5 10, LHS 5, LTT 167, LPM 16, and LFT 36.

Zeta Tucanae B?

Spectroscopic analysis suggests that Zeta Tucanae may have an unseen companion.

Hunt for Substellar Companions

A radial velocity study failed to detect a brown dwarf sized companion (with 20 to 80 times the mass of Jupiter) within 10 AUs of Zeta Tucanae (Murdoch et al, 1993). The orbit of an Earth-like planet (with liquid water) around this star would be centered around 1.14 AU -- somewhat outside the orbital distance of Earth in the Solar System -- with an orbital period of about one and a quarter of an Earth year. Astronomers are hoping to use NASA's Terrestrial Planet Finder (TPF) and the ESA's Darwin planned groups of observatories to search for a rocky inner planet in the so-called "habitable zone" (HZ) around Zeta Tucanae. As currently planned, the TPF will include two complementary observatory groups: a visible-light coronagraph to launch around 2014; and a "formation-flying" infrared interferometer to launch before 2020, while Darwin will launch a flotilla of three mid-infrared telescopes and a fourth communications hub beginning in 2015.

Closest Neighbors

The following star systems are located within 10 light-years of Zeta Tucanae.

Star System	Spectra & Luminosity	Distance (light-years)
CD-68 47	K0 V	3.1
L 49-19	K0 V	6.2
p Eridani3?	K0-2 V K3-5 V ?	6.4
Beta Hydri	G1-2 IV	6.7
L 119-44	M V	7.5
CD-76 1182	M V	7.7
Gamma Pavonis	F6-8 V	9.3

Other Information

Up-to-date technical summaries on these stars can be found at: the Astronomiches Rechen-Institut at Heidelberg's ARICNS, the Nearby Stars Database, and the Research Consortium on Nearby Stars (RECONS). Additional information may be available at Roger Wilcox's Internet Stellar Database.

Tucana is a small constellation located around the South Pole. For more information about the stars and objects in this constellation and an illustration, go to Christine Kronberg's Tucana. For another illustration, see David Haworth's Tucana.

For more information about stars including spectral and luminosity class codes, go to ChView's webpage on The Stars of the Milky Way.